http://www.cnn.com/2001/TECH/space/11/16/solar.cycles.ap/index.html
WASHINGTON (AP) -- The brightening and dimming of the sun may account for a
1,500-year cycle of cooling and warming on parts of the Earth, a study of ice
in the North Atlantic suggests.
Researchers found that a very slight difference in the amount of solar energy
reaching the Earth can have a powerful chilling effect on the climate: ice
builds up in lands bordering the North Atlantic, the average temperature
drops in Europe and North America.
"Whether the whole Earth is affected, we don't know for sure yet, but it is
certainly implied," said Gerard C. Bond, a researcher at the Lamont-Doherty
Earth Observatory of Columbia University in Palisades, New York.
"The effect does extend from the high northern latitudes down, maybe even to
the tropics," said Bond, first author of a study appearing Friday in the
journal Science.
The cycle of sunlight intensity roughly follows a 1,500-year pattern, based
on analysis of the past 12,000 years. But the difference from the top of the
cycle to the bottom is very small, with less than a 0.1 percent difference in
energy levels, he said...>>
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