From forests to ice in a single year

Not by Fire but by Ice


Discover What Killed the Dinosaurs . . . and Why it Could Soon Kill Us

From forests to ice in a single year


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?
Thanks to Edward Nowak and Viv Forbes for this link



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