Friday, August 21, 2009

The Solar Connection

Meteorologists aren’t the only people to pick out this period as unusual: they’re joined by astronomers who study sunspots (pictured, below). Today, these dark patches – marking magnetic storms on the Sun - come and go in an 11-year cycle. But there was a complete dearth of dark spots on the Sun from 1645 to 1715, the time that the Earth plunged into the Little Ice Age.
This apparent link between the Sun’s magnetic activity and the Earth’s climate could be coincidence. But German researcher Sami Solanski has confirmed the effect. Based at the Max Planck Institute for Solar System Research, in Katlenburg-Lindau, Solanski has pushed the Sun’s magnetic record back to 9000 BC. No-one was observing sunspots then, of course, but the Sun’s activity shows up in certain isotopes - carbon-14 and beryllium-10 - that are preserved in ancient pieces of wood and deep in the ice of Greenland and Antarctica.
Solanski has found that the Sun’s magnetism and the Earth’s temperature march hand-in-hand over the millennia. When the Sun is violent, our temperatures go up. When the Sun is dormant (as in the Little Ice Age), our temperatures drop. He finds, however, that this correlation stops around 1970, when manmade global warming starts to kick in. Solanski reckons that solar activity can account for only 30%, at best, of the Earth’s warming in the past 40 years.

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