12 New Papers Affirm A 21st Century Cessation Of Arctic Warming And A Rapid Cooling Across Antarctica

Where’s The Anthropogenic Signal?

Since 2000s, An Arctic Warming & Sea Ice Pause

Cooling In Antarctica Undermine AGW Claims

It was 3 years ago when scientists first began documenting the pause in Arctic sea ice decline that began in 2007.

While detailing the potential for “cherry-picking” such a short span of years to arrive at “misleading” conclusions, Swart et al. (2015) pointed out that there was a “near-zero” trend in sea ice extent during the brief 2007-2013 period.

Swart et al., 2015

“Arctic sea-ice extent was lost at a considerably higher rate from 2001–2007 than in the preceding decades (Fig. 1), which caught the attention of scientists and the public alike. In contrast, from 2007–2013 there was a near-zero trend in observed Arctic September sea-ice extent, in large part due to a strong uptick of the ice-pack in 2013, which has continued into 2014. By deliberately cherry-picking these periods we will demonstrate how using short-term trends can be misleading about longer-term changes, when such trends show either rapid or slow ice loss.”

That “cherry-picked” 6-year pause in Arctic sea ice decline has now been extended another 4 years.  As illustrated below, there has been no detectable trend in September Arctic sea ice for the 10 years between 2007-2017.

Image Source (top): NSIDC

While Swart and colleagues correctly assess that “using short-term trends can be misleading about longer-term changes”, they apparently only consider the 1979-2013  Arctic September sea ice trend as “longer-term”.   And yet this 34-year period could easily be considered of “cherry-picked” length too because it is also a very short record relative to what is available.

Reconstructions of Arctic (and regional Arctic) sea ice extent reveal that modern values aren’t unusual relative to the longer-term context of the last 100+ years.

Image Source: Connolly et al., 2017  and Alekseev et al., 2016

Image Source: Ran et al., 2010

Image Source: Kryk et al., 2017

Image Source: Durantou et al., 2012

12 New Papers Affirm A 21st Century Arctic Warming

Pause As Well As A Rapid Cooling Across Antarctica


1. Since 2005, There Has Been A ‘Warming Hiatus’ In The Arctic

Ding et al., 2018

[W]e find that there was a warming hiatus/slowdown since 2005 at Ny-Ålesund. Additionally, the variation of air temperature lags by 8–9 years, which implies that the warming hiatus probably exists in the Arctic but lags behind, globally. This phenomenon is not an isolated instance, An et al. [2017] reported that the warming rate above 4000 m of the Tibetan Plateau has been slowing since the mid-2000s. In the Antarctic Peninsula, the slowdown of the increasing temperature trend was also found after 1998/1999, however, the reason is attributed to local phenomena, such as the deepening of Amundsen Sea Low and not due to the global hiatus [Turner et al., 2016]. … From the correlation analysis, we found Ny-Ålesund could represent most Arctic areas, especially the Atlantic-Arctic sector. … Especially air temperature, the record of Ny-Ålesund can capture the variation of surface temperature over most of [the] Arctic. … The oscillations of atmospheric dynamic systems, the methods of energy transport from low to high latitudes, and feedback mechanisms of the Arctic on climate change may contribute to the warming hiatus. … [C]limate changes in polar areas remain difficult to predict, which indicates that the underlying mechanisms of polar amplification remain uncertain and debatable.”

2. ‘Marked Cooling’ In Siberia Since 2000

Suvorov and Kitov, 2018  (Eastern Sayan, Siberia)

“The authors examined the variability of activity of modern glaciation and variation of natural conditions of the periglacial zone on climate and on dendrochronological data. Results of larch and Siberian stone pine growth data were revealed at the higher border of forest communities. …  It is believed that the temperature could be 3.5 °C warmer at the Holocene optimum than at the present time (Vaganov and Shiyatov 2005). … Since 2000, there has been growth of trees instability associated with a decrease in average monthly summer temperatures. …  Since the beginning of 2000, decrease in summer temperatures was marked.”

3. ‘A Cooling Is Observed’ During 2001-2015 In Greenland

Westergaard-Nielsen et al., 2018

“Here we quantify trends in satellite-derived land surface temperatures and modelled air temperatures, validated against observations, across the entire ice-free Greenland. … Warming trends observed from 1986–2016 across the ice-free Greenland is mainly related to warming in the 1990’s. The most recent and detailed trends based on MODIS (2001–2015) shows contrasting trends across Greenland, and if any general trend it is mostly a cooling. The MODIS dataset provides a unique detailed picture of spatiotemporally distributed changes during the last 15 years. … Figure 3 shows that on an annual basis, less than 36% of the ice-free Greenland has experienced a significant trend and, if any, a cooling is observed during the last 15 years (<0.15 °C change per year).”

4. Slight Cooling During 2005-2015 In Greenland

Kobashi et al., 2017

For the most recent 10 years (2005 to 2015), apart from the anomalously warm year of 2010, mean annual temperatures at the [Greenland] Summit exhibit a slightly decreasing trend in accordance with northern North Atlantic-wide cooling.  The Summit temperatures are well correlated with southwest coastal records (Ilulissat, Kangerlussuaq, Nuuk, and Qaqortoq).”

5. A Cooling Observed between 1997-2016 In Arctic Canada

Mallory et al., 2018

“From 1988 to 1996, the summer intensity of the AO was largely in the positive phase, with a mean value of 0.207 (± 0.135 SE), and this was a period of population stability or growth for each of the three herds that we examined here. In contrast, from 1997 to 2016 the summer AO has remained largely in the negative phase [cooling], with a mean value of − 0.154 (± 0.077 SE), and over this period the Bathurst, Beverly, and Qamanirjuaq herds declined in abundance.”


21st Century Cooling Across Antarctica

6. 2006-’15 Antarctic Peninsula Cooling  – A Thinning Ice Sheet Linked To Cooling?

Hrbáček et al., 2018

Active layer monitoring in Antarctica: an overview of results from 2006 to 2015 … Air temperatures showed significant regional differences within the study areas. In the western Antarctic Peninsula region, Vestfold Hills and northern Victoria Land, a slight air temperature cooling was detected, while at other sites in Victoria Land and East Antarctica the air temperature was more irregular, showing no strong overall trend of warming or cooling during the study period (Figure 2). The Antarctic Peninsula region has been reported as the most rapidly warming part of Antarctica (e.g. Turner et al., 2005, 2014), but cooling has been reported since 2000 (Turner et al., 2016). Relatively stable air temperature conditions during the past 20 years were reported in Victoria Land (Guglielmin & Cannone, 2012).”
“Significantly, thicker thaw depths were observed in the colder regions of the eastern Antarctic Peninsula and the coastal zone of East Antarctica. The general pattern suggests that factors other than regional climate should be considered when examining the ground thermal regime (e.g. Hrbáček, 2016). Between 2009 and 2014, substantial active layer thinning was observed at all sites in the western Antarctic Peninsula. The thinning was attributed to climate cooling in the region (Oliva, Navarro, et al., 2017; Turner et al., 2016) and changes in snow cover accumulation, as well as snow persistence during the summer, reducing active layer thaw (de Pablo et al., 2017). In contrast, pronounced active layer thickening between 2010 and 2013 was recorded at Novolazarevskaya in coastal East Antarctica.”

7. The Northern Antarctic Peninsula Cooled By -1.98°C between 2008 and 2014

Fernandoy et al., 2018

“As shown by firn core analysis, the near-surface temperature in the northern-most portion of the Antarctic Peninsula shows a decreasing trend (−0.33°C year−1) between 2008 and 2014 [-1.98°C].”

8. Antarctic Peninsula and East Antarctica Cooling Since 1998

Vignon et al., 2018

“The near‐surface Antarctic atmosphere experienced significant changes during the last decades (Steig et al., 2009; Turner et al., 2006). In particular, the near‐surface air over the Western part of Antarctica exhibits one of the major warming over the globe (Bromwich et al., 2013a), with heating rates larger than 0.5 K per decade at some places. Despite a significant warming in the end of the 20th century, the Antarctic Peninsula has been slightly cooling since 1998, reflecting the high natural variability of the climate in this region (Turner et al., 2016). East Antarctica has experienced a slight cooling trend (Nicolas & Bromwich, 2014; Smith & Polvani, 2017) particularly marked during autumn. … General circulation models (GCMs) are very powerful tools for investigating the mechanisms responsible for global or regional changes in the Earth climate. However, we can wonder to what extent they are able to correctly represent the near‐surface temperature field over Antarctica. Although the models involved in the fifth Coupled Models Intercomparison Experiment (CMIP) have a realistic climatology and interannual variability in Antarctica, they fail in reproducing the nearsurface temperature trends in the period 1979–2005 (Smith & Polvani, 2017) and particularly the contrast between west and east Antarctica.”

9. Most Of East Antarctica Has Been Cooling Since 1990s, ‘Significant Cooling’ In Antarctic Peninsula

Ramesh and Soni, 2018

“The present paper reviews the progress of India’s scientific research in polar meteorology. The analysis of 25 years meteorological data collected at Maitri station for the period 1991–2015 is presented in the paper. The observed trend in the temperature data of 19 Antarctic stations obtained from READER project for the period 1991–2015 has also been examined. The 25 years long term temperature record shows cooling over Maitri station. The Maitri station showed cooling of 0.054 °C per year between 1991 and 2015, with similar pronounced seasonal trends. The nearby Russian station Novolazarevskaya also showed a cooling trend of 0.032 °C per year. … The temperature trend in average temperature of 19 Antarctica stations is also examined to ascertain the extent of cooling or warming trend (Supplementary Table_S1). The majority of stations in East Antarctica close to the coast show cooling or no significant trend. … Turner et al. (2016) using stacked temperature record found a significant cooling trend for the Antarctic Peninsula for the period 1999–2014. Their study suggests that the warming on the Antarctic Peninsula during 1979–1997 and subsequent cooling during 1999–2014 are both within the limits of the decadal time scale natural climate variability of the region. Smith and Polvani (2017) examined the relationship between the SAM and Antarctic surface air temperature trends, in both models and reanalyses. They also found convincing evidence that natural climate variability is the major contributor to the warming of West Antarctica and Antarctic Peninsula.  … The Antarctic Sea-ice extent has been showing increasing trend in the recent past few decades. The rate of change in Antarctic sea-ice extent exhibit strong regional differences with increase in some regions and decrease in other. The mean Antarctic sea-ice extent increased at a rate of 1.2–1.8% per decade between 1979 and 2012 (IPCC, 2013). Gagné et al. (2015) attributed increase in Antarctic sea-ice extent to internal variability.”

10. Models Fail To Simulate The Southern Ocean Cooling And Circumpolar Increase In Sea Ice 

Purich et al., 2018

Observed Southern Ocean changes over recent decades include a surface freshening (Durack and Wijffels 2010; Durack et al. 2012; de Lavergne et al. 2014), surface cooling (Fan et al. 2014; Marshall et al. 2014; Armour et al. 2016; Purich et al. 2016a) and circumpolar increase in Antarctic sea ice (Cavalieri and Parkinson 2008; Comiso and Nishio 2008; Parkinson and Cavalieri 2012).  … [A]s high-latitude surface freshening is associated with surface cooling and a sea ice increase, this may be another factor contributing to the CMIP5 models excessive Southern Ocean surface warming contrasting the observed surface cooling (Marshall et al. 2014; Purich et al. 2016a), and sea ice decline contrasting the observed increases (Mahlstein et al. 2013; Polvani and Smith 2013; Swart and Fyfe 2013; Turner et al. 2013; Zunz et al. 2013; Gagne et al. 2015) over recent decades. … Our results suggest that recent multi-decadal trends in large-scale surface salinity over the Southern Ocean have played a role in the observed surface cooling seen in this region. … The majority of CMIP5 models do not simulate a surface cooling and increase in sea ice (Fig. 8b), as seen in observations.”

11. Temperature (Non) Trend Across Antarctica (90°S To 60°S)

Tang et al., 2018

“The study of Antarctic precipitation has attracted a lot of attention recently. The reliability of climate models in simulating Antarctic precipitation, however, is still debatable. This work assess the precipitation and surface air temperature (SAT) of Antarctica (90°S to 60°S) using 49 Coupled Model Intercomparison Project phase 5 (CMIP5) global climate models”

12. ‘Ubiquitous’ Cooling Across East Antarctica Since The 1970s

Clem et al., 2018

Over the past 60 years, the climate of East Antarctica cooled while portions of West Antarctica were among the most rapidly warming regions on the planet. The East Antarctic cooling is attributed to a positive trend in the Southern Annular Mode (SAM) and a strengthening of the westerlies, while West Antarctic warming is tied to zonally asymmetric circulation changes forced by the tropics. This study finds recent (post-1979) surface cooling of East Antarctica during austral autumn to also be tied to tropical forcing, namely, an increase in La Niña events. … The South Atlantic anticyclone is associated with cold air advection, weakened northerlies, and increased sea ice concentrations across the western East Antarctic coast, which has increased the rate of cooling at Novolazarevskaya and Syowa stations after 1979. This enhanced cooling over western East Antarctica is tied more broadly to a zonally asymmetric temperature trend pattern across East Antarctica during autumn that is consistent with a tropically forced Rossby wave rather than a SAM pattern; the positive SAM pattern is associated with ubiquitous cooling across East Antarctica.

59 responses to “12 New Papers Affirm A 21st Century Cessation Of Arctic Warming And A Rapid Cooling Across Antarctica”

  1. SebastianH

    As illustrated below, there has been no detectable trend in September Arctic sea ice for the 10 years between 2007-2017.
    http://notrickszone.com/wp-content/uploads/2018/04/Arctic-Sea-Ice-Pause-2007-2017.jpg

    Isn’t this getting old by now? One or two extremes can not be the start or the end of any “trend”. You even posted a graph that displays the long term trend and makes it very clear that the years after those two extreme years are continuing the trend. At most you can look at this graph and determine that those two downward extremes demonstrate that the decrease in Arctic ice extent can temporarily be much faster than the overall longterm trend.

    Calling this a hiatus is classic disinformer talk.

    1. Kenneth Richard

      Isn’t this getting old by now? One or two extremes can not be the start or the end of any “trend”.

      Great! So you do agree we should not consider graphs that have 1979 as their start year, as that was probably the coldest year in the Arctic in the last 100 years, as shown here:

      http://notrickszone.com/wp-content/uploads/2016/11/Arctic-Surface-Temps-Since-1920-copy-768×394.jpg

      If you agree we shouldn’t start sea ice trends in anomalously cold or high extent years, surely you will agree that 1979 is not acceptable as a starting point. You want to be consistent, right?

      So what year do you prefer to start the trend, SebastianH?

      Use one of these graphs of 100+ year records to make your selection (so that we can eliminate the potential for cherry-picking short-term trends starting/ending in extreme years).

      http://notrickszone.com/wp-content/uploads/2018/04/Arctic-Sea-Ice-Extent-1900-2013-Alekseev-2015-Connolly-2017.jpg

      http://notrickszone.com/wp-content/uploads/2018/03/Holocene-Arctic-Sea-Ice-North-Iceland-Ran-2010.jpg

      http://notrickszone.com/wp-content/uploads/2017/06/Holocene-Cooling-Greenland-SW-Kryk-2017.jpg

      1. SebastianH

        Great! So you do agree we should not consider graphs that have 1979 as their start year

        *sigh* … you really have a talent for ignoring the actual criticism and turning it around towards your opponent in an effort to distract from your mistake.

        The longer the period the better, obviously. Do you somehow disagree that the trend pictured in this graph (http://notrickszone.com/wp-content/uploads/2018/04/Arctic-Sea-Ice-Pause-2007-2017.jpg) exists? Do you want to go back a billion years and look at a trend from back then until today?

        So what year do you prefer to start the trend, SebastianH?

        What year do you prefer?

        Use one of these graphs of 100+ year records to make your selection (so that we can eliminate the potential for cherry-picking short-term trends starting/ending in extreme years).

        You are kidding, right? With your talent to pick the one graph from a paper that might slightly agree with your weird view of the world … wth.

        That Alekseev/Connolly graph. Have you even looked at the other graphs in that paper and what the paper actually did? The tried to “adjust” reconstructions by scaling them with unadjusted temperature records. To make the variability before 1979 a bit larger, I guess.
        https://www.tandfonline.com/doi/full/10.1080/02626667.2017.1324974?scroll=top&needAccess=true

        And you manage to pick out a reconstruction that is also based on temperature proxies. Further below you commented that wind plays a big role … why this inconsistency?

        BTW: this is their “adjusted” reconstruction graph:
        https://www.tandfonline.com/na101/home/literatum/publisher/tandf/journals/content/thsj20/2017/thsj20.v062.i08/02626667.2017.1324974/20170612/images/large/thsj_a_1324974_f0012_oc.jpeg

    2. AndyG55

      No trend, seb

      https://s19.postimg.cc/umq1x3h4j/Arctic_ice_area_trend.png

      And the volume has no trend either

      https://s19.postimg.cc/84aexi5k3/DMI_Arctic_sea_Ice_Volume.png

      Arctic sea ice extent and volume are FAR above the Holocene average.

      At least have the courage to ADMIT to this FACT, seb.

      1. SebastianH

        Should I also admit to the fact the sea ice extent is dramatically increasing since 2012? Despite the 2016/2017 sea ice extent being almost exactly on the longterm trendline?
        http://notrickszone.com/wp-content/uploads/2018/04/Arctic-Sea-Ice-Pause-2007-2017.jpg

        1. AndyG55

          The linear trend monkey strikes again!

          Sure you don’t want to use a polynomial, in a know CYCLIC system ???

          That would be even funnier.

        2. AndyG55

          Good think about the Alekseev et al., 2016 graph is that it actually matches real temperatures.

          And seb has always said that Arctic sea ice is driven by temperatures.

          https://s19.postimg.cc/vws4z68s3/arctic_temp.png

          https://s19.postimg.cc/5ffms4j1v/iceland_8.jpg

          Even down as far as Ireland

          https://s19.postimg.cc/5if59yngz/Ireland_AMO_article.jpg

          CYCLIC, seb..

          plus some recovery from the anomalous cold of the LIA

          NOT linear,

          NOT polynomial

          ??? comprehend ???

          1. AndyG55

            thing, not a k !!!

  2. Philip Clarke

    “Reconstructed September SIE shows the minimum in 1936 that is twice higher then minimum 2012”

    – Genrikh Alekseev

    Source: http://svalbard.aari.ru/docs/Merop/2016/prez_16_03_3.pdf

    (See also figure 1.3)

    Same old tricks…

    1. Kenneth Richard

      “Reconstructed September SIE shows the minimum in 1936 that is twice higher then minimum 2012”

      As you may or may not realize, that statement is derived from mixing the reconstructed values with the “observed” values (1980-2013). When using the reconstructed values for both periods (based upon the negligible discrepancy in Arctic temperatures between the 1930s and 2000s), the difference disappears — which is what is shown in the Connolly et al (2017) graph. 2012 is clearly an anomalous outlier year in the “observed” record; it stands alone and does not represent a part of the overall area trend which has risen since 2012 and now is no higher than the early 2000s (or 1930s). In other words, Arctic sea ice extent — like the 21st centuryex pause in temperatures — has not been cooperating with models. This is illustrated here:

      http://notrickszone.com/wp-content/uploads/2018/04/CO2-Emissions-and-Arctic-Air.jpg

      (See also figure 1.3)

      Yes, please do look at Figure 1.3 from the link you provided (thanks). It shows the difference between the reconstructed sea ice values (blue) and the observed (red). The Connolly graph uses the reconstructed values, which are based on the negligible difference between Arctic temperatures in the 1930s vs. the 2000s. (Humans emitted 1 GtC/yr during the 1930s, but 9 GtC/yr during the 2000s…and yet there is effectively no difference in Arctic temperatures between the two periods.) The uptick in sea ice extent after 2012 is not shown but if it was it would clearly show that sea ice has not continued a downwards path since about 2007. It’s paused, even risen. 2012 is clearly an outlier year.

      Same old tricks…

      Please identify the “tricks” you might be referring to, Philip. Do you disagree with scientists pointing out that Greenland, Siberia, the Canadian Arctic…have been cooling since the early 2000s? Do you disagree that the Anatarctic Peninsula has been cooling dramatically since 1999? That East Antarctica has been cooling ubiquitously since the 1960s and 1970s? Do you disagree with the other graphs of centennial-scale sea ice extent showing nothing unusual has happened during the last few decades in Arctic regions like West Greenland, North Iceland, or the Beaufort Sea?

      1. yonason (from my cell phone)

        I thought it was the wind what done it, gov’ner.
        https://rmets.onlinelibrary.wiley.com/doi/pdf/10.1002/asl2.423

      2. Philip Clarke

        ” Notice that there are 2 outlier years — 2007 and 2012 — that fall below the previous cluster of low sea ice years during the 1930s, ”

        Really? I see four, maybe more. So you agree that modern ice is less than the 1930s. Also, all the ‘observed’ data points are at or below the reconstructed equivalent after around 2004, which is why you removed that plot (Trick 1). Why would you prefer a reconstructed regression to real observed data? I think I know the answer.

        Trick 2 would be pretending Greenland is the whole Arctic. Trick 3 would be not giving a link to the paper, I don’t think you want people to read that, or even the abstract

        “This reconstructed SIE shows a substantial decrease in the 1930–1940s with a minimum occurring in 1936, which, however, is only a *half of the decline in 2012*. The strong relationship between the summer SAT and September SIE was used to assess the onset of summer sea ice disappearance in the Arctic Ocean. According to the estimates made with a simple regression model, we can expect a seasonally ice‐free Arctic Ocean *as early as in the mid‐2030s*. ”

        Do you agree with Alekseev’s prediction? Or is your use for his work confined to reposting manipulated graphs?

  3. yonason (from my cell phone)

    While shipping gets stuck in ice on Lake Superior, warmists are still ‘stuck on stupid’.
    https://realclimatescience.com/2018/04/frozen-minnesotans-believe-the-arctic-is-hot/

  4. AndyG55

    How did it all get so bas-ackwards !!

    A decrease in Arctic sea ice, a RECOVERY from the anomalous LIA extremes and similar late 1970s extent..

    …would be absolutely beneficial for the whole region.

    Yet this natural recovery has been co-opted by the anti-CO2 brigade as being a BAD thing.

    ZERO evidence humans have any affect on Arctic sea ice, (except soot and ice-breakers)

    Same with enhanced atmospheric CO2.

    A MASSIVE BENEFIT to all life on Earth,

    ZERO evidence of any downside of continued increase to 1000+ ppm

    Yet somehow co-opted by the AGW scaremongers as their “demon”

    The whole thing is quite BIZARRE in a surrealistic kind of way.

    How did the planet become so short-sighted and mal-informed??.

    How did this moronic, zero-science anti-CO2 agenda ever get off the ground.??

  5. AndyG55

    As everyone should be well aware of by now, There is absolutely no anthropogenic signal in the Satellite temperature data either.

    The ONLY warming has come from El Ninos which cannot, in any possible way, be influenced by human anything.

    Between those El Ninos, even in RSSv$, there is NO WARMING.\

    No warming from 1980-1997

    https://s19.postimg.cc/kr0uu9cz7/RSS_V4_before_El_Nino.png

    No warming from 2001-2015

    https://s19.postimg.cc/jcuv319ir/RSS_V4_2001_-_2015.png

    There is IN FACT absolutely NO anthropogenic signal in any real data, except UHI/airport effects in badly positioned surface stations.

    Plenty of anthropogenic agenda signal in anything from the NCDC stable, (There’s at least 4 of them based on that farcical not-data) but that is not real warming.

  6. Ozonebust

    AndyG65
    I am with you, and the quote from the paper that attributes the loss to the wind, which in turn pushes the ocean into the Arctic.

    This is what occurs when increased heat is released from the mid latitude’s, EPTG which is also an increase in pressure gradient.

    The years 2007, 2012 and to a slightly lesser extent (no pun) 2016 witnessed a bias of atmosphere displacement toward the Arctic because of blocking mechanisms in the SH. But the trick is, how does one measure this annual hemisphere displacement bias.

    Perhaps the other chart jockeys commenting here should start looking, instead of squabling over other folks work, and trends without a known cause.

    There is zero human signature in the Arctic ice trend.
    Regards

  7. Bitter&twisted

    Here’s new paper that further undermines “consensus science

    A paper just published by the Journal of Climate concludes that high estimates of future global warming from most computer climate simulations are inconsistent with observed warming since 1850. The implication is that future warming will be 30 to 45% lower than suggested by the simulations.

    The study estimates climate sensitivity — how much the world will warm when carbon dioxide levels increase* — from changes in observed temperatures and estimates of the warming effect of greenhouse gases and other drivers of climate change, from the mid/late 19th century until 2016.

    The paper also addresses previous criticisms of the methodology used, finding that these are unfounded.

    Nicholas Lewis explains,

    “Our results imply that, for any future emissions scenario, future warming is likely to be substantially lower than the central computer model-simulated level projected by the IPCC, and highly unlikely to exceed that level.”

    Nicholas Lewis adds,

    “Our new sensitivity estimates are slightly lower than those obtained in a predecessor study published several years ago, despite the inclusion of the strong 2015–16 El Niño warming. Importantly, the upper uncertainty bounds of the new estimates are much lower.”

    Nicholas Lewis and Judith Curry, 2018: The impact of recent forcing and ocean heat uptake data on estimates of climate sensitivity. Journal of Climate, Early Online Release [https://doi.org/10.1175/JCLI-D-17-0667.1]

    Abstract

    Energy budget estimates of equilibrium climate sensitivity (ECS) and transient climate response (TCR) are derived based on the best estimates and uncertainty ranges for forcing provided in the IPCC Fifth Assessment Scientific Report (AR5). Recent revisions to greenhouse gas forcing and post-1990 ozone and aerosol forcing estimates are incorporated and the forcing data extended from 2011 to 2016. Reflecting recent evidence against strong aerosol forcing, its AR5 uncertainty lower bound is increased slightly. Using a 1869–1882 base period and a 2007−2016 final period, which are well-matched for volcanic activity and influence from internal variability, medians are derived for ECS of 1.50 K (5−95%: 1.05−2.45 K) and for TCR of 1.20 K (5−95%: 0.9−1.7 K). These estimates both have much lower upper bounds than those from a predecessor study using AR5 data ending in 2011. Using infilled, globally-complete temperature data gives slightly higher estimates; a median of 1.66 K for ECS (5−95%: 1.15−2.7 K) and 1.33 K for TCR (5−95%:1.0−1.90 K). These ECS estimates reflect climate feedbacks over the historical period, assumed time-invariant. Allowing for possible time-varying climate feedbacks increases the median ECS estimate to 1.76 K (5−95%: 1.2−3.1 K), using infilled temperature data. Possible biases from non-unit forcing efficacy, temperature estimation issues and variability in sea-surface temperature change patterns are examined and found to be minor when using globally-complete temperature data. These results imply that high ECS and TCR values derived from a majority of CMIP5 climate models are inconsistent with observed warming during the historical period.

  8. Polar Climate Anomalies: Where's The Anthropogenic Signal? | Principia Scientific International

    […] Read more at notrickszone.com […]

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