- Human activity is making the planet darker as well as
warmer, scientists say. They believe levels of sunlight reaching Earth's
surface have declined by up to 20% in recent years because air pollution
is reflecting it back into space and helping to make bigger, longer-lasting
clouds.
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- The "global dimming" effect could have implications
for everything from the effectiveness of solar power to the growth of plants
and trees. "Over the past couple of years it's become clear that the
solar irradiance at the Earth's surface has decreased," said Jim Hansen,
a climate scientist with Nasa's Goddard Institute for Space Science in
New York.
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- Experts say global dimming is probably down to tiny particles
such as soot, and chemical compounds such as sulphates accumulating in
the atmosphere. "Data from 100 stations around the world show that
the amount of black carbon in the atmosphere is twice as big as we assumed,"
said Dr Hansen.
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- Guardian Unlimited © Guardian Newspapers Limited
2003
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- http://www.guardian.co.uk/climatechange/story/0,12374,1109374,00.html
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