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Solar Irradiance and Arctic Temperatures
Soon, W. W.-H.  2005.  Variable solar irradiance as a plausible agent for multidecadal variations in the Arctic-wide surface air temperature record of the past 130 years.  Geophysical Research Letters 32 L16712, doi:10.1029/2005GL023429.

What was done
It has long been debated which variable is the dominant driver of 20th-century temperature change in the Arctic: rising atmospheric CO2 concentrations or variations in solar irradiance.  The author explores this question by examining what roles these two variables may have played in decadal, multi-decadal and longer-term variations in the surface air temperature (SAT) record of the Arctic.  More specifically, he performed a number of statistical analyses on (1) a composite Arctic-wide SAT record constructed by Polyakov et al. (2003), (2) global CO2 mixing ratios taken from estimates given by the NASA GISS climate modeling group, and (3) a total solar irradiance (TSI) record developed by Hoyt and Schatten (1993, updated by Hoyt in 2005) over the period 1875-2000.

What was learned
The results of the analyses indicated a much stronger statistical relationship between SATs and TSI, as opposed to SATs and CO2 mixing ratios.  In fact, solar forcing generally explained well over 75% of the variance in decadal-smoothed seasonal and annual Arctic temperatures, while CO2 forcing only explained between 8 and 22%.  Wavelet analysis further supported the case for solar forcing of the SAT record, revealing similar time-frequency characteristics for annual and seasonally-averaged temperatures at decadal and multi-decadal time scales.  In contrast, wavelet analysis gave little to no indication of a CO2 forcing of Arctic SSTs.

What it means
Based on these data and analyses, it would appear that it is the sun, and not atmospheric CO2, that is driving temperature change in the Arctic.  The results of this study thus call for further research into the solar-climate connection and the means by which it operates.

Hoyt, D.V. and Schatten, K.H.  1993.  A discussion of plausible solar irradiance variations, 1700-1992.  Journal of Geophysical Research 98: 18,895-18,906.

Polyakov, I.V., Bekryaev, R.V., Alekseev, G.V., Bhatt, U.S., Colony, R.L., Johnson, M.A., Maskshtas, A.P. and Walsh, D.  2003.  Variability and trends of air temperature and pressure in the maritime Arctic, 1875-2000.  Journal of Climate 16: 2067-2077.

Reviewed 23 November 2005