ScienceDaily (Aug. 2, 2007) — To accurately assess the effects of human-induced climate change, scientists must be able to quantify the contribution of natural variation in solar irradiance to temperature changes.

The existence of a long-term trend in solar output is controversial, but its periodic change within an 11-year cycle has been measured by satellites.

To assess how this less-controversial oscillatory forcing affects climate on Earth, Camp and Tung compare surface temperature measurements across the globe between years of solar maximum (with higher heat output) and years of solar minimum.

They find that times of high solar activity are on average 0.2º C warmer than times of low solar activity, and that there is a polar amplification of the warming. This result is the first to document a statistically significant globally coherent temperature response to the solar cycle, the authors note.

Title: Surface warming by the solar cycle as revealed by the composite mean difference projection

Authors: Charles D. Camp and Ka Kit Tung: Department of Applied Mathematics, University of Washington, Seattle, Washington, U.S.A.

Source: Geophysical Research Letters (GRL) paper 10.1029/2007GL030207, 2007

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