IF NEW satellite data can be trusted, changes in solar activity warmed the Earth when they should have cooled it.
of Imperial College London studied measurements of solar radiation between 2004 and 2007, when overall solar activity was in decline. The sun puts out less energy when its activity is low, but different types of radiation vary to different degrees. Until now, this had been poorly studied.
Haigh鈥檚 measurements showed that visible radiation increased between 2004 and 2007, when it was expected to decrease, and ultraviolet radiation dropped four times as much as predicted.
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Haigh then plugged her data into an atmospheric model to calculate how the patterns affected energy filtering through the atmosphere. Previous studies have shown that Earth is normally cooler during solar minima.Yet the model suggested that more solar energy reached the planet鈥檚 surface during the period, warming it by about 0.05 掳C ().
The effect is slight, but it could call into question our understanding of the sun鈥檚 subtle effects on climate. Or could it? of the University of Bern in Switzerland says Haigh鈥檚 study shows the importance of looking at radiation changes in detail but cautions that the results could be a one-off. He points out that the sun鈥檚 most recent cycle is known to have been atypical.
