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19 Jun 08 - Climate change
obliterated Greenland's leafy cover, turning it into an icy island in as
little as a single year, a new study says,
while trying to make us fear global warming.
Extensive spruce forests used to
cover the southern half of Greenland, according to a Canadian study that
gives a remarkable glimpse of the icy island's green past and possible
future.
The work, by a team at the Universite du Quebec a Montreal, shows the
impact of past climate warming on the massive ice sheet was much greater
than previously believed.
Anne de Vernal and Claude Hillaire-Marcel report in the journal Science
Friday. The journal also features a second report showing how North
America's climate suddenly flipped from a cold to a warm state at the
end of the last ice age, with dramatic changes in atmospheric
circulation in as little as a single year.
The shifts happened so quickly it is "as if someone had pushed a
button," says Dorthe Dahl-Jensen of the University of Copenhagen, who
led the international team. There were two huge temperature spikes in
the Northern Hemisphere at the end of last ice age - one 14,700 years
ago associated with a 10C rise in temperatures over 50 years. Then icy
conditions returned before another abrupt warming about 11,700 years
ago.
The ice core points to a "reorganization" of atmospheric circulation
over one or two years in the Northern Hemisphere before each temperature
spike, say the scientists.
Pollen shows Greenland was much greener than it is today during several
warm periods over the million-year span, with extensive fernlike
vegetation 125,000 ago and widespread spruce forests 400,000 years ago.
"It was probably much like the forest in Norway is today, with a
relatively mild climate," de Vernal said.
"What's remarkable about this (the past ice retreats) is that they
occurred with greenhouse gas emissions that are about 30 per cent lower
than they are today," said University of Alberta paleoclimatologist
Alexander Wolfe, co-author of a Science commentary that discusses the
findings.
This is somehow supposed to make us worry about
global warming? No, we should be worried about
sudden global cooling.
And what about humans? Did a handful humans cause
those sudden changes?
http://www.sciam.com/article.cfm?id=ice-core-reveals-how-quickly-climate-can-change
Thanks to Edward Nowak and Viv Forbes for this link |