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Tue, 27 Jun 2006 09:33:30 -0700

[Zepps_News] #Earth's Climate Warming Abruptly, Scientist Says

 

 

 

 

 

http://www.washingtonpost.com/wp-dyn/content/article/2006/06/26/AR2006062601237.\

html

 

Earth's Climate Warming Abruptly, Scientist Says

Tropical-Zone Glaciers May Be at Risk of Melting

 

By Doug Struck

Washington Post Staff Writer

Tuesday, June 27, 2006; Page A03

 

COLUMBUS, Ohio -- Earth's climate is undergoing an abrupt change, ending

a cooler period that began with a swift " cold snap " in the tropics 5,200

years ago that coincided with the start of cities, the beginning of

calendars and the biblical great flood, a leading expert on glaciers has

concluded.

 

The warming around Earth's tropical belt is a signal suggesting that the

" climate system has exceeded a critical threshold, " which has sent

tropical-zone glaciers in full retreat and will melt them completely " in

the near future, " said Lonnie G. Thompson, a scientist who for 23 years

has been taking core samples from the ancient ice of glaciers.

 

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Thompson, writing with eight other researchers in an article published

Monday in the Proceedings of the National Academy of Sciences, said the

ice samples show that the climate can and did cool quickly, and that a

similarly abrupt warming change started about 50 years ago. Humans may

not have the luxury of adapting to slow changes, he suggests.

 

" There are thresholds in the system, " Thompson said in an interview in

his lab at Ohio State University. When they are crossed, " there is the

risk of changing the world as we know it to some form in which a lot of

people on the planet will be put at risk. "

 

" I think the temperature will continue to rise, the glaciers will

continue to melt. Sea levels will continue to rise. I think there is a

good indication now that the magnitude of severe storms will rise, " he

said.

 

Thompson's work summarizes evidence from around the world and ice core

sampling from seven locations in the South American Andes and the Asian

Himalayas. It considerably extends the reach of a growing number of

scientific findings documenting the historically unusual warming of

Earth. A top scientific panel last week endorsed an earlier study, by

Penn State professor Michael E. Mann, that concluded the recent warming

in the Northern Hemisphere is of a scale probably unseen for 400 to

1,000 years.

 

Thompson, whose research has focused on glaciers in the high mountains

of the tropics, writes that the warming there " is unprecedented for at

least two millennia. " He teamed with his wife, Ellen Mosley-Thompson, an

expert in polar ice sampling, and concluded that the glacial retreat

" signals a recent and abrupt change in the Earth's climate system. "

 

Caspar Amman, a scientist at the National Center for Atmospheric

Research in Boulder, Colo., said Thompson's " perspective of the changes

over the past 2,000 years is striking. Something is definitely different

towards the end of the 20th century. "

 

But the finding likely to cause the most debate is Thompson's conclusion

that a swift and sudden cooling of the climate five millennia ago

occurred simultaneously with key changes in civilizations.

 

" It represents a time where, for many parts of the world, people ceased

to be hunters and gatherers and formed cities, " he said. " Many of the

modern calendars began around this time. It would also fall in the

general time frame of the biblical flood. "

 

Thompson said he does not know what caused the abrupt change -- one

possibility is a " mega La Ni?a " shift in upper air currents. But he said

the evidence from such diverse sources as Mount Kilimanjaro; African

lakes; Greenland and Antarctic ice cores; the Andes and the Alps point

to a sudden arrival of cool and often wet conditions, all about the same

time.

 

That time saw cities form in the Nile Valley and Mesopotamia, his paper

says, and the end of a humid period in Africa that " seems to have begun

and ended abruptly, within decades to a century. " In what is now

Florida, water levels rose rapidly. In Washington state, glaciers

covered whole trees. In the Alps, a mortally wounded hunter nicknamed

Otzi was buried quickly by snow and captured within a growing glacier

until it melted enough to expose him in 1991.

 

Theories linking climate change with changes in the history of humans

are increasingly popular. The book " The Winds of Change " by Eugene

Linden argues that climate shifts accompanied the fall of many

civilizations.

 

Gavin Schmidt, a scientist at NASA's Goddard Institute for Space Studies

in New York, applauded Thompson's work but said his conclusions about

events 5,200 years ago have many skeptics.

 

" You would have to put that argument as more intriguing rather than

definitive, " Schmidt said. " There are a number of issues in the tropical

ice cores that are problematic for dating things 4,000 to 5,000 years

ago. "

 

Thompson and other scientists typically drill down to layers of glaciers

put down by snow thousands of years ago. The air bubbles caught in those

cores are analyzed to determine the atmosphere at the time. Sediment,

insects and pollen are further clues to the climate in ancient history.

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