Personally I find it difficult to believe some people are unable to comprehend the sun’s impact on our climate, especially when something like 99 point-something-percent of the earth’s energy comes from the sun. Even a vegetable notices when a cloud blocks out the sun, when the sun sets, or when it doesn’t get very high above the horizon. So I guess when it comes to solar sciences it wouldn’t be much of a stretch to argue that solar deniers are probably even dumber than a plant.
At any rate, geologist Dr. Sebastian Lüning and Professor Fritz Vahrenholt bring us the latest literature on the sun’s clear impact on the earth’s climate at their Die kalte Sonne site.
By Sebastian Lüning and Fritz Vahrenholt
(German text translated/edited by P Gosselin)
The sun is a major climate factor – also in America. In May 2014 Gorji Sefidmazgi and colleagues underscored this in a study appearing in the journal Nonlinear Processes in Geophysics. The scientists investigated the temperature development of North Carolina over the past 60 years. Here they found that the fluctuations are almost totally explainable by solar and oceanic cycles. Here’s the abstract:
Trend analysis using non-stationary time series clustering based on the finite element method
In order to analyze low-frequency variability of climate, it is useful to model the climatic time series with multiple linear trends and locate the times of significant changes. In this paper, we have used non-stationary time series clustering to find change points in the trends. Clustering in a multi-dimensional non-stationary time series is challenging, since the problem is mathematically ill-posed. Clustering based on the finite element method (FEM) is one of the methods that can analyze multidimensional time series. One important attribute of this method is that it is not dependent on any statistical assumption and does not need local stationarity in the time series. In this paper, it is shown how the FEM-clustering method can be used to locate change points in the trend of temperature time series from in situ observations. This method is applied to the temperature time series of North Carolina (NC) and the results represent region-specific climate variability despite higher frequency harmonics in climatic time series. Next, we investigated the relationship between the climatic indices with the clusters/trends detected based on this clustering method. It appears that the natural variability of climate change in NC during 1950–2009 can be explained mostly by AMO and solar activity.”
Some months later, in October 2014, a team of scientists led by Erich Osterberg published a study in the Journal of Geophysical Research that examined the influence of solar activity fluctuations on the Aleutian Low in the Gulf of Alaska. The results show: The changes in the Aleutian Low over the past 1500 years correlate strongly with solar activity. Strong solar activity is typically related with a weak Aleutian Low and Tropical La Nina conditions. The abstract:
Mount Logan ice core record of tropical and solar influences on Aleutian Low variability: 500–1998 A.D.
Continuous, high-resolution paleoclimate records from the North Pacific region spanning the past 1500 years are rare; and the behavior of the Aleutian Low (ALow) pressure center, the dominant climatological feature in the Gulf of Alaska, remains poorly constrained. Here we present a continuous, 1500 year long, calibrated proxy record for the strength of the wintertime (December–March) ALow from the Mount Logan summit (PR Col; 5200 m asl) ice core soluble sodium time series. We show that ice core sodium concentrations are statistically correlated with North Pacific sea level pressure and zonal wind speed. Our ALow proxy record reveals a weak ALow from circa 900–1300 A.D. and 1575–1675 A.D., and a comparatively stronger ALow from circa 500–900 A.D., 1300–1575 A.D., and 1675 A.D. to present. The Mount Logan ALow proxy record shows strong similarities with tropical paleoclimate proxy records sensitive to the El Niño–Southern Oscillation and is consistent with the hypothesis that the Medieval Climate Anomaly was characterized by more persistent La Niña-like conditions while the Little Ice Age was characterized by at least two intervals of more persistent El Niño-like conditions. The Mount Logan ALow proxy record is significantly (p < 0.05) correlated and coherent with solar irradiance proxy records over various time scales, with stronger solar irradiance generally associated with a weaker ALow and La Niña-like tropical conditions. However, a step-like increase in ALow strength during the Dalton solar minimum circa 1820 is associated with enhanced Walker circulation. Furthermore, rising CO2 forcing or internal variability may be masking the twentieth century rise in solar irradiance.”
Then a month later, in November 2014, a group of scientists lead by Keyan Fang published a paper appearing in the Journal of Climate, on the relationship between solar activity with the climate development in North America and North America. Using a dataset spanning 600 years the authors show that there is a close coupling between the continents. The abstract:
Covarying Hydroclimate Patterns between Monsoonal Asia and North America over the Past 600 Years
Proxy data with large spatial coverage spanning to the preindustrial era not only provide invaluable material to investigate hydroclimate changes in different regions but also enable studies on temporal changes in the teleconnections between these regions. Applying the singular value decomposition (SVD) method to tree-ring-based field reconstructions of the Palmer drought severity index (PDSI) over monsoonal Asia (MA) and North America (NA) from 1404 to 2005, the dominant covarying pattern between the two regions is identified. This pattern is represented by the teleconnection between the dipole pattern of southern–northern latitudinal MA and the dipole of southwest NA (SWNA)–northwest NA (NWNA), which accounts for 59.6% of the total covariance. It is dominated by an antiphase low MA and SWNA teleconnection, driven by the El Niño–Southern Oscillation (ENSO), and is most significant at an interannual time scale. This teleconnection is strengthened (weakened) in periods of increased (decreased) solar forcing and high (low) temperature, which is associated with intensified (weakened) ENSO variability. Additional forcing by SST anomalies in the Indian and western Pacific Oceans appears to be important too.”
Now let’s jump to the southern hemisphere to South America. In June 2015 a group of scientists led by C. Turney of the University of New South Wales in Sydney published a study in the journal Climate of the Past Discussions on the climate history of the Falkland Islands. Using a charcoal record the scientists reconstructed the strength of the westerly airflow over the past 2600 years. Using spectral analysis Turney and his team found the 250-year characteristic cycle, which is in the range of the Suess-de Vries cycle. One fascinating result: The westerly airflow of the Southern Hemisphere blew in sync with the cycles of the sun. Here’s the abstract:
A 250 year periodicity in Southern Hemisphere westerly winds over the last 2600 years
Southern Hemisphere westerly airflow has a significant influence on the ocean–atmosphere system of the mid- to high-latitudes with potentially global climate implications. Unfortunately historic observations only extend back to the late nineteenth century, limiting our understanding of multi-decadal to centennial change. Here we present a highly resolved (30 yr) record of past westerly air strength from a Falkland Islands peat sequence spanning the last 2600 years. Situated under the core latitude of Southern Hemisphere westerly airflow, we identify highly variable changes in exotic pollen derived from South America which can be used to inform on past westerly air strength and location. The results indicate enhanced airflow over the Falklands between 2000 and 1000 cal. yr BP, and associated with increased burning, most probably as a result of higher temperatures and/or reduced precipitation, comparable to records in South America. Spectral analysis of the charcoal record identifies a 250 year periodicity within the data, suggesting solar variability has a modulating influence on Southern Hemisphere westerly airflow with potentially important implications for understanding global climate change through the late Holocene.”
Just like we reported some time ago: Solar activity also in South American monsoons over the last 1500 years.
Of course readers have the choice of believing a growing mountain of solar-climate papers authored by dozens of distinguished scientists, or an amateur who doesn’t even read the papers.