Solheim, J.-E., Stordahl, K. and Humlum, O. 2012. The long sunspot cycle 23 predicts a significant temperature decrease in cycle 24. Journal of Atmospheric and Solar-Terrestrial Physics 80: 267-284.
The authors indicate that Archibald (2008) was the first person to realize that the previous sunspot cycle length (PSCL) has a predictive power for the temperature in the next sunspot cycle, if the raw (unsmoothed) value for the sunspot cycle length (SCL) is used, which he demonstrated with data from (1) de Bilt in the Netherlands, (2) Hanover, New Hampshire, USA, (3) Portland, Maine, USA, (4) Providence, Rhode Island, USA, and (5) Archangel, Russia.
What was done
In further exploring the nature and generality of this relationship, Solheim et al. compared the relations between raw (unsmoothed) SCL values and temperatures in both the same and the next sunspot cycles for a selection of Norwegian and other European weather stations possessing long weather records at places with small populations (to minimize urban heat island effects) in both coastal and inland locations, as well as for a selection of sites spread across the North Atlantic region, including Armagh, Archangel, the Faroe Islands, Iceland, Svalbard and Greenland.
What was learned
The three Norwegian researchers found significant linear relationships between the average air temperature in a solar cycle and the length of the previous solar cycle for 12 out of 13 weather stations in Norway and in the North Atlantic, as well as for 60 European stations and for the HadCRUT3N database. And in the case of Norway and the other European stations, they report that "the solar contribution to the temperature variations in the period investigated is of the order 40%," while "an even higher contribution (63-72%) is found for stations at the Faroe Islands, Iceland and Svalbard," which they note is considerably "higher than the 7% attributed to the sun for the global temperature rise in AR4 (IPCC, 2007)."
What it means
With respect to what their findings suggest about the future, Solheim et al. say they imply "an annual average temperature drop of 0.9°C in the Northern Hemisphere during solar cycle 24," while "for the measuring stations south of 75°N, the temperature decline is of the order 1.0-1.8°C and may already have started." For Svalbard, they say that "a temperature decline of 3.5°C is forecasted in solar cycle 24 for the yearly average temperature," and that "an even higher temperature drop is forecasted in the winter months (Solheim et al., 2011)." They do caution, however, that "since solar forcing on climate is present on many timescales, we do not claim that our result gives a complete picture of the sun's forcing on our planet's climate.
Archibald, D. 2008. Solar cycle 24: Implications for the United States. International Conference on Climate Change. < www.davidarchibald.info/>.
IPCC. 2007. Climate Change 2007: The Physical Science Basis. In: Solomon, S., et al. (Eds.). Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom.
Solheim, J.-E., Stordahl, K. and Humlum, O. 2011. Solar activity and Svalbard temperatures. Advances in Meteorology 2011: 10.1155/2011/543146.Reviewed 21 November 2012