Skeptic Papers 2017 (1)

Part 1. Natural Mechanisms Of Weather, Climate Change  

Solar Influence On Climate (121)
ENSO, NAO, AMO, PDO Climate Influence (44)
Modern Climate In Phase With Natural Variability (13)
Cloud/Aerosol Climate Influence (9)
Volcanic/Tectonic Climate Influence (6)
The CO2 Greenhouse Effect – Climate Driver? (15)

Part 2. Unsettled Science, Failed Climate Modeling

Climate Model Unreliability/Biases/Errors and the Pause (28)
Failing Renewable Energy, Climate Policies (12)
Wind Power Harming The Environment, Biosphere (8)
Elevated CO2 Greens Planet, Produces Higher Crop Yields (14)
Warming Beneficial, Does Not Harm Humans, Wildlife (7)
Warming, Acidification Not Harming Oceanic Biosphere (18)
Decreases In Extreme, Unstable Weather With Warming (3)
Urban Heat Island: Raising Surface Temperatures Artificially (5)
No Increasing Trends In Intense Hurricanes (4)
No Increasing Trends In Drought/Flood Frequency, Severity (3)
Natural CO2, Methane Sources Out-Emit Human Source (4)
Increasing Snow Cover Since The 1950s (3)
Miscellaneous (7)

Scientists: We Don’t Know (3)

Part 3 here

Part 1. Natural Mechanisms Of Weather, Climate Change

Solar Influence On Climate (121)

 Yan et al., 2017     Morpho- and hydrodynamic variations seem to coincide with northern hemispheric solar forcing.  The Medieval Warm Period (MWP) until about 1270 CE displays generally moist and warm climate conditions with minor fluctuations [stability], likely in response to variations in summer monsoon intensity. The three-partite period of the Little Ice Age (LIA), shows hydrologically unstable conditions between 1350 and 1530 CE with remarkably colder periods, assigned to a prolonged seasonal ice cover. … Seasonal freezing periods in excess of the average time of frozen water bodies also occurred in periods of the well-known grand solar minima and indicate stronger seasonality, possibly independent from variations in summer monsoon strength but with links to global northern hemispheric climate.
Li et al., 2017     We suggest that solar activity may play a key role in driving the climatic fluctuations in NC [North China] during the last 22 centuries, with its quasi ∼100, 50, 23, or 22-year periodicity clearly identified in our climatic reconstructions. … It has been widely suggested from both climate modeling and observation data that solar activity plays a key role in driving late Holocene climatic fluctuations by triggering global temperature variability and atmospheric dynamical circulation  … In short, the mechanism of the climatic variations in NC can be likely summarized as follows. The strengthened solar activity could be significantly amplified by the variations in ultraviolet radiation as well as clouds (e.g., Haigh, 1996; Tinsley, 2000), resulting in the marked variability in global surface temperature. … Additionally, increased El Nino-Southern Oscillation (ENSO) strength (possibly El Niño-like phases) during drying periods, increased volcanic eruptions and the resulting aerosol load during cooling periods, as well as high volumes of greenhouse gases such as CO2 and CH4 during the recent warming periods, may also play a role in partly affecting the climatic variability in NC, superimposing on the overall solar-dominated long-term control (e.g., Wanner et al., 2008; Tan et al., 2011; Kobashi et al., 2013; Chen et al., 2015a,b).

Yndestad and Solheim, 2017     Deterministic models based on the stationary periods confirm the results through a close relation to known long solar minima since 1000 A.D. and suggest a modern maximum period from 1940 to 2015. The model computes a new Dalton-type sunspot minimum from approximately 2025 to 2050 and a new Dalton-type period TSI minimum from approximately 2040 to 2065. … Periods with few sunspots are associated with low solar activity and cold climate periods. Periods with many sunspots are associated with high solar activity and warm climate periods. … Studies that employ cosmogenic isotope data and sunspot data indicate that we are currently leaving a grand activity maximum, which began in approximately 1940 and is now declining (Usoskin et al., 2003; Solanki et al., 2004; Abreu et al., 2008). Because grand maxima  and minima occur on centennial or millennial timescales, they can only be investigated using proxy data, i.e., solar activity reconstructed from 10Be and 14C time-calibrated data. The conclusion is that the activity level of the Modern Maximum (1940–2000) is a relatively rare event, with the previous similarly high levels of solar activity observed 4 and 8 millennia ago (Usoskin et al., 2003). Nineteen grand maxima have been identified by Usoskin et al. (2007) in an 11,000-yr series. … Twenty-seven grand minima are identified with a total duration of 1900 years, or approximately 17% of the time during the past 11,500 years (Usoskin et al., 2007). An adjustment-free reconstruction of the solar activity over the last three millennia confirms four grand minima since the year 1000: Maunder (1640–1720), Spörer (1390–1550), Wolf (1270–1340) and Oort (1010–1070) (Usoskin et al., 2007). … A cold period was also observed during the time of the Dalton minimum. The Maunder and the Dalton minima are associated with less solar activity and colder climate periods. In this investigation, minimum solar activity periods may serve as a reference for the identified minimum irradiations in the TSI oscillations.

Smith, 2017     Yearly mean temperatures in the CET [Central England Temperature] record show an increase in temperature of approximately 1.3°C degrees from the end of the 17th Century to the end of the 20th Century/beginning of 21st Century.  …  Subtle difference in timing between the warming/cooling phases between the Central England record and the other localities may reflect local climate variation, but the similarity in events between continents suggests the CET [Central England Temperature] record is recording global temperature patterns.  Records of sunspot numbers began in 1610 such that detailed estimates of solar variation for the years covered by the CET record can be made without resort to the use of proxy data. Reconstructions of TSI [e.g. 16-18] differ in magnitude (Table 1), but there is agreement in form with 4 peaks and 4 to 6 troughs occurring over the time-scale of the CET record (Fig. 4). These are: a minimum in TSI associated with the Maunder Sunspot Minimum in the latter half of the 17th Century; a peak, possibly bi-modal approaching modern TSI values during the 18th Century; a well-defined trough corresponding with the Dalton Sunspot Minimum between 1800- 1820; a poorly defined TSI peak in the mid 19th Century; a reduction in TSI during the late 19th Century; increasing TSI during the early 20th Century; a decrease in TSI from around 1950- 1975; and a second phase of TSI increase in the late 20th Century. There is good correspondence with TSI throughout the CET record, with warm events correlating with high TSI and cool phases correlating with plateaus or decreases in TSI (Fig. 4). … However, for temperature increases from the beginning of the Industrial Revolution (Maunder Minimum and Dalton Minimum to end of 20th Century), high TSI models can account for only 63-67% of the temperature increase. This would suggest that one third of Global Warming/Climate Change can be attributed to AGW. … Approximately two-thirds [0.8°C to 0.9°C] of climate warming since the mid-late 18th Century [1.3°C] can be attributed to solar causes, suggesting warming due to anthropogenic causes over the last two centuries is 0.4 to 0.5°C.

Nan et al., 2017     The SST variation shows a millennial period of ~ 1500-yr and centennial periods of 131-yr and 113-yr. The ~ 1.5 kyr cycle dominated the period of 8.9–5.5 cal. kyr BP, suggesting a tele-connection between the Yellow Sea SST and global climate changes, might through the Kuroshio current. Centennial periods dominated almost all of cold periods recorded in core BY14, implying the signature of solar irradiance cycles by means of the strengthened East Asia Winter Monsoon (EAWM).
Nurtaev and Nurtaev, 2017     A reconstruction of total solar irradiance since 1610 to the present estimated by various authors an increase in the total solar irradiance since the Maunder Minimum of about 1.3 W/m² [2]. This is a huge amount of energy, taking into account the Earth’s total land mass. … More sunspots deliver more energy to the atmosphere, by way of increased brightness of the Sun and solar wind what tend to warm the Earth. Solar activity affects the Earth in many ways, some which we are still coming to understand. In accordance with National Geophysical Data Center (NGDC) forecasting the solar cycles 24 and 25 will be very weak: averaged sunspot numbers W-35 for the solar cycle 24 and for the solar cycle 25 less than W-35 , NGDC (2009). Total Solar Irradiance will equal -1365 [during solar cycle 25]. (23 cycle -1366). This actually will lead to a decrease of the temperature on 0.5 – 0.7°C in both averaged solar cycles, in Geneva will decrease to 1.5 °C. Temperature of air will be lower in the Northern Hemisphere. Precipitation rate in Caucasus will be more in average on 100-150 mm in dependence from location. The World Ocean level also will be lower, due to more snow and glacier accumulation on continents.

Kawakubo et al., 2017     Annual mean SSTs show interdecadal variations, notably cold intervals between 1670-1700 during the Maunder Minimum (MM) and between 1766-1788 characterized by a negative phase of the North Atlantic Oscillation (NAO). Cold summers in 1783 and 1784 coincide with the long-lasting Laki eruption that had a profound impact on the northern hemisphere climate, including the severe ‘Tenmei’ famine in Japan. The decades between 1855-1900 are significantly cooler than the first half of the 20th century, while those between 1700-1765, following the MM, are warmer than average. … Although the impact of the solar cycle on the global climate is small (Schurer et al., 2014), an amplified regional response to the variability in ultraviolet solar irradiance through atmospheric teleconnections is now widely accepted (e.g. Meehl et al., 2009). … Spring-summer climate south of Japan is mainly controlled by solar radiation and surface heat fluxes, with lesser ocean current influence on SST, with a few exceptions as mentioned above for the summers of 1998 and 2001. … The cold period between 1660-1700 in the coral record aligns with the minimum total solar irradiance that defines the Maunder Minimum (MM) ca. 1645-1715 (Steinhilber et al., 2009).

Sun et al., 2017     The contrast analysis between the periodic movement of the planetary system and the periodicity of solar activity shows that the two phenomena exhibit a period change rule of 179.5 years. Moreover, orderly orbits correspond to high periods of solar activity and disorderly orbits correspond to low periods of solar activity. … Therefore, a certain relationship exists between the movement of the planetary system, solar activity, and global climate change. The movement of the planetary system can thus be used to interpret the periodic trends of the movement of the Sun and global climate change. … A period change rule of a 179.5-year cycle is observed. This period change rule is consistent with the change that takes place once every 2 centuries (about 160 to 210 years) for solar activity and global climate change The Sun is headed into a grand minimum, that is, a period of unusually low solar activity. A relatively low number of or nonexistent sunspots are observed during the protracted solar minimum. Since 1000 AD, there have been six protracted solar minimums, namely, the Oort minimum (1040–1080 AD), Medieval Minor minimum (1150 1200 AD), Wolf minimum (1270–1350 AD), Spörer minimum (1430–1520 AD), Maunder minimum (1620–1710 AD), and Dalton minimum (1787–1843 AD).  [A]ll the orbits of the planetary system are in disorder during the six protracted solar minimums. The planet juncture index and heliocentric longitude are also in disorder during the six protracted solar minimums.  The numerical simulation results show a high number of sunspots and strong solar activity during the orderly orbit and a low number of sunspots, low solar activity, and the occurrence of a protracted solar minimum or little ice age during the disorderly orbit. …  [T]he results indicate that the solar minimum and little ice ages correspond to the planetary system’s disorderly orbit.
Carlson , 2017     The Holocene includes six warm periods (including the current one) and five cool periods, some of which have been named. Named warm periods include Holocene Climate Optimum, first portion, 6200 to 7700 years before present (BP); Holocene Climate Optimum, second portion, 3500 to 4700 BP; Roman Climate-Optimum, 300 BC to 400 anno domini (AD); and Medieval Warm Period, 700 to 1300 AD. Named cool periods include Dark Age, 400 to 700 AD; and Little Ice Age, 1300 to 1850 AD. Another unnamed period is a cool period that was between 750 and 300 BC. The question to consider is how similar is each of the periods to the current Modern Warm Period in terms of temperature and concentrations of greenhouse gas and other measured properties as recorded in either ice cores, cave formations, or fossils. … It appears that the current warm period has statistically significant higher concentrations of greenhouse gases than earlier warm periods. However, the temperature data appear to be more equivocal. Overall, it appears that solar irradiance has had more of an effect on temperature than greenhouse gases.
Oliveira et al., 2017     [T]he millennial-scale vegetation changes in SW Iberia under warm interglacial climate conditions might be essentially generated by hydrological changes primarily induced by insolation [solar variability], as they are reproduced in the simulations despite the absence of ice sheet dynamics and all associated feedbacks in our experiments. … The transient simulations under the combined effect of insolation and CO2 indicate that the interglacial vegetation and climate dynamics over SW Iberia have no apparent relationship to atmospheric CO2 concentration, as suggested by the pollen-based reconstructions (Fig. 8a, b). Although the direct impact of CO2 changes on the vegetation growth is not included in the model, a prominent example for this negligible CO2 forcing is given by its relatively high concentrations over the end of the interglacials, in particular for MIS 1 and MIS 11c, while the forest cover, annual temperature and annual precipitation achieved minimum values (Fig. 8a, b). We find that the vegetation and climate changes at this time scale are mainly driven by astronomical forcing, in particular precession [solar variability], in agreement with the strong impact of precession on the climate of the Mediterranean region south of 40°N

Lüning et al., 2017     The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000-1200 AD. Here we present a palaeotemperature synthesis for the MCA in Africa and Arabia, based on 44 published localities. … Offshore cores from outside upwelling systems mostly show warm MCA conditions. The most likely key drivers of the observed medieval climate change are solar forcing and ocean cycles. Conspicuous cold spikes during the earliest and latest MCA may help to discriminate between solar (Oort Minimum) and ocean cycle (Atlantic Multidecadal Oscillation, AMO) influence.
Mörner, 2017     There is a total absence of data supporting the notion of a present sea level rise; on the contrary all available facts indicate present sea level stability. On the centennial timescale, there was a +70 cm high level in the 16th and 17th centuries, a -50 cm low in the 18th century and a stability (with some oscillations) in the 19th, 20th and early 21st centuries. This is almost identical to the sea level change documented in the Maldives, Bangladesh and Goa (India). … The Intergovernmental Panel on Climate Change has claimed that sea level is rising and that an additional acceleration is soon to be expected as a function of global warming. This proposition only works if the present warming would be a function of increased CO2 content in the atmosphere (a hypothesis termed AGW from Anthropogenic Global Warming). On a longer-term basis, it seems quite clear, however, that the dominant factor of global changes in temperature is changes in solar variability.
Ollila, 2017     In this paper, the author describes a semi empirical climate model (SECM) including the major forces which have impacts on the global warming namely Greenhouse Gases (GHG), the Total Solar Irradiance (TSI), the Astronomical Harmonic Resonances (AHR), and the Volcanic Eruptions (VE). The effects of GHGs have been calculated based on the spectral analysis methods. The GHG effects cannot alone explain the temperature changes starting from the Little Ice Age (LIA). The known TSI variations have a major role in explaining the warming before 1880. There are two warming periods since 1930 and the cycling AHR effects can explain these periods of 60 year intervals. The warming mechanisms of TSI and AHR include the cloudiness changes and these quantitative effects are based on empirical temperature changes. The AHR effects depend on the TSI, because their impact mechanisms are proposed to happen through cloudiness changes and TSI amplification mechanism happen in the same way. Two major volcanic eruptions, which can be detected in the global temperature data, are included. The author has reconstructed the global temperature data from 1630 to 2015 utilizing the published temperature estimates for the period 1600 – 1880, and for the period 1880 – 2015 he has used the two measurement based data sets of the 1970s together with two present data sets. The SECM [semi empirical climate model] explains the temperature changes from 1630 to 2015 with the standard error of 0.09°C, and the coefficient of determination r 2 being 0.90. The temperature increase according to SCEM [semi empirical climate model] from 1880 to 2015 is 0.76°C distributed between the Sun 0.35°C, the GHGs 0.28°C (CO2 0.22°C), and the AHR 0.13°C. [CO2 accounts for less than 1/3rd of 1880-2015 warming.] The AHR effects can explain the temperature pause of the 2000s. The scenarios of four different TSI trends from 2015 to 2100 show that the temperature decreases even if the TSI would remain at the present level. … The TSI variation is the major driving force of the temperature increase having the contribution of 71-73% during 19th and 20th centuries. Lean et al. (1995) have carried out the correlation analysis between the NH surface temperature and the reconstructed solar irradiation and they found that a solar induced warming was 0.51°C from the LIA in the 1990’s and the correlation was 0.86.
Kong et al., 2017     The general SST [sea surface temperatures] variation pattern matches well with total solar irradiance (TSI) changes. Relatively warm period between 800 and 1400 AD and cool period 1400-1850 AD could be identified, in agreement with the commonly defined periods of Medieval Warm Period and Little Ice Age. Within chronological uncertainty, notable short cooling events at 640-670 AD, 1030-1080 AD, 1260-1280 AD and 1420-1450 AD, coincide with large volcanic eruption events. The general coincidence of SST changes with TSI and volcanic eruption events suggests strong impact of external forcing on sea surface conditions in the studied area.
Dong et al., 2017    Our composite record shows that solar forcing dominated hydroclimatic changes regionally, including an intensified monsoon at the Holocene Optimum from the termination of Younger Dryas to 6.5 ka BP, and a subsequent multi-millennial weakening monsoon, that agrees with cave records in central and southern China.
Deng et al., 2017     The results indicate that the climate of the Medieval Climate Anomaly (MCA, AD 900–1300) was similar to that of the Current Warm Period (CWP, AD 1850–present), which contradicts previous studies. … As for the Little Ice Age (LIA, AD 1550–1850), the results from this study, together with previous data from the Makassar Strait, indicate a cold and wet period compared with the CWP and the MCA in the western Pacific. The cold LIA period agrees with the timing of the Maunder sunspot minimum and is therefore associated with low solar activity.

Koutsodendris et al., 2017     Th record represents the southernmost annually laminated (i.e., varved) archive from the Balkan Peninsula spanning the Little Ice Age, allowing insights into critical time intervals of climate instability such as during the Maunder and Dalton solar minima. … [W]et conditions in winter prevailed during 1740–1790 AD, whereas dry winters marked the periods 1790–1830 AD (Dalton Minimum) and 1830–1930 AD, the latter being sporadically interrupted by wet winters. This variability in precipitation can be explained by shifts in the large-scale atmospheric circulation patterns over the European continent that affected the Balkan Peninsula (e.g., North Atlantic Oscillation). … Representing one of the strongest global climate instabilities during the Holocene, the Little Ice Age (LIA) is marked by a multicentennial-long cooling (14the19th centuries AD) that preceded the recent ‘global warming’ of the 20th century. The cooling has been predominantly attributed to reduced solar activity and was particularly pronounced during the 1645-1715 AD and 1790-1830 AD solar minima, which are known as Maunder and Dalton Minima, respectively.

Tejedor et al., 2017     Reconstructed long-term temperature variations match reasonably well with solar irradiance changes since warm and cold phases correspond with high and low solar activity, respectively. … The main driver of the large-scale character of the warm and cold episodes may be changes in the solar activity. The beginning of the reconstruction starts with the end of the Spörer minimum. The Maunder minimum, from 1645 to 1715 (Luterbacher et al., 2001) seems to be consistent with a cold period from 1645 to 1706. In addition, the Dalton minimum from 1796 to 1830 is detected for the period 1810 to 1838. However, a considerably cold period from 1778 to 1798 is not in agreement with a decrease in the solar activity. Four warm periods – 1626–1637, 1800–1809, 1845– 1859, and 1986–2012 – have been identified to correspond to increased solar activity.

Zawiska et al., 2017    The chironomid-based temperature reconstruction from Lake Atnsjøen in Eastern Norway with mean resolution of 30 years provided evidence that large-scale processes, such as the NAO fluctuations and solar activity modified local climate, and subsequently affected lakes functioning. The three minor cooling periods were reconstructed in the first half of the Millennium: 1050–1150, 1270–1370, 1440–1470 CE, that coincide with solar activity minima: Oort, Wulf, and Spörer respectively. Furthermore, a two peaked cooling period in the second half of the Millennium was identified that coincided with the LIA. These changes co-occurred with the prevailing negative NAO index. … The beginning of the 1270–1370 CE cooling coincide with Wulf solar activity minimum suggesting that the climate was responding to Sun activity. The climate cooling synchronous to this solar minimum had almost global range and it has been recorded from Europe, Arctic, North America and Antarctica (Osborn and Briffa, 2006; PAGES 2k Consortium, 2013) but again not in Greenland (Osborn and Briffa, 2006). … The beginning of the 1440–1470 CE cold period is synchronous to the pronounce negative NAO phase (Trouet et al., 2009). … Maunder solar minimum caused a very deep negative NAO index phase (Shindell et al., 2001), which consecutively lead to significant drop in the reconstructed temperature. …  The temperature reconstruction from Lake Atnsjøen indicates that recent and ongoing climate warming began already in 1800 CE following the LIA. Temperatures increased very fast, from 8.5 to 12.8 °C during the first 75 years [1800-1875], but in the 20th century the increase became less pronounced. … The warming at the beginning of 19th century in the region of Lake Atnsjøen coincides with a reconstruction from Southern Finland (Luoto, 2013), and a record from Northern Sweden (Osborn and Briffa, 2006).  Its onset correlates with the positive NAO index and increased solar activity.

Rydval et al., 2017     [T]he recent summer-time warming in Scotland is likely not unique when compared to multi-decadal warm periods observed in the 1300s, 1500s, and 1730sAll six [Northern Hemisphere] records show a warmer interval in the period leading up to the 1950s, although it is less distinct in the CEU reconstruction. [E]xtreme cold (and warm) years observed in NCAIRN appear more related to internal forcing of the summer North Atlantic Oscillation. … There is reasonable agreement in general between the records regarding protracted cold periods which occur during the LIA and specifically around the Maunder solar minimum centred on the second half of the seventeenth century and to some extent also around the latter part of the fifteenth century coinciding with part of the Spörer minimum (Usoskin et al. 2007).

Abrantes et al., 2017     Reconstructed cold conditions in Iberia, with an average 0.5 ºC colder SST in the northern sites and 1.2ºC in the southern sites, characterize most of the 15th to 18th centuries. The transition from warm to colder climatic conditions occurs around 1300 CE associated with the Wolf solar minimum. The coldest SSTs are detected between 1350 and 1850 CE, on Iberia during the well-known Little Ice Age (LIA) (Bradley and Jones, 1993), with the most intense cooling episodes related with other solar minima events, and major volcanic forcing and separated by intervals of relative warmth (e.g. (Crowley and Unterman, 2013; Solanki et al., 2004; Steinhilber et al., 2012; Turner et al., 2016; Usoskin et al., 2011). During the 20th century, the southern records show unusually large decadal scale SST oscillations in the context of the last 2 millennia, in particular after the mid 1970’s, within the Great Solar Maximum (1940 – 2000 (Usoskin et al., 2011)) and the “greater salinity anomaly” event in the northern Atlantic (Dickson et al., 1988), or yet the higher global temperatures of the last 1.4 ky detected by (Ahmed et al., 2013).

Cui e thal, 2017     According to Chinese history, the Ming dynasty (1368-1644) was subjected to intensive environmental and economic crises that accompanied the unfavorable climate of the Little Ice Age (LIA).  This situation likely led to the collapse of the Ming dynasty. … During this period, central China experienced frequent periods of increased desertification and decreased biological productivity, which limited the expansion of the Ming domain northward and the dynasty’s control over western China.  [G]enerally weak monsoons [occurred] from the 14th to the 19th centuries punctuated by four severe droughts during 1476-1502, 1509-1537, 1577-1590 and 1604-1653.  These drought events are evident in all three time series, indicating that the climatic trends were regional rather than local. These dry periods are correlated with reduced summer insolation [solar minima] in the Northern Hemisphere, a southward displacement of the Intertropical Convergence Zone (ITCZ) and a weak EASM [East Asian Summer Monsoon].
Williams et al., 2017     Reconstructed SSTs significantly warmed 1.1 ± 0.30°C … from 1660s to 1800 (rate of change: 0.008 ± 0.002°C/year), followed by a significant cooling of 0.8 ± 0.04°C …  until 1840 (rate of change: 0.02 ± 0.001°C/year), then a significant warming of 0.8 ± 0.16°C from 1860 until the end of reconstruction in 2007 (rate of change: 0.005 ± 0.001°C/year).” [Sea surface temperatures warmed faster from 1660s-1800 than they did from 1860-2007.] … In fact, the SST reconstruction significantly co-varied with a reconstruction of solar irradiance [Lean, 2000] on the 11-year periodicity only from ~1745 to 1825. In addition, the reconstructed SSTs were cool during the period of lower than usual solar irradiance called the Maunder minimum (1645–1715) but then warmed and cooled during the Dalton minimum (1795–1830), a second period of reduced solar irradiance. … The Dalton solar minimum and increased volcanic activity in the early 1800s could explain the decreasing SSTs from 1800 to 1850 …  [T]hese data suggest a complex combination of solar irradiance, volcanic activity, internal ocean dynamics and external anthropogenic forcing explain the variability in Aleutian SSTs for the past 342 years.

Didkovsky et al., 2017     Radiative forcing of the Earth’s atmosphere plays a significant role in its thermal and chemical balance (Haigh, 1994; Haigh et al., 2010). Effects of heating and cooling are influenced by long-term solar-cycle changes. One example of such change compiled from sources that show sensitivity to the changes of solar activity (Hoyt and Schatten, 1998) is the Maunder Minimum of 1645 to about 1715 (Maunder, 1890). These observations demonstrate the effects of solar-activity changes during the Maunder Minimum for which low to near-zero sunspot numbers persisted for about six solar cycles (SC) with a SC-averaged period (for SC 1 to 22) of 11 years (Hathaway, 2010).
Nan et al., 2017     Furthermore, our temperature records, within age uncertainty, coincides with the changes of the solar irradiance changes, suggesting a possible link between solar forcing and climate variability. … The relationship between the solar irradiance and climate change has been demonstrated by lots of studies (He et al., 2013; Kroonenberg et al., 2007; Sagawa et al., 2014; Soon et al., 2014). It was suggested that the solar activity was a primary driving force of climatic variations in the Holocene (Bond et al., 2001; Wang et al., 2005). Small solar perturbations can be magnified by different feedback mechanisms and may ultimately lead to climatic oscillations on several time scales, such as annual to decadal and/or centennial scales, as well as millennial scales (Haigh, 1996; Bond et al., 2001).
Pandey and Dubey, 2017     The Maunder minimum (1645-1715) refers to a period when very few sunspots were observed. During this period, the Earth climate was cooler than normal. This period mimics the solar cycle climate change connections. The particles and electromagnetic radiations flowing from solar activity outbursts are important for long-term climate variations. There is an abrupt and drastic cooling in the climate can be possible in near future due to large scale melting of global ice by global warming, and prolonged sunspot minima. There is a close correlation between variations in the 11-year sunspot cycle and Earth’s climate. Solar activity varies on shorter-time scales, including the 11- year sunspot cycle and longer-term as Milankovitch cycle.
Park, 2017     Late Holocene climate change in coastal East Asia was likely driven by ENSO variation.   Our tree pollen index of warmness (TPIW) shows important late Holocene cold events associated with low sunspot periods such as Oort, Wolf, Spörer, and Maunder Minimum. Comparisons among standard Z-scores of filtered TPIW, ΔTSI, and other paleoclimate records from central and northeastern China, off the coast of northern Japan, southern Philippines, and Peru all demonstrate significant relationships [between solar activity and climate]. This suggests that solar activity drove Holocene variations in both East Asian Monsoon (EAM) and El Niño Southern Oscillation (ENSO). In particular, the latter seems to have predominantly controlled the coastal climate of East Asia to the extent that the influence of precession was nearly muted during the late Holocene.

Chapanov et al., 2017     DECADAL CYCLES OF EARTH ROTATION, MEAN SEA LEVEL AND CLIMATE, EXCITED BY SOLAR ACTIVITY … But recently, another mechanism of climate variations, due to cosmic rays was proposed (Kilifarska and Haight, 2005; Kilifarska, 2008, 2011; Velinov et al., 2005). According to the new models, the cosmic rays produce a ionization of the atmosphere, changes of atmosphere conductivity, lightning, and an increase of ozone concentration. The ozone plays significant role in climate variations, so the new models of cosmic ray influences on Earth atmosphere may explain the observed correlation between cosmic rays and climate variations. … The shape of solar cycles is rather different from sinusoidal form, so they affect geosystems by many short-term harmonics. A possible solar origin of decadal variations of Earth rotation, mean sea level and climate indices is investigated by the harmonics of Jose, de Vries and Suess cycles with centennial periods of 178.7, 208 and 231 years. The common decadal cycles of solar-terrestrial influences are investigated by long time series of Length of Day (LOD), Mean Sea Level (MSL) variations at Stockholm, ElNiño/Southern Oscillation (ENSO), temperature and precipitation over Eastern Europe, Total Solar Irradiance (TSI), Wolf’s Numbers Wn and North-South solar asymmetry. A good agreement exists between the decadal cycles of LOD [length of day], MSL [mean sea level], climate and solar indices whose periods are between 12-13, 14-16, 16-18 and 28-33 years. … The Total Solar Irradiance (TSI), Wolf’s Numbers (Wn) and North-South (N-S) solar asymmetry expose different spectral peaks, amplitude modulation and phases from these bands. These solar time series represent thermal heating over the Earth, solar wind (space weather) and solar magnetic field variations. The decadal cycles of N-S [North-South] solar asymmetry strongly affect corresponding cycles of El Nino/Southern Oscillation (ENSO).

Helama et al., 2017 (full)     Solar proxy data (Steinhilber et al., 2009) consistently illustrate low activity between AD 400 and 700, with a notable seventh-century solar minimum, the millennial-scale solar changes culminating over these centuries and thus during the DACP [Dark Ages Cold Period] (Scafetta, 2012).  Interestingly, there is multiple proxy evidence showing that reduced solar activity may modulate the North Atlantic Oscillation (NAO) towards its negative phase (Gray et al., 2010). Since the NAO is a leading pattern of climate variability in the global atmosphere, and the negative NAO phase is generally associated with cooler temperatures particularly over western Europe and eastern North-America for both the winter (Wanner et al., 2001; Hurrell and Deser, 2010) and summer seasons (Folland et al., 2009), a prolonged negative NAO phase could thus result in cold temperatures at least over some parts of the Northern Hemisphere continents.
Yukimoto et al., 2017     A delayed response of the winter North Atlantic oscillation (NAO) to the 11-year solar cycle has been observed and modeled in recent studies. The result of this study supports a previous hypothesis that suggests that the 11-year solar cycle signals on the Earth’s surface are produced through a downward penetration of the changes in the stratospheric circulation. … The importance of the North Atlantic oscillation (NAO) for the European weather and climate conditions has been known for a long time (Walker and Bliss 1932; van Loon and Rogers 1978; Hurrell et al. 2003). NAO is the dominant intrinsic mode of atmospheric variability over the Atlantic sector (Hurrell and Deser 2009). … The present result confirms the previous hypothesis reported by Kodera et al. (2016), which stated that the major solar influence on the Earth’s surface can be produced through changes in stratospheric circulation, and the spatial structure of the solar signal at the Earth’s surface is largely conditioned by atmosphere’s interaction with the ocean.
Wang et al., 2017     The identification of causal effects is a fundamental problem in climate change research. Here, a new perspective on climate change causality is presented using the central England temperature (CET) dataset, the longest instrumental temperature record, and a combination of slow feature analysis and wavelet analysis. The driving forces of climate change were investigated and the results showed two independent degrees of freedom —a 3.36-year cycle and a 22.6-year cycle, which seem to be connected to the El Niño–Southern Oscillation cycle and the Hale sunspot cycle, respectively.
Gray et al., 2017     There are several proposed mechanisms through which the 11-year solar cycle (SC) could influence the Earth’s climate, as summarised by Figure 1. These include: (a) the direct impact of solar irradiance variability on temperatures at the Earth’s surface, characterised by variation in the total incoming solar irradiance (TSI); (b) the indirect impact of variations through the absorption of Ultra-Violet (UV) radiation in the upper stratosphere associated with the presence of ozone, with accompanying dynamical responses that extend the impact to the Earth’s surface; (c) the indirect impact of variations in energetic particle fluxes into the thermosphere, mesosphere and upper stratosphere at high geomagnetic latitudes; and (d) the impact of variations in the generation of ions by galactic cosmic ray (GCR) penetration into the troposphere. Although different in their nature, these four pathways may not work in isolation but their influence could be synergetic.

Zharkova et al., 2017     “Using a summary curve of two eigen vectors of solar magnetic field oscillations derived with Principal Components Analysis (PCA) from synoptic maps for solar cycles 21-24 as a proxy of solar activity, we extrapolate this curve backwards three millennia revealing 9 grand cycles lasting 350-400 years each. The summary curve shows a remarkable resemblance to the past sunspot and terrestrial activity: grand minima – Maunder Minimum (1645-1715 AD), Wolf minimum (1280-1350 AD), Oort minimum (1010-1050 AD) and Homer minimum (800 900 BC); grand maxima – modern warm period (1990-2015), medieval warm period (900-1200 AD), Roman warm period (400-10 BC) and others. We verify the extrapolated activity curve by the pre-telescope observations of large sunspots with naked eye, by comparing the observed and simulated butterfly diagrams for Maunder Minimum (MM), by a maximum of the terrestrial temperature and extremely intense terrestrial auroras seen in the past grand cycle occurred in 14-16 centuries.”
We confirm the occurrence of upcoming Modern grand minimum in 2020-2053, which will have a shorter duration (3 cycles) and, thus, higher solar activity compared to MM [Maunder Minimum]. … One of the examples of fitting incorrectly the oscillating function with a linear regression approach is shown by Akasofu (2010) (see her Fig. 9), when explaining the modern era recovery of the Earth from the little ice period and the incorrect use of a linear part of the temperature variations for the extremely incorrect prediction of the terrestrial temperature growth in the next century.
Harde, 2017     [A] naturally generated [CO2 emission] contributes more than 95% to the overall emission, and its generation rate and the respective absorption rate sensitively respond on global temperature variations. … [The] well known delayed response of CO2 and methane (CH4) to sea and air temperature changes (see, e.g., Petit et al. [2]; Monnin et al. [3]; Caillon et al. [4]; Torn and Harte [5]; Humlum et al. [6]; Salby [7]) are not considered in AR5. … As long as any natural variations in the CO2 concentrations are not accurately known, the ECS [equilibrium climate sensitivity to CO2 doubling] cannot be used as a reliable indicator only for an anthropogenic global warming. … The IPCC denies any noticeable solar influence on the actual climate, although strong evidence of an increasing solar activity over the last century exists (see, e.g., Hoyt & Schatten [8]; Willson & Mordvinov [9]; Shapiro et al. [10]; Ziskin & Shaviv [11]; Scafetta & Willson [12]; Usoskin et al. [13]; Zhao & Feng [14]; Soon et al. [15]). … From these studies we conclude that the measured temperature increase of 0.74∘ C over the time 1880–2000 and the observed cloud changes of −4% over the period 1983– 2000 can best be explained by a cloud feedback mechanism, which is dominated by the solar influence. Therefore, it seems quite reasonable to use a model mean of [climate sensitivity to doubled CO2] = 0.7°C, yielding a CO2 initiated warming of 0.3°C [1880-2000] and a solar contribution of 0.44°C [1880-2000].
Pande et al., 2017     Ozone is a highly reactive, naturally occurring ingredient of the stratosphere that is produced from oxygen by sunlight.  It is one of the most important chemicals in both the stratosphere and troposphere.  Apart from absorbing the harmful ultaviolet radiation from the sun, it [ozone] also plays an important role in determining earth’s climate.  Solar variability affects ozone through radiative heating in atmosphere.  Solar UV radiation is absorbed by atmospheric ozone.  It is responsible for both the creation and destruction of ozone.  … The total ozone was found to be enhanced during magnetically disturbed conditions which are associated with peak solar activity periods.  Angell and Korshover (1976) concluded that there is nearly in-phase relationship between sunspot number and total ozone.
Le Mouël et al., 2017     [S]olar activity contains an important component that has undergone clear oscillations of  ≈90  years over the past three centuries, with some small but systematic longer-term evolution of “instantaneous” period and amplitude. Half of the variance of solar activity on these time scales can be satisfactorily reproduced as the sum of a monotonous multi-secular increase, a  ≈90 -year Gleissberg cycle, and a double-peaked (≈10.0  and 11.0 years) Schwabe cycle (the sum amounts to 46% of the total variance of the signal). The Gleissberg-cycle component definitely needs to be addressed when attempting to build dynamo models of solar activity. The first SSA component offers evidence of an increasing long-term trend in sunspot numbers, which is compatible with the existence of the modern grand maximum.
Wen et al., 2017     A warmer and wetter climate prevailed since ∼4800 a BP and was interrupted by a sharp cold reversal at approximately 3300 a BP that was likely caused by solar irradiance forcing, which resulted in a global cold climatic change and glacier advance.
Munz et al., 2017     Decadal resolution record of Oman upwelling indicates solar forcing of the Indian summer monsoon (9–6 ka) … We use geochemical parameters, transfer functions of planktic foraminiferal assemblages and Mg /  Ca palaeothermometry, and find evidence corroborating previous studies showing that upwelling intensity varies significantly in coherence with solar sunspot cycles. The dominant  ∼  80–90-year Gleissberg cycle apparently also affected bottom-water oxygen conditions.
Allan et al., 2017     Speleothem is now regarded as valuable archive of climatic conditions on the continents, offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores. … [T]race elements in speleothems have the potential to provide high resolution insights into palaeoclimatic variability during the Holocene. A deeper analysis reveals several periods of significant rapid climate change during the Holocene (at 10.7-9.2 ka, 8.2-7.9 ka, 7.2-6.2 ka, 4.8-4.5 ka, and 3-2.4 ka BP), which are similar to the cold events detected from different natural paleoclimate archivers. A comparison between the geochemical analysis of Père Noël speleothem and solar activity (sunspot number) reveals a significant correlation. Spectral analysis methods reveal common solar periodicities (Gleissberg cycle, de Vries cycle, unnamed 500 year, Eddy cycles, and Hallstatt cycle). The geochemical analyses have the potential to prove that PN speleothem is sensitive to changes in solar activity on centennial and millennial timescales during the Holocene.
Woodson et al., 2017     The last ca. 1000 years recorded the warmest SST averaging 28.5°C. We record, for the first time in this region, a cool interval, ca. 1000 years in duration, centered on 5000 cal years BP concomitant with a wet period recorded in Borneo. The record also reflects a warm interval from ca. 1000 to 500 cal years BP that may represent the Medieval Climate Anomaly. Variations in the East Asian Monsoon (EAM) and solar activity are considered as potential drivers of SST trends. However, hydrology changes related to the El Nino-Southern Oscillation (ENSO) variability, ~ shifts of the Western Pacific Warm Pool and migration of the Intertropical Convergence Zone are more likely to have impacted our SST temporal trend. …  The SA [solar activity] trends (Steinhilber et al., 2012) are in general agreement with the regional cooling of SST (Linsley et al., 2010) and the SA [solar activity] oscillations are roughly coincident with the major excursions in our SST data.

Li et al., 2017     The main driving forces behind the Holocene climatic changes in the LYR [Lower Yangtze Region, East China] area are likely summer solar insolation associated with tropical or subtropical macro-scale climatic circulations such as the Intertropical Convergence Zone (ITCZ), Western Pacific Subtropical High (WPSH), and El Niño/Southern Oscillation (ENSO).

Chen et al., 2017     The 11-year cycle suggests the influence of sunspot activity (Hale, 1924) on streamflow variations in the Tien Shan. The impact of variations in solar activity on streamflow series and other climate phenomena have been reported from North America and Europe, based on instrumental records (Zanchettin et al., 2008; Perry, 2006 ;  Prokoph et al., 2012). A strong positive correlation was also found between solar activity and streamflow in South American rivers (Mauas et al., 2011). … To further investigate the links between the solar activity and streamflow of the Tien Shan, we examined the relationship between PC1 and the number of sunspots, using correlation and wavelet coherency analyses. A significant linkage was found at the quasi-11-year scale from the 1700–2000s.
Kuroda, 2017     The Polar-night Jet Oscillation (PJO) is the dominant mode of stratospheric variability in the Southern Hemisphere (SH), and persists from mid-winter to spring. The influence of the 11-year solar cycle on modulation of the PJO from late winter to spring is examined using observations and three 42-year simulations from a chemistry-climate model. … We suggest that UV modulation of the interactions between planetary waves and zonal-mean flow in the stratosphere, rather than direct diabatic processes as suggested in a previous study, is the source of solar cycle modulation of the PJO.
Shi et al., 2017     Meanwhile, the stronger (weaker) EASM/ASM during the MCA (LIA) was associated with expansion (retreat) of the local Intertropical Convergence Zone and an enhanced (reduced) zonal temperature gradient over the equatorial Pacific. Our results imply that the synchronous change in the Asian–Australian monsoon may be caused by inherent solar variations, further strengthening previous findings.
Xiao et al., 2017     Spectral analysis of Tsuga and evergreen oak pollen percentages shows statistically significant periodicities of ~1500 and ~200 years at the ≥95% confidence level, which suggests that insolation and feedback interactions on millennial to centennial scales are the primary forcing mechanisms of the southwest monsoon and past climatic change during the Holocene in northwestern Yunnan Province, southwestern China.
Chang et al., 2017     The chironomid-based record from Heihai Lake shows a summer temperature fluctuation within 2.4°C in the last c. 5000 years from the south-east margin of the QTP [Qinghai–Tibetan Plateau]. … The summer temperature changes in this region respond primarily to the variation in the Asian Summer Monsoon. The variability of solar activity is likely an important driver of summer temperatures, either directly or by modifying the strength and intensity of the Indian Ocean Summer Monsoon. … We observed a relatively long-lasting summer cooling episode (c. 0.8°C lower than the 5000-year average) between c. 270 cal. BP and AD c. 1956. … The record shows cooling episodes occurred at c. 3100, 2600, 2100 and 1600 cal. BP.  This is likely related to the period defined as the Northern Hemisphere Little Ice Age (LIA; c. AD 1350–1850, equivalent to 600–100 cal. BP). These possibly relate to the 500-year quasi-periodic solar cycle. Cooling stages between c. 270 and 100 cal. BP were also recorded and these are possibly linked to the LIA suggesting a hemisphere-wide forcing mechanism for this event.

Lei et al., 2017     The precipitation variability on decadal to multi-centurial generally always reflects changes in solar activity and large-scale circulation, e.g., the ENSO and the EASM [East Asian Summer Monsoon] (Chen et al., 2011; Vleeschouwer et al., 2012; Feng et al., 2014). [D]uring the MWP [Medieval Warm Period], the wetter climate in this region was consistent with more frequent ENSO events, stronger EASM and higher solar activity, whereas the opposite was found for the LIA. In particular, d13Cac fluctuations on multi-decadal to centennial scales is consistent with the changes in solar activity, with fewer dry intervals corresponding to periods of minimum solar activity within dating errors, which are referred to as the Oort Minimum (AD 1010-1050), Wolf Minimum (AD 1280-1340), Sporer Minimum (AD 1420-1530), Maunder Minimum (AD 1645-1715) and Dalton Minimum (AD 1795-1820). These results suggest that climate change in southeastern China is sensitive to ENSO and the EASM, which may be driven by solar activity.

Zhang et al., 2017     The record suggests the summer temperature varies by ~2.5 °C across the entire period. A generally warmer period occurred between c.8500 and c.6000 cal yr BP and a cooling trend was initiated from c.5500 cal yr BP. The overall pattern broadly matches the summer insolation at 30N and the Asian Summer Monsoon records from the surrounding regions suggesting that summer temperatures from the southeast margin of the QTP respond to insolation forcing and monsoon driven variability on a multi-millennial time scale. Modifications of this overall trend are observed on the finer temporal resolution and we suggest that solar activity could be an important mechanism driving the centennial-scale variability. It may have a strengthened effect in the late Holocene when the monsoon influence weakened.

Luoto and Nevalainen, 2017     Here, we use completely synchronized paleolimnological proxy-based records of air temperature and effective precipitation from two Scandinavian lakes with ∼2000-year sediment profiles. We show that the relationship between air temperature and precipitation (T/P ratio) is synchronous in both study sites throughout the records suggesting warm and dry conditions at ∼300–1100 CE and cold and wet conditions at ∼1200–1900 CE. Owing to the significantly increased air temperatures, the most recent T/P ratio has again turned positive. During the first millennium of the Common Era, the T/P mimics patterns in Southern Oscillation index, whereas the second millennium shows response to the NAO index but is also concurrent with solar irradiance shifts [T]he causes for the LIA [Little Ice Age [1200-1900 CE], are not well defined owing to its highly variable nature (Wanner et al. 2011; Luoto and Nevalainen 2016; Zawiska et al. 2017). Yet, in addition to a persistent strongly negative NAO index phase during the LIA, it was most likely forced by decreased solar irradiance (including Spörer, Maunder and Dalton solar minima), increased volcanic activity (aerosols), and changes in Atlantic Ocean circulation patterns (Grove 2001; Goosse et al. 2005; Wanner et al. 2011).

Li et al., 2017     Correlations between paleotemperature records from the North Atlantic and solar activity suggest that changes in solar output may cause significant shifts in the climate of the North Atlantic region. To test the role of solar activity on summer SST at our study site in West Greenland, we conducted a cross-correlation analysis between our reconstructed summer SST record and a total solar irradiance (TSI) series. The results indicate that the maximum correlation coefficient (0.284) of summer SST [sea surface temperatures] and TSI [total solar irradiance] records is obtained at nearly zero time-lag (-6 time-lag), which means that variations in solar activity affected the summer SST variability in the study area. … A significant positive relationship between summer SSTs on the North Icelandic shelf and solar irradiance reconstructed from 10Be and 14C records during the Holocene was also demonstrated by Jiang et al. This finding is also supported by recent climate model simulations using the Community Climate System Model version 4 (CCSM4). The model results show a strong positive correlation between SST and solar irradiance in the pathway of the IC, indicating that a reduced frequency of Atlantic blocking events during periods of high solar irradiance promotes warmer and saltier conditions in the pathway of the IC due to stronger circulation of the subpolar gyre. … Spectral analyses indicate that significant centennial-scale variations are superimposed on the long-term orbital trend. The dominant periodicities are 529, 410, and 191 years, which may be linked to the well-known 512- and 206-year solar cycles. Cross-correlation analyses between the summer SSTs and total solar irradiance through the last 5000 years indicate that the records are in phase, providing evidence that variations in solar activity impacted regional summer SST variability. Overall, the strong linkage between solar variability and summer SSTs is not only of regional significance, but is also consistent over the entire North Atlantic region.

Orme et al., 2017     The north-south index shows that storm tracks moved from a southern position to higher latitudes over the past 4000 yr, likely driven by a change from meridional to zonal atmospheric circulation, associated with a negative to positive North Atlantic Oscillation shift. We suggest that gradual polar cooling (caused by decreasing solar insolation in summer and amplified by sea-ice feedbacks) and mid-latitude warming (caused by increasing winter insolation) drove a steepening of the winter latitudinal temperature gradient through the late Holocene, resulting in the observed change to a more northern winter storm track.
Serykh and Sonechkin, 2017     The global climate is a quasi-periodically forced dynamic system [1, 2]. In addition to the annual cycle of the heat transport from the Sun and the diurnal cycle of the Earth’s rotation, other external periodical forces exist, which are potentially able to cause climate fluctuations. The lunar and solar tides are such causes on the time scales of the order of one day. On the decadal scale, these causes are 11-year variations in the Sun spots (the Wolf cycle) and its double period manifested in the changes in the heliospheric field polarity (the Hale cycle). The existence of secular solar cycles is also possible (Gleissberg and Suess cycles found in a number of Sun spots). Calculations indicate that an approximately 180-year cycle exists in the rotation of the Sun around the center of mass of the Solar system. The authors of [3] suggest that it is related to the sequence of significant decreases in the solar activity in the last millennium known as the Oort, Wolf, Spörer, Maunder, and Dalton periods. Paleoclimatic evidence of climate cooling during these periods exists. We can conclude on this basis that the ONI [ENSO index] dynamics [are] governed predominantly by two periodical external forces (the annual heat transport to the climatic system from the Sun and the Chandler wobble of the Earth’s poles) and that the system is not chaotic. This fact indicates that a principal possibility exists for long-term (many years in advance) ENSO forecasts.
Kitaba et al., 2017     The weakening of the geomagnetic field causes an increase in galactic cosmic ray (GCR) flux. Some researchers argue that enhanced GCR flux might lead to a climatic cooling by increasing low cloud formation, which enhances albedo (umbrella effect). Recent studies have reported geological evidence for a link between weakened geomagnetic field and climatic cooling. … Greater terrestrial cooling indicates that a reduction of insolation [solar radiation reaching the surface] is playing a key role in the link between the weakening of the geomagnetic field and climatic cooling. The most likely candidate for the mechanism seems to be the increased albedo of the umbrella effect.
Allan et al., 2017     The occurrence of significant solar periodicities (i.e., cycles of Gleissberg, de Vries, unnamed 500 years, Eddy and Hallstat) supports for an impact of solar forcing on PN speleothem trace elements contents. Moreover, several intervals of significant rapid climate change were detected during the Holocene at 10.3, 9.3-9.5, around 8.2, 6.4-6.2, 4.7-4.5, and around 2.7 ka BP. Those intervals are similar to the cold events evidenced in different natural paleoclimate archivers, suggesting common climate forcing mechanisms related to changes in solar irradiance.
Ramos-Román et al., 2017     In turn, this record shows centennial-scale climate oscillations in temperature that correlate with well-known climatic events during the Late Holocene in the western Mediterranean region, synchronous with variability in solar and atmospheric dynamics. … Enhanced arid conditions, co-occurring with overall positive NAO conditions and increasing solar activity, are observed between ~ 1550 to ~ 450 cal yr BP (~ 400 to ~ 1400 CE) and colder and warmer conditions happened during the Dark Ages and Medieval Climate Anomaly, respectively. Slightly wetter conditions took place during the end of the MCA and the first part of the Little Ice Age, which could be related to a change towards negative NAO conditions and minima in solar activity.
Lüdecke and Weiss, 2017     The Sun as climate driver is repeatedly discussed in the literature but proofs are often weak. In order to elucidate the solar influence, we have used a large number of temperature proxies worldwide to construct a global temperature mean G7 over the last 2000 years. The Fourier spectrum of G7 shows the strongest components as ~1000-, ~460-, and ~190 – year periods whereas other cycles of the individual proxies are considerably weaker. The G7 temperature extrema coincide with the Roman, medieval, and present optima as well as the well-known minimum of AD 1450 during the Little Ice Age. We have constructed by reverse Fourier transform a representation of G7 using only these three sine functions, which shows a remarkable Pearson correlation of 0.84 with the 31-year running average of G7 [global temperature over the last 2000 years]. The three cycles are also found dominant in the production rates of the solar-induced cosmogenic nuclides 14C and 10Be, most strongly in the ~190 – year period being known as the De Vries/Suess cycle. By wavelet analysis, a new proof has been provided that at least the ~190-year climate cycle has a solar origin.  … G7 [global temperature over the last 2000 years], and likewise the sine representations have maxima of comparable size at AD 0, 1000, and 2000. We note that the temperature increase of the late 19th and 20th century is represented by the harmonic temperature representation, and thus is of pure multiperiodic nature [it is of natural solar origin]. It can be expected that the periodicity of G7, lasting 2000 years so far, will persist also for the foreseeable future. It predicts a temperature drop from present to AD 2050, a slight rise from 2050 to 2130, and a further drop from AD 2130 to 2200, upper panel, green and red curves).

Warrier et al., 2017     Climatic periodicities recorded in lake sediment magnetic susceptibility data: Further evidence for solar forcing on Indian summer monsoon … The results obtained from this study show that solar variations are the main controlling factor of the southwest monsoon and, like other archives from different regions in India, the TK [Thimmannanayakanakere –a small lake in southern India] sediments have also recorded these solar signatures.
Malik et al., 2017     We find robust statistical evidence that Atlantic multi-decadal oscillation (AMO) has intrinsic positive correlation with solar activity in all datasets employed. The strength of the relationship between AMO and solar activity is modulated by volcanic eruptions and complex interaction among modes of ocean variability. The observational dataset reveals that El Niño southern oscillation (ENSO) has statistically significant negative intrinsic correlation with solar activity on decadal to multi-decadal timescales (16–27-year)
Yukimoto et al., 2017     For the Pacific internal mode (Pacific Decadal Oscillation), the power is largest for the longer periods of the 15−25 year band (Minobe 1999). As the NAO has some power near the 11-year cycle, resonance may take place more easily. In fact, the numerical simulation of Thiéblemont et al. (2015) suggested a phase locking of the NAO with the 11-year solar cycle. The present result confirms the previous hypothesis reported by Kodera et al. (2016), which stated that the major solar influence on the Earth’s surface can be produced through changes in stratospheric circulation, and the spatial structure of the solar signal at the Earth’s surface is largely conditioned by atmosphere’s interaction with the ocean.
Ge et al., 2017     This paper presents new high-resolution proxies and paleoclimatic reconstructions for studying climate changes in China for the past 2000 years. Multi-proxy synthesized reconstructions show that temperature variation in China has exhibited significant 50–70-yr, 100–120-yr, and 200–250-yr cycles. Results also show that the amplitudes of decadal and centennial temperature variation were 1.3°C and 0.7°C, respectively, with the latter significantly correlated with long-term changes in solar radiation, especially cold periods, which correspond approximately to sunspot minima. The most rapid warming in China occurred over AD 1870–2000, at a rate of 0.56◦ ± 0.42◦C (100 yr)−1; however, temperatures recorded in the 20th century may not be unprecedented for the last 2000 years, as data show records for the periods AD 981–1100 and AD 1201–70 are comparable to the present.

Usoskin, 2017     Another aspect is the link between solar-activity variations and the Earth’s climate … [I]t should be noted that the modern epoch was characterized, until the earlier 2000s by high solar activity dominated by an 11-year cyclicity … contrary to some predictions, a Grand minimum of activity has not started. Thus, we may experience, in the near future, the interplanetary conditions quite different with respect to those we got used to during the last decades. … The longest direct series of solar activity is the 400-year-long sunspot-number series, which depicts the dramatic contrast between the (almost spotless) Maunder minimum and the modern period of very high activity.

Lu et al., 2017     Ozone absorption of solar radiation in the ultraviolet (UV) band is known to affect upper atmospheric chemistry and temperature, and thus its circulation via photochemical, radiative and dynamical interactions (Brasseur and Solomon 2005). The enhanced UV forcing during high solar (HS hereafter) activity years leads to a 2-4% increase of annual mean stratospheric ozone and ~1 K increase of annual mean temperature in the equatorial upper stratosphere and lower mesosphere (e.g. Haigh 1994; Scaife et al. 2000; Hood 2004; Frame and Gray 2010; Chiodo et al. 2012; Hood and Soukharev 2012; Remsberg 2014; Mitchell et al. 2014, Hood et al. 2015). … Studies show that a regional circulation pattern in the Northern Hemispheric (NH) winter that resembles the positive phase of the North Atlantic Oscillation (NAO) occur during HS [high solar activity] winters (e.g. Ruzmaikin and Feynman 2002; Kodera 2002; Woollings et al. 2010a; Lockwood et al. 2010; Ineson et al. 2011; Gray et al. 2013; 2016). A number of different mechanisms have been proposed to explain the solar-NAO connection. A ‘top-down’ mechanism, first proposed by Hines (1974) and later developed by Kodera (1995), is often invoked to account for the downward transfer of a solar UV signal from the upper stratosphere (e.g. Kodera and Kuroda 2002; Matthes et al. 2004; 2006; Ineson et al. 2011; Thiéblemont et al. 2016).
Ogurtsov et al., 2017     It is widely accepted also that this global warming is caused primarily by anthropogenic increase of greenhouse gases concentration . However debates on this question still continues.  Some experts maintain that current warming does not exceed the natural fluctuations of climateEvidence of appreciable contribution to global warming of non-greenhouse factors has been obtained by many authors.   Soon et al., 2015 noted that if the urbanization effect is properly taken into account, one can conclude that solar variability is the dominant factor of Northern Hemisphere long-term temperature changes since at least 1881.   Zhao and Feng, 2014 reported that variations in solar activity play an important role in changes of climate over global scale during the last more than 100 years.  According to Harde (2014)the Sun is the main contributor to global warming of the last century. … [I]t is reasonable to regard the global warming as a phenomenon exceptional from the point of view of intrinsic climatic oscillations, which need an additional external forcing factor for explanation. On the other hand, the statistical experiments showed that an appreciable part of the global warming might be a result of natural fluctuations of climatic system. … [O]ur results show that the contribution of these external factors (including greenhouse effect) to the global warming could be less than is often believed. … Changes in the solar radiation at the Earth’s surface (global brightening) might be important source of the warming of the last decades (Ogurtsov et al., 2012).
Arppe et al., 2017     These negative shifts overlap with the latter part of a cooling known as the Dark Ages Cold Period (DACP, ca. 1500–1000 cal. yr BP; Bianchi and McCave, 1999; McDermott et al., 2001). The event is directly preceded by a minimum in total solar irradiation (Renssen et al., 2006; Steinhilber et al., 2009) … A wealth of proxy evidence testifies to the LIA [Little Ice Age] cooling, thought to have been triggered by reduced solar irradiance, extended volcanism, and internal characteristics of the ocean–atmosphere system (Miller et al., 2010, 2012; Wanner et al., 2011). … Factoring in respective age-model uncertainties, it appears that all major negative shifts, that is, ‘cold’ periods, in the δ18Olw record are roughly synchronous with periods of major negative anomalies in total solar irradiation and high modeled probabilities for extremely cold years in the Nordic Seas (Renssen et al., 2006), and widespread evidence of North Atlantic ‘cold spells’ (Bond et al., 2001; Sarnthein et al., 2003; Solomina et al., 2015; Wanner et al., 2008) linked to solar forcing.

Wang et al., 2017     The driving forces of climate change were investigated and the results showed two independent degrees of freedom —a 3.36-year cycle and a 22.6-year cycle, which seem to be connected to the El Niño–Southern Oscillation cycle and the Hale sunspot cycle, respectively. … Solar variability has been shown to be a major driver of climate in central Europe during the past two millennia using Δ14C records. Furthermore, this result is essentially in good agreement with the findings of Scafetta (2007, 2012, 2016), who found that the climate system was mostly characterized by a specific set of oscillations and these oscillations (61, 115, 130 and 983 years) appeared to be synchronous with major astronomical oscillations (solar system, solar activity and long solar/lunar tidal cycles).
Huo and Xiao, 2017     This paper uses the sunspot number (SSN) index and the El Niño modoki index (EMI) to examine the possible modulation of El Niño Modoki events by variations in solar activity. A significant positive correlation was found between SSN and EMI with a lag of two years, and both SSN and EMI have an obvious period of about 11–12 years. … Two possible mechanisms are proposed, one is the direct mechanism that the solar radiation warms up the tropical pacific with a geographical difference, due to the cloud distribution. The warming response in the central Pacific is amplified by the coupled positive feedback between the ocean and atmosphere with 1–2 years lag. Another possible way can be described as follows: the solar heating effect propagating from the upper atmosphere modulates the strength and variation of atmospheric anomaly at high and mid-latitudes in the northern hemisphere winter, which results in an anomalous subtropical cyclone over the northeastern Pacific in the winter seasons following the solar peak years. The anomalous cyclone reduces the cloud cover over the northeastern Pacific and enhances the local input of solar radiation. As a result, a positive sea surface temperature (SST) anomaly occurs over the northeastern Pacific and extends towards the central tropical Pacific along the path of anomalous southwesterly winds, which may trigger an El Niño Modoki event in the following years.
Li et al., 2017     Studies on Sun-climate connection have been carried out for several decades, and almost all of them focused on the effects of solar total irradiation energy. As the second major terrestrial energy source from outer space, the solar wind energy flux exhibits more significant long-term variations. … Here we investigate the possible modulation of the total energy flux input from the solar wind into the Earth’s magnetosphere on the global tropical cyclone activity during 1963–2012. From a global perspective, the accumulated cyclone energy increases gradually since 1963 and start to decrease after 1994. Compare to the previously frequently used parameters, e,g., the sunspot number, the total solar irradiation, the solar F10.7 irradiation, the tropical sea surface temperature, and the south oscillation index, the total solar wind energy flux input exhibits a better correlation with the global tropical cyclone activity. Furthermore, the tropical cyclones seem to be more intense with higher geomagnetic activities. A plausible modulation mechanism is thus proposed to link the terrestrial weather phenomenon to the seemly-unrelated solar wind energy input.
Ning et al., 2017     Our findings suggest that changes in solar activity may have primarily controlled the fluctuations of ISM [Indian Summer Monsoon] intensity on the multi-decadal to centennial time-scale. Cooling of the North Atlantic climate and the interactions between tropical-ocean and atmosphere may have amplified the solar signal.
Schwander et al., 2017     Weather types and reanalysis data show that the 11-year solar cycle influences the late winter atmospheric circulation over central Europe with colder (warmer) conditions under low (high) solar activity.
Bauchi Danladi and Akçer-Ön, 2017     Periods of higher lake levels are consistent with solar maxima in total solar irradiance and vice versa. Moreover, the Lake Salda records clearly show dry Dark Ages Cold Period (DACP), humid Medieval Climatic Anomaly (MCA), dry Little Ice Age (LIA), and humid Modern Warm Period (MoWP). These records suggest that the solar forcing, through its influence on the atmospheric circulation, is the main mechanism of climate change during the DACP [Dark Ages Cold Period], MCA [Medieval Climate Anomaly], LIA [Little Ice Age] and MoWP [Modern Warm Period] in this region. … The dry periods, within age uncertainties, correlates well with high authigenic carbonate precipitation (Ca, cps) which correspond to time-intervals with lower lake water levels and low solar activity such as Grand Minimum, Oort Minimum, Wolf Minimum, Sporer Minimum, Maunder Minimum, and Dalton Minimum. On the other hand, the wet periods in Lake Salda correspond to higher lake water levels, and high solar activity such as Medieval Maximum and Modern Maximum. … The climate records of Lake Salda over the last 1400 years are closely linked to the solar activity, possibly through its influence on atmospheric circulations.

Ön et al., 2017      [T]he abrupt decline in both precipitation and temperature around 3.5 ka, 2.8 ka and 1.8 ka BP, which were also documented in the seismic records (Eris¸ et al., submitted), may have been the result of a coincidence of the strengthening of the Siberian high pressure system during winters (Rohling et al., 2002; Çagatay et al., 2014), and the gradual decrease in solar irradiance, especially around 2.8 ka BP (Roth and Joos, 2013), in accordance with changes in the North Atlantic (Bond et al., 2001). For the Holocene, the most striking result is that the spikes in precipitation and temperature records appear to closely follow the North Atlantic Bond events, whereas the trends do not. If the cause of the Bond events is indeed solar forcing, as claimed by Bond et al. (2001), then we can also state that the climate oscillations in the region were also greatly influenced by solar forcing.

Shekhar et al., 2017     [T]he Hindu Kush-Himalaya (HKH) harbors ~50% (by area) of all the glaciers outside of the polar regions. … Our research is the maiden attempt to reconstruct the longest regional scale glacier mass balance records for the Western Himalaya based on tree-ring sampling at an unprecedented scale. Another highlight of our study is that it presents valid evidence of the significant mass loss experienced by the Himalayan glaciers even during the LIA [1500-1850].  … [W]e believe that the episodes of significantly negative mass balances … were the result of an enhanced El Niño affecting the ISM [Indian Summer Monsoon] and increasing the temperatures … [and] a more direct relationship between the high TSI and more negative mass balances during the LIA in the years with potentially weaker El Niño …  In the case of the Himalaya, the […] phase of rising regional temperatures, and the start of the strong solar cycles that in later years (since the 1970s), started showing substantial coupling with strong El Niño episodes. … [M]ass balance periodicities of 9–12 years during ~1970–1990 [are] a representation of the response to a few of the strongest consecutive solar cycles in past 400 years. In fact, we see that ~50% of the years since 1970 experienced an exceptionally high TSI of >1361 W m−2, ~40% of which also underwent warm phases of ENSO. … Although, the study acknowledges the contributions of anthropogenic drivers of climate change in the Himalayan region, it also highlights a strong effect from the increased yearly concurrence of extremely high TSI with El Niño in the past five decades, resulting in severe glacial mass loss. … Although external anthropogenic forcing can partly control the glacial regime in the Himalaya, the natural climate variability still emerges as the key deciding element governing the Himalayan glacier mass balances. Similar to several other studies for the region, our study also identifies ENSO, NAO, and AMO as the primary drivers of the regional mass balance variability. The fact that the past few decades have experienced intensified episodes of NAO, closely correlating with rising temperature, also suggests a robust natural climatic control over the Himalayan glaciers.

Ogurtsov et al., 2017     Significant correlation was found between SST [sea surface temperatures] in NA [the North Atlantic] and solar activity (both instrumental data and proxies) during AD 1716–1986. Thus, the connection between Northern Fennoscandian climate and solar activity, which has been previously established at century-scale (Ogurtsov et al., 2001, 2002, 2013) and millennial-scale (Helama et al., 2010), is confirmed for AD 1716–1986 over the entire frequency range using unfiltered records (with the exception for AMO reconstruction after Mann et al. (2009)). … Changes in solar ultra-violet (UV) radiation might provide a solar-climatic link over Northern Europe. Actually, modeling work by (Ineson et al., 2011) showed that that solar UV (200-320 nm) decadal variability drives appreciable temperature changes in mesosphere and upper stratosphere largely through absorption of UV by ozone. This variation results in a corresponding change in the pattern of stratospheric winds, which propagates downwards and appreciably influences atmospheric circulation over the North Atlantic basin. Studies using an atmosphere–ocean coupled climate model have shown that solar-induced changes in atmospheric circulation also influence changes of heat storage in North Atlantic Ocean that can integrate and amplify solar effect (Ineson et al., 2011; Scaife et al., 2013).

Perșoiu et al., 2017     Throughout the Holocene, the subterranean ice block in Scărișoara Ice Cave responded sensitively to changes in both winter temperature and moisture source. During this time period, winter temperature in ECE [East Central Europe] was mainly controlled by insolation [solar radiation] changes. The interplay between insolation variability, SST changes in the North Atlantic, and the influence of the lingering Laurentide Ice Sheet modulated the dynamics of large-scale atmospheric circulation.

Luthardt and Rößler     The 11 yr solar cycle, also known as Schwabe cycle, represents the smallest-scaled solar cyclicity and is traced back to sunspot activity (Douglass, 1928; Lean, 2000), which has a measurable effect on the Earth’s climate, as indicated by the Maunder minimum (Usoskin et al., 2015). Global climate feedback reactions to solar irradiance variations caused by sunspots are complex and hypothesized to be triggered by (1) variation in total energy input (Cubasch and Voss, 2000), (2) the influence of ultraviolet light intensity variation on composition of the stratosphere (Lean and Rind, 2001), (3) the effect of cosmic rays on cloud formation (Marsh and Svensmark, 2000; Sun and Bradley, 2002), and/or (4) the effect of high-energy particles on the strato- and mesosphere (Jackman et al., 2005). …  [L]ike today, sunspot activity caused fluctuations of cosmic radiation input to the atmosphere, affecting cloud formation and annual rates of precipitation
Cosentino et al., 2017     A review of the literature indicates that the climate was significantly less stable than previously supposed during the Holocene, since its warming trend was characterized by relevant short-term cooling events occurring at decennial and centennial scale (Dansgaard et al., 1993; Bond et al., 1999; Mayewski et al., 2004). The most recent cold phase was the Little Ice Age (LIA), which caused the expansion of glaciers in the alpine regions at lower latitudes. Several authors have linked this cooler climatic condition to a period of reduced solar activity (Mauquoy et al., 2002), which caused a decrease in summer insolation (Wanner et al., 2011). … [T]he cooling event known as Little Ice Age (LIA)… persisted more or less from the 13th to the 19th century (Perry and Hsu, 2000). … Furthermore, the fluctuations occurring in the frequency curve of H. balthica could be related to several brief cooling events which characterize the LIA, namely Wolf, Sporer, Maunder and Dalton [solar minimum periods] (Lamb, 1984; Mauquoy et al., 2002).
Huo and Xiao, 2017     In this paper, the authors investigate a particular feature, the ocean heat content (OHC) anomaly, in different phases of the total solar irradiance (TSI) cycle. The results show that almost opposite spatial patterns appear in the tropical Pacific during the ascending and declining phases of the TSI cycle. Further analysis reveals the presence of the quasi-decadal (~11-year) solar signal in the SST [sea surface temperature], OHC [ocean heat content] and surface zonal wind anomaly field over the tropical Pacific with a high level of statistical confidence (>95%). … In Misios and Schmidt (2012), the ensemble simulations from an AOGCM showed that the tropical SST oscillates almost in-phase with the 11-year solar cycle. White and Liu (2008) also found the fluctuation of the upper ocean warming to be in-phase with TSI on the decadal scale during the twentieth century, governed by a resonant excitation of the tropical delay action oscillator and solar forcing, and the warming stage lagged the solar peak year by one to three years. … [P]atterns of OHC and potential temperature anomalies in the tropical Pacific are quite spatially symmetric in the ascending and declining phases, which seems phase-locked with the phases of the TSI cycle. The most significant regions of the OHC anomaly are locate just in the high correlation areas (beyond the 95% confidence level), which are ‘solar-sensitive’ regions with a clear quasi-11-year period.
Stein et al., 2017     The causes that are controlling the decrease in sea ice are still under discussion. In several studies changes in extent, thickness and drift of Arctic sea ice are related to changes in the overall atmospheric circulation patterns as reflected in the North Atlantic Oscillation (NAO) and Arctic Oscillation (AO). The NAO and AO are influencing changes of the relative position and strength of the two major surface-current systems of the Arctic Ocean. … The increase in sea ice extent during the late Holocene seems to be a circum-Arctic phenomenon, coinciding with major glacier advances on Franz Josef Land, Spitsbergen and Scandinavia.  The increase in sea ice may have resulted from the continuing cooling trend due to decreased solar insolation and reduced heat flow from the Pacific.The increase in sea ice extent during the late Holocene seems to be a circum-Arctic phenomenon as PIP25-based sea ice records from the Fram Strait, Laptev Sea, East Siberian Sea and Chukchi Sea  display a generally quite similar evolution, all coinciding with the decrease in solar radiationThe main factors controlling the millennial variability in sea ice and surface-water productivity are probably changes in surface water and heat flow from the Pacific into the Arctic Ocean as well as the long-term decrease in summer insolation, whereas short-term centennial variability observed in the high-resolution middle Holocene record was possibly triggered by solar forcing.

Schmutz, 2017     For the first time, model calculations show a plausible way that fluctuations in solar activity could have a tangible impact on the climate. Studies funded by the Swiss National Science Foundation expect human-induced global warming to tail off slightly over the next few decades. A weaker sun could reduce temperatures by half a degree.
Yamamoto et al., 2017     Millennial to multi-centennial variability in the quartz / feldspar ratio (the BG [Beaufort Gyre] circulation) is consistent with fluctuations in solar irradiance, suggesting that solar activity affected the BG [Beaufort Gyre] strength on these timescales. … The intensified BSI [Bering Strait in-flow] was associated with decrease in sea-ice concentrations and increase in marine production, as indicated by biomarker concentrations, suggesting a major influence of the BSI on sea-ice and biological conditions in the Chukchi Sea. Multi-century to millennial fluctuations, presumably controlled by solar activity, were also identified in a proxy-based BSI record characterized by the highest age resolution. … Proxy records consistent with solar forcing were reported from a number of paleoclimatic archives, such as Chinese stalagmites (Hu et al., 2008), Yukon lake sediments (Anderson et al., 2005), and ice cores (Fisher et al., 2008), as well as marine sediments in the northwestern Pacific (Sagawa et al., 2014) and the Chukchi Sea (Stein et al., 2017).

Rimbu et al., 2017     The River Ammer discharge during summer shows no significant linear trend from 1926 to 2015. The frequency of flood days >125m3 /s discharge shows pronounced decadal variations within the period 1926-2015. … Previous studies (Wirth et al., 2013; Glur et al., 2015; Czymzik et al., 2016) have identified connections between solar activity changes and flood variability in the Alpine realm and, in particular, the Ammer region. A higher frequency of floods in the Alpine region is associated with reduced solar activity as well as with colder conditions.  … Flood days are relatively frequent during the periods 1950-1980  and 2000-2015 [reduced solar activity], but less frequent from 1980 to 2000. [enhanced solar activity][T]here is a clear increase in blocking frequency over northeastern Europe during summers with reduced solar activity … Analysis of Holocene flood reconstructions in the European Alps (Wirth et al., 2013) reveals a rich spectrum of periodicities at multidecadal (87yr), centennial (104, 150, 208, 350, 500 and 265 710yr) and millennial (900-1200 and 2500-3000yr) time scales. Similar periodicities characterize solar activity reconstructions (e.g. Stuiver and Braziunas, 1989). It was shown that flood frequency in the Alpine region was higher during cool periods in the Alpine region, coinciding with lows in solar activity (Wirth et al., 2013). … One modeled Sun-climate connection is the so-called solar top-down mechanism (Haigh, 1996; Gray et al., 2010; Ineson et al., 2011). Thereby, during periods of reduced solar activity, comparably large reductions in solar UV emissions are expected to induce reduced meridional pressure gradients favoring atmospheric blocking and meridional airflow, consistent with our results (e.g. Haigh, 1996; Ineson et al., 280 2011). Therefore, this mechanism might have also caused the detected changes in flood frequency in the Ammer region.
Sha et al., 2017     The reconstruction indicates warm conditions with reduced sea-ice cover, associated with the Holocene Thermal Maximum, from ca. 6700 to 5000 cal. yr BP. … A distinct increase in sea-ice cover began at 1750 cal. yr BP, with absolute maximum values during the last millennium.  … In order to assess the contribution of different potential forcing factors to sea-ice conditions off West Greenland, we evaluated the relationship between our sea-ice reconstruction and solar activity, as well as with the strength of ocean circulation. The observed agreement between the sea-ice record and solar activity suggests that solar forcing may have been an important trigger for sea-ice variability off West Greenland during the last 5000 yr.

Huang et al., 2017  (full paper)     Various scientific studies have investigated the causal link between solar activity (SS) and the earth’s temperature (GT). [T]he corresponding CCM [Convergent Cross Mapping] results indicate increasing significance of causal effect from SS [solar activity] to GT [global temperature] since 1880 to recent years, which provide solid evidences that may contribute on explaining the escalating global tendency of warming up recent decades. … The connection between solar activity and global warming has been well established in the scientific literature. For example, see references [1–10]. … Among which, the SSA [Singular Spectrum Analysis] trend extraction is identified as the most reliable method for data preprocessing, while CCM [Convergent Cross Mapping] shows outstanding performance among all causality tests adopted. The emerging causal effects from SS [solar activity] to GT [global temperatures], especially for recent decades, are overwhelmingly proved, which reflects the better understanding of the tendency of global warming.
Matveev et al., 2017     An increase in atmospheric moisture for the warm period of the year (May–September) since 1890s, and mean annual temperatures since the 1950s was identified. During the same time period, there was a marked increase in amplitude of the annual variations for temperature and precipitation. … These fluctuations are consistent with 10–12-years Schwabe–Wolf, 22-years Hale, and the 32–36-years Bruckner Solar Cycles. There was an additional relationship found between high-frequency (short-period) climate fluctuations, lasting for about three years, and 70–90-years fluctuations of the moisture regime in the study region corresponding to longer cycles.
Schwander et al., 2017     Influence of solar variability on the occurrence of Central European weather types from 1763 to 2009 … Weather types and reanalysis data show that the 11-year solar cycle influences the late winter atmospheric circulation over Central Europe with colder (warmer) conditions under low (high) solar activity. … The 247-year long analysis [1763-2009]  of the 11-year solar cycle impact on late winter European weather patterns suggest a reduction in the occurrence of westerly flow types linked to a reduced mean zonal flow under low solar activity. Following these observation, we estimate the probability to have cold conditions in winter over Europe to be higher under low solar activity than under high activity. Also similar [cold] conditions can occur during periods of prolonged reduced total solar irradiance. …  Solar activity can have effects on the atmospheric circulation through three different mechanisms. These effects may arise from direct changes in total solar irradiance (TSI), from changes in stratospheric ozone induced by changes in solar UV, or from changes in stratospheric ozone induced by energetic particles, whose flux is modulated by solar activity. The ~1 Wm-2 variation in TSI over an 11-yr sunspot cycle corresponds to a change in the radiation forcing of about ~0.17 Wm-2.
Fu et al., 2017     The influences of solar activity and large-scale climate modes (e.g. the El Niño/Southern Oscillation — ‘ENSO’) have been identified in many geophysical processes.  The combined influences of solar activity and ENSO on the first leaf and bloom dates of lilacs were identified for most of the stations with records spanning ≥ 33 years. In the 11-year band, both increasing solar activity (SSN) and El Niño caused delays in the first leaf and bloom events of the cloned lilac during the 1980s in the northeastern United States.
Zielhofer et al., 2017     Western Mediterranean Holocene record of abrupt hydro-climatic changes … Imprints of North Atlantic meltwater discharges, NAO and solar forcing …Early Holocene winter rain minima are in phase with cooling events and millennial-scale meltwater discharges in the sub-polar North Atlantic. … [A] significant hydro-climatic shift at the end of the African Humid Period (∼5 ka) indicates a change in climate forcing mechanisms. The Late Holocene climate variability in the Middle Atlas features a multi-centennial-scale NAO-type pattern, with Atlantic cooling and Western Mediterranean winter rain maxima generally associated with solar minima.
Sun et al., 2017     [A]t least six centennial droughts occurred at about 7300, 6300, 5500, 3400, 2500 and 500 cal yr BP. Our findings are generally consistent with other records from the ISM [Indian Summer Monsoon]  region, and suggest that the monsoon intensity is primarily controlled by solar irradiance on a centennial time scale. This external forcing may have been amplified by cooling events in the North Atlantic and by ENSO activity in the eastern tropical Pacific, which shifted the ITCZ further southwards. The inconsistency between local rainfall amount in the southeastern margin of the QTP and ISM intensity may also have been the result of the effect of solar activity on the local hydrological cycle on the periphery of the plateau.

Zhai, 2017     ENSO is negatively/positively correlated with SSN [sunspot number] when SSN is large/small. … [S]olar activity may take effect on the ENSO, and such an impact should undergo an accumulation procedure (phase delay). XWT also indicates the existence of the impact. It is found that the index is negatively correlated with SSN when SSN is large during a certain long-term interval, and positively when SSN is small. Strong El Niño is inferred to be taken place in decade(s) to come.
Fischel et al., 2017     On a Holocene timescale, we conclude that the northeastern Caribbean SST [sea surface temperatures]  and circulation regime have been mainly dependent on the position of the ITCZ [inter-tropical convergence zone], which, in turn, is controlled by changes in hemispheric solar insolation.  Caribbean climate is directly controlled by the position of the inter-tropical convergence zone (ITCZ), where converging NE and SE trade winds creates a lowpressure convection zone with high precipitation rates (Philader et al., 1996; Schmidt et al., 2006).  In addition to the seasonal variations in the position of the ITCZ, the long-term N–S migration of the ITCZ is largely determined by decadal to millennial changes in solar forcing (Haug et al., 2001; Schneider et al., 2014).

Zhu et al., 2017     Abrupt enhancements in the flux of pedogenic magnetite in the stalagmite agree well with the timing of known regional paleofloods and with equatorial El Niño−Southern Oscillation (ENSO) patterns, documenting the occurrence of ENSO-related storms in the Holocene. Spectral power analyses reveal that the storms occur on a significant 500-y cycle, coincident with periodic solar activity and ENSO variance, showing that reinforced (subdued) storms in central China correspond to reduced (increased) solar activity and amplified (damped) ENSO. Thus, the magnetic minerals in speleothem HS4 preserve a record of the cyclic storms controlled by the coupled atmosphere−oceanic circulation driven by solar activity.
Du et al., 2017     Although the global warming has been successfully attributed to the elevated atmospheric greenhouses gases, the reasons for spatiotemporal patterns the warming rates are still under debate. In this paper, we report surface and air warming based on observations collected at 1,977 stations in China from 1960 to 2003. Our results show that the warming of daily maximum surface (Ts-max) and air (Ta-max) temperatures showed a significant spatial pattern, stronger in the northwest China and weaker in South China and the North China Plain. These warming spatial patterns are attributed to surface shortwave solar radiation (SSR) and precipitation, the key parameters of surface energy budget.
Zhai, 2017     The time series of sunspot number and the precipitation in the north-central China (108° ∼ 115° E, 33° ∼ 41° N) over the past 500 years (1470–2002) are investigated, through periodicity analysis, cross wavelet transform and ensemble empirical mode decomposition analysis. The results are as follows: the solar activity periods are determined in the precipitation time series of weak statistical significance, but are found in decomposed components of the series with statistically significance; the Quasi Biennial Oscillation (QBO) is determined to significantly exist in the time series, and its action on precipitation is opposite to the solar activity; the sun is inferred to act on precipitation in two ways, with one lagging the other by half of the solar activity period.
Malik et al., 2017     [W]e investigate the impact of internal climate variability and external climate forcings on ISMR on decadal to multi-decadal timescales over the past 400 years. The results show that AMO, PDO, and Total Solar Irradiance (TSI) play a considerable role in controlling the wet and dry decades of ISMR [Indian summer monsoon rainfall]. Resembling observational findings most of the dry decades of ISMR occur during a negative phase of AMO and a simultaneous positive phase of PDO.
Xiao et al., 2017     Solar wind and electric-microphysical process is the key mechanism that affects climate … We investigated the influencing mechanism of high-energetic particle precipitation modulated by solar wind on the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). On a day-to-day time scale, Zhou, Tinsley, and Huang (2014) and Huang et al. (2013) found that the minima in AO and NAO indices only lagged 0~2 days of the solar wind speed (SWS) minima during years of high stratospheric aerosol loading, which suggests a much faster mechanism of solar influence on the atmospheric system compared to the ozone destruction process. From the perspective of year-to-year variation, Xiao and Li (2016) and Zhou et al. (2016) showed a robust relationship between SWS [solar wind speed] and NAO in boreal winter. These aforementioned studies indicate that the wintertime Iceland Low in the North Atlantic was very sensitive to solar wind variations and played an important role in the process of solar wind and electric-microphysical effects on climate. Moreover, under the condition of a weak electric field, we have demonstrated the marked impact of cloud droplet electricity on the collision efficiency of cloud condensation nuclei. This, in turn, suggests that the collision in a cloud microphysics process constitutes the core link between atmospheric electricity and climate (Tinsley and Leddon 2013; Tinsley and Zhou 2013, 2014). Furthermore, Tinsley and Zhou (2015) improved the collision and parameterization scheme that varied with electric quantity in a cloud microphysics process and quantitatively evaluated the effects of high-energetic particle flux on cloud charge. This achievement not only supports the marked association of solar activity with weather and climate change on various time scales, but also but also avails the quantitative accession of solar impacts on climate. It is worth noting that the successful establishment development of a theoretical model regarding of the influencing process of solar energetic particles on the atmosphere improves the development of global climate models.
Vyklyuk et al., 2017     Hurricane genesis modelling based on the relationship between solar activity and hurricanes … There are a number of works concerning the Sun–Earth connections and their influence on atmospheric motions. There are a number of observations which show that within a few days after energetic solar eruptions (flares, coronal mass ejections and eruptive prominences), there are diverse meteorological responses of considerable strength (Gomes et al. 2012). … Conclusion: [T]here are several indications which are in favor that the beginning of violent cyclonic motions in Earth’s atmosphere may be caused by charged particles from the solar wind.
Katsuki et al., 2017     Typhoon frequency in East Asia is synchronous with the solar irradiance. … Several studies documented typhoon pattern changes in response to the El Niño/Southern Oscillation (ENSO). … The fluctuation of the solar activity plays a key role in regulating the westerly jet movement. The multi-centennial scale of the typhoon frequency in mid-latitude East Asia is therefore caused by changes in the solar activity and ENSO conditions.
Moreno et al., 2017     Understanding the Sun-Earth’s climate coupling system is both an essential and an urgent issue, with great progress achieved over the last decades (e.g., Haigh, 2007; Soon et al., 2014 for a review). Recently, Brugnara et al. (2013) referred that the Euro–Atlantic sector, in which Portugal is located, seems to be a region with a particularly strong solar influence on the troposphere, finding a significant change in the mean late winter circulation over Europe, which culminates in detectable impacts on the near-surface climate. Jiang et al. (2015) suggested that (i) climate in the northern North Atlantic regions follows SA [solar activity] fluctuations on multidecadal to centennial time scales, and (ii) it is more susceptible to the influence of those fluctuations throughout cool periods with, for instance, less vigorous ocean circulation. Similar results were found by Gómez-Navarro et al. (2012) in the context of climate simulations for the second millennium over the Iberian Peninsula, recognizing that temperature and precipitation variability is significantly affected at centennial time scales by variations in the SA [solar activity]. … Grand Minima and Dalton-type Minimum scenarios are broadly characterized by (i) lower TSI (i.e., lower available PAR) (Lean, 1991, and references therein), (ii) development of cloudiness (e.g., Usoskin and Kovaltsov, 2008), and (iii) decreased global/regional air surface temperatures (e.g., Neukom et al., 2014) in tandem with greater regional precipitation variability. … The connections between solar phenomena and the lower atmosphere processes can be explained by two kind of mechanisms: (i) “top-to-down”, influencing the pole-to-equator temperature gradient and exerting an impact on the modulation of the atmospheric circulation cells, weakening or strengthening the zonal winds, and (ii) “bottom-to up” that directly impact on the radiation fluxes, energy balance and temperatures on the ground. Both finally impact the atmospheric circulation modes responsible for the global/regional precipitation and temperature patterns (e.g., Gray et al., 2010; Martin-Puertas et al., 2012; Thiéblemont et al., 2015).
Douglass et al., 2017     Using a newly reported Pacific sea surface temperature data set, we extend a prior study that assigned El Niño episodes to distinct sequences. Within these sequences the episodes are phase-locked to subharmonics of the annual solar irradiance cycle having two- or three-year periodicity. There are 40 El Niño episodes occurring since 1872, each found within one of eighteen such sequences. Our list includes all previously reported events. Three El Niño episodes have already been observed in boreal winters of 2009, 2012 and 2015, illustrating a sequence of 3-year intervals that began in 2008. If the climate system remains in this state, the next El Niño is likely to occur in boreal winter of 2018.
Zhang et al., 2017     The frequencies represent the influence of the Pacific Decadal Oscillation (PDO) and solar activity on the precipitation from the southwestern United States. In addition, solar activity has exerted a greater effect than PDO on the precipitation in the southwestern United States over the past 120 years. By comparing the trend of droughts with the two fundamental frequencies, we find that both the droughts in the 1900s and in the 21st century were affected by the PDO and solar activity, whereas the droughts from the 1950s to the 1970s were mainly affected by solar activity.
Hood, 2017     QBO/Solar Modulation of the Boreal Winter Madden-Julian Oscillation: A Prediction for the Coming Solar Minimum … The Madden-Julian Oscillation (MJO), also known as the 30-60 day oscillation, is the strongest of the intraseasonal climate oscillations in the tropics and has significant derivative effects on extratropical circulation and intraseasonal climate. … Here, evidence is presented that tropical upwelling changes related to the 11-year solar cycle also modulate the boreal winter MJO. Based on 37.3 years of MJO amplitude data, the largest amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, occur during the QBOE phase under solar minimum (SMIN) conditions while the smallest amplitudes and strongest static stabilities occur during the QBOW phase under solar maximum (SMAX) conditions.
Orme et al., 2017     Past changes in the North Atlantic storm track driven by insolation and sea-ice forcing … We suggest that gradual polar cooling (caused by decreasing solar insolation in summer and amplified by sea-ice feedbacks) and mid-latitude warming (caused by increasing winter insolation) drove a steepening of the winter latitudinal temperature gradient through the late Holocene, resulting in the observed change to a more northern winter storm track.
Page, 2017     Data related to the solar climate driver are discussed and the solar cycle 22 low in the neutron count (high solar activity) in 1991 is identified as a solar activity millennial peak and correlated with the millennial peak – inversion point – in the RSS temperature trend in about 2004. The cyclic trends are projected forward and predict a probable general temperature decline in the coming decades and centuries. Estimates of the timing and amplitude of the coming cooling are made. If the real climate outcomes follow a trend which approaches the near term forecasts of this working hypothesis, the divergence between the IPCC forecasts and those projected by this paper will be so large by 2021 as to make the current, supposedly actionable, level of confidence in the IPCC forecasts untenable. Unless the range and causes of natural variation, as seen in the natural temperature quasi-periodicities, are known within reasonably narrow limits, it is simply not possible to even begin to estimate the effect of anthropogenic CO2 on climate. Given the lack of any empirical CO2-climate connection reviewed earlier and the inverse relationship between CO2 and temperature [during the Holocene, when CO2 rose as temperatures declined] seen in Figure 2, and for the years 2003.6–2015.2 in Figure 4, during which CO2 rose 20 ppm, the simplest and most rational working hypothesis is that the solar ‘activity’ increase is the chief driver of the global temperature increase since the LIA.

Huhtamaa and Helama, 2017     Throughout the written history of Finland, delayed onset of summer and night frost have been named as the main reasons for crop failure and famine. … Our reconstruction suggests that in the 8th–10th centuries AD, when continuous crop cultivation was established in Finland, the risk of temperature-driven crop failure was notably lower and the crops were generally higher than during the historical period (c. 13th century ad onwards). The continuous period of high crop yields coincides with an episode of multi-centennial summer season warmth, associated with the MCA [Medieval Climate Anomaly] in the region and around north-west Europe (Goosse et al., 2012; Luoto and Helama, 2010; Ogilvie et al., 2000; Sundqvist et al., 2010). … The rapid mid-15th century cooling, which followed a major atmospheric circulation change over the North Atlantic (Dawson et al., 2007; Meeker and Mayewski, 2002) and coincided with the culmination of the Spörer solar minimum (Miyahara et al., 2006), has been evidenced in various summer and winter season reconstructions of the region (Haltia-Hovi et al., 2007; Helama et al., 2009b; Klimenko and Solomina, 2010; Luoto and Helama, 2010; Zhang et al., 2015). … The culmination of the ‘LIA’ [Little Ice Age] in Finland has been commonly dated to the late 17th and early 18th centuries ad (Luoto, 2013; Luoto and Helama, 2010; Tiljander et al., 2003), which is synchronous with the onset of the phase of the lowest yield ratios in our reconstruction. The Maunder solar minima (c. 1645–1715) and several volcanic eruptions preceded the culmination (Shindell et al., 2003).

Svensmark et al., 2017     In conclusion, a mechanism by which ions condense their mass onto small aerosols and thereby increase the growth rate of the aerosols, has been formulated theoretically and shown to be in good agreement with extensive experiments. The mechanism of ion-induced condensation may be relevant in the Earth’s atmosphere under pristine conditions, and able to influence the formation of CCN [clouds]. It is conjectured that this mechanism could be the explanation for the observed correlations between past climate variations and cosmic rays, modulated by either solar activity or supernova activity in the solar neighborhood on very long time scales. The theory of ion-induced condensation should be incorporated into global aerosol models, to fully test the atmospheric implications.
(press release)    The impact of changes in solar activity on Earth’s climate was up to seven times greater than climate models suggested according to new research published today in Nature Communications.   Researchers have claimed a breakthrough in understanding how cosmic rays from supernovas react with the sun to form clouds, which impact the climate on Earth.  The findings have been described as the “missing link” to help resolve a decades long controversy that has big implications for climate science.
Gray et al., 2017     There is growing evidence that variability associated with the 11-year solar cycle has an impact at the Earth’s surface and influences its weather and climate. Although the direct response to the Sun’s variability is extremely small, a number of different mechanisms have been suggested that could amplify the signal, resulting in regional signals that are much larger than expected. In this paper the observed solar cycle signal at the Earth’s surface is described, together with proposed mechanisms that involve modulation via the total incoming solar irradiance and via modulation of the ultra-violet part of the solarspectrum that influences ozone production in the stratosphere.
Hood, 2017     QBO/Solar Modulation of the Boreal Winter Madden-Julian Oscillation … The Madden-Julian Oscillation (MJO), also known as the 30-60 day oscillation, is the strongest of the intraseasonal climate oscillations in the tropics and has significant derivative effects on extratropical circulation and intraseasonal climate. … Here, evidence is presented that tropical upwelling changes related to the 11-year solar cycle also modulate the boreal winter MJO. Based on 37.3 years of MJO amplitude data, the largest amplitudes and occurrence rates, and the weakest static stabilities in the tropical lower stratosphere, occur during the QBOE phase under solar minimum (SMIN) conditions while the smallest amplitudes and strongest static stabilities occur during the QBOW phase under solar maximum (SMAX) conditions. Conversely, when the QBO and solar forcings are opposed (QBOW/SMIN and QBOE/SMAX), the difference in occurrence rates becomes statistically insignificant.
Gan et al., 2017     Temperature responses to the 11-year solar cycle in the mesosphere from the 31-year (1979-2010) … Atmospheric response to the solar cycle (SC) here refers to atmospheric variability induced by the 11-year solar activity cycle. The SC [solar cycle] response originates mainly from large (4-8%) solar UV spectral irradiance change (in the range of 200-250 nm) from solar minimum to maximum condition, while the total solar flux stays nearly constant (0.1%) [Donnelly, 1991; Lean et al., 1997; Woods and Rottman, 1997; Beig et al., 2008; Gary et al., 2010]. The variability of the solar UV spectral irradiance affects the thermal structure of the atmosphere by directly changing the total energy deposited and indirectly modifying the photochemistry and dynamics of the atmosphere. In addition to the equatorial Quasi-Biennial Oscillation (QBO) [Baldwin et al., 2011] and the El Niño-Southern Oscillation (ENSO) [Li et al., 2013], the 11-year SC is also a significant source to the inter-annual variability in the mesosphere and lower (MLT) region.
Lihua, 2017     The modulation action from solar activity plays an important role in the temperature change, and there is a possible association existing in the global land-ocean temperature and solar activity on decade time scales. … About 11-year period, a remarkable oscillation of solar activity, continually exists in wavelet transform of solar variation. According to the cross wavelet transform, solar activity influences global land-ocean temperature change on ~11-year time scales during 1935-1995 with above the 5 % significance level.
Utomo, 2017     A similar result was also found for the relationship between solar activity and cosmic ray flux with a negative correlation, i.e. 0.69/year. When solar activities decrease, the clouds cover rate increase due-0.61/month and – to secondary ions produced by cosmic rays. The increase in the cloud cover rate causes the decrease in solar constant value and solar radiation on the earth’s surface [cooling]. … The increase in the formation rate of cloud would affect the decrease in the intensity of solar radiation reaching the Earth’s surface. The relationship between cosmic rays and solar constant is an “opposite” relationship because of the negative correlation type (r < 0). The phenomenon of “opposite” is in a good agreement with the result by Svensmark (1997) who found a correlation between temperature and global cloud coverage with the cosmic rays. … [T]he climate also depends on variations in the flux of solar energy received by the earth’s surface. Variation in the solar energy flux is caused by variations in solar activity cycle. Thus the climate is a manifestation of how solar radiation is absorbed, redistributed by the atmosphere, land and oceans, and ultimately radiated back into space. Every variation of solar energy received at the earth’s surface and reradiated by the earth into space will have a direct impact on climate change on Earth.
Biktash, 2017     The effects of total solar irradiance (TSI) and volcanic activity on long-term global temperature variations during solar cycles 19–23 [1954-2008] were studied. It was shown that a large proportion of climate variations can be explained by the mechanism of action of TSI [total solar irradiance] and cosmic rays (CRs) on the state of the lower atmosphere and other meteorological parameters. … Recent studies by Pudovkin and Raspopov, Tinsley, and Swensmark have shown that the Earth’s cloud coverage is strongly influenced by cosmic ray intensity. Conditions in interplanetary space, which can influence GCRs and climate change, have been studied in numerous works. As has been demonstrated by Biktash, the long-term CR count rate and global temperature variations in 20–23 solar cycles are modulated by solar activity and by the IMF (interplanetary magnetic field). A possible geophysical factor which is able to affect the influence of solar activity on the Earth’s climate is volcanism. The effects of volcanism can lead to serious consequences in the atmosphere and the climate.
Sokeland, 2017     The scattering of solar energy due to the small particles of supernova debris is also reflected in TSI data as shown in Fig. 3 [which] shows an excellent correspondence between sunspot minimums, irradiance depressions, and supernova impact times. … It was the debris stream of Nova WZ Sagittae that started our current global warming episode near 1966. … [T]he duration of a single supernova debris stream flowing past our planet is at least 50 years and at times more than 100 years. … Incoming supernova debris streams cause warming and melting ice caps that produce increased sea levels.  … Termination of the last ice age results due to melting of numerous supernova impacts that correlate time of impact by changing sea level and geothermal energy released for 2,800 years. … Supernova 393 debris impacted earth near 857 AD and started the Medieval Warming Period. … Two supernovas, G299 and G296.7-0.9, impacted the earth to produce first the Roman warming period. … It should be concluded that the increase in CO2 caused by supernovas 1006 and 1054 that is currently being observed is a boon to mankind and will protect us from the coming cold phase that will be caused by these currently impacting supernovas. … Since supernovas 1054 and 1006 are currently incoming, the planet’s average temperatures should continue to increase, global warming. Global warming will not be reduced by reducing man made CO2 emissions

Tartakovsky et al., 2017     Along with its direct impact, the Sun regulates other effects on the geospheres. It modulates the flows of cosmic charged particles and the solar wind, which then change the conditions of energy conversion in the troposphere. As the Earth passes through the regions of the interplanetary magnetic field, it changes the radiation balance, which leads to changes in the temperature and pressure in the surface atmosphere, with large variability mainly in the ultraviolet part of the solar radiation spectrum which, due to photochemical reactions, regulates the formation of ozone in the stratosphere affecting the surface temperatureThere is a theory that the effect of solar forcing on the geosphere is insufficient and, therefore, it is not able to change the climate. However, there are mechanisms through which a small energy of the regulator can initiate substantial climatic processes. … The mechanisms of solar energy transformations in the atmosphere are still subjects of debate. The physical nature of the solar-terrestrial connections has not been fully understood yet, and additional research is required for its clarification.

Warming Trend Since 1980s Explained By Surface Solar Radiation (Cloud Cover Reduction)

Sanchez-Lorenzo et al., 2017     Trends of all-sky downward surface solar radiation (SSR) from satellite-derived data over Europe (1983–2010) are first presented. The results show a widespread (i.e., non-local dimension) increase in the major part of Europe, especially since the mid-1990s in the central and northern areas and in springtime. There is a mean increase of SSR of at least 2 W m− 2 per decade from 1983 to 2010 over the whole Europe, which, taking into account that the satellite-derived product lacks of aerosol variations, can be mostly related to a decrease in the cloud radiative effects over Europe. … Downward surface solar radiation (SSR) is a critical part of the Global Energy Balance and the climate system … A widespread decrease of SSR from the 1950s to the 1980s [when global cooling occurred] has been observed (Liepert, 2002; Stanhill and Cohen, 2001; Wild, 2009), followed by an increase of SSR since the mid-1980s [when global warming occurred]… Pinker et al. (2005) used a different product (2.5° resolution) and found that the derived global mean SSR [surface solar radiation] series underwent a significant increase of 1.6 W m−2 per decade from 1983 to 2001. … On the other hand, Hatzianastassiou et al. (2005) derived a SSR product from 1984 to 2000 (2.5° resolution) and reported a significant increase of +2.4 W m−2 per decade in the global mean series, which is considerably higher than the results from Pinker et al. (2005) and Hinkelman et al. (2009).
Urban et al., 2017     An important work that covered as many as 237 stations grouped into the five climatic regions and concerned, inter alia, sunshine duration trends from 1961 to 2004 in six South American countries, was published by Raichijk (2012). The results of that study confirm downward trends in sunshine duration from the 1950s until the 1980s and upward ones since the beginning of the 1990s, which were also observed in other regions of the world. Satellite short-wave radiation data spanning the period from 1984 to 2005 confirm the results obtained at ground sunshine duration measurement stations in all five climatic regions of South America. Upward sunshine duration trends are associated with an increase in the intensity of solar radiation and a decrease in cloud cover (Raichijk 2012). 
Boers et al., 2017     A 50-year [1966-2015] hourly dataset of global shortwave radiation, cloudiness and visibility over the Netherlands was used to quantify the contribution of aerosols and clouds to trends in all-sky radiation. The trend in all-sky radiation was expressed as a linear combination of trends in fractional cloudiness, clear-sky radiation and cloud-base radiation (radiation emanating from the bottom of clouds). All three trends were derived from the data records. The results indicate that trends in all three components contribute significantly to the observed trend in all-sky radiation. Trends (per decade) in fractional cloudiness, all-sky, clear-sky and cloud-base radiation were respectively 0.0097 ± 0.0062, 1.81 ± 1.07 W m−2, 2.78 ± 0.50 W m−2, and 3.43 ± 1.17 W m−2.
Antón et al., 2017     This study focuses on the analysis of the daily global solar radiation (GSR) reconstructed from sunshine duration measurements at Madrid (Spain) from 1887 to 1950. Additionally, cloud cover information recorded simultaneously by human observations for the study period was also analyzed and used to select cloud-free days. First, the day-to-day variability of reconstructed GSR data was evaluated, finding a strong relationship between GSR and cloudiness. The second step was to analyze the long-term evolution of the GSR data which exhibited two clear trends with opposite sign: a marked negative trend of − 36 kJ/m2 per year for 1887–1915 period and a moderate positive trend of + 13 kJ/m2 per year for 1916–1950 period, both statistically significant at the 95% confidence level. Therefore, there is evidence of “early dimming” and “early brightening” periods in the reconstructed GSR [global solar radiation] data for all-sky conditions in Madrid from the late 19th to the mid-20th centuries.
Sanchez-Lorenzo et al., 2017     Clouds play a major role in the climate system, but large uncertainties remain about their decadal variations. Here we report a widespread decrease in cloud cover since the 1970 s over the Mediterranean region, in particular during the 1970 s–1980s, especially in the central and eastern areas and during springtime. Confidence in these findings is high due to the good agreement between the interannual variations of cloud cover provided by surface observations and several satellite-derived and reanalysis products, although some discrepancies exist in their trends.
Alexandri et al., 2017     In this work, the spatiotemporal variability of surface solar radiation (SSR) is examined over the Eastern Mediterranean region for a 31-year period (1983–2013). … The satellite-based data from CERES (Cloud and the Earth’s Radiant Energy System), GEWEX (Global Energy and Water Cycle Experiment) and ISCCP (International Satellite Cloud Climatology Project) underestimate SSR while the reanalysis data from the ERA-Interim overestimate SSR compared to CM SAF SARAH. Using a radiative transfer model and a set of ancillary data, these biases are attributed to the atmospheric parameters that drive the transmission of solar radiation in the atmosphere, namely, clouds, aerosols and water vapor [CO2 not mentioned].. … The CM SAF SARAH SSR trend was found to be positive (brightening) and statistically significant at the 95% confidence level (0.2 ± 0.05 W/m2/year [2 W m-2 per decade].”
Hukuba et al., 2017     At 36 locations worldwide, we estimate the cloud radiative effect (CREatm) on atmospheric solar absorption (ASRatm) by combining ground-based measurements of surface solar radiation (SSR) with collocated satellite-derived surface albedo and top-of-atmosphere net irradiance under both all-sky and clear-sky conditions. To derive continuous clear-sky SSR from Baseline Surface Radiation Network (BSRN) in-situ measurements of global and diffuse SSR, we make use of the Long and Ackerman (2000) algorithm that identifies clear-sky measurements and empirically fits diurnal clear-sky irradiance functions using the cosine of the solar zenith angle as the independent variable. The 11-year average (2000-2010) CREatm (all-sky minus clear-sky) is overall positive at around +11 Wm-2 using direct measurements form ground and space, and at 4 Wm−2 in the CERES EBAF dataset. This discrepancy arises from a potential overestimation in clear-sky absorption by the satellite product or underestimation by the combined BSRN/CERES dataset. The forcing ratio R shows that clouds enhance ASRatm most distinctly at desert-like locations that overall experience little occurrence of clouds. This relationship is captured by both the combined dataset and CERES EBAF.
Wild et al., 2017      Detection of decadal changes in the downward shortwave radiation GEBA [Global Energy Balance Archive] has played a key role in the discovery that downward shortwave radiation at the Earth’s surface is not stable over time, but undergoes substantial multidecadal variations. Based on European GEBA sites, Ohmura and Lang (1989) identified a decline in downward shortwave radiation from the 1950s to the 1980s, later popularly known as “global dimming”. Follow-up studies found similar tendencies at GEBA sites around the world. When updating the GEBA records into the 2000s, Wild et al. (2005) noted a trend reversal and widespread recovery from previous dimming, which they coined “brightening”. Norris and Wild (2007, 2009) used the GEBA data and a satellite-derived regression method to estimate the effects of changes in cloud cover on dimming and brightening. A recent update of the trends in homogeneous European GEBA records is reported in Sanchez-Lorenzo et al. (2016).

Natural Oscillation (ENSO, NAO, AMO, PDO) Climate Influence (44)

Belohpetsky et al., 2017     It is well known that most short term global temperature variability is due to the well-defined ENSO natural oscillation (see: Wang and Fiedler, 2006). During strong El Niño events global average temperature rises by a few tenths Kelvin and reverts back subsequently. … The residual dynamics left after adjusting global surface temperature anomalies (1950-2014) for short-term variability from El Niño Southern Oscillation (ENSO) and volcanic eruptions have a staircase pattern. Linear trends for three quasi-stable periods 1950-1987, 1988-1997 and 1998-2014 are near zero with nearly all warming occurring during two step-like shifts in the years 1987/1988 and 1997/1998.  A notable consequence of the staircase dynamics of recent warming is that observed temperature anomalies (HadCRUT4.5) from 1950 till 2014 could be almost reproduced as the linear sum of only two factors(!) : ENSO variability and the staircase function.

Jones and Ricketts, 2017     [S]ince the mid-20th century, most observed warming has taken place in four events: in 1979/80 and 1997/98 at the global scale, 1988/89 in the Northern Hemisphere and 1968–70 in the Southern Hemisphere. Temperature is more step-like than trend-like on a regional basis. Satellite temperature is more step-like than surface temperature. … [S]tep-like changes are also present in tide gauge observations, rainfall, ocean heat content and related variables. [A]cross a selection of tests, a simple stepladder model better represents the internal structures of warming than a simple trend, providing strong evidence that the climate system is exhibiting complex system behaviour on decadal timescales. This model indicates that in situ warming of the atmosphere does not occur; instead, a store-and-release mechanism from the ocean to the atmosphere is proposed. It is physically plausible and theoretically sound. The presence of step-like – rather than gradual – warming is important information for characterising and managing future climate risk. [Climate models predicated on CO2 forcing indicate a gradual, not step-like warming.]
Park et al., 2017     According to our results, the central Mexican climate has been predominantly controlled by the combined influence of the 20-year Pacific Decadal Oscillation (PDO) and the 70-year Atlantic Multidecadal Oscillation (AMO). However, the AMO probably lost much of its influence in central Mexico in the early 20th century and the PDO has mostly driven climate change since.
Zhu et al., 2017     This study analyzes the effects of fifteen major teleconnections on terrestrial ecosystem carbon fluxes during 1951-2012 using an ensemble of nine Dynamic Global Vegetation Models. We map the global pattern of the dominant teleconnections and find that these teleconnections significantly affect GPP variations over more than 82.1% of the global vegetated area, through mediating the global temperature, and regional precipitation and cloud cover. The El-Niño/Southern Oscillation, the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation are strongly correlated with global, hemispherical, and continental carbon fluxes and climatic variables, while the Northern Hemisphere teleconnections have only regional influences.
Muñoz et al., 2017     Temperature and humidity display rapid and significant changes over the Holocene. The rapid transition from a cold (mean annual temperature (MAT) 3.5°C lower than today) and wet Younger Dryas to a warm and dry early Holocene is dated at 11,410 cal yr BP. During the Holocene, MAT [mean annual temperature] varied from ca. 2.5°C below to 3.5°C above present-day temperature. Warm periods (11,410, 10,700, 9700, 6900, 4000, 2400 cal yr BP) were separated by colder intervals. The last 2.4 kyr of the record is affected by human impact [on the pollen proxy record]. The Holocene remained dry until 7500 cal yr BP. Then, precipitations increased to reach a maximum between 5000 and 4500 cal yr BP. A rapid decrease occurred until 3500 cal yr BP and the late Holocene was dry. … The highest rainfall intervals correlate with the highest activity of ENSO. Variability in solar output is possibly the main cause for this millennial to decadal cyclicity. We interpret ENSO [El Niño-Southern Oscillation] and ITCZ [Intertropical Convergence Zone] as the main climate change-driving mechanisms in Frontino.  … From ca. 8000 cal yr BP, climate in both areas was under the dual influence of ENSO and ITCZ, thereby showing existing teleconnections between the tropical Pacific and Atlantic oceans.
Clarke et al., 2017     Corresponding ~4-8 year periodicities identified from Wavelet analysis of particle size data from Pescadero Marsh in Central Coast California and rainfall data from San Francisco reflect established ENSO periodicity, as further evidenced in the Multivariate ENSO Index (MEI), and thus confirms an important ENSO control on both precipitation and barrier regime variability.

Douglass et al., 2017     Using a newly reported Pacific sea surface temperature data set, we extend a prior study that assigned El Niño episodes to distinct sequences. Within these sequences the episodes are phase-locked to subharmonics of the annual solar irradiance cycle having two- or three-year periodicity. There are 40 El Niño episodes occurring since 1872, each found within one of eighteen such sequences.
Macdonald and Sangster, 2017     Statistically significant relationships between the British flood index, the Atlantic Meridional Oscillation and the North Atlantic Oscillation Index are identified. The use of historical records identifies that the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented. … Solar forcing can manifest itself in a variety of different ways on flood patterns through modification of the climate (Benito et al., 2004). Several series indicated increased flood frequency during the late eighteenth century corresponding to the Dalton Minimum (AD 1790–1830), with notable flooding across catchments in the 8-year period AD 1769 1779, which was a climatic period considered to include the sharpest phases of temperature variability during the “Little Ice Age” (Lamb, 1995; Wanner et al., 2008).
de Inglés and Jesús, 2017     The temperature in Azores depends on the position of the Gulf Stream (GS). A positive (negative) NAO phase enhances (reduces) the Gulf Stream (GS) velocity that increases (reduce) the amount of Eddies around Bermuda driving towards north (east) the GS and heating up high (medium) latitudes. Therefore, a negative phase of NAO favors the GS [Gulf Stream] heat to reach Azores. Since the temperature in Azores is modulated by the oceanic circulation, the AMO also plays an important role. The AMO is reflected in Ponta Delgada by the amplitude between maximum and minimum mean annual temperatures, which means an increase on seasonality. The AMO positive phase is reflected as an increase on temperatures in Lake Azul reconstruction. Otherwise, the AMO negative phase is masked by other climatic patterns. The precipitation in Azores is mainly triggered by the NAO phase
Muller et al., 2017     Over the past two decades, the number of paleotempestology records has increased substantially for sites along the Northwest Atlantic Ocean, Gulf of Mexico and Caribbean Sea, the South Pacific Ocean, and the Northwest Pacific and Indian Ocean regions. The most obvious characteristic of these records is that they reveal extended alternating periods of either greater or lesser tropical cyclone activity over centennial and millennial timescales. In these studies, researchers have shown that large-scale climatic features such as ENSO, sea surface temperatures (SSTs), the latitudinal position of the intertropical convergence zone (ITCZ), and the North Atlantic Oscillation (NAO) are likely driving the alternating long-term behavior of tropical cyclones in global oceanic basins.
Lapointe et al., 2017     This paper investigates an annually-laminated (varved) record from the western Canadian Arctic and finds that the varves are negatively correlated with both the instrumental Pacific Decadal Oscillation (PDO) during the past century and also with reconstructed PDO over the past 700 years, suggesting drier Arctic conditions during high-PDO phases, and vice versa. These results are in agreement with known regional teleconnections, whereby the PDO is negatively and positively correlated with summer precipitation and mean sea level pressure respectively. This pattern is also evident during the positive phase of the North Pacific Index (NPI) in autumn. Reduced sea-ice cover during summer–autumn is observed in the region during PDO− (NPI+) and is associated with low-level southerly winds that originate from the northernmost Pacific across the Bering Strait and can reach as far as the western Canadian Arctic. These climate anomalies are associated with the PDO− (NPI+) phase and are key factors in enhancing evaporation and subsequent precipitation in this region of the Arctic.
Levine et al., 2017     The Atlantic Multidecadal Oscillation (AMO) is the dominant mode of multi-decadal SST variability in the Atlantic Ocean. Changes in AMO-related tropical Atlantic SSTs are known to force changes in the Walker Circulation in the tropical Pacific Ocean. We show that these changes to the Walker Circulation modify ENSO stability on both annual and multi-decadal timescales leading to a distinctive pattern of multi-decadal ENSO variability that we find in observations, ocean reanalyses and conceptual and coupled model experiments.
Valdés-Pineda et al., 2017     This study analyzes these low-frequency patterns of precipitation in Chile (>30 years), and their relationship to global Sea Surface Temperatures (SSTs), with special focus on associations with the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO) indices. … We conclude that a significant multi-decadal precipitation cycle between 40 and 60 years is evident at the rain gauges located in the subtropical and extratropical regions of Chile. This low-frequency variability seems to be largely linked to PDO and AMO modulation.
Liu et al., 2017     Land and sea surface temperatures, precipitation, and storm tracks in North America and the North Pacific are controlled to a large degree by atmospheric variability associated with the Pacific North American (PNA) pattern.  … Our reconstruction shows that PNA has been strongly and consistently correlated with sea surface temperature variation, solar irradiance, and volcanic forcing over the period of record, and played a significant role in translating these forcings into decadal-to-multidecadal hydroclimate variability over North America.
Manatsa et al., 2017     ENSO has been known to influence the trends of summer warming over Southern Africa. In this work, we used observational and reanalysis data to analyze the relationship between ENSO and maximum surface air temperature (SATmax) trends during the three epochs created by the ENSO phase shifts around 1977 and 1997 for the period 1960 to 2014. We observed that while ENSO and cloud cover remains the dominant factor controlling SATmax [maximum surface air temperature] variability, the first two epochs had the predominant La Niña (El Niño)-like events connected to robust positive (negative) trends in cloud fraction.
Kozachek et al., 2017     No unusual recent change is detected in the isotopic composition or in the accumulation rate record, in contrast with the observed warming trend from regional meteorological data. The accumulation rate appears significantly related to the NAO index, in agreement with the earlier results for the Djankuat glacier (Shahgedanova et al., 2005).  As a result, the isotopic composition of the ice cores appears mostly related to characteristics of large–scale atmosphere circulation such as the NAO index…. Tielidze (2016) reports a recent increase in the annual mean temperatures at different elevations in the Georgian Caucasus. The region experienced glacier area loss over the 20th century at an average annual rate of 0.4 %, with a higher rate in eastern Caucasus than in the central and western sections. The analysis of the temperature and radiation regime of glaciers at the ablation period has been performed in the vicinity of El’brus recently (Toropov et al., 2016). The authors prove that the observed waning of glaciers cannot be explained by an increase in temperature during the ablation period because of an increase in precipitation during the accumulation period. They concluded that the main driver of glacier retreat is the increase in the solar radiation balance by 4 % for the 2001–2010 period, which corresponds to the increase in ablation by 140 mm per ablation season (Toropov et al., 2016).

Lim et al., 2017     Our study demonstrated that flood frequency and climate changes at centennial-to-millennial time scales in South Korea have been coupled mainly with ENSO activity, suggesting that the hydrologic changes, including flooding and drought, in East Asia are coupled to the centennial-to-millennial-scale atmospheric-oceanic circulation changes represented by the ENSO pattern.
Valdés-Pineda et al., 2017     This study analyzes these low-frequency patterns of precipitation in Chile (>30 years), and their relationship to global Sea Surface Temperatures (SSTs), with special focus on associations with the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO) indices. … We conclude that a significant multi-decadal precipitation cycle between 40 and 60 years is evident at the rain gauges located in the subtropical and extratropical regions of Chile. This low-frequency variability seems to be largely linked to PDO and AMO modulation.
Reynolds et al., 2017     Evidence derived from instrumental observations suggest that Atlantic variability, associated with changes in SSTs and fluctuations in the strength of the Atlantic Meridional Overturning Circulation (AMOC), is directly linked with broader scale climate variability, including Brazilian and Sahel precipitation (Folland et al., 1986 and Folland et al., 2001), Atlantic hurricanes and storm tracks (Goldenberg et al., 2001 and Emanuel, 2005), and North American and European temperatures (Sutton and Hodson, 2005, Knight et al., 2006 and Mann et al., 2009). Furthermore, evidence derived from palaeoceanographic records suggests that a reduction in the meridional heat transport through the surface components of the AMOC was in part responsible for the reductions in temperatures associated with the Medieval Climate Anomaly (MCA; 1000–1450) to Little Ice Age (LIA; 1450–1850) transition (Lund et al., 2006, Trouet et al., 2009, Trouet et al., 2012, Wanamaker et al., 2012 and Moffa-Sánchez et al., 2014).
Fan and Yang, 2017     The wintertime Arctic temperature decreased from 1979 to 1997 and increased rapidly from 1998 to 2012, in contrast to the global mean surface air temperature [which] increased between 1979 and 1997, followed by a hiatus… A recent study suggests a possible role of the Pacific Ocean decadal oscillation in regulating wintertime climate in the Arctic (Screen and Francis 2016).  … The ‘‘greenhouse effect’’ of water vapor and clouds [CO2 not mentioned as contributing to the GHE] may amplify the effect of winds on Arctic winter climate. …  The objectives of this study are to assess how much natural–internal variability has contributed to climate changes in these [Arctic] regions from 1979 to 2012 … In summary, the correlation analyses presented in this paper shows a natural mode of Arctic winter variability resulting from the Nordic–Siberian seesaw of meridional winds […] is associated with two-thirds of the interannual variance [cooling-warming] of winter-mean Arctic temperature between 1979 and 2012, and possibly contributed a substantial fraction of the observed Arctic amplification [1998-2012 warming] in this period.

Myoung et al., 2017     This study examines the relationship between the North Atlantic Oscillation (NAO) and snowmelt in spring in the upper southwestern states of the US (UP_SW) including California, Nevada, Utah, and Colorado, using SNOTEL datasets for 34 years, 1980-2014. We find statistically significant negative correlations between NAO averages in the snowmelt period and timings of snowmelt, i.e., positive NAO phases in spring enhance snowmelt, and vice versa. … The underlying mechanism for this link is that a positioning of upper-tropospheric anticyclonic (cyclonic) circulations over the western US that are associated with development of the positive (negative) NAO phases tend to bring warmer-and-drier (colder-and-wetter) spring weather conditions to the region. The temperature variations related with the NAO phases also strongly modulate the snowfall-rainfall partitioning. The relationship between NAO and spring snowmelt can serve as key information for the warm season water resources management in the UP_SW.
Gao et al., 2017     We find that negative correlations between the atmospheric temperature in the tropics and ENSO are observed at 17–30 km in the lower stratosphere at a lag of 1 to 4 months and at a lead of 1 month. Out-of-phase temperature variation is observed in the troposphere over the mid-latitude band and in-phase behaviour is observed in the lower stratosphere. Interestingly, we also find that there is a significant negative correlation at a lag of 1–3 months from 32 km to 40 km in the mid-latitude region of the Northern Hemisphere. The atmospheric temperature variations over mid-latitude regions in both hemispheres are closely related to the QBO [quasi-biennial oscillation].
Hao and He, 2017     Using long-term observational data and numerical model experiments, this study found that the Atlantic Multidecadal Oscillation (AMO) affects the influence of ENSO-like sea surface temperature anomalies (SSTAs, which contain variability of both El Niño-Southern Oscillation and Pacific Decadal Oscillation) on the interannual change in the East Asian winter monsoon (EAWM). In the observations, the out-of-phase relationship between the ENSO-like and EAWM was significantly intensified when the AMO and ENSO-like were in-phase. Warmer-than-normal winters occurred across East Asia when the ENSO-like and AMO were positively in-phase, with a significantly weakened Siberian High and anomalous anticyclones over the western North Pacific. The opposite patterns occurred under negatively in-phase conditions.
Zaitchik, 2017     The Madden-Julian Oscillation (MJO) is the dominant mode of sub-seasonal climate variability in the global tropics. As such it represents an opportunity for intra-seasonal rainfall prediction and, perhaps, for explaining dynamics that underlie longer term variability and trends. … A number of studies have identified statistical links between MJO and sub-seasonal rainfall variability in West, East, and Southern Africa. … On longer time scales, there is evidence that MJO activity both modulates and is modulated by the El Niño Southern Oscillation and the Indian Ocean Dipole. The implications of these interactions for MJO connections to Africa require further research, as does the potential for trends in MJO behavior and impacts on Africa under global climate change.
Reischelmann et al., 2017     We document that long-term patterns in temperature and precipitation are recorded in dripwater patterns of Bunker Cave and that these are linked to the North Atlantic Oscillation (NAO).
Lopez et al., 2017     This study reconstructs a century-long South Atlantic Meridional Overturning Circulation (SAMOC) index. The reconstruction is possible due to its covariability with sea surface temperature (SST). A singular value decomposition (SVD) method is applied to the correlation matrix of SST and SAMOC. The SVD is performed on the trained period (1993-present) for which Expendable Bathythermographs (XBT) and satellite altimetry observations are available. The joint modes obtained are used in the reconstruction of a monthly SAMOC timeseries from 1870 to present. The reconstructed index is highly correlated to the observational-based SAMOC timeseries during the trained period and provides a long historical estimate. It is shown that the Interdecadal Pacific Oscillation (IPO) is the leading mode of SAMOC-SST covariability, explaining ~85% with the Atlantic Niño accounting for less than 10%. The reconstruction shows that SAMOC has recently shifted to an anomalous positive period, consistent with a recent positive shift of the IPO.
Wu et al., 2017     The enhanced warming observed in the Eastern China Coastal Waters (ECCW) during the last half-century has received considerable attentions. However, the reason for this warming is still a subject of debate. Based on four different Sea Surface Temperature datasets, we found that the most significant warming occurred in boreal winter during 1982–1998, although the warming trends derived from these datasets differ in magnitude. We suggest that the rapid warming during winter is a result of the asymmetry in the El Niño–Southern Oscillation teleconnection, through which El Niño events induce significant warming over the ECCW at its peak, whereas La Niña events fail to do the opposite that would completely reverse the trends; in addition, there were more El Niño than La Niña events during the recent decades. All these contribute to the winter warming during 1982–1998.
Schwartz and Garfinkel, 2017     European and eastern United States (U.S.) wintertime weather is strongly influenced by large-scale modes of variability in the Northern Hemisphere such as the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). The negative phase of the NAO has been linked to both the Madden Julian Oscillation (MJO) phase with convection in the West Pacific (phase 6 and 7) and to stratospheric sudden warmings (SSW), but the relative role of each phenomena is not clear, and the two phenomena are themselves linked, as more than half of SSW events were preceded by blackphases 6 and 7 of the MJO.
He et al., 2017     As pointed out by Cohen et al. (2014) that continental winter SAT [surface temperature] trends since 1990 exhibit cooling over the midlatitudes. The negative trends extend from Europe eastward to East Asia, with a center of maximum magnitude to the west of the Baikal.  As reviewed above, the AO/NAO [Arctic Oscillation/North Atlantic Oscillation] shows an in-phase relationship with the SAT [surface temperatures] over Eurasia. … [T]he negative trend in the AO/NAO might explain the recent Eurasian winter cooling. … Additionally, the relationship between the winter AO and surface-climate anomalies in the following spring might be modulated by the 11-year solar cycle (Chen and Zhou, 2012). The spring temperature anomalies in northern China related to the previous winter AO were larger and more robust after high solar cycle winters. However, spring temperature anomalies became very small and insignificant after the low solar cycle winters. … Numerous atmospheric scientists have documented that the AO could impact significantly the climate over Europe and Far East. …  It is evident that a positive winter AO causes warmer winters over East Asia through enhancing Polar westerly jet which prevents cold Arctic air from invading low latitudes.

Bianchette et al., 2017     Seven periods of increased water level, varying in duration, occurred during the backbarrier period, with El Niño-Southern Oscillation (ENSO) likely the main climatic mechanism causing these periodic shifts in the paleo-precipitation levels. We suggest that the deepest water levels detected over the last ~3200 years correlate with periods of increased ENSO activity.
Lachniet et al., 2017     [M]onsoon dynamics appear to be linked to low-frequency variability in the ENSO and NAO, suggesting that ocean-atmosphere processes in the tropical oceans drive rainfall in Mesoamerica. … Climate model output suggests decreasing rainfall as a consequence of anthropogenic greenhouse gas radiative forcing (Rauscher et al., 2008; Saenz-Romero et al., 2010). Our data show, however, that the response of the monsoon will be strongly modulated by the changes in ENSO and the NAO mean states … Our data also show that the magnitude of Mesoamerican monsoon variability over the modern era when the anthropogenic radiative forcing has dominated over solar and volcanic forcings (Schmidt et al., 2012) is within the natural bounds of rainfall variations over the past 2250 years. This observation suggests that if anthropogenic forcing has impacted the Mesoamerican monsoon, the signal has yet to be detected above the level of natural climate variability, and the monsoon response to direct radiative forcing and indirect ocean-atmosphere forcings may yet to be fully realized.
Cheung, 2017     The sea surface temperature (SST) of the Eastern Equatorial Pacific (EEP) exerts primary control on global surface temperature (e.g. Halpert and Ropelewski 1992; Wigley 2000) and regional climate (e.g. Ropelewski and Halpert 1987) through different modes of climate variability including the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). With such profound impacts, it is important to understand the evolution of SST in EEP, specifically the dynamics of these climate modes. Rigorous studies over the past decades have shed insights on these two climate modes. ENSO is known to affect regional and global climates on interannual timescales. During an El Niño event, a weakening of easterly trade wind stimulates propagation of Kelvin waves from the western equatorial Pacific to the EEP, which in turn reduces the slope of the thermocline and suppresses upwelling. The decrease in pressure gradient reinforces the weakening of the trade winds through the Bjerknes feedback and ultimately creates an El Niño condition (e.g. Collins et al. 2010). The reorganization of the ocean and the atmosphere due to El Niño raises the global mean surface temperature (e.g. Halpert and Ropelewski 1992; Wigley 2000) and alters regional climate, for example causing drought in Australia (Cai et al. 2011), pluvial in Southwest United States (Ropelewski and Halpert 1987), and changing tropical cyclone frequencies in the Western North Pacific (Camargo and Sobel 2005; Chan 1985). The opposite spatial pattern and teleconnections happen during a La Niña event.

Dieng et al., 2017     We can note that the correlation between GMST [global mean surface temperature] trends and AMO trends is quite high. It amounts 0.88 over the whole time span. At the beginning of the record, the correlation with PDO trends is also high (equal to 0.8) but breaks down after the mid-1980s.  The GMST and AMO trends shown in Figure 6 show a low in the 1960s and high in the 1990s, suggestive of a 60-year oscillation, as reported for the global mean sea level by Chambers et al. (2012). Thus the observed temporal evolution of the GMST [global mean surface temperature] trends may just reflect a 60-year natural cycle driven by the AMO.

B et al., 2017     The recent Indian Ocean (IO) warming and its relation with the El Niño Southern Oscillation (ENSO) is investigated using available ocean and atmospheric reanalyses. By comparing the events before and after 1976 (identified as a threshold separating earlier and recent decades with respect to global warming trends), our results indicate that the IO had experienced a distinct change in the warming pattern. After 1976, during the boreal summer season the cold anomalies in the IO [Indian Ocean] were replaced by warm anomalies in both warm (El Niño) and cold (La Niña) ENSO events. Strong sinking by upper level winds and the associated anomalous equatorial easterly winds created favourable conditions for the IO warming from 90°E towards the western IO. Our study highlights that after 1976, atmospheric and oceanic fields changed mostly during La Niña, with both ENSO phases contributing to the warming of the IO. Warm anomalies of 0.2 °C are seen over large areas of the IO in the post-1976 La Niña composites. Our analysis suggests that the IO warming during La Niña events after 1976 may have a relation to the warm anomalies persisting from the preceding strong El Niño events.
Mermelstein, 2017      [T]he 1940-1978 decrease in CONUS [continental U.S.] temperatures was caused more by the negatively trending oscillatory modes of the AMO/PDO than other factors, and the 1978-2001 increase in temperatures was caused more by the positively trending oscillatory modes of the same oscillations. The small increase, or rather stagnant nature in U.S. CONUS temps since 2001, was likely due to peaking positive modes of the AMO/PDO. In the same way that the AMO and PDO can modify the regional temperatures, we see the same types of effects on precipitation, snowfall and drought in the different regions of the U.S. … It was not until 2003 (Anastasios, Swanson, & Kravtsov, 2003, 2007) that models were created that suggested that these cycles, namely the Pacific Decadal Oscillation (PDO) and the Atlantic Multidecadal Oscillation (AMO) synchronized with each other. Using this as a base, we can explain the major climate shifts that have occurred since scientists began collecting data in the late 1800’s: 1908, 1932, 1973, and 2000. While the most noticeable change in these shifts was on global temperature, effects on the regional, sensible weather in the U.S. were also identified in these same time frames. Through analysis it has been theorized that these shifts are caused by the oceans, and are in fact the main drivers of the climate, and the sensible weather experienced in the United States (Klotzbach & Gray, 2009).
Vaideanu et al., 2017     Here, we identify the global footprint of the Atlantic Multidecadal Oscillation (AMO) on high cloud cover, with focus on the tropical and North Atlantic, tropical Pacific and on the circum-Antarctic sector. In the tropical band, the sea surface temperature (SST) and high cloud cover (HCC) anomalies are positively correlated, indicating a dominant role played by convection in mediating the influence of the AMO-related SST anomalies on the HCC field. … Despite the inherent imperfection of the observed and reanalysis data sets, the AMO footprint on HCC is found to be robust to the choice of dataset, statistical method, and specific time period considered.
Kolling et al., 2017     [O]ur reconstructions reveal several oscillations with increasing/decreasing sea ice concentrations that are linked to the known late Holocene climate cold/warm phases, i.e. the Roman Warm Period, Dark Ages Cold Period, Medieval Climate Anomaly and Little Ice Age. The observed changes seem to be connected to general ocean atmosphere circulation changes, possibly related to North Atlantic Oscillation and Atlantic Multidecadal Oscillation regimes. Furthermore, we identify a cyclicity of 73–74 years in sea ice algae and phytoplankton productivity over the last 1.2 kyr, which may indicate a connection to Atlantic Multidecadal Oscillation mechanisms.

Bjørk et al., 2017     Changes in Greenland’s peripheral glaciers linked to the North Atlantic Oscillation … [W]e map glacier length fluctuations of approximately 350 peripheral glaciers and ice caps in East and West Greenland since 1890. Peripheral glaciers are found to have recently undergone a widespread and significant retreat at rates of 12.2 m per year and 16.6 m per year in East and West Greenland, respectively; these changes are exceeded in severity only by the early twentieth century post-Little-Ice-Age retreat. Regional changes in ice volume, as reflected by glacier length, are further shown to be related to changes in precipitation associated with the North Atlantic Oscillation (NAO), with a distinct east–west asymmetry; positive phases of the NAO increase accumulation, and thereby glacier growth, in the eastern periphery, whereas opposite effects are observed in the western periphery. Thus, with projected trends towards positive NAO in the future, eastern peripheral glaciers may remain relatively stable, while western peripheral glaciers will continue to diminish.
Starczak Weinberg, 2017     ENSO has been the predominant climate driver for the Eastern Pacific, affecting coastal Peru to varying degrees on a multi-decadal scale since it onset at modern frequencies during the Middle Holocene. At local scales, geomorphological evidence and archaeological settlement pattern data suggest changes in precipitation, temperature, and climate variability, with specific relevance for human subsistence and resource access within the coastal desert.

Rossby Waves, Ozone Climate Modulation

Gong et al., 2017     During the past three decades, the most rapid warming at the surface has occurred during the Arctic winter. By analyzing daily ERA-Interim data, we found that the majority of the winter warming trend north of 70°N can be explained by the trend in the downward infrared radiation (IR). This downward IR trend can be attributed to an enhanced poleward flux of moisture and sensible heat into the Arctic by poleward propagating Rossby waves, which increases the total column water and temperature within this region. This enhanced moisture flux is mostly due to changes in the planetary-scale atmospheric circulation rather than an increase in moisture in lower latitudes. The results of this study lead to the question of whether Arctic amplification has mostly arisen through changes in the Rossby wave response to greenhouse gas forcing and its impact on moisture transport into the Arctic.
Xie et al., 2017     Antarctic stratospheric ozone depletion is thought to influence the Southern Hemisphere tropospheric climate. Recently, Arctic stratospheric ozone (ASO) variations have been found to affect the middle-high latitude tropospheric climate in the Northern Hemisphere. This paper demonstrates that the impact of ASO can extend to the tropics, with the ASO variations leading El Niño-Southern Oscillation (ENSO) events by about 20 months.
Rydbeck et al., 2017     Intraseasonal sea surface warming in the western Indian Ocean by oceanic equatorial Rossby waves … A novel process is identified whereby equatorial Rossby (ER) waves maintain warm sea surface temperature (SST) anomalies against cooling by processes related to atmospheric convection in the western Indian Ocean. As downwelling ER waves enter the western Indian Ocean, SST anomalies of +0.15°C develop near 60°E. These SST anomalies are hypothesized to stimulate convective onset of the Madden-Julian Oscillation. The upper ocean warming that manifests in response to downwelling ER [equatorial Rossby] waves is examined in a mixed layer heat budget using observational and reanalysis products, respectively. In the heat budget, horizontal advection is the leading contributor to warming, in part due to an equatorial westward jet of 80 cm s−1 associated with downwelling ER waves. When anomalous currents associated with ER waves are removed in the budget, the warm intraseasonal temperature anomaly in the western Indian Ocean is eliminated in observations and reduced by 55% in reanalysis.
Gong et al., 2017     The inter-annual relationship between the boreal winter Arctic Oscillation (AO) and summer sea surface temperature (SST) over the western tropical Indian Ocean (TIO) for the period from 1979 to 2015 is investigated. The results show that the January–February–March AO [Arctic Oscillation] is significantly correlated with the June–July–August SST and SST tendency. … The multi-month SST tendency, i.e., the SST difference of June–July–August minus April–May, is correlated with the winter AO at r = 0.75.Investigation of the regional air–sea fluxes and oceanic dynamics reveals that the net surface heat flux cannot account for the warming, whereas the oceanic Rossby wave plays a predominant role. During positive AO winters, the enhanced Arabian High causes stronger northern winds in the northern Indian Ocean and leads to anomalous cross-equatorial air-flow. … The winter AO-forced Rossby wave propagates westward and arrives at the western coast in summer, resulting in the significant SST increase.

Yuan et al., 2017     On the timescale of decades, changes in MJO [Madden-Julien Oscillation]phases can result in temperature and sea ice changes in the polar regions of both hemispheres. Moreover, the long-term changes in SST of the western tropical Pacific, tropical Atlantic, and North Atlantic Ocean have been linked to the rapid winter warming around the Antarctic Peninsula, while SST changes in the central tropical Pacific have been linked to the warming in West Antarctica. Rossby wave trains emanating from the tropics remain the key mechanism for tropical and polar teleconnections from intraseasonal to decadal timescales. ENSO related tropical SST anomalies affect higher latitude annular modes, by modulating mean zonal winds in both the subtropics and mid-latitudes. Recent studies have also revealed the details of the interactions between the Rossby wave and atmospheric circulations in high latitudes. .. In addition to atmospheric Rossby waves forced from the tropics, large polar temperature changes and amplification, in part associated with variability in orbital configuration and solar irradiance, affected the low-high latitude connections.

Modern Climate In Phase With Natural Variability (13)

Seviour, 2017     Weakening and shift of the Arctic stratospheric polar vortex: Internal variability or forced response? … By comparing large ensembles of historical simulations with pre-industrial control simulations for two coupled climate models, the ensemble mean response of the vortex is found to be small relative to internal variability. There is also no relationship between sea-ice decline and trends in either vortex location or strength. Despite this, individual ensemble members are found to have vortex trends similar to those observed, indicating that these trends may be primarily a result of natural internally-generated climate variability.
Xie and Zhang, 2017     The North America continent experienced an extremely anomalous dipole climate in the 2014/2015 winter with record-breaking cold temperature anomalies in the east and warm anomalies in the west. … [W]e conclude that the 2014/2015 winter extreme dipole climate is a low-probability event that is primarily caused by internal atmospheric variability based on the single model CAM4.
Shi et al., 2017     Five of the six coupled ocean-atmosphere climate models of the Paleoclimate Modeling Intercomparison Project Phase III (PMIP3), can reproduce the south-north dipole mode of precipitation in eastern China, and its likely link with ENSO. However, there is mismatch in terms of their time development. This is consistent with an important role of the internal variability in the precipitation field changes over the past 500 years.

Conroy et al., 2017     20th century precipitation variability in southern Tibet falls within the range of natural variability in the last 4100 yr, and does not show a clear trend of increasing precipitation as projected by models. Instead, it appears that poorly understood multidecadal to centennial internal modes of monsoon variability remained influential throughout the last 4100 yr. … Until we have a predictive understanding of multidecade to multi-century variability in the Asian monsoon system, it would be wise to consider the risk of prolonged periods of anomalously dry and wet monsoon conditions to be substantial (Ault et al., 2014). Such variability may also explain why the predicted anthropogenic increase in Asian monsoon precipitation is not widely observed.
Macdonald and Sangster, 2017     The findings identify that whilst recent floods are notable, several comparable periods of increased flooding are identifiable historically, with periods of greater frequency (flood-rich periods). Statistically significant relationships between the British flood index, the Atlantic Meridional Oscillation and the North Atlantic Oscillation Index are identified. The use of historical records identifies that the largest floods often transcend single catchments affecting regions and that the current flood-rich period is not unprecedented.
Verdon-Kidd et al., 2017     Overall, the inter-annual and inter-decadal variability of rainfall and runoff observed in the modern record (Coefficient of Variation (CV) of 22% for rainfall, 42% for runoff) is similar to the variability experienced over the last 500 years (CV of 21% for rainfall and 36% for runoff). However, the modern period is wetter on average than the pre-instrumental (13% higher for rainfall and 23% higher for runoff). Figure 9 also shows that the reconstructions contain a number of individual years (both wet and dry) of greater magnitude than what has been recorded in the instrumental record.

Kostyakova et al., 2017     A nested July–June precipitation reconstruction for the period AD 1777–2012 was developed from multi-century tree-ring records of Pinus sylvestris L. (Scots pine) for the Republic of Khakassia in Siberia, Russia. … The longest reconstructed dry period, defined as consecutive years with less than 25th percentile of observed July–June precipitation, was 3 years (1861–1863)There was no significant difference in the number dry and wet periods during the 236 years of the reconstructed precipitation.

Hu et al., 2017     [I]t was a challenge to predict the evolution of this warm event, especially for its growth. That is consistent with the fact that the SSTAs [sea surface temperature anomalies] in extratropical oceans are largely a consequence of unpredictable atmospheric variability.  [T]he marked differences in both the spatial distribution and amplitude between Figs. 4 and 3 suggest that maybe only a fraction of the observed variability in NEPO was forced by the SSTA while a large amount of the observed variability may have been a consequence of the atmospheric internal variability (noise). That is consistent with the conclusion from some recent works in examining the climate variability in mid- and high latitudes of the Northern Hemisphere, such as Baxter and Nigam (2015), Hartmann (2015), Lee et al. (2015), Seager et al. (2015), Watson et al. (2016), and Jha et al. (2016). … The remarkable amplitude differences between the observations (Fig. 3) and the simulations (Fig. 4) plus the large fluctuation of the pattern correlation (Figs. 5a, 6a), are indicative of the importance of the atmospheric internal variability (noise) in driving the observed anomalies in NEPO [northeastern Pacific Ocean].  [I]t was a challenge to predict the persistent SST anomalies in the northeastern Pacific because the SST anomaly in NEPO [northeastern Pacific Ocean] is largely controlled by unpredictable stochastic [random] atmosphere variability.    [CO2 and/or anthropogenic forcing is not mentioned once in the paper.]
Goldsmith et al., 2017     The EAM [East Asian Monsoon] intensity and northern extent alternated rapidly between wet and dry periods on time scales of centuries. Lake levels were 60 m higher than present during the early and middle Holocene, requiring a twofold increase in annual rainfall [relative to today], which, based on modern rainfall distribution, requires a ∼400 km northward expansion/migration of the EAM.
Stegall and Kunkel, 2017     These results indicate that there is potential skill in use of GCMs [climate models] to provide projections of hot and cold extremes on the 30-yr timescale. However, it is important to note that natural variability is comparable to the forced signal on this timescale and thus introduces uncertainty.
Bordbar et al,, 2017     The observed trends in the tropical Pacific surface climate are still within the range of the long-term internal variability spanned by the models but represent an extreme realization of this variability. Thus, the recent observed decadal trends in the tropical Pacific, though highly unusual, could be of natural origin. We note that the long-term trends in the selected PWC indices exhibit a large observational uncertainty, even hindering definitive statements about the sign of the trends.
Bhaskar et al., 2017     Quantitative assessment of drivers of recent [1984-2005] global temperature variability … Measurements of greenhouse gases: CO2,  CH4  and  N2O; volcanic aerosols; solar activity: UV radiation, total solar irradiance (TSI) and cosmic ray flux (CR); El Niño Southern Oscillation (ENSO) and Global Mean Temperature Anomaly (GMTA) made during 1984–2005 are utilized to distinguish driving and responding signals of global temperature variability.  Estimates of their relative contributions reveal that  CO2  ( 24%),  CH4  ( 19%) and volcanic aerosols ( 23%) are the primary contributors to the observed variations in GMTA [Global Mean Temperature Anomaly]. While UV ( 9%) and ENSO ( 12%) act as secondary drivers of variations in the GMTA, the remaining play a marginal role in the observed recent global temperature variability. Interestingly, ENSO and GMTA mutually drive each other at varied time lags. … [A]ll the constituents of natural forcings together seem to make contributions equal to the greenhouse gases in the context of recent global temperature variability.  [76% of changes global temperatures are not driven by CO2.  Water vapor and clouds, the dominant contributors to the greenhouse effect, are oddly excluded from consideration in this study.]

Abbot and Marohasy, 2017    The largest deviation between the ANN [artificial neural network] projections and measured temperatures for six geographically distinct regions was approximately 0.2 °C, and from this an Equilibrium Climate Sensitivity (ECS) of approximately 0.6 °C [for a doubling of CO2 from 280 ppm to 560 ppm plus feedbacks] was estimated. This is considerably less than estimates from the General Circulation Models (GCMs) used by the Intergovernmental Panel on Climate Change (IPCC), and similar to estimates from spectroscopic methods. … The proxy measurements suggest New Zealand’s climate has fluctuated within a band of approximately 2°C since at least 900 AD, as shown in Figure 2. The warming of nearly 1°C since 1940 falls within this band. The discrepancy between the orange and blue lines in recent decades as shown in Figure 3, suggests that the anthropogenic contribution to this warming could be in the order of approximately 0.2°C. [80% of the warming since 1940 may be due natural factors]. … Importantly, an upward trend is generally apparent for both the proxy measurements and the ANN model projection for the 20th century. This would suggest that the increase in temperature over the last 100 years can be largely attributed to natural phenomena.
(press release)      [O]ur new technical paper in GeoResJ (vol. 14, pages 36-46) will likely be ignored.  Because after applying the latest big data technique to six 2,000 year-long proxy-temperature series we cannot confirm that recent warming is anything but natural – what might have occurred anyway, even if there was no industrial revolution. … [E]ven if there had been no industrial revolution and burning of fossil fuels, there would have still been warming through the twentieth century – to at least 1980, and of almost 1°C.

Cloud/Aerosol Climate Influence (9)

Stozhkov et al., 2017     One of the most important problems facing humanity is finding the physical mechanism responsible for global climate change, particularly global warming on the Earth. … Summation of these periodicities for the future (after 2015) allows us to forecast the next few decades. The solid heavy line in Fig. 1 shows that cooling (a drop in ΔT values) is expected in the next few decades. … Figure 2 shows the dependence between the annual average changes ΔT in the global temperature in the near-surface air layer and charged particle flux N in the interval of altitudes from 0.3 to 2.2 km. We can see there is a connection between values ΔТ [temperature] and N [charged particle flux]: with an increase in cosmic ray flux N, the values of changes of global temperature decrease. This link is expressed by the relation ΔT = –0.0838N + 4.307 (see the dashed line in Fig. 2), where the ΔT values are given in °C, and the N values (in particle/min units) are related to the charged particle flux measured at an altitude of 1.3 km. The correlation coefficient of the line with the experimental data is r = –0.62 ± 0.08. … Our results could be connected with the mechanism of charged particle fluxes influencing the Earth’s climate; it includes, first of all, the effect charged particles have on the accelerated formation of centers of water vapor condensation, and thus on the increase in global cloud cover. The total cloud cover is directly connected with the global temperature of the near surface air layer.

Tang et al., 2017     The results show that aerosol direct effect cannot fully explain the decadal variations in the global radiation over China between 1980 and 2010, though it has a considerable effect on global radiation climatology. There are significant differences between the trends of clear-sky global radiation impacted by aerosols and those of all-sky global radiation impacted by aerosols and clouds, and the correlation coefficient for the comparison is very low. Therefore, the variations in all-sky global radiation over China are likely to be due to changes in cloud properties and to interactions between clouds and aerosols.
Glotfelty and Zhang, 2017     Enhancements in cloud formation in the Arctic and Southern Ocean and increases of aerosol optical depth (AOD) in central Africa and South Asia dominate the change in surface radiation in both scenarios [during 2050 – 2100], leading to global average dimming of 1.1 W m−2 and 2.0 W m−2 in the RCP4.5 and RCP8.5 scenarios, respectively. Declines in AOD [aerosol optical depth], cloud formation, and cloud optical thickness from reductions of emissions of primary aerosols and aerosol precursors under RCP4.5 result in near surface warming of 0.2 °C from a global average increase of 0.7 W m−2 in surface downwelling solar radiation. This warming leads to a weakening of the Walker Circulation in the tropics, leading to significant changes in cloud and precipitation that mirror a shift in climate towards the negative phase of the El Nino Southern Oscillation.  [Cloud and aerosols dominate the change in surface solar radiation, overwhelming the effects of anthropogenic CO2 emissions.]
Solomon et al., 2017     A number of feedbacks are found that damp the warming effect of the clouds. Thin mixed-phase clouds increase the downward longwave fluxes by 100 W m−2, but upward daytime surface longwave fluxes increase by 20 W m−2 (60 W m−2 at night) and net shortwave fluxes decrease by 40 W m−2 (partially due to a 0.05 increase in surface albedo), leaving only 40 W m−2 available for melt. This 40 W m−2 is distributed between the turbulent and conductive ground fluxes, so it is only at times of weak turbulent fluxes (i.e., at night or during melt) that this energy goes into the conductive ground flux, providing energy for melt. From these results it is concluded that it is the integrated impact of the clouds over the diurnal cycle (the preconditioning of the snowpack by the clouds at night) that made melt possible during this 3-day period. These findings are extended to understand the pattern of melt observed over the GIS. … Mixed-phase clouds are common at Summit (Shupe et al. 2013) and play a critical role in the Arctic surface energy balance (Shupe and Intrieri 2004), radiatively warming the highly reflective surface at Summit year-round (Miller et al. 2015).
Nicolas et al., 2017     During the short Antarctic summer, strong onshore winds may by themselves raise the ice sheet’s surface temperature (Ts) up to the melting point (through exchange of sensible heat), especially at low elevations. However, Ts [surface temperature] is ultimately controlled by the full surface energy budget (SEB), being the net of radiative (short- and longwave) and turbulent (sensible and latent) heat fluxes. Clouds exert an important influence on the SEB by modulating the radiative fluxes, primarily by enhancing downwelling longwave radiation and attenuating incoming solar radiation. In particular, low-level liquid-bearing clouds can have a determinant role in either causing or prolonging melting conditions over ice sheets. … Positive (anticyclonic) geopotential height anomalies in the South Pacific, such as those observed in January 2016, are a typical signature of El Niño teleconnections, as seen both in observations and climate model simulations. This type of atmospheric pattern promotes warm air advection to the Ross sector, which explains why surface melt in this area tends to be associated with El Niño-like conditions.  [CO2 not mentioned as a factor in West Antarctica ice melt]
Scott et al., 2017     Clouds are an essential parameter of the surface energy budget influencing the West Antarctic Ice Sheet (WAIS) response to atmospheric warming and net contribution to global sea level rise.  … Owing to perennial high-albedo snow and ice cover, cloud infrared emission dominates over cloud solar reflection and absorption leading to a positive net all-wave cloud radiative effect (CRE) at the surface … The annual-mean CRE [cloud radiative effect] at the WAIS [West Antarctic Ice Sheet] surface is 34 W m−2, representing a significant cloud-induced warming of the ice sheet. … In summer, clouds warm the WAIS by 26 W m−2, on average, despite maximum offsetting shortwave CRE.
Ott et al., 2017     Understanding the earth’s energy balance is key to understanding global warming. The incoming solar radiation, and hence the energy received, is influenced by absorption and reflection processes during its travel through the atmosphere. Of particular interest is the effect of clouds on the reflection of solar radiation compared to a clear-sky situation, known as the cloud radiative effect (CRE). …  Using the pre-industrial control run of the CMIP5 models for all BSRN sites, an overall annual variability in clear-sky radiation of 6.1 W/m2 between the 5th and 95th percentile was found. Extreme values reach up to 20 W/m2 in annual variability.
Yamasoe et al., 2017     We analyzed the variability of downward solar irradiance reaching the surface at São Paulo city, Brazil, and estimated the climatological aerosol and cloud radiative effects. Eleven years of irradiance were analyzed, from 2005 to 2015. … Results showed that, climatologically, clouds can be 4 times more effective than aerosols. The cloud shortwave radiative effect presented a maximum reduction of about −170 W m−2 in January and a minimum in July, of −37 W m−2. [T]he 24 h radiative effect due to aerosol only was estimated to be −50 W m−2. Throughout the rest of the year, the mean aerosol effect was around −20 W m−2 and was attributed to local urban sources.
Jones et al., 2017     The net radiative forcing from clouds can be as high as four times as large as the radiative forcing from a doubling of CO2 levels in the atmosphere, which needs to be taken into account when ascribing coral bleaching events in the GBR solely to GHG warming. … The growth of CCN [cloud condensation nuclei] can lead to the formation of low level cloud (LLC) such as cumulous and stratocumulus clouds, decreasing solar radiation and sea surface temperatures (SST), thus influencing climate as a negative climate feedback.

Volcanic/Tectonic Climate Influence (6)

Kelley, 2017     Volcanology: Vulcan rule beneath the sea … Over 70% of the volcanism on Earth occurs beneath an ocean veil. … Satellite data reveal more than 100,000 extinct and active seamounts that mark sites of past and present volcanic activity.  [O]bservations imply that submarine volcanoes may play an important role in cycling carbon and sulfur through the Earth, oceans and atmosphere. … [T]he flux of volatiles from these systems remains poorly quantified and the significance of these volcanoes as part of the deep carbon and sulfur cycles on a global scale is unknown.
Viterito, 2017     The Correlation of Seismic Activity and Recent Global Warming (CSARGW) demonstrated that increasing seismic activity in the globe’s high geothermal flux areas (HGFA) is strongly correlated with global temperatures (r=0.785) from 1979-2015. The mechanism driving this correlation is amply documented and well understood by oceanographers and seismologists. Namely, increased seismic activity in the HGFA (i.e., the mid-ocean’s spreading zones) serves as a proxy indicator of higher geothermal flux in these regions. The HGFA include the Mid-Atlantic Ridge, the East Pacific Rise, the West Chile Rise, the Ridges of the Indian Ocean, and the Ridges of the Antarctic/Southern Ocean. This additional mid-ocean heating causes an acceleration of oceanic overturning and thermobaric convection, resulting in higher ocean temperatures and greater heat transport into the Arctic. This manifests itself as an anomaly known as the “Arctic Amplification,” where the Arctic warms to a much greater degree than the rest of the globe. Applying the same methodology employed in CSARGW, an updated analysis through 2016 adds new knowledge of this important relationship while strengthening support for that study’s conclusions. The correlation between HGFA seismic frequency and global temperatures moved higher with the addition of the 2016 data: the revised correlation now reads 0.814, up from 0.785 for the analysis through 2015. This yields a coefficient of determination of .662, indicating that HGFA [high geothermal flux area] seismicity accounts for roughly two-thirds of the variation in global temperatures since 1979.
Smirnov et al., 2017     Here we use the Wiener-Granger causality approach along with well-established cross-correlation analysis to investigate the causal relationship between solar activity, volcanic forcing, and climate as reflected in well-established Intertropical Convergence Zone (ITCZ) rainfall proxy records from Yok Balum Cave, southern Belize. Our analysis reveals a consistent influence of volcanic activity on regional Central American climate over the last two millennia. However, the coupling between solar variability and local climate varied with time, with a regime shift around 1000–1300 CE after which the solar-climate coupling weakened considerably.
Huhtemaa and Helama, 2017     Large tropical volcanic eruptions can have considerable impact on climates and societies far away from the physical source of the eruption.  … [C]ooling caused by volcanism led to severe crop failures in seventeenth-century Ostrobothnia, Finland. … [M]ore than half of the agricultural crises in the study region can be associated with cooling caused by volcanism. …[A]gricultural crises were followed by impoverishment and hunger.
Slawinska and Robock, 2017     We evaluate different hypotheses of the origin of the Little Ice Age, focusing on the long-term response of Arctic sea ice and oceanic circulation to solar and volcanic perturbations. …We argue that large volcanic forcing is necessary to explain the origin and duration of Little-Ice-Age-like perturbations in the Last Millennium Ensemble. Other forcings might play a role as well. In particular, prolonged fluctuations in solar irradiance associated with solar minima potentially amplify the enhancement of the magnitude of volcanically-triggered anomalies of Arctic sea ice extent.
Herndon, 2017     Climate models evaluated by the IPCC are based on the assumptions that: (1) Heat derived from the Sun is constant; (2) Heat derived from within the Earth is constant; and, (3) Anthropogenic contributions to atmospheric warming stem mainly from heat retention by CO2 and other greenhouse gases. Geophysical evidence of variable earthquake activity and geological evidence of variable submarine volcanism presented here indicate that heat added to the oceans is variable. The increasing occurrences of earthquakes of magnitudes ≥6 and ≥7 during 1973-2015 indicate volcanic activity is increasing and therefore Earth-heat, as well as volcanic CO2 additions, is increasing. Moreover, increased heat additions to the ocean act to decrease seawater solubility of CO2, ultimately releasing additional CO2 to the atmosphere. Furthermore, increasing submarine volcanic activity implies increasing ocean acidification, but data are insufficient to make quantitative estimates. The validity of IPCC evaluations and assessments depends critically upon due consideration being given to all processes that potentially affect Earth’s heat balance. In addition to the geological and geophysical processes discussed, the scientific community, including IPCC scientists, has turned a blind eye to ongoing tropospheric geoengineering that in recent years has been occurring on a near-daily, near-global basis. Tropospheric aerosolized particulates, evidenced as coal fly ash, inhibit rainfall, heat the atmosphere, and cause global warming. Evidence obtained from an accidental air-drop release indicates efforts to melt glacial ice and enhance global warming.  By ignoring ongoing tropospheric geoengineering, IPCC assessments are compromised, as is the moral authority of the United Nations.

Challenging The Theoretical CO2 Greenhouse Effect As Temperature Driver (15)

Hertzberg et al., 2017     This study examines the concept of ‘greenhouse gases’ and various definitions of the phenomenon known as the ‘Atmospheric Radiative Greenhouse Effect’. The six most quoted descriptions are as follows: (a) radiation trapped between the Earth’s surface and its atmosphere; (b) the insulating blanket of the atmosphere that keeps the Earth warm; (c) back radiation from the atmosphere to the Earth’s surface; (d) Infra Red absorbing gases that hinder radiative cooling and keep the surface warmer than it would otherwise be – known as ‘otherwise radiation’; (e) differences between actual surface temperatures of the Earth (as also observed on Venus) and those based on calculations; (f) any gas that absorbs infrared radiation emitted from the Earth’s surface towards free space. It is shown that none of the above descriptions can withstand the rigours of scientific scrutiny when the fundamental laws of physics and thermodynamics are applied to them.
Blaauw, 2017     This paper demonstrates that global warming can be explained without recourse to the greenhouse theory. This explanation is based on a simple model of the Earth’s climate system consisting of three layers: the surface, a lower and an upper atmospheric layer. The distinction between the atmospheric layers rests on the assumption that the latent heat from the surface is set free in the lower atmospheric layer only. The varying solar irradiation constitutes the sole input driving the changes in the system’s energy transfers. All variations in the energy exchanges can be expressed in terms of the temperature variations of the layers by means of an energy transfer matrix. It turns out that the latent heat transfer as a function of the temperatures of the surface and the lower layer makes this matrix next to singular. The near singularity reveals a considerable negative feedback in the model which can be identified as the ‘Klimaversta¨rker’ presumed by Vahrenholt and Lu¨ning. By a suitable, yet realistic choice of the parameters appearing in the energy transfer matrix and of the effective heat capacities of the layers, the model reproduces the global warming: the calculated trend in the surface temperature agrees well with the observational data from AD 1750 up to AD 2000.

Nikolov and Zeller, 2017     Our analysis revealed that GMATs [global mean annual temperatures] of rocky planets with tangible atmospheres and a negligible geothermal surface heating can accurately be predicted over a broad range of conditions using only two forcing variables: top-of-the-atmosphere solar irradiance and total surface atmospheric pressure. The hereto discovered interplanetary pressure-temperature relationship is shown to be statistically robust while describing a smooth physical continuum without climatic tipping points. This continuum fully explains the recently discovered 90 K thermal effect of Earth’s atmosphere. The new model displays characteristics of an emergent macro-level thermodynamic relationship heretofore unbeknown to science that has important theoretical implications. A key entailment from the model is that the atmospheric ‘greenhouse effect’ currently viewed as a radiative phenomenon is in fact an adiabatic (pressure-induced) thermal enhancement analogous to compression heating and independent of atmospheric composition. Consequently, the global down-welling long-wave flux presently assumed to drive Earth’s surface warming appears to be a product of the air temperature set by solar heating and atmospheric pressure. In other words, the so-called ‘greenhouse back radiation’ is globally a result of the atmospheric thermal effect rather than a cause for it. … The down-welling LW radiation is not a global driver of surface warming as hypothesized for over 100 years but a product of the near-surface air temperature controlled by solar heating and atmospheric pressure The hypothesis that a freely convective atmosphere could retain (trap) radiant heat due its opacity has remained undisputed since its introduction in the early 1800s even though it was based on a theoretical conjecture that has never been proven experimentally.
Allmendinger, 2017     The cardinal error in the usual greenhouse theory consists in the assumption that photometric or spectroscopic IR-measurements allow conclusions about the thermal behaviour of gases, i.e., of the atmosphere. They trace back to John Tyndall who developed such a photometric method already in the 19th century. However, direct thermal measurement methods have never been applied so far. Apart from this, at least twenty crucial errors are revealed which suggest abandoning the theory as a whole. In spite of its obvious deficiencies, this theory has so far been an obstacle to take promising precautions for mitigating the climate change. They would consist in a general brightening of the Earth surface, and in additional measures being related to this. However, the novel effects which were found by the author, particularly the absorption of incident solar-light by the atmosphere as well as its absorption capability of thermal radiation, cannot be influenced by human acts.
Munshi, 2017     A key relationship in the theory of anthropogenic global warming (AGW) is that between annual fossil fuel emissions and annual changes in atmospheric CO2. The proposed causation sequence is that annual fossil fuel emissions cause annual changes in atmospheric CO2 which in turn intensifies the atmosphere’s heat trapping property. … A testable implication of the proposed causation sequence is that annual changes in atmospheric CO2 must be related to annual fossil fuel emissions at an annual time scale. This work is a test of this hypothesis. We find that detrended correlation analysis of annual emissions and annual changes in atmospheric CO2 does not support the anthropogenic global warming hypothesis because no evidence is found that changes in atmospheric CO2 are related to fossil fuel emissions at an annual time scale.
Reinhart, 2017     Our results permit to conclude that CO2 is a very weak greenhouse gas and cannot be accepted as the main driver of climate change. … The assumption of a constant temperature and black body radiation definitely violates reality and even the principles of thermodynamics. … [W]e conclude that the temperature increases predicted by the IPCC AR5 lack robust scientific justification. … A doubling [to 800 ppm] of the present level of CO2 [400 ppm] results in [temperature change] < 0.24 K. … [T]he scientific community must look for causes of climate change that can be solidly based on physics and chemistry. … The observed temperature increase since pre-industrial times is close to an order of magnitude higher than that attributable to CO2.
Lightfoot and Mamer, 2017     Robust scientific evidence shows the sun angle controls water vapour content of the atmosphere, the main component of back radiation, as it cycles annually. Water vapour content measured as the ratio of the number of water molecules to CO2 molecules varies from 1:1 near the Poles to 97:1 in the Tropics. The effect of back radiation [water vapour] on Earth’s atmosphere is up to 200 times larger than that of CO2 and works in the opposite direction. Thus, if CO2 has any effect on atmospheric temperature and climate change we show it is negligible. Consequently, current government policies to control atmospheric temperature by limiting consumption of fossil fuels will have negligible effect. Measured data reported in IPCC report Climate Change 2013: The Physical Science Basis (AR5) indicate increased water vapour content of the atmosphere is the cause of the 0.5℃ temperature increase from the mid-1970s to 2011.

Pontius, 2017     Using a Climate Sensitivity best estimate of 2°C, the increase in [global] temperature resulting from a doubling of atmospheric CO2 is estimated at approximately 0.009°C/yr which is insignificant compared to natural variability.  … Estimates of climate sensitivity differ widely suggesting that this characteristic of the climate system is not well-understood (Schwartz et al., 2014).  Judgments and arbitrary choices must be made in model construction to apply fundamental laws to describe turbulent fluid flow. The large size and complexity of the atmosphere prohibit the direct application of general theory.  In general, ensemble model forecasts have been found unreliable for long-term climate prediction (Green and Armstrong, 2007, Mihailović et al., 2014). … Historical evidence of a significant increase in surface temperatures due to increases in atmospheric CO2 is absent from these data.   [C]limate models are useful but limited in their representation of underlying physical processes.  Uncertainties and other limitations discussed previously render such models unreliable for long-term global temperatures or local climate change prediction. … If atmospheric CO2 continues to increase at its current rate the small annual temperature increase expected at Riverside will likely be insignificant (e.g. < 0.01°C/yr) compared to natural temperature variability.

Kramm et al., 2017     The planetary radiation balance plays a prominent role in quantifying the effect of the terrestrial atmosphere (spuriously called the atmospheric greenhouse effect). Based on this planetary radiation balance, the effective radiation temperature of the Earth in the absence of its atmosphere of Te ≅ 255 K is estimated. This temperature value is subtracted from the globally averaged near-surface temperature of about Tns 288 K resulting in Tns − Te 33 K. This temperature difference [33 K] commonly serves to quantify the atmospheric effect. The temperature difference is said to be bridged by optically active gaseous gases, namely H2O (20.6 K); CO2 (7.2 K) Since the “thought experiment” of an Earth in the absence of its atmosphere does not allow any rigorous assessment of such results, we considered the Moon as a testbed for the Earth in the absence of its atmosphere.  […] Based on our findings, we may conclude that the effective radiation temperature yields flawed results when used for quantifying the so-called atmospheric greenhouse effect. … (1) Only a planetary radiation budget of the Earth in the absence of an atmosphere is considered [in the 288 K – 255 K = 33 K “thought experiment” greenhouse effect], i.e., any heat storage in the oceans (if at all existing in such a case) and land masses is neglected. … (2) The assumption of a uniform surface temperature for the entire globe is rather inadequate. … (3) The choice of the planetary albedo of αE=0.30 is rather inadequate… (4) Comparing Te [Earth’s temperature without an atmosphere] with ⟨Tns⟩ [Earth’s globally averaged near surface temperature] is rather inappropriate because the meaning of these temperatures is quite different. The former is based on an energy-flux budget at the surface even though it is physically inconsistent because of the non-uniform temperature distribution on the globe. Whereas the latter is related to globally averaging near-surface temperature observations made at meteorological stations (supported by satellite observations). … (Equation 1.4, [the 288 K – 255 K = 33 K “thought experiment” green house effect]) is based on physically irrelevant assumptions and its results considerably disagree with observations. Consequently, the difference of ΔTae  33 K [the alleged planetary temperature difference due to the greenhouse effect] lacks adequate physical meaning as do any contributions from optically active gaseous components calculated thereby.
Munshi, 2017     A study of regional temperature reconstructions of the instrumental record 1850-2016 for five global regions is presented. No evidence is found to relate warming of sea surface temperature (SST) in either hemisphere to global emissions. The rate of warming over land in the Northern Hemisphere appears to show some evidence of correlation with global emissions in five of the twelve calendar months but the statistical significance of the correlation could not be verified with station data from the region. No correlation with emissions could be found in regional temperature reconstructions for land in the Southern Hemisphere or for combined land and ocean in either hemisphere. These results taken together do not support the claim that the observed warming in surface temperatures worldwide since the Industrial Revolution is driven by fossil fuel emissions or that observed changes in tropical cyclone characteristics due to rising SST are anthropogenic.
Allmendinger, 2017     Besides a critical discussion of the convenient atmosphere theory profoundly questioning the greenhouse thesis by disclosing several basic errors, the here reported investigation reveals the discovery of direct absorption of shortwave IR-radiation by air. It is part of the incident solar light, but also of artificial light which enables a more exact detection. It is caused by another effect than the one which is responsible for the longer-wave absorption being observed at carbon dioxide, and it is not detectable by IR-spectroscopy since its absorption coefficient is too low. However, it is clearly detectable by means of the here applied apparatus leading to a distinct temperature elevation up to a limiting temperature which depends on the radiative emission. The limiting temperature depends on the gas kind, whereby practically no difference between air and carbon-dioxide could be found. … Nevertheless, that direct absorption effect [shortwave] which was discovered thanks to this method probably contributes significantly to the warming up of the atmosphere while the warming-up due to carbon-dioxide can be neglected. … But since the direct absorption cannot be influenced, the surface albedo must be focused as the governing factor providing the only [anthropogenic] opportunity to mitigate the climate, or at least the microclimate, by changing colour and structure of the surface, particularly in urban areas. However, a prediction seems not feasible since the global climate is too complex. But the greenhouse theory turns out to be a phantasm delivering the wrong diagnosis for the climate change, and a wrong diagnosis cannot enable a healing.
Smirnov, 2017     It is shown that infrared emission of the atmosphere is determined mostly by atmospheric water. One can separate the flux of outgoing infrared radiation of the atmosphere from that towards the Earth. The fluxes due to rotation-vibration transitions of atmospheric   CO2  molecules are evaluated. Doubling of the concentration of  CO2 molecules in the atmosphere that is expected over 130 years leads to an increase of the average Earth temperature by (0.4±0.2) K mostly due to the flux towards the Earth if other atmospheric parameters are not varied.
Robertson and Chilingar, 2017     One can summarize our findings as follows:
The anthropogenic impact on the global atmospheric temperature is negligible, i.e., 5% (Matthews, 1998).
• Changes in the solar irradiation (global temperature) precede the corresponding changes in the carbon dioxide concentration in the atmosphere.
• Any attempt to mitigate undesirable climatic changes using restrictive regulations are condemned to failure, because global forces of nature are at least 4 orders of magnitude greater than the available human controls

Christy and McNider, 2017     We identify and remove the main natural perturbations (e.g. volcanic activity, ENSOs) from the global mean lower tropospheric temperatures (TLT) over January 1979 – June 2017 to estimate the underlying, potentially human-forced trend. The unaltered value is +0.155 K dec−1 while the adjusted trend is +0.096 K dec−1, related primarily to the removal of volcanic cooling in the early part of the record. This is essentially the same value we determined in 1994 (+0.09 K dec−1, Christy and McNider, 1994) using only 15 years of data. If the warming rate of +0.096 K dec−1 represents the net TLT response to increasing greenhouse radiative forcings, this implies that the TLT tropospheric transient climate response (ΔTLT at the time CO2 doubles) is +1.10 ± 0.26 K which is about half of the average of the IPCC AR5 climate models of 2.31 ± 0.20 K. Assuming that the net remaining unknown internal and external natural forcing over this period is near zero, the mismatch since 1979 between observations and CMIP-5 model values suggests that excessive sensitivity to enhanced radiative forcing in the models can be appreciable. 
Davis, 2017     [I]f anthropogenic CO2 emissions continue at today’s levels or increase in the coming decades, the consequent increasing concentration of CO2 in the atmosphere from anthropogenic sources will have exponentially smaller forcing impact on global temperature. The half-decay of CO2marginal forcing (~337 ppmv) was surpassed in 1980, while the exponential marginal forcing decay constant (~367 ppmv) was exceeded in 1999. At the current atmospheric CO2 concentration, which is approaching 410 ppmv, atmospheric CO2 has lost nearly two-thirds of its cumulative marginal forcing power. … [A]s atmospheric CO2 concentration increases, any unit reductions in atmospheric CO2 concentration that may be achieved by deliberate mitigation of CO2 emissions will yield exponentially smaller reductions of temperature forcing. Diminishing returns in marginal forcing by atmospheric CO2 ensure, therefore, that efforts to mitigate global warming by reducing emissions of CO2, exemplified by carbon sequestration, will become relatively more expensive per unit of climate benefit returned. This consequence of atmospheric physics will increase the cost-benefit ratio of CO2 mitigation policies exponentially, at least insofar as the cost-benefit ratio is limited to climate. … Diminishing returns in the forcing power of atmospheric CO2 as its concentration increases ensure that in a CO2-rich environment like the Phanerozoic climate, large variations in CO2 exert little or negligible effects on temperature. Therefore, decoupling between atmospheric CO2 concentration and temperature is not only demonstrated empirically in Phanerozoic data, but is also expected from first principles. This straightforward consequence of atmospheric physics provides a simple physical explanation for the lack of correlation between atmospheric CO2 concentration and temperature across most of the Phanerozoic.

Part 2. Unsettled Science, Ineffective Climate Modeling

Climate Model Unreliability/Biases/Errors and the Pause (28)

Scafetta et al., 2017     [T]he AGWT [Anthropogenic Global Warming Theory] was globally advocated by the IPCC in 2001 because it appeared to be supported by the ‘infamous’ Hockey Stick temperature reconstructions by Mann et al. [1998, 1999].  … However, since 2005 novel Northern Hemisphere proxy temperature reconstructions were published revealing the existence of a large millennial oscillation that contradicts the Hockey Stick temperature pattern. … The new findings were consistent with alternative climatic and solar activity records showing that a quasi-millennial oscillation occurred throughout the entire Holocene for the last 10,000 years. … The severe discrepancy between observations and modeled predictions found during the 1922-1941 and 2000-2016 periods further confirms, according to the criteria proposed by the AGWT [anthropogenic global warming theory] advocates themselves, that the current climate models have significantly exaggerated the anthropogenic greenhouse warming effect.  [A]ccording to the AGWT advocates’ own criteria, a divergence between observations and climate models occurring at the bi-decadal scale would provide strong convincing evidences that the GCMs used to support the AGWT [Anthropogenic Global Warming Theory] are severely flawed. … In conclusion, the temperature records clearly manifest several fluctuations from the inter-annual scale to the multidecadal one. Detailed spectral analyses have determined the likely existence of harmonics at about 9.1, 10.5, 20 and 60- year periods. By contrast, the CMIP5 GCMs simulations used by the IPCC (2013) to advocate the AGWT show a quite monotonic accelerating warming since 1860 …Thus, the models are not able to reproduce the natural variability observed in the climate system and should not be trusted for future energy planning.
Scafetta et al., 2017     A millennial climatic oscillation would suggest that a significant percentage of the warming observed since 1850 could simply be a recovery from the Little Ice Age of the 14th – 18th centuries and that throughout the 20th century the climate naturally returned to a warm phase as it happened during the Roman and the Medieval warm periods. … We critically analyze the year 2015-2016, which has been famed as the hottest year on record. We show that this anomaly is simply due to a strong El-Niño event that has induced a sudden increase of the global surface temperature by 0.6 °C. This event is unrelated to anthropogenic emissions. …  Herein, the authors have studied the post 2000 standstill global temperature records. It has been shown that once the ENSO signature is removed from the data, the serious divergence between the observations and the CMIP5 GCM projections becomes evident. … Since 2000 there has been a systematic tendency to find lower climate sensitivity values. The most recent studies suggest a transient climate response (TCR) of about 1.0 °C, an ECS less than 2.0 °C and an effective climate sensitivity (EfCS) in the neighborhood of 1.0 °C. …Thus, all evidences suggest that the IPCC GCMs at least increase twofold or even triple the real anthropogenic warming. The GHG theory might even require a deep re-examination.

Blackall, 2017     The science publication Nature Climate Change this year published a study demonstrating Earth this century warmed substantially less than computer-generated climate models predict. Unfortunately for public knowledge, such findings don’t appear in the news. Sea levels too have not been obeying the ‘grand transnational narrative’ of catastrophic global warming. Sea levels around Australia 2011–2012 were measured with the most significant drops in sea levels since measurements began. This phenomenon was due to rainfall over Central Australia, which filled vast inland lakes. It was not predicted in the models, nor was it reported in the news. The 2015–2016 El-Niño, a natural phenomenon, drove sea levels around Indonesia to low levels such that coral reefs were bleaching. The echo chamber of news repeatedly fails to report such phenomena and yet many studies continue to contradict mainstream news discourse. Whistle-blower Dr. John Bates exposed the U.S. National Oceanic Atmospheric Administration (NOAA) when it manipulated data to meet politically predetermined conclusions for the 2015 Paris (Climate) Agreement. This was not reported. Observational scientific analyses and their data sets continue to disagree with much of climate science modelling, and are beginning to suggest that some natural phenomena, which cause variability, may never be identified. … Scientists test, measure, observe and retest, and they must be able to verify and repeat results (Errington et al., 2014). Uncertainty is always present (van Der Sluijs, 2005), but when uncertainty is replaced by ‘consensus’ (post-normal science), a culture of gatekeeping ensues (Lindzen, 2009). Post-normal science is said to be appropriate when ‘traditional methodologies are ineffective. In those circumstances, the quality assurance of scientific inputs to the policy process requires an ‘extended peer community’, consisting of all those with a stake in the dialogue on the issue’ (Funtowicz & Ravetz, 1993). Then, and dangerously, dissenters are silenced so that chosen and ‘necessary’ discourses arrive in journals, conferences and boardrooms. In such a climate, it is difficult for the assertion to be made that there might be other sources, than a nontoxic greenhouse gas called carbon dioxide (CO2), that could be responsible for ‘climate disruption’. A healthy scientific process would allow such a proposition.
Power et al., 2017    All of the model simulations examined simulate multi-decadal warming in the Pacific over the past half-century that exceeds observed values. This difference cannot be fully explained by observed internal multi-decadal climate variability, even if allowance is made for an apparent tendency for models to underestimate internal multi-decadal variability in the Pacific. Models which simulate the greatest global warming over the past half-century also project warming that is among the highest of all models by the end of the twenty-first century, under both low and high greenhouse gas emission scenarios. Given that the same models are poorest in representing observed multi-decadal temperature change, confidence in the highest projections is reduced.
Hedemann et al., 2017  (full paper)     During the first decade of the twenty-first century, the Earth’s surface warmed more slowly than climate models simulated. This surface-warming hiatus is attributed by some studies to model errors in external forcing, while others point to heat rearrangements in the ocean caused by internal variability, the timing of which cannot be predicted by the models. However, observational analyses disagree about which ocean region is responsible. Here we show that the hiatus could also have been caused by internal variability in the top-of-atmosphere energy imbalance. Energy budgeting for the ocean surface layer over a 100-member historical ensemble reveals that hiatuses are caused by energy-flux deviations as small as 0.08 W m−2, which can originate at the top of the atmosphere, in the ocean, or both. Budgeting with existing observations cannot constrain the origin of the recent hiatus, because the uncertainty in observations dwarfs the small flux deviations that could cause a hiatus. The sensitivity of these flux deviations to the observational dataset and to energy budget choices helps explain why previous studies conflict, and suggests that the origin of the recent hiatus may never be identified. … The observed trend deviated by as much as −0.17 ◦C per decade from the CMIP5 (Coupled Model Intercomparison Project Phase 5) ensemble-mean projection—a gap two to four times the observed trend. The hiatus therefore continues to challenge climate science.
Xie et al., 2017     As the recent global warming hiatus has attracted worldwide attention, we examined the robustness of the warming hiatus in China and the related dynamical mechanisms in this study. Based on the results confirmed by the multiple data and trend analysis methods, we found that the annual mean temperature in China had a cooling trend during the recent global warming hiatus period, which suggested a robust warming hiatus in China. The warming hiatus in China was dominated by the cooling trend in the cold season, which was mainly induced by the more frequent and enhanced extreme-cold events.
Xian and Fu, 2017     Despite continually increasing concentrations of greenhouse gas, there has been a hiatus in rising global temperatures during the 21st century.
Liu and Zhou, 2017     Here, we divided recent decades into the recent hiatus period [1998-2013] and the preceding warming period (1983–1998) to investigate the atmospheric footprint. We use a process-resolving analysis method to quantify the contributions of different processes to the total temperature changes. We show that the increasing rate of global mean tropospheric temperature was also reduced during the hiatus period. The decomposed trends due to physical processes, including surface albedo, water vapour, cloud, surface turbulent fluxes and atmospheric dynamics, reversed the patterns between the two periods. … [C]limate models designed to represent the physics and dynamics of the climate system project that GMST [global mean surface temperature] continued to rise in the early 2000s. Dominant mechanisms proposed to understand the hiatus included the internal climate variability and ocean heat uptake and transport; however, the differences in the atmospheric footprint of recent warming slowdown remains unclear in terms of the dynamical and physical processes.
Rosenblum and Eisenman, 2017     Observations indicate that the Arctic sea ice cover is rapidly retreating while the Antarctic sea ice cover is steadily expanding. State-of-the-art climate models, by contrast, typically simulate a moderate decrease in both the Arctic and Antarctic sea ice covers. … [W]e find that simulated Arctic sea ice retreat as fast as observed would occur less than 1% of the time. This implies that the models are not consistent with the observations. In the Antarctic, we find that simulated sea ice expansion as fast as observed typically corresponds with too little global warming, although these results are more equivocal. We show that because of this, the simulations do not capture the observed asymmetry between Arctic and Antarctic sea ice trends. This suggests that the models may be getting the right sea ice trends for the wrong reasons in both polar regions.
Zanchettin, 2017     Multiple lines of evidence from climate observations, reconstructions, and simulations point to the potential of volcanic eruptions, tropospheric aerosols, and solar activity to substantially impact on decadal climatic variability. However, uncertainties and gaps of knowledge in the characterization of forced decadal climate responses remain large, and only a few studies have systematically tackled the implication of these forcing agents for decadal predictability and prediction. For all forcing agents, major limitations in understanding arise from incompleteness and shortness of the instrumental observations concerning the forcing as well as the climate response. Further issues concern the deficient representation of key processes in climate models and limitations inherent to reconstructed evidence.
Zuidema et al., 2017     Most contemporary coupled atmosphere–ocean general circulation models (CGCMs) produce a climate that is significantly more symmetric about the equator than in observations (Mechoso et al. 1995; Davey et al. 2002; Biasutti et al. 2006; de Szoeke and Xie 2008; Richter et al. 2016; Richter 2015; Siongco et al. 2015). Outstanding features include positive sea surface temperature (SST) errors south-southeast of the equator (Fig. 1a), collocated in part with an intertropical convergence zone (ITCZ) precipitation band (Fig. 1b) much stronger than that observed in nature. The “double ITCZ” error is further implicated in the simulated Hadley circulation, seasonal cycle and winds on the equator, and equatorial modes of variability, such as El Niño–Southern Oscillation (ENSO) in the Pacific, casting doubt on the ability to model and predict both regional and global climate. … OAFlux allows for more ocean warming than is observed, an error that implies the CMIP5 model net flux biases are even larger, by at least 10 W m−2 …  Mean CMIP5 net CRE biases are very large, up to 40 W m−2, relative to CERES values. … The CMIP5 models generally continue to underestimate subtropical stratocumulus cloud cover relative to observations, similar to CMIP3 (Klein et al. 2013) … The history in understanding the wind contribution to SST error growth is closely tied to that of model resolution. …The wind bias is linked to incorrect model-dependent distributions of tropical precipitation (Biasutti et al. 2006; Richter and Xie 2008; Richter et al. 2012; Siongco et al. 2015).
Ahlström et al., 2017     Our results suggest that climate biases could be responsible for a considerable fraction of the large uncertainties in ESM [Earth system models] simulations of land carbon fluxes and pools, amounting to about 40% of the range reported for ESMs. We conclude that climate bias-induced uncertainties must be decreased to make accurate coupled atmosphere-carbon cycle projections.
Zhang et al., 2017    [R]obust projections for extreme short-duration rainfall is challenging … because of our poor understanding of its past and future behaviour. The characterization of past changes is severely limited by the availability of observational data. Climate models, including typical regional climate models, do not directly simulate all extreme rainfall producing processes, such as convection. … [T]he observed precipitation–temperature scaling relationships have been established almost exclusively by linking precipitation extremes with day-to-day temperature variations. These scaling relationships do not appear to provide a reliable basis for projecting future precipitation extremes.
Zhou et al., 2017     The evaluation results show that 5 out of 30 climate models can well capture the observed APO [Asian-Pacific Oscillation]-related features in a comprehensive way, including the strengthened South Asian high (SAH), deepened North Pacific trough (NPT) and northward East Asian jet (EAJ) in the upper troposphere. [83% of climate models cannot capture the APO features comprehensively.]
Stouffer et al., 2017     There are a number of systematic model biases that appear in all phases of CMIP that remain a major climate modeling challenge. These biases need increased attention to better understand their origins and consequences through targeted experiments. Improving understanding of the mechanisms’ underlying internal climate variability for more skillful decadal climate predictions and long-term projections remains another challenge for CMIP6.
Oka and Watanabe, 2017     The warming rate of global-mean surface temperature slowed down during 1998-2012. Previous studies pointed out role of increasing ocean heat uptake during this global warming slowdown, but its mechanism remains under discussion.
Zhou and Penner, 2017     Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models.
Barcikowska et al., 2017      How global temperature will evolve over the next decade or so remains unclear (Knutson et al. 2016), although the most recent warming hiatus, observed in surface temperature records over the period 1998–2014, has challenged the scientific community in terms of consistency of models versus observations and in the attribution of the phenomena (Kosaka and Xie 2013; England et al. 2014; McGregor et al. 2014; Fyfe et al. 2012).  …  [N]ot only cooling over the North Atlantic but also preceding cooling over the tropical Pacific appears to be related to the three reconstructed global SST stagnation periods (1880–1900s, 1940s–60s, and 2000s–10s). The results suggest that the observed decadal SST stagnation periods (including the recent pause) stem from more than one climate component (internal variability and/or radiatively forced)
Cionco and Soon, 2017     We found important relative differences up to ± 5%, which correspond to errors of 2.5 W m −2 in the daily mean insolation, for exactly the same calendar day and set of astro-climatic parameters. This previously unrecognized error could have a significant impact in both the initial and boundary conditions for any climate modeling experiment. … A close inspection from the United Nations Fifth Assessment Report tells us that STOF [short-term orbital forcing]  is indirectly assumed to be unimportant and play no climatic role. The primary argument and assumption in neglecting changes in orbital forcing for climatic changes over the last few thousand years, last century or even last decade seemed to be from the claim that globally-averaged radiative forcing is small or negligible. … We wish to call for a more direct accounting for STOF, as a true boundary condition, in all climatic simulations in that the effects from local and regional perspective are clearly not negligible nor unimportant in terms of seasonal dynamical evolution of the coupled air-sea-land system.
Hope et al., 2017     We evaluate GMST using two approaches: analysis of archived output from atmospheric, oceanic general circulation models (GCMs) and calculations conducted using a computational framework developed by our group, termed the Empirical Model of Global Climate (EM-GC). Comparison of the observed rise in GMST over the past 32 years with GCM output reveals these models tend to warm too quickly, on average by about a factor of two. Most GCMs likely represent climate feedback in a manner that amplifies the radiative forcing of climate due to greenhouse gases (GHGs) too strongly.
Smith et al., 2017     Here, we used coupled atmosphere-biosphere simulations using the Community Earth System Model (CESM) to assess how acclimation-induced changes in photosynthesis influence global climate under present-day and future (RCP 8.5) conditions. … In the present-day simulations, the photosynthetic response was not as strong and cooling in highly vegetated regions was less than warming elsewhere, leading to a net global increase in temperatures of 0.04°C. Precipitation responses were variable and rates did not change globally in either time period. These results, combined with carbon-cycle effects, suggest that models without acclimation may be overestimating positive feedbacks between climate and the land surface in the future.
Molteni et al., 2017     It is widely accepted that natural decadal variability played a major role in the slowdown in global warming observed in the 21st century, with sea-surface cooling in the tropical Pacific recognized as a major contributor. However, the warming pause was most pronounced during boreal winter, with northern-hemisphere flow anomalies also playing a role. Here we quantify the contribution of extra-tropical heat exchanges by comparing geopotential and temperature anomalies simulated by ensembles of seasonal forecasts with similar ocean temperature but different heat fluxes north of 40 N, as a result of planetary-wave variability. We show that an important part of heat flux anomalies is associated with decadal variations in the phase of a specific planetary-wave pattern. In model simulations covering the last three decades, this variability pattern accounts for a decrease of 0.35 °C/decade in the post-1998 wintertime temperature trend over northern continents.
Kravtsov, 2017     Global and regional warming trends over the course of the twentieth century have been nonuniform, with decadal and longer periods of faster or slower warming, or even cooling. Here we show that state-of-the-art global models used to predict climate fail to adequately reproduce such multidecadal climate variations. In particular, the models underestimate the magnitude of the observed variability and misrepresent its spatial pattern. Therefore, our ability to interpret the observed climate change using these models is limited.
Zhou and Wang, 2017      Land surface air temperature (Ta) is one of the fundamental variables in weather and climatic observations, modeling, and applications. Despite the ongoing increase in atmospheric greenhouse gases, the global mean surface temperature (GMST) has remained rather steady and has even decreased in the central and eastern Pacific since 1998. This cooling trend is referred to as the global “warming hiatus”
Coats and Karnauskas, 2017     None of the 83 simulations have a positive trend in the SST gradient, a strengthening of the climatological SST gradient with more warming in the western than eastern tropical Pacific, as large as the mean trend across the five observational data sets. If the observed trends are anthropogenically forced, this discrepancy suggests that state-of-the-art climate models are not capturing the observed response of the tropical Pacific to anthropogenic forcing, with serious implications for confidence in future climate projections. … [C]onfident validation of anthropogenic SST gradient trends in climate models will require further emergence of anthropogenic trends. Regardless, the differences in SST gradient trends between climate models and observational data sets are concerning and motivate the need for process-level validation of the atmosphere-ocean dynamics relevant to climate change in the tropical Pacific.
O’Reilly et al., 2017     Seasonal hindcast experiments, using prescribed sea surface temperatures (SSTs), are analyzed for Northern Hemisphere winters from 1900 to 2010. Ensemble mean Pacific/North American index (PNA) [climate model] skill varies dramatically, dropping toward zero during the mid-twentieth century, with similar variability in North Atlantic Oscillation (NAO) hindcast skill. … Overall, negative PNA [Pacific/North American] events are less predictable and seem likely to arise more from internal atmospheric variability than positive PNA events.
Dommenget and Rezny, 2017     State-of-the-art coupled general circulation models (CGCMs) have substantial errors in their simulations of climate. In particular, these errors can lead to large uncertainties in the simulated climate response (both globally and regionally) to a doubling of CO2. Currently, tuning of the parameterization schemes in CGCMs is a significant part of the developed. It is not clear whether such tuning actually improves models. The tuning process is (in general) neither documented, nor reproducible. Alternative methods such as flux correcting are not used nor is it clear if such methods would perform better. In this study, ensembles of perturbed physics experiments are performed with the Globally Resolved Energy Balance (GREB) model to test the impact of tuning. The work illustrates that tuning has, in average, limited skill given the complexity of the system, the limited computing resources and the limited observations to optimize parameters. While tuning may improve model performance (such as reproducing observed past climate), it will not get closer to the ‘true’ physics nor will it significantly improve future climate change projections. Tuning will introduce artificial compensating error interactions between sub-models that will hamper further model development.
Exarchou et al., 2017     The substantial warm sea surface temperature bias in the eastern Tropical Atlantic reported in most CMIP5 climate simulations with various models, in particular along the coast of Namibia and Angola, remains an issue in more recent and CMIP6-ready versions of climate models such as EC-Earth. A complete and original set of experiments with EC-Earth3.1 is performed to investigate the causes and mechanisms responsible for the emergence and persistence of this bias. … Our study points at a need for better representation of clouds in the vicinity of eastern boundaries in atmosphere models, and better representation of solar penetration and turbulent mixing in the ocean models in order to eliminate the Tropical Atlantic biases.

Failing Renewable Energy, Climate Policies (12)

Janković and Shultz, 2017     [A] preindustrial climate may remain a policy goal, but it is unachievable in reality. … In 2011, the nonprofit science and outreach organization Climate Communication—whose staff and science advisors include, among others, Richard Sommerville, Jerry Melillo, Ken Kaldeira, Kerry Emanuel, Michael Mann, and Michael Oppenheimer—issued the following statement: “As the climate has warmed, some types of extreme weather have become more frequent and severe in recent decades, with increases in extreme heat, intense precipitation, and drought. … All weather events are now influenced by climate change because all weather now develops in a different environment than before.”   Yet, this statement, as well as numerous others in the popular literature and media stories, contradicts the scientific evidence.  [R]educing the complexity of climate change (as if a single outcome were known) into the soundbite of “climate change means more extreme weather” is a massive oversimplification—if not misstatement—of the true state of the science. … With such events seemingly outside the expected natural range of possibilities, the media increasingly turned to blaming climate change for the severe weather (e.g., Janković 2006; Hulme 2014).   “The good cause—one that most of us support—can all too readily corrupt the conduct of science, especially science informing public policy, because we prefer answers that support our political preferences, and find science that challenges them less comfortable” (Kellow 2008).  …  [A]ttribution claims allow policy-makers to put forward a case for morally robust policies based on mitigation of greenhouse emissions. Weather extremes are proxies of climate crisis, dismantling the climate complexity into the simpler and more visible conventional idiom of atmospheric hazard. … [I]t remains to be determined whether such [CO2 emission reduction] plans ought to be legitimized by a presumed rise in future weather extremes and whether a successful implementation of such plans would result in a demonstrable reduction of socioeconomic damages caused by supercharged weather. If neither of these results is justified, a policy based on attribution claims (and [fear]) runs the risk of being ill advised, ineffective, and disingenuous. … Reducing carbon emissions, regardless of how effective, cannot of itself reduce weather impacts (e.g., Schultz and Janković 2014). …  Climate change is not a discrete problem independent of development imperatives, nor is it manageable by a policy based on a mere scientific consensus (Prins et al. 2010). [E]ven if anthropogenic climate change were effectively stopped, extreme weather would continue. Members of the public and governmental representatives who had been sold on the idea that “stopping climate change will reduce extreme weather events” would understandably question their bill of goods, reducing scientific credibility.
Harris, 2017     China’s Paris pledge on climate change: inadequate and irresponsibleChina’s pledge is little more than business as usual. Significant ethical obligations arise from China’s role as the largest national source of greenhouse gas pollution and home to hundreds of millions of affluent consumers. The Paris Agreement disregards such obligations. The inadequacy and irresponsibility of China’s Paris pledge exposes some fundamental flaws in the international climate change negotiations and agreements, demonstrating that science and environmental studies cannot be disconnected from ethics and justice.
Clack et al., 2017     The scenarios of [Jacobson et al., 2015, “Low-cost solution to the grid reliability problem with 100% penetration of intermittent wind, water, and solar for all purposes”] can, at best, be described as a poorly executed exploration of an interesting hypothesis. The study’s numerous shortcomings and errors render it unreliable as a guide about the likely cost, technical reliability, or feasibility of a 100% wind, solar, and hydroelectric power system. It is one thing to explore the potential use of technologies in a clearly caveated hypothetical analysis; it is quite another to claim that a model using these technologies at an unprecedented scale conclusively shows the feasibility and reliability of the modeled energy system implemented by midcentury. From the information given by [Jacobson et al., 2015], it is clear that both hydroelectric power and flexible load have been modeled in erroneous ways and that these errors alone invalidate the study and its results.
Heard et al., 2017     While many modelled scenarios have been published claiming to show that a 100% renewable electricity system is achievable, there is no empirical or historical evidence that demonstrates that such systems are in fact feasible. Of the studies published to date, 24 have forecast regional, national or global energy requirements at sufficient detail to be considered potentially credible. We critically review these studies using four novel feasibility criteria for reliable electricity systems needed to meet electricity demand this century. [N]one of the 24 studies provides convincing evidence that these basic feasibility criteria can be met. Of a maximum possible unweighted feasibility score of seven, the highest score for any one study was four. … On the basis of this review, efforts to date seem to have substantially underestimated the challenge and delayed the identification and implementation of effective and comprehensive decarbonization pathways. … To date, efforts to assess the viability of 100% renewable systems, taking into account aspects such as financial cost, social acceptance, pace of roll-out, land use, and materials consumption, have substantially underestimated the challenge of excising fossil fuels from our energy supplies. This desire to push the 100%-renewable ideal without critical evaluation has ironically delayed the identification and implementation of effective and comprehensive decarbonization pathways. We argue that the early exclusion of other forms of technology from plans to decarbonize the global electricity supply is unsupportable, and arguably reckless. … The realization of 100% renewable electricity (and energy more broadly) appears diametrically opposed to other critical sustainability issues such as eradication of poverty, land conservation and reduced ecological footprints, reduction in air pollution, preservation of biodiversity, and social justice for indigenous people.
Vass, 2017     Renewable energies cannot compete with forest carbon sequestration to cost-efficiently meet the EU carbon target for 2050 … [T]he average cost per unit emissions reduction is more than twice as high for renewables as for forest carbon sequestration. Hence, the results indicate that renewables are unable to compete with forest carbon sequestration unless they receive continued government support.
Emery et al., 2017     Although climate change mitigation and energy security policies are generally expected to be compatible with air pollution and health cost reductions (McCollum et al., 2013), there is evidence that first-generation alternative fuels such as corn ethanol lead to higher health costs due to air pollution than conventional fuels [gasoline]  (Hill et al., 2009). … We find that life-cycle non-GHG air pollutant emissions, particularly NOX [nitrous oxides] and PM [particulates], are higher for corn ethanol and other biofuel blends than conventional petroleum fuels. Emissions of volatile organic compounds (VOCs) and carbon monoxide (CO) increase by 9–50% per 100 km traveled for high-ethanol blends from corn grain and combined grain and stover feedstocks. NOX, PM [particulates], and SOX [sulfur dioxides] increase by 71–124% from corn grain and 56–110% from combined grain and stover, relative to conventional gasoline. Biodiesel blends show an increase of 1–11% (B20) and 4–55% (B100) in air pollution, with the largest increases in VOC [volatile organic compounds] and SOX [sulfur dioxides] emissions. … The total social costs of ethanol blends are higher than that of gasoline, due in part to higher life-cycle emissions of non-GHG pollutants and higher health and mortality costs per unit.
Mahapatra and Ratha, 2017     The Paris deal is founded on a voluntary basis without any legally binding caps. The Paris Agreement is a relatively toothless one, which does not bind countries to actual emission limits, and has no mechanisms to impose actions. No sanctions will fall on any country that fails to come up to these intentions. The poor nations want clear promises to increase the aid for them, while the USA and other rich nations favour vaguer wording. Professor James Hansen—credited as being the father of climate change awareness— said that ‘the deal is worthless words’ (Wente, 2015).  The final text contains only bland platitudes. There is no necessary connection between the legally binding nature of an international agreement and its effectiveness in producing outcomes (Lake, 2015). The agreement delineates an aim for reducing temperatures to a 2°C above pre-industrial levels, but does not commit.
Richardson and Kumar, 2017     A growing human population creates a larger demand for food products and makes conservation of resources and increased efficiency of agricultural production more vital. … These results conclude that feed production systems are more energy efficient and less environmentally costly than corn-based ethanol. … [A]ccording to the findings of this study, biofuels, derived for the purpose of producing energy with little environmental impacts, actually use more energy at a higher environmental cost than the alternative crop use. As technology stands now, in terms of energy and environmental sustainability, the benefits of switching land uses to the production of corn-based transportation biofuels are not as favorable as continuing to produce corn for feed/food consumption.
Onn et al., 2017     EVs [electric vehicles] running with Malaysian electricity grid produce substantial GHG emissions. … [T]he benefits of grid-dependent EVs can only be harvested under the condition that their use is coupled with a low carbon electricity grid. Thus, it is an additional challenge for Malaysia’s that are largely dependent on fossil fuels for electricity generation. … Overall the GHG emissions produced through the usage of EVs are substantial based on the well-to-wheel analysis, as the environmental profile of EVs is linked with the national grid.
Ensslen et al., 2017     Our results indicate that charging in France causes only about ten percent of the carbon dioxide emissions compared to Germany, where the carbon intensity is more diverse [due to heavy fossil fuel dependency].  During the evaluation period of six months about 3.2 tons of CO2 were emitted.  As the major part of the electricity generated in France is based on “carbon-free” nuclear power, specific PTW CO2 emissions are substantially lower for the EV (16.4 g CO2/km in France compared to 147.1 g CO2/km for Germany).  … PTW [plant-to-wheel] CO2 emissions for charging EV in France are consequently about 10 times lower than CO2 emissions of comparable ICEV [internal combustion engine vehicle] and about 10 times lower than charging in Germany. These results underline the effects of the different electricity generation mixes in France and Germany on operational, charging and time dependent CO2 emissions of EV. … Comparing CO2 emissions according to norm consumption of a conventional Nissan NV200 [a commercial petrol-powered van with low-average fuel efficiency]  also having an identical chassis (128 g CO2/km) with the CO2 emissions calculated based on the norm energy consumption of the project EV (11 g CO2/km in France and 108 g CO2/km in Germany) leads to the conclusion that EV usage in France (Germany) is – with regard to CO2 –  more environmentally friendly than usage of comparable ICEV [internal combustion engine vehicle]. CO2 emission reduction potentials in France (Germany) consequently amount to 91.4 [France]% (15.6% [Germany]).  However, additional efficiency losses in the batteries and the AC/DC charging unit (charging efficiency) increases the amount of energy needed for charging. This consequently also increases CO2 emissions and results in reduction potentials compared to ICEV [internal combustion engine vehicle] of about 90.7% in France and 8.7% in Germany [EV use in Germany only results in a potential reduction of only 8.7% in CO2 emissions relative to fossil-fuel powered vehicles.]
Qiao et al., 2017     In this study, the life cycle energy consumption and greenhouse gas emissions of vehicle production are compared between battery electric and internal combustion engine vehicles in China’s context. … Greenhouse gas emissions of battery electric vehicles are 50% higher than internal combustion engine vehicles [in China].  … Electric Drive Vehicles (EDVs) are considered to be environmentally-friendly and have attracted much attention worldwide, and Battery Electric Vehicles (BEVs) are the most popular vehicles among all kinds of EDVs. In China, the country with the world’s largest automotive market, the government is determined to develop BEV industry and produced over 250 thousand BEVs in 2015, and the annual growth rate was 420%. In addition, according to the production plan, the cumulative output of BEVs in China will reach 5 million in 2020, meaning that BEVs will gradually replace Internal Combustion Engine Vehicles (ICEVs).  BEVs [Battery Electric Vehicles] are designed to obtain more environmental benefits, but the energy consumption and GHG emissions of BEV production are much larger than those of ICEV [Internal Combustion Engine Vehicles] production in China.
Victor et al., 2017     All major industrialized countries are failing to meet the pledges they made to cut greenhouse-gas emissions.  Wishful thinking and bravado are eclipsing reality. Countries in the European Union are struggling to increase energy efficiency and renewable power to the levels that they claimed they would. Japan promised cuts in emissions to match those of its peers, but meeting the goals will cost more than the country is willing to pay. 

Wind Power Harming The Environment, Biosphere (8)

Gortsas et al., 2017     Infrasound, low frequency noise and soil vibrations produced by large wind turbines might disturb the comfort of nearby structures and residents. In addition repowering close to urban areas produces some fears to the nearby residents that the level of disturbance may increase. Due to wind loading, the foundation of a wind turbine interacts with the soil and creates micro-seismic surface waves that propagate for long distances and they are able to influence adversely sensitive measurements conducted by laboratories located far from the excitation point.
Frick et al., 2017     Large numbers of migratory bats are killed every year at wind energy facilities. However, population-level impacts are unknown as we lack basic demographic information about these species. We investigated whether fatalities at wind turbines could impact population viability of migratory bats, focusing on the hoary bat (Lasiurus cinereus), the species most frequently killed by turbines in North America. Using expert elicitation and population projection models, we show that mortality from wind turbines may drastically reduce population size and increase the risk of extinction. For example, the hoary bat population could decline by as much as 90% in the next 50 years if the initial population size is near 2.5 million bats and annual population growth rate is similar to rates estimated for other bat species (λ = 1.01). Our results suggest that wind energy development may pose a substantial threat to migratory bats in North America. If viable populations are to be sustained, conservation measures to reduce mortality from turbine collisions likely need to be initiated soon. Our findings inform policy decisions regarding preventing or mitigating impacts of energy infrastructure development on wildlife.
Liu and Barlow, 2017     Wind energy has developed rapidly over the last two decades to become one of the most promising and economically viable sources of renewable energy. Although wind energy is claimed to provide clean renewable energy without any emissions during operation, but it is only one side of the coin. The blades, one of the most important components in the wind turbines, made with composite, are currently regarded as unrecyclable.  With the first wave of early commercial wind turbine installations now approaching their end of life, the problem of blade disposal is just beginning to emerge as a significant factor for the future. … The research indicates that there will be 43 million tonnes of blade waste worldwide by 2050 with China possessing 40% of the waste, Europe 25%, the United States 16% and the rest of the world 19%.
Ramirez-Tejeda et al., 2017     Globally, more than seventy thousand wind turbine blades were deployed in 2012 and there were 433 gigawatts (GW) of wind installed capacity worldwide at the end of 2015. Moreover, the United States’ installed wind power capacity will need to increase from 74 GW to 300 GW3 to achieve its 20% wind production goal by 2030.  … The wind turbine blades are designed to have a lifespan of about twenty years, after which they would have to be dismantled due to physical degradation or damage beyond repair. … Estimations have suggested that between 330,000 tons/year by 2028 and 418,000 tons/year by 2040 of composite material from blades will need to be disposed worldwide. That would be equivalent to the amount of plastics waste generated by four million people in the United States in 2013. This anticipated increase in blade manufacturing and disposal will likely lead to adverse environmental consequences. … Despite its negative consequences, landfilling has so far been the most commonly utilized wind turbine blade disposal method. …  Landfilling is especially problematic because its high resistance to heat, sunlight, and moisture means that it will take hundreds of years to degrade in a landfill environment. The wood and other organic material present in the blades would also end up in landfills, potentially releasing methane, a potent greenhouse gas, and other volatile organic compounds to the environment.
Hammerson et al, 2017     Conservationists are increasingly concerned about North American bats due to the arrival and spread of the White-nose Syndrome (WNS) disease and mortality associated with wind turbine strikes. To place these novel threats in context for a group of mammals that provides important ecosystem services, we performed the first comprehensive conservation status assessment focusing exclusively on the 45 species occurring in North America north of Mexico. Although most North American bats have large range sizes and large populations, as of 2015, 18–31% of the species were at risk (categorized as having vulnerable, imperiled, or critically imperiled NatureServe conservation statuses) and therefore among the most imperiled terrestrial vertebrates on the continent.
Vasilakis et al., 2017     Numerous wind farms are planned in a region hosting the only cinereous vulture population in south-eastern Europe. We combined range use modelling and a Collision Risk Model (CRM) to predict the cumulative collision mortality for cinereous vulture under all operating and proposed wind farms. Four different vulture avoidance rates were considered in the CRM.  Cumulative collision mortality was expected to be eight to ten times greater in the future (proposed and operating wind farms) than currently (operating wind farms), equivalent to 44% of the current population (103 individuals) if all proposals are authorized (2744 MW). Even under the most optimistic scenario whereby authorized proposals will not collectively exceed the national target for wind harnessing in the study area (960 MW), cumulative collision mortality would still be high (17% of current population) and likely lead to population extinction
Ferrão da Costa et al., 2017     Over the last 15 years, more than 900 wind turbines were built inside the range of the Portuguese wolf. Due to the endangered status of this large carnivore in Portugal, several monitoring plans were conducted, resulting in a reasonable amount of information being collected on the effects of wind farms on wolves. We reviewed the methodological approaches, compiled major findings and summarised the mitigation/compensation measures used in Portuguese wind farms. The overall outcomes show increasing human disturbance in wind farm areas, resulting in lower wolf reproduction rates during construction and the first years of operation, as well as shifts in denning site locations of more than 2.5 km away from the wind farm. … According to a review by Lovich and Ennen (2013), the construction and operation of wind farms have both potential and known impacts on terrestrial vertebrates, such as: (i) increase in direct mortality due to traffic collisions; (ii) destruction and modification of the habitat, including road development, habitat fragmentation and barriers to gene flow; (iii) noise effects, visual impacts, vibration and shadow flicker effects from turbines; (iv) electromagnetic field generation; (v) macro and microclimate change; (vi) predator attraction; and (vii) increase in fire risks.
Krekel and Zerrahn, 2017     We show that the construction of wind turbines close to households exerts significant negative external effects on residential well-being … In fact, beyond unpleasant noise emissions (Bakker et al., 2012; McCunney et al., 2014) and impacts on wildlife (Pearce-Higgins et al., 2012; Schuster et al., 2015), most importantly, wind turbines have been found to have negative impacts on landscape aesthetics (Devine-Wright, 2005; Jobert et al., 2007; Wolsink, 2007). … We show that the construction of a wind turbine within a radius of 4,000 metres has a significant negative and sizeable effect on life satisfaction. For larger radii, no negative externalities can be detected.

Elevated CO2 Greens Planet, Enhances Crop Yields (14)

Bastos et al., 2017     The sustained increasing vegetation activity trend (greening) in the Northern Hemisphere (NH) has been a prominent feature in satellite observations since the 1980s and is consistently simulated by models. The trend in vegetation greenness has been linked to increasing growing season length at high latitudes and enhanced terrestrial CO2 uptake in northern ecosystems. The greening pace has been associated with asymmetric effects of climate trends in vegetation activity or variations in the climate forcing. It has also been shown that regional greening trends are further attributed to land use change, land management, CO2 fertilization, and nitrogen deposition
Li et al., 2017     [M]aternal CO2 environment modulated the response of wheat plants to drought stress in terms of biomass production, [such that] plants reared from seeds harvested from the e[levated CO2] maternal growth environment eliminated the negative impact of drought stress on DM [dry biomass]. … [T]ransgenerational exposure to e[CO2] also attenuated the negative impact of drought on evapotranspiration in wheat plants. … [T]ransgenerational exposure of wheat plants to e[CO2] could attenuate the negative impact of drought stress in terms of DM and WUE [water use efficiency].
Brandt et al., 2017     Here we used a passive microwave Earth observation data set to document two different trends in land area with woody cover for 1992–2011: 36% of the land area (6,870,000 km2) had an increase in woody cover largely in drylands, and 11% had a decrease (2,150,000 km2), mostly in humid zones. Increases in woody cover were associated with low population growth, and were driven by increases in CO2 in the humid zones and by increases in precipitation in drylands, whereas decreases in woody cover were associated with high population growth.
[press release]     Africa has become greener in the last 20 years [M]ore CO2 in the atmosphere together with a wetter, warmer planet, provides conditions that help trees and bushes to grow.
Bastin et al., 2017     We show that in 2015, 1327 million hectares of drylands had more than 10% tree-cover, and 1079 million hectares comprised forest. Our estimate is 40 to 47% higher than previous estimates, corresponding to 467 million hectares of forest that have never been reported before. This increases current estimates of global forest cover by at least 9%.
Thinh et al., 2017     In summer experiment, yam vine length, leaf area, leaf dry weight (DW), and total DW were significantly higher under elevated [CO2] than ambient [CO2] in both temperature regimes. Additionally, number of leaves, vine DW, and root DW were significantly higher under elevated [CO2] than under ambient [CO2] in the low-temperature regime. In autumn experiment, tuber DW was significantly higher under elevated [CO2] than under ambient [CO2] in the high-temperature regime. These results demonstrate that yam shows positive growth responses to elevated [CO2].
Nakano et al., 2017     [T]he improvement of source activity by increased atmospheric CO2 concentrations can lead to enhanced grain yield in rice lines that have a large sink capacity. Therefore, introducing alleles that increase sink capacity into conventional varieties represents a strategy that can be used to develop high-yielding varieties under increased atmospheric CO2concentrations, such as those predicted in the near future.
Pandey et al., 2017     Impact of elevated CO2 (free air COenrichment) was studied on wheat (Triticum aestivum L. var Kundan) growth, yield and proteome. Elevated COsignificantly impacted both underground (+24%) and aboveground (+15%) biomass. Grain weight/plant and harvest index were increased by 35% and 11.4%, respectively under high CO2.
Pretzsch et al., 2017     Based on tree ring analyses in ten metropolises worldwide, we show that, in general, urban trees have undergone accelerated growth since the 1960s. In addition, urban trees tend to grow more quickly than their counterparts in the rural surroundings. However, our analysis shows that climate change seems to enhance the growth of rural trees more than that of urban trees. The benefits of growing in an urban environment seem to outweigh known negative effects
Karthykeyan, 2017     The rooted stem cuttings of C. equisetifolia inoculated with Frankia showed a higher number of nodules under 900 ppm of CO2 and cuttings without Frankia inoculation exhibited poor growth. Tissue Nitrogen (N) content was also higher under 900 ppm of CO2 than ambient control and 600 ppm levels. The photosynthetic rate was higher (17.8 μ mol CO2 m−2 s−1) in 900 ppm of CO2than in 600 ppm (13.2 μ mol CO2 m−2 s−1) and ambient control (8.3 μ mol CO2 m−2 s−1). This study showed that Frankia can improve growth, N fixation and photosynthesis of C. equietifoliarooted stem cuttings under extreme elevated CO2 level conditions (900 ppm).
Verhage et al., 2017     Carbon dioxide fertilization offsets negative impacts of climate change on Arabica coffee yield in Brazil … The model projects that yield losses due to high air temperatures and water deficit will increase, while losses due to frost will decrease. Nevertheless, extra losses are offset by the CO2 fertilization effect, resulting in a small net increase of the average Brazilian Arabica coffee yield of 0.8% to 1.48 t ha−1 in 2040–2070, assuming growing locations and irrigation remain unchanged. … A major failure of nearly all climate change impact studies of future crop yields rests in their poor construct and design, where they near-unanimously fail to incorporate the beneficial effects of atmospheric CO2 enrichment on plant growth. As a result, yield projections in such studies are almost always shown to decline as a result of anticipated future temperature- and moisture-related stresses.
Bourgault et al., 2017     Atmospheric CO2 concentrations ([CO2]) are predicted to increase from current levels of about 400 ppm to reach 550 ppm by 2050. Elevated [CO2] increased lentil yields by approximately 0.5 t ha−1 [18% to 168%].  The greatest response of grain yield to elevated [CO2] was during a terminal drought.  Biomass accumulation post-flowering was increased considerably by elevated [CO2].
Yadav, 2017     A significant (F= 9.800; P<0.02) change was noticed in the post-harvest index of rice. However, there no change was noticed in the post-harvest percentage of maize. Leaf area of rice (P<0.01) and maize (P<0.005) increased significantly at flowering stage of plants under enriched CO2 environment over the ambient. Under elevated CO2 condition, biological yields of rice and maize were improved by 14.3% and 17.2% respectively. Carbon dioxide enrichment exposure improved the grain yield by 16. 2% (P<0.02) and 13.8% ( P<0.02) for rice and maize respectively.
Pau et al., 2017     Long-term increases in tropical flowering activity across growth forms in response to rising CO2 and climate change … We show that a multidecadal increase in flower activity is most strongly associated with rising atmospheric CO2 concentrations using yearly aggregated data. Compared to significant climatic factors, CO2 had on average an approximately three-, four-, or fivefold stronger effect than rainfall, solar radiation, and the Multivariate ENSO Index, respectively. Peaks in flower activity were associated with greater solar radiation and lower rainfall during El Niño years.


Szoboszlay et al., 2017     The effect of elevated atmospheric CO2 concentration [CO2 ] on the diversity and composition of the prokaryotic community inhabiting the rhizosphere of winter barley (Hordeum vulgare L.) was investigated in a field experiment, using open-top chambers. … Above-ground plant biomass was not affected by elevated [CO2 ] at anthesis, but plants exposed to elevated [CO2] had significantly higher grain yield.

Warming Beneficial, Does Not Harm Humans, Wildlife (7)

Fan et al., 2017     Summer insolation [surface solar radiation] in the Northern Hemisphere began to increase 12,000 yr ago and reached a maximum (7% greater than the present value) from 10,000 to 9000 yr ago (Laskar et al., 2004). … We suggest that hydrological and ecological changes in the EASM margin during the Holocene were closely related to the combined effects of regional precipitation and temperature which were ultimately controlled by the Northern Hemisphere summer insolation [solar radiation], the boundary conditions and the physical environment of ocean current.  Our data suggest that future global warming scenarios would potentially be beneficial for the hydrological and ecological conditions of the EASM margin, while small decreases in the precipitation and temperature superimposed on the long-term deteriorated climate may cause large declines in the hydrology and ecology in the semi-arid regions of northern China.
Crockford, 2017     Data collected between 2007 and 2015 reveal that polar bear numbers have not declined as predicted and no subpopulation has been extirpated. Several subpopulations expected to be at high risk of decline have remained stable and at least one showed a marked increase in population size over the entire period. Another at-risk subpopulation was not counted but showed marked improvement in reproductive parameters and body condition with less summer ice. As a consequence, the hypothesis that repeated summer sea ice levels of below 5 mkm2 will cause significant population declines in polar bears is rejected. This result indicates that the ESA and IUCN judgments to list polar bears as threatened based on future risks of habitat loss were hasty generalizations that were scientifically unfounded, which suggests that similar predictions for Arctic seals and walrus may be likewise flawed, while the lack of a demonstrable ‘sea ice decline = population decline’ relationship for polar bears invalidates updated survival model outputs that predict catastrophic population declines should the Arctic become ice-free in summer.
Baresel et al., 2017     The Earth has known several mass extinctions over the course of its history. One of the most important happened at the Permian-Triassic boundary 250 million years ago. Over 95% of marine species disappeared and, up until now, scientists have linked this extinction to a significant rise in Earth temperatures. But researchers have now discovered that this extinction took place during a short ice age which preceded the global climate warming. It’s the first time that the various stages of a mass extinction have been accurately understood and that scientists have been able to assess the major role played by volcanic explosions in these climate processes.
Wang et al., 2017     Numerous previous studies have reported that human health risk is extremely sensitive to temperature. … At the community level, the mean value of relative extreme cold risk (1.63) of all 122 communities was higher than that of extreme high temperature (1.15). … A prolonged impact of low temperature [cold] on human health was observed in China
Wong et al., 2017     Strong and transparent relationships between polar bear researchers and Inuit communities are necessary to overcome persisting research (and community) misconceptions.  For community members, most types of research have been viewed as inseparable from government agendas through funding and consulting programmes (Bocking 2007) and past histories and power relations have politicised views of scientific research as a whole (Reed and McIlveen 2006). …  All [Inuit] participants reported having more bear encounters in recent years than in the past. Some participants indicated that the bears they have encountered are healthy.  … Last year he said that there’s more bears that are more fat … they rarely see unhealthy bears … the only time they would see one is when it’s pretty old … it won’t hunt—hunt as much … and it’s skinny. (AB9)  … Our elders, they say, they migrate, into other area… for years, and then they come back … that’s what we’re experiencing now … back in early 80s, and mid 90s, there were hardly any bearsthere’s too many polar bears now. (AR16) Bears can catch seals even—even if the—if the ice is really thin … they’re great hunters those bears … they’re really smart … they know how to survive … Though dietary changes have been attributed to sea ice changes limiting access to primary prey (ringed and harp seal; Thiemann and others 2008a), evidence for bears foraging on land-based foods (Dyck and Romberg 2007; Rockwell and Gormezano 2009; Gormezano and Rockwell 2013a) – reported as typical behaviour by most participants here – might also suggest an opportunistic feeding strategy (Thiemann and others 2008a). This suggests that bears pursue readily available food sources even in the presence of preferred ones (Gormezano and Rockwell 2013b).  Bears foraging for land-based foods have been reported in the literature prior to recent concerns over climate change (Russell 1975; Derocher and others 1993; Gormezano and Rockwell 2013a). Observations of bears consuming garbage are not uncommon (Russell 1975; Lunn and Stirling 1985; Gormezano and Rockwell 2013b)

Bårdsen et al., 2017     We investigated the population dynamics of Swedish semi-domestic reindeer from 1945 to 2012 at the reindeer herding district-level (Sameby) to identify possible population collapses or declines […] but found no evidence of large-scale reindeer population declines and no visible synchrony across adjacent populations. Our findings were unexpected as both reindeer populations and the pastoral lifestyle face increased habitat loss, predation, fragmentation and climate change.
Che-Castaldo et al., 2017     [A]ggregated abundance [for 267 Adélie penguin colonies] across all sites in this region showed extended periods of both increasing and decreasing abundance over the last three decades [1982-2015]. We also find a long-term decline in abundance in the South Orkney Islands, following an initial period of increase in the early 1980s. In contrast, we found a marked and steady increase in abundance around the rest of the Antarctic continent, including both Eastern Antarctica and the Ross Sea. … Commensurate with other studies [Lynch et al., 2013], we find that the population of Adélie penguins on the Antarctic Peninsula declined between 2000 and 2008, though we found an unexpected rebound in abundance starting in 2008. This regional increase in abundance may, in part, be driven by sites in the Marguerite Bay area, where Adélie penguins are stable or even increasing. However, this increase may also reflect a cessation of regional warming on the Antarctic Peninsula since the late 1990s [Turner et al., 2016], which may benefit ice-dependent species like the Adélie penguin. We find that while Eastern Antarctica appears to have been increasing steadily in abundance since at least 1982, the increasing abundance of Adélie penguins in the Ross Sea is more recent, beginning in 2002.

Warming, Acidification Not Harming Oceanic Biosphere (18)

McElhany, 2017    Documenting an effect of OA [ocean acidification] involves showing a change in a species (e.g. population abundance or distribution) as a consequence of anthropogenic changes in marine carbonate chemistry. To date, there have been no unambiguous demonstrations of a population level effect of anthropogenic OA [ocean acidification], as that term is defined by the IPCC. … [I]t is important to acknowledge that there are no studies that directly demonstrate modern day effects of OA [ocean acidification] on marine species.
Cooper et al., 2017     We determined tolerances of E. pacifica to prolonged exposure to pH levels predicted for 2100 by maintaining adults at two pCO2 levels (380 and 1200 µatm) for 2 months. Rates of survival and moulting were the same at both pCO2 levels. High pCO2 slowed growth in all size classes.
Toyofuku et al., 2017    Ongoing ocean acidification is widely reported to reduce the ability of calcifying marine organisms to produce their shells and skeletons. Whereas increased dissolution due to acidification is a largely inorganic process, strong organismal control over biomineralization influences calcification and hence complicates predicting the response of marine calcifyers. Here we show that calcification is driven by rapid transformation of bicarbonate into carbonate inside the cytoplasm, achieved by active outward proton pumping. Moreover, this proton flux is maintained over a wide range of pCO2 levels. We furthermore show that a V-type H+ ATPase is responsible for the proton flux and thereby calcification. External transformation of bicarbonate into CO2 due to the proton pumping implies that biomineralization does not rely on availability of carbonate ions, but total dissolved CO2 may not reduce calcification, thereby potentially maintaining the current global marine carbonate production.
(press release)     [A] group of scientists discovered to their own surprise that some tiny unicellular shellfish (foraminifera) make better shells in an acidic environment. This is a completely new insight.
Schaum et al., 2017     Here, we use a decade-long experiment in outdoor mesocosms to investigate mechanisms of adaptation to warming (+4 °C above ambient temperature) in the green alga Chlamydomonas reinhardtii, in naturally assembled communities. Isolates from warmed mesocosms had higher optimal growth temperatures than their counterparts from ambient treatments. Consequently, warm-adapted isolates were stronger competitors at elevated temperature and experienced a decline in competitive fitness in ambient conditions, indicating adaptation to local thermal regimes. Higher competitive fitness in the warmed isolates was linked to greater photosynthetic capacity and reduced susceptibility to photoinhibition. These findings suggest that adaptive responses to warming in phytoplankton could help to mitigate projected declines in aquatic net primary production by increasing rates of cellular net photosynthesis.
Ollier, 2017     The coast contains ‘carbonate sand factories’ where organisms produce vast amounts of sand by fixing carbon dioxide as carbonates. Far from dissolving carbonate by acidification, carbon dioxide is an essential part of carbonate production and the continued maintenance and growth of coasts and reefs. Government policies to adapt renewable energy are unlikely to affect the system.
Mardones et al., 2017      Exposure of the toxigenic dinoflagellate Alexandrium catenella to variations in pCO2/pH, comparable to current and near-future levels observed in Southern Chilean fjords, revealed potential functional adaptation mechanisms. Under calculated conditions for pH(total scale) and pCO2 ranging from 7.73–8.66 to 69.7–721.3 μatm, respectively, the Chilean strain Q09 presented an optimum growth rate and dissolved inorganic carbon (DIC) uptake at near-equilibrium pCO2/pH conditions (8.1). … We suggest that A. catenella Chilean strains are highly adapted to spatio-temporal pCO2/pH fluctuations in Chilean fjords, becoming a resilient winner from expected climate change effects.
Glandon et al., 2017     No effect of high pCO2 on juvenile blue crab, Callinectes sapidus, growth and consumption despite positive responses to concurrent warming … Our study is the first to examine the effect of multiple climate stressors on blue crab and therefore basic responses, including the growth per molt (GPM), inter-molt period (IMP), and food consumption, were quantified. GPM [growth per molt] was not affected by either increased temperature or pCO2.
Poulton et al., 2017     For the first time, this study investigated the independent and combined impacts of elevated carbon dioxide (CO2) and anthropogenic noise [produced by shipping, seismic surveys, and pile-driving] on the behaviour of a marine fish, the European sea bass (Dicentrarchus labrax).  … Elevated CO2 did not alter the ventilation rate response to noise. Furthermore, there was no interaction effect between elevated CO2 and pile-driving noise, suggesting that OA [ocean acidification] is unlikely to influence startle or ventilatory responses of fish to anthropogenic noise.
Hassenrück et al., 2017     Our results suggest that on mature settlement surfaces in situ, pH does not have a strong impact on the composition of bacterial biofilms. Other abiotic and biotic factors such as light exposure and interactions with other organisms may be more important in shaping bacterial biofilms on mature surfaces than changes in seawater pH.
Lee and Kim, 2017     High atmospheric CO2 dissolves into the surface of the ocean and lowers the pH of seawater and is thus expected to pose a potential threat to various marine organisms. We investigated the physiological and behavioural responses of adult Manila clams, Venerupis philippinarum (n = 96, shell length 25.32 ± 1.66mm and total wet weight 3.10 ± 0.54 g), to three levels (400, 700, and 900 μatm) of CO2 partial pressure (pCO2) for 48 days. There were no significant differences in mortality, growth, respiration rate, or emergence from the sediment between the three levels, indicating that near future atmospheric levels of CO2 do not seem to have a serious effect on the physiology and behaviour of adult Manila clams.
Page et al., 2017     Here, we test the hypotheses that elevated pCO2 will differently impact the relative concentrations of divalent cations (Ca2+, Mg2+, Sr2+, and Mn2+) in four closely related species of porcelain crabs … Overall, the effect of reduced pH/elevated pCO2 on exoskeleton mineral composition was muted in mid-intertidal species relative to low-intertidal species, indicating that extant adaptation to the variable intertidal zone may lessen the impact of ocean acidification (OA) on maintenance of mineralized structures.
Long et al., 2017     In this study, we determine the effects of decreased pH on the morphology, growth, and survival of juvenile blue king crab, Paralithodes platypus. Crabs were reared at three pH levels: ambient (control, pH ∼8.1), pH 7.8, and pH 7.5, for 1 year and monitored for morphological changes, survival, and growth. Exposure to seawater at pH 7.8 had no effect on morphology or mortality and had only a minor effect on growth compared with the ambient treatment.
Comeau et al., 2017     Here, we tested the response of net photosynthesis, gross photosynthesis, dark respiration, and light-enhanced dark respiration (LEDR) of eight coral taxa and seven calcified alga taxa to six different pCO2 levels (from 280 to 2000 µatm). Organisms were maintained during 7–10 days incubations in identical conditions of light, temperature, and pCO2 to facilitate comparisons among species. Net photosynthesis was not affected by pCO2 in seven of eight corals or any of the algae; gross photosynthesis did not respond to pCO2 in six coral taxa and six algal taxa; dark respiration also was unaffected by pCO2 in six coral and six algae; and LEDR did not respond to pCO2 in any of the tested species. Overall, our results show that pCO2 levels up to 2000 µatm likely will not fertilize photosynthesis or modify respiration rates of most of the main calcifiers on the back reef of Moorea, French Polynesia.
Bailey et al., 2017     Early life stages of the Arctic copepod Calanus glacialis are unaffected by increased seawater pCO2 … In this study, we investigated the effect of increased pCO2 on the early developmental stages of the key Arctic copepod Calanus glacialis. Eggs from wild-caught C. glacialis females from Svalbard, Norway (80°N), were cultured for 2 months to copepodite stage C1 in 2°C seawater under four pCO2 treatments (320, 530, 800, and 1700 μatm). … All endpoints were unaffected by pCO2 levels projected for the year 2300. These results indicate that naupliar development in wild populations of C. glacialis is unlikely to be detrimentally affected in a future high CO2 ocean.
Kwan et al., 2017    Neither constant nor oscillating CO2-induced acidification affected blacksmith individual light/dark preference, inter-individual distance in a shoal or the shoal’s response to a novel object, suggesting that blacksmiths are tolerant to projected future OA conditions.
Kienzle et al., 2017     Rising temperatures increased recruitment of brown tiger prawn (Penaeus esculentus) in Moreton Bay (Australia)
Barkley et al., 2017    [C]alcification rates of two reef-building coral genera (Porites and Favia) do not change across Palau’s steep Ωar gradient (Ωar = 3.7 to 2.3) [a pH range of 7.84 to 8.04]. … [R]egardless of reef of origin, corals in the CO2 manipulation experiment showed no calcification sensitivity to Ωar after eight weeks in experimental conditions. … [C]orals in Palau are not living close to their Ωar threshold and are tolerant to acidification levels far below those to which they are currently exposed.
Ern et al., 2017     [T]he effect of elevated CO2 on oxygen supply capacity is either absent, or insufficient to cause a significant change in the oxygen limit for thermal tolerance. … [O]cean acidification is therefore unlikely to act as a significant synergistic stressor with hypoxia on the upper thermal limits of this species. … [T]he lack of significant change in CTmax of C. atripectoralis in normoxia suggests that the thermal tolerance of the physiological mechanisms responsible for setting CTmax is also not affected by elevated CO2.

Decreases In Extreme, Unstable Weather With Warming (3)

Zhang et al., 2017     Based on continuous and coherent severe weather reports from over 500 manned stations, for the first time, this study shows a significant decreasing trend in severe weather occurrence across China during the past five decades. The total number of severe weather days that have either thunderstorm, hail and/or damaging wind decrease about 50% from 1961 to 2010. It is further shown that the reduction in severe weather occurrences correlates strongly with the weakening of East Asian summer monsoon which is the primary source of moisture and dynamic forcing conducive for warm-season severe weather over China.
Kawamura et al., 2017     Numerical experiments using a fully coupled atmosphere-ocean general circulation model with freshwater hosing in the northern North Atlantic showed that climate becomes most unstable in intermediate glacial conditions associated with large changes in sea ice and the Atlantic Meridional Overturning Circulation. Model sensitivity experiments suggest that the prerequisite for the most frequent climate instability with bipolar seesaw pattern during the late Pleistocene era is associated with reduced atmospheric CO2 concentration via global cooling and sea ice formation in the North Atlantic, in addition to extended Northern Hemisphere ice sheets. [Cooling elicits more climate instability.]
Heller, 2017     The hurricane analysis conducted by Burn and Palmer (2015) determined that hurricane activity was subdued during the [warm] Medieval Climate Anomaly (MCA) (~900-1350 CE) and became more produced during the [cold] Little Ice Age (LIA) (~1450-1850 CE), followed by a period of variability occurred between ~1850 and ~1900 before entering another subdued state during the industrial period (~1950-2000 CE). In general, the results of this study corroborate these findings … [W]hile hurricane activity was greater during the LIA, it also had more frequent periods of drought compared to the MCA (Burn and Palmer 2014), suggesting that climate fluctuations were more pronounced in the LIA compared to the MCA. The changes in the diatom distribution and fluctuations in chl-a recorded in this study starting around 1350 also indicate that variations in climate have become more distinct during the LIA and from ~1850-1900. … [C]limate variability has increased following the onset of the Little Ice Age (~1450-1850 CE), however it is difficult to distinguish the impacts of recent anthropogenic climate warming on hurricane activity from those of natural Atlantic climate regimes, such as ENSO.

Urban Heat Island: Raising Surface Temperatures Artificially (5)

Parker and Ollier 2017     The global reconstructions as GISS (Hansen et al. 2010, GISTEMP Team 2017) are artificially biased upwards to reproduce the carbon dioxide emission trend, but the strong natural oscillation signal prevails. The very likely overrated warming rate since 1880 is 0.00654°C/year or 0.654°C/century. … Because the GISS temperature record is biased upwards, as many supporting stations have upwards biased temperatures rather than the actual thermometer reading As there is no way to perform a better measurement going back in the past, there is no legitimate way to correct recorded data of the past. Therefore, we should stick to the raw data. … The climate trend maps compiled by Bureau of Meteorology in their climate change section are completely unreliable, as the alleged increasing temperature is obtained by lowering temperatures of the past by “adjustments”. The longest of the Australian temperature records that were considered the most reliable by Bureau of Meteorology on February 2009 (BOM 2009) are still available as raw temperatures in the climate data online section and consistently show no warming and no increased extreme events within the limit of accuracy of measurements.

Levermore et al., 2017   The increasing trend of the urban heat island intensity … The urban heat island intensity in Manchester has a highly significant rising trend which by the end of the century could add 2.4 K to the average annual urban temperature, on top of the predicted climate change increase. An analysis of the urban morphology showed that the urban site had indeed become more urban over 9 years of the study, losing green spaces which mitigate against the UHII.
Liao et al., 2017     We examine the urban effect on surface warming in Eastern China, where a substantial portion of the land area has undergone rapid urbanization in the last few decades. Daily surface air temperature records during the period 1971–2010 at 277 meteorological stations are used to investigate temperature changes. Owing to urban expansion, some of the stations formerly located in rural areas are becoming increasingly influenced by urban environments. To estimate the effect of this urbanization on observed surface warming, the stations are dynamically classified into urban and rural types based on the land use data for four periods, i.e. 1980, 1990, 2000 and 2010. After eliminating the temperature trend bias induced by time-varying latitudinal distributions of urban and rural stations, the estimated urban-induced trends in the daily minimum and mean temperature are 0.167 and 0.085 °C decade−1, accounting for 33.6 and 22.4% of total surface warming, respectively. The temperature difference between urban and rural stations indicates that urban heat island intensity has dramatically increased owing to rapid urbanization, and is highly correlated with the difference in fractional coverage of artificial surfaces between these two types of stations. This study highlights the importance of dynamic station classification in estimating the contribution of urbanization to long-term surface warming over large areas.
Kyriakodis and Santamouris, 2017    UHI is the most studied phenomenon of climate change and refers to the increased ambient temperature of cities compared to rural settings. Implementation of reflective materials to urban structures, such as roads and pavements, reduces the surface and ambient temperature and contributes to counterbalance the impact of the phenomenon. … Conclusion: [T]he use of cool non-aged asphalt can reduce the ambient temperature by up to 1.5 °C and the maximum surface temperature reduction could reach 11.5 °C Surface temperatures reduction up to 7.5 °C and 6.1 °C respectively in the summer period.
Dienst et al., 2017      We here assess these influences and demonstrate that even in villages urban heat island biases might affect the temperature readings. … Due to the station movement from the village centre to the outskirts, the net correction results in an additional warming trend over the past 155 years. The trend increase is most substantial for minimum temperatures (+0.03 °C /10 years−1) [+0.3°C  per century] . … An increase in trend is even more severe if the 20th century is regarded exclusively, displaying a rise in annual mean temperature trend by +0.03 °C /10 years−1 and +0.07 °C /10 years−1 in annual minimum temperatures, respectively.  … The adjustment of the Haparanda station record results in an increased warming trend.

No Increasing Trends In Intense Hurricanes (4)

Choi et al., 2017     This study analysed the time series of tropical cyclone (TC) frequency during October–December (OND) for 32 years (1980–2011). There was a strong decreasing trend of TCs until recently, and the TC sharply decreased from 1996 after the statistical change-point analysis was applied to this time series.
Chen et al., 2017     Results indicate that the midlatitude summer cyclone activity over East Asia exhibits decadal changes in the period of 1979–2013 and is significantly weakened after early 1990s. …  Moreover, there is a close linkage between the weakening of cyclonic activity after the early 1990s and the nonuniform surface warming of the Eurasian continent. Significant warming to the west of Mongolia tends to weaken the north–south temperature gradient and the atmospheric baroclinicity to its south and eventually can lead to weakening of the midlatitude cyclone activity over East Asia.
Wellford et al., 2017     Since the late 1800s, in contrast to much of the Southeastern USA, the Georgia coast has experienced infrequent hurricane landfalls, particularly in recent decades. As a result, coastal storm preparedness complacency appears to be rampant along the Georgia coastline. Both local and state governments were unprepared for shadow evacuation during Hurricane Floyd in 1999. The study described here includes an examination of temporal and spatial trends in hurricane landfall along the Georgia coast from 1750 to 2012. Since 1750, 18 of the 24 recorded hurricanes that made landfall along the Georgia coast occurred between 1801 and 1900, yet the hurricane intensities have declined since 1851.
Yoshida et al., 2017     Projected future changes in global tropical cyclone (TC) activity are assessed using 5,000 year scale ensemble simulations for both current and 4 K surface warming climates with a 60 km global atmospheric model. The global number of TCs [tropical cyclones] decreases by 33% in the future projection. Although geographical TC occurrences decrease generally, they increase in the central and eastern parts of the extra tropical North Pacific. Meanwhile, very intense (category 4 and 5) TC occurrences increase over a broader area including the south of Japan and south of Madagascar. The global number of category 4 and 5 TCs [tropical cyclones] significantly decreases, contrary to the increase seen in several previous studies.

No Increasing Trends In Drought/Flood Frequency, Severity (3)

McAneney et al., 2017     [A] 122-year record of major flooding depths at the Rarawai Sugar Mill on the Ba River in the northwest of the Fijian Island of Viti Levu is analysed. … It exhibits no statistically significant trends in either frequency or flood heights, once the latter have been adjusted for average relative sea-level rise. This is despite persistent warming of air temperatures as characterized in other studies. There is a strong dependence of frequency (but not magnitude) upon El Niño-Southern Oscillation (ENSO) phase, with many more floods in La Niña phases. The analysis of this long-term data series illustrates the difficulty of detecting a global climate change signal from hazard data, even given a consistent measurement methodology (cf HURDAT2 record of North Atlantic hurricanes) and warns of the strong dependence of any statistical significance upon choices of start and end dates of the analysis.
McCabe et al., 2017     In this study, a monthly water-balance model is used to simulate monthly runoff for 2109 hydrologic units (HUs) in the conterminous United States (CONUS) for water-years 1901 through 2014. … Results indicated that … the variability of precipitation appears to have been the principal climatic factor determining drought, and for most of the CONUS, drought frequency appears to have decreased during the 1901 through 2014 period.
Hodgkiins et al., 2017     In the current study, trends in major-flood occurrence from 1961 to 2010 and from 1931 to 2010 were assessed using a very large dataset (>1200 gauges) of diverse catchments from North America and Europe … Overall, the number of significant trends in major-flood occurrence across North America and Europe was approximately the number expected due to chance alone. Changes over time in the occurrence of major floods were dominated by multidecadal variability rather than by long-term trends. There were more than three times as many significant relationships between major-flood occurrence and the Atlantic Multidecadal Oscillation than significant long-term trends. … The Intergovernmental Panel on Climate Change (IPCC) concluded (Hartmann et al., 2013) that globally there is no clear and widespread evidence of changes in flood magnitude or frequency in observed flood records. … North American trends in … frequency of extremes in the 1980s and 1990s were similar to those of the late 1800s and early 1900s. There was no discernible trend in the frequency of extreme events in Canada. The results of this study, for North America and Europe, provide a firmer foundation and support the conclusion of the IPCC (Hartmann et al., 2013) that compelling evidence for increased flooding at a global scale is lacking.

Natural CO2, Methane Sources Out-Emit Human Source (4)

Harde, 2017     The anthropogenic contribution to the actual CO2 concentration is found to be 4.3%, its fraction to the COincrease over the Industrial Era is 15% and the average residence time 4 years.Under present conditions the natural emissions contribute 373 ppm and anthropogenic emissions 17 ppm to the total concentration of 390 ppm (2012). For the average residence time we only find 4 years. … The stronger increase of the concentration over the Industrial Era up to present times can be explained by introducing a temperature dependent natural emission rate as well as a temperature affected residence time. With this approach not only the exponential increase with the onset of the Industrial Era but also the concentrations at glacial and cooler interglacial times can well be reproduced in full agreement with all observations. So, different to the IPCC’s interpretation the steep increase of the concentration since 1850 finds its natural explanation in the self accelerating processes on the one hand by stronger degassing of the oceans as well as a faster plant growth and decomposition, on the other hand by an increasing residence time at reduced solubility of CO2 in oceans. … Together this results in a dominating temperature controlled natural gain, which contributes about 85 % to the 110 ppm CO2 increase over the Industrial Era, whereas the actual anthropogenic emissions of 4.3 % only donate 15 %. These results indicate that almost all of the observed change of CO2 during the Industrial Era followed, not from anthropogenic emission, but from changes of natural emission.
Carey et al., 2017     While scientists and policy experts debate the impacts of global warming, Earth’s soil is releasing roughly nine times more carbon dioxide to the atmosphere than all human activities combined.
Ruppel and Kessler, 2017     On the contemporary Earth, gas hydrate is dissociating in specific terrains in response to post-LGM [last glacial maximum] climate change and probably also due to warming since the onset of the Industrial Age. Nevertheless, there is no conclusive proof that the released methane is entering the atmosphere at a level that is detectable against the background of ~555 Tg yr−1 CH4 emissions. The IPCC estimates are not based on direct measurements of methane fluxes from dissociating gas hydrates, and many numerical models adopt simplifications that do not fully account for sinks, the actual distribution of gas hydrates, or other factors, resulting in probable overestimation of emissions to the ocean-atmosphere system.
Turner et al., 2017     We conclude that the current surface observing system does not allow unambiguous attribution of the decadal trends in methane without robust constraints on OH variability, which currently rely purely on methyl chloroform data and its uncertain emissions estimates.
[press release]      [M]ethane emissions might not have increased dramatically in 2007 after all. Instead, the most likely explanation has less to do with methane emissions and more to do with changes in the availability of the hydroxyl (OH) radical, which breaks down methane in the atmosphere. As such, the amount of hydroxyl in the atmosphere governs the amount of methane. If global levels of hydroxyl decrease, global methane concentrations will increase — even if methane emissions remain constant, the researchers say. … When atmospheric concentrations of methane increase, it may not be correct to chalk it up solely to an increase in methane emissions

Increasing Snow Cover Since The 1950s (2)

Coleman and Schwartz, 2017     Data revealed 713 blizzards over the 55 years, with a mean of 13 events per season. Seasonal blizzard frequency ranged from one blizzard in 1980/81 to 32 blizzards in 2007/08Federal disaster declarations resulting from blizzards totaled 57, with more than one-half of them occurring in the twenty-first centuryStorm Data attributed 711 fatalities during the 55-yr study period, with an average of one individual per event; 2044 injuries were reported, with a mean of nearly three per blizzard. Property damage totaled approximately $9.11 billion in unadjusted dollars, with an approximate mean of $12.6 million per storm. Seasonal blizzard frequencies displayed a distinct upward trend, with a more substantial rise over the past two decades. … The modeled increase in blizzard activity showed a nearly fourfold upsurge between the start and end of the study period at 5.9 and 21.6 blizzards, respectively. On the basis of current model trends, the expected blizzard total for a season is 32 blizzards by 2050; uncertainty exists on whether the linear trend will continue or stabilize in the near future.

Changnon, 2017     Heavy 30-day snowfall amounts were evaluated to identify spatial and temporal characteristics east of the Rockies in the United States during the period 1900-2016. An extensive data assessment identified 507 stations for use in this long-term climate study. The top 30-day heavy snowfall amount and the average of the top five 30-day heavy snowfall amounts were examined. … The northern Great Plains, Great Lakes, Midwest, and Northeast experienced more top five periods [more snow] in the second half of the 117-year period [1958-2016], where most of the southern states experienced top five periods throughout the study period. Examining extremes at periods beyond the daily event and less than the season contributes to our knowledge of climate and provides useful information to snow-sensitive sectors.

Hatchett et al., 2017     Winter Snow Level Rise in the Northern Sierra Nevada from 2008 to 2017. … Positive SST anomalies offshore of California were associated with reductions in observed winter snow fractions. … If such a connection between SSTs, moisture plume strength, and snow fractions does exist, it suggests that snow accumulation may further decline with continued regional warming.

Miscellaneous (7)

Stenhouse et al., 2017     American Meteorological Society [m]embers who said the global warming of the last 150 years was mostly caused by human activity (53% of full sample) …  Members who are convinced of largely human-caused climate change expressed that debate over global warming sends an unclear message to the public. Conversely, members who are unconvinced of human-caused climate change often felt that their peers were closed-minded and suppressing unpopular views. These two groups converged, however, on one point: politics was seen as an overwhelmingly negative influence on the debate.
Remy et al., 2017     We compared palaeofire and simulated climatic data over the last 7000 years to assess causes of large wildfire events in three coniferous boreal forest regions in north-eastern Canada. These regions span an east-west cline, from a hilly region influenced by the Atlantic Ocean currently dominated by Picea mariana and Abies balsamea to a flatter continental region dominated by Picea mariana and Pinus banksiana. The largest wildfires occurred across the entire study zone between 3000 and 1000 cal. BP. In western and central continental regions these events were triggered by increases in both the fire-season length and summer/spring temperatures, while in the eastern region close to the ocean they were likely responses to hydrological (precipitation/evapotranspiration) variability.
Pearce et al., 2017     There is little evidence here that supports the notion shared by Cook, Oreskes and various fossil fuel companies: that disinformation about scientific consensus begets public opposition to policy.  Despite this evidence, Cook (2017) and Oreskes (2017) appear convinced that public understanding of scientific consensus is essential for developing effective climate policies. Even if this “gateway belief model” could be proved in laboratory studies, it holds questionable significance in the real world where sources of competing information always exist (Kahan & Carpenter, 2017). … First, the debate over the hiatus/pause in global temperature increase was not invented by fossil fuel interests, but is a subject of genuine scientific disagreement (Medhaug, Stolpe, Fischer, & Knutti, 2017). Second, there is increasing expert debate regarding how much carbon dioxide can be emitted while keeping global temperature rise below 1.5°C (Millar et al., 2017a, 2017b; Peters, 2017; Rathi, 2017). For climate scientists, there is no obvious consensus about questions such as these. On the other hand, Cook, Oreskes and others persist in messaging the minimalist fact that human influence on a changing climate is uncontroversial amongst scientists. … Cook (2017) interprets our argument as playing into the hands of climate disinformers. Far from it. It is the insistent demand that publics will only engage in relevant policy debates once they have adopted a “gateway belief” that is playing into the hands of those who wish to slow-down climate policy design and implementation.
Ivy et al., 2017     Recent research has demonstrated that the concentrations of anthropogenic halocarbons have decreased in response to the worldwide phaseout of ozone depleting substances. Yet, in 2015 the Antarctic ozone hole reached a historical record daily average size in October. Model simulations with specified dynamics and temperatures based on a reanalysis suggested that the record size was likely due to the eruption of Calbuco, but did not allow for fully-coupled dynamical or thermal feedbacks. We present simulations of the impact of the 2015 Calbuco eruption on the stratosphere using the Whole Atmosphere Community Climate Model with interactive dynamics and temperatures. Comparisons of the interactive and specified dynamics simulations indicate that chemical ozone depletion due to volcanic aerosols played a key role in establishing the record-sized ozone hole of October 2015. The analysis of an ensemble of interactive simulations with and without volcanic aerosols suggests that the forced response to the eruption of Calbuco was an increase in the size of the ozone hole by 4.5 million km2.
Alcock et al., 2017     The rise in greenhouse gas emissions from air travel could be reduced by individuals voluntarily abstaining from, or reducing, flights for leisure and recreational purposes. In theory, we might expect that people with pro-environmental value orientations and concerns about the risks of climate change, and those who engage in more pro-environmental household behaviours, would also be more likely to abstain from such voluntary air travel, or at least to fly less far. … [W]e found that, after accounting for potential confounders, there was no association between individuals’ environmental attitudes, concern over climate change, or their routine pro-environmental household behaviours, and either their propensity to take non-work related flights, or the distances flown by those who do so.
Maibach et al., 2017     Nearly half of weathercasters (49%) are convinced that the climate change over the past 50 years has been mostly or entirely due to human activity.
Kretschmer et al., 2017     Despite global warming, recent winters in the Northeastern United States (US), Europe and especially in Asia were anomalously cold. Some mid-latitude regions like Central Asia and eastern Siberia even show a downward temperature trend in winter over the past decades (Cohen et al. 2014a; McCusker et al. 2016). … [O]ver the last 37 years, the frequency of weak vortex states in mid to late winter (January and February) has increased which were accompanied by subsequent cold extremes in mid-latitude Eurasia. For this region 60% of the observed cooling in the era of Arctic amplification, i.e. since 1990, can be explained by the increased frequency of weak stratospheric polar vortex states, a number which increases to almost 80% when El Niño/Southern Oscillation (ENSO) variability is included as well.


Scientists: We Don’t Know (3)

McKinley et al., 2017     That the growth of the partial pressure of CO2 gas in the atmosphere ( pCO2 atm) drives a growing oceanic sink is consistent with our basic understanding that, as the globally averaged atmosphere-to-ocean pCO2 gradient increases, carbon accumulation in the ocean will occur at an increasing rate (Section 3). This behavior has been illustrated clearly with models [not observations] forced with only historically observed increases in pCO2 atm and no climate variability or change (Graven et al. 2012, Ciais et al. 2013). Nonetheless, critical mysteries remain and weigh heavily on our ability to quantify relationships between the perturbed global carbon cycle and climate change. … The current inability to accurately quantify the mean CO2 sink regionally or locally also suggests that present-day observational constraints are inadequate to support a detailed, quantitative, and mechanistic understanding of how the ocean carbon sink works and how it is responding to intensifying climate change. This lack of mechanistic understanding implies that our ability to model (Roy et al. 2011, Ciais et al. 2013, Frolicher et al. 2015, Randerson et al. ¨ 2015), and thus to project the future ocean carbon sink, including feedbacks caused by warming and other climate change, is seriously limited. … The sum of the available evidence indicates that variability in the ocean carbon sink is significant and is driven primarily by physical processes of upwelling, convection, and advection. Despite evidence for a growing sink when globally integrated (Khatiwala et al. 2009, 2013; Ciais et al. 2013; DeVries 2014), this variability, combined with sparse sampling, means that it is not yet possible to directly confirm from surface observations that long-term growth in the oceanic sink is occurring. … [T]his CESM-LE analysis further illustrates that variability in CO2 flux is large and sufficient to prevent detection of anthropogenic trends in ocean carbon uptake on decadal timescales.
Kitaba et al., 2017      Debate continues over whether changes in the galactic cosmic ray (GCR) flux may induce climate change. Weakening of the geomagnetic field and its shielding properties leads to an increase in GCR flux, and this increased GCR may induce more active low cloud formation (Svensmark effect), which in turn increases albedo and hence reduces temperature. Two possible mechanisms have been proposed for how GCR affects clouds: one theory argues that the highly-charged GCR ionises a number of atmospheric molecules, leading to combination and nucleation of aerosol particles which grow into cloud condensation nuclei (CCN); the other proposes that GCR affects clouds through the modulation of the global electric circuit. … Interest is strong in proving or disproving the Svensmark effect as an important factor affecting climate because, if the hypothesis is correct, it would comprise an important mechanism in which solar variation may control climate through the modulation of GCR flux. … Significant GCR change, however, occurs rarely and on geological time scales and is not suitable for direct observation. Therefore, the GCR linkage to climate change is accordingly difficult to assess within a manageable time frame. Numerous experiments and modelling studies have examined the production and growth of cloud condensation nuclei by the atmospheric ionisation generated by GCR. These studies, however, have been inconclusive because the physical scale and complexity of this process is too large to be reproduced experimentally or in model simulation.
Kent et al., 2017     The term SST has typically been used to describe the mean temperature of the upper few meters of the ocean. Historically measurements taken at depths from the surface and down to about 20 m have all been assumed representative of the SST. Under well-mixed conditions this is a good assumption. However, there are well-known variations of ocean temperature with depth, especially at low wind speeds and sunny conditions (Kawai and Wada 2007). … SST has been measured in different ways over the past 200 years. The observations record real variations in temperature but also contain an imprint of how they were measured. Both the real variations and the biases are affected by the ambient environmental conditions, making them hard to disentangle. … The earliest observations were probably made by sampling seawater in a bucket. Maury (1858) recommended wooden buckets, which were likely used around this time. … Once a bucket leaves the sea, both the bucket and the water sample exchange heat with the atmosphere in a way that is dependent on their volume, thermal properties, and the environmental conditions. The temperature continues to change while the thermometer is read; the change is related to the length of time taken to get a stable reading and to whether the bucket is taken out of the wind and/or into the shade.
Detailed information on the ships and the different methods of measurement, now known to be of immense value to assess changes, has been lost. … Reconciling all of this to make consistent estimates of SST changes would be a challenge with good documentation. The patchy availability of observational and platform metadata, and sparse sampling in some regions and periods, makes it even harder. … Although ICOADS [International Comprehensive Ocean–Atmosphere Data Set] is often thought of as “raw” data, it is derived from a larger, more heterogeneous underlying databank from diverse sources. Further reprocessing of the databank could help to better resolve duplicate observations, incomplete ship identifiers, scale conversions, missing metadata, and positional errors among other basic problems. … [C]omplete authoritative archives of data and metadata do not exist for moored buoys, ocean weather ships, or research vessels. Land-based coastal observations are difficult to identify in global and regional archives, and multivariate records are often fragmented (Thorne et al. 2017). … SST biases are statistically and computationally challenging. … The data are of varied quality. Metadata are sometimes incomplete or conflicting. Reference observations are few and not always of unimpeachable quality. … Older ICOADS acquisitions are often lacking metadata and are compromised by legacy deficiencies in data management and storage formats. … The comparison shows we are yet to fully reconcile the biases in all types of SST observations throughout the historical record.