Monday, December 22, 2008

Sunspot data vital clues to climate change

University of New England News (Australia): New discoveries linking periodic changes in the Sun’s magnetic field with global weather patterns could enable scientists to gain a clearer understanding of how additional factors – such as greenhouse gases – contribute to those weather patterns. A newly-published paper by the University of New England’s Dr Robert Baker establishes the connection between solar cycles and the weather by correlating sunspot activity and rainfall figures for south-eastern Australia over the past 130 years.

Cycles of sunspot activity are a visible indication of the periodic changes in magnetic forces within the Sun. The most well-known sunspot cycle is the 11-year “Schwab” cycle, which comprises alternating five-and-a-half-year periods of relatively high and low sunspot activity.

Dr Baker’s paper, “Exploratory analysis of similarities in solar cycle magnetic phases with Southern Oscillation Index fluctuations in Eastern Australia” (Geographical Research, December 2008), shows that periods of increased sunspot activity are consistently associated with those periods of high rainfall in south-eastern Australia predicted by the Southern Oscillation Index (SOI). Periods of drought, such as that which has afflicted Australia for the past six years, are associated with minimal sunspot activity.

...“We have to benchmark the natural system (i.e., the Sun) before looking at additions to it (e.g. carbon dioxide),” he explained. “Comparing current data with those of a century ago can give us an idea of the added effect of greenhouse gases. But sticking your head in the sand and saying the Sun has no effect on climate change is a virtual denial of historical reality.”

It was a quiet day on the Sun in September of 2000. The above image from NASA's sun-observing TRACE spacecraft shows, however, that even during "off days" the Sun's surface is a busy place. Shown in ultraviolet light, the relatively cool dark regions have temperatures of thousands of degrees.

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