Arctic subjected to intense warm climate intervals

June 22nd, 2012 - 5:13 pm ICT by IANS  

University of Massachusetts Washington, June 22 (IANS) Intense warm climate intervals - warmer than scientists thought possible - have occurred in the Arctic over the past 2.8 million years, reveals a research by climatologists.

The result comes from the first analyses of the longest sediment cores ever retrieved on land, from beneath the ice-covered Lake El’gygytgyn, or Lake E, in the northeast Russian (Siberian) Arctic.

They show that the extreme warm periods in the Arctic correspond closely with times when parts of Antarctica were also ice-free and warm, suggesting a strong connection between Northern and Southern Hemisphere climates, the journal Science reports.

The polar regions are much more vulnerable to climate change than researchers thought, say the National Science Foundation (NSF) funded Lake E project’s co-chief scientists, Martin Melles of the University of Cologne, Germany, Julie Brigham-Grette of the University of Massachusetts Amherst, and Pavel Minyuk of Russia’s North-East Interdisciplinary Scientific Research Institute in Magadan.

Scientists say that the exceptional climate warming in the Arctic, and the inter-hemispheric interdependencies, weren’t known before the Lake E studies.

Lake E was formed 3.6 million years ago when a huge meteorite hit Earth, leaving an 11-mile-wide crater. It’s been collecting layers of sediment ever since, according to the NSF statement.

The lake is of interest to scientists since it has never been covered by glaciers, which has allowed uninterrupted build-up of sediment at the bottom of the lake, recording hitherto undiscovered information on climate change.

Cores from Lake E go far back in time, almost 30 times farther than Greenland ice cores covering the past 110,000 years.

The sediment cores from Lake E reflect the climate and environmental history of the Arctic with great sensitivity, say Brigham-Grette and colleagues.

The physical, chemical and biological properties of Lake E’s sediments match the known global glacial and interglacial pattern of the ice ages.

Some warm phases are exceptional, however, marked by extraordinarily high biological activity in the lake, well above that of “regular” climate cycles.

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