New paper finds large increase in Northern Hemisphere sunshine since 1982; dwarfs alleged effect of CO2

A new paper published in Atmospheric Chemistry and Physics finds from direct measurements that there was a significant increase in solar radiation at the surface of the Northern Hemisphere from 1982 to 2008. According to the authors, "the average increase of [surface solar radiation] from 1982 to 2008 is estimated to be 0.87 W m⁻² per decade," which equates to 2.26 W m-2 over the 26 year period. By way of comparison, this forcing was 12.5 times greater than the surface forcing alleged by the IPCC from increased CO2 over the same period:

5.35*ln(386.59/341.44) = 0.66 W m-2 alleged CO2 forcing at the top of the atmosphere  

which equates to only 0.66 * 1/3.7 = 0.18 W m-2 at the Earth's surface

The paper adds to several others showing that a decrease in cloudiness was largely responsible for warming in the latter 20th century, rather than man-made greenhouse gases.

Related:

New paper finds large increase in sunshine since the 1980's; dwarfs alleged effect of CO2

Atmos. Chem. Phys., 12, 9581-9592, 2012
www.atmos-chem-phys.net/12/9581/2012/
doi:10.5194/acp-12-9581-2012
Atmospheric impacts on climatic variability of surface incident solar radiation

K. C. Wang¹, R. E. Dickinson², M. Wild³, and S. Liang^4
1State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Global Change and Earth System Science, Beijing Normal University, Beijing, 100875, Beijing, China
²Department of Geological Sciences, The University of Texas at Austin, Austin, TX 78712, USA
³Institute for Atmospheric and Climate Science, ETH Zürich, 8092 Zürich, Switzerland
⁴Department of Geography, University of Maryland, College Park, MD 20742, USA
 Abstract. The Earth's climate is driven by surface incident solar radiation (R_s). Direct measurements have shown that R_s has undergone significant decadal variations. However, a large fraction of the global land surface is not covered by these observations. Satellite-derived R_s has a good global coverage but is of low accuracy in its depiction of decadal variability. This paper shows that daily to decadal variations of R_s, from both aerosols and cloud properties, can be accurately estimated using globally available measurements of Sunshine Duration (SunDu). In particular, SunDu shows that since the late 1980's R_s has brightened over Europe due to decreases in aerosols but dimmed over China due to their increases. We found that variation of cloud cover determines R_s at a monthly scale but that aerosols determine the variability of R_s at a decadal time scale, in particular, over Europe and China. Because of its global availability and long-term history, SunDu can provide an accurate and continuous proxy record of R_s, filling in values for the blank areas that are not covered by direct measurements. Compared to its direct measurement, R_s from SunDu appears to be less sensitive to instrument replacement and calibration, and shows that the widely reported sharp increase in R_s during the early 1990s in China was a result of instrument replacement. By merging direct measurements collected by Global Energy Budget Archive with those derived from SunDu [Sunshine Duration], we obtained a good coverage of R_s [surface incident solar radiation] over the Northern Hemisphere. From this data, the average increase of R_s [surface incident solar radiation] from 1982 to 2008 is estimated to be 0.87 W m⁻² per decade.

The full paper is available here:

 Final Revised Paper (PDF, 794 KB)   Discussion Paper (ACPD)