WASHINGTON: Scientists have claimed
that global wind shifts many have ushered in a warmer climate and the birth of
human civilisation at the end of the last Ice Age about 20,000 years ago.
An international team has looked to a global shift in winds and
propose a chain of events that began with melting of the large northern
hemisphere ice sheets about 20,000 years ago, the 'Science' journal reported.
The melting ice sheets reconfigured the planet's wind belts, pushing
warm air and seawater south, and pulling carbon dioxide from the deep ocean into
the atmosphere, allowing the planet to heat even further. Their hypothesis makes
use of climate data preserved in cave formations, polar ice cores and deep-sea
sediments to describe how Earth finally thawed out.
"Finally, we
have a clear picture of the global teleconnections in Earth's climate system
that are active across many time scales.
"These same linkages that
brought the earth out of the last ice age are active today, and they will almost
certainly play a role in future climate change as well," Bob Anderson at
Columbia University, who led the team.
Earth regularly goes into an
ice age every 100,000 years or so, as its orientation toward the sun shifts in
what are called Milankovitch cycles.
At the peak of the last ice
age, about 20,000 years ago, with New York City and large parts of Europe and
Asia buried under thick sheets of ice, Earth's orbit shifted.
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