Tuesday, August 25, 2009

Another Little Ice Age? Solar activity and climate change

Some scientists are suggesting that the slow return to a more active phase of the solar cycle may portend a general decline in solar activity. If sunspots shut down, does that mean that we could stop worrying about climate change?

By John Timmer

Over the weekend, a paper published in the American Geophysical Union's journal Eos attracted a lot of attention, as it suggested that the levels of magnetic activity associated with recent sunspots indicated that the sun might be returning to a state of low activity, similar to that of the Maunder Minimum, which occurred in the late 17th century. That change in solar activity was notable for setting off what's called the Little Ice Age, which plunged Europe into a deep chill. Left undiscussed is what that might mean in a world where greenhouse gas changes are threatening a period of extended high temperatures.
To understand how a significant change in sunspot levels might be felt in the Earth's climate, we'll back up and look at how sunspots relate to solar output, how that output gets felt on Earth, and how it interacts with changing levels of greenhouse gasses. The answer appears to be that it could reverse the climate change that occurred during past century, but would only delay the changes expected by the end of this century.
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