Friday, June 22, 2012

Past periodic warmth in arctic may be related to melting Antarctic ice sheets

UMassAmherst: First analyses of the longest sediment core ever collected on land in the Arctic, published this week inScience, provide dramatic, “astonishing” documentation that intense warm intervals, warmer than scientists thought possible, occurred there over the past 2.8 million years.

Further, these extreme inter-glacial warm periods correspond closely with times when parts of Antarctica were ice-free and also warm, suggesting strong inter-hemispheric climate connectivity, say the project’s three co-chief scientists. The Polar Regions are much more vulnerable to change than once believed, they add. The team was led by Martin Melles of Germany’s University of Cologne, Julie Brigham-Grette of the University of Massachusetts Amherst and Pavel Minyuk of Russia’s Northeast Interdisciplinary Scientific Research Institute in Magadan.

Brigham-Grette, the lead U.S. scientist says, “What we see is astonishing. We had no idea that we’d find this. It’s astonishing to see so many intervals when the Arctic was really warm, enough so forests were growing where today we see tundra and permafrost. And the intensity of warming is completely unexpected. The other astounding thing is that we were able to determine that during many times when the West Antarctic ice sheet disappeared, we see a corresponding warm period following very quickly in the Arctic. Arctic warm periods cluster with periods when the Western Antarctic ice sheet is gone.”
Data reported by Melles, Brigham-Grette, Minyuk and colleagues come from analyzing sediment cores collected in 2009 from under ice-covered Lake El’gygytgyn in the northeast Russian Arctic. “Lake E” was formed 3.6 million years ago when a huge meteorite hit the Earth and blasted out an 11-mile (18 km) wide crater. It has been collecting layers of sediment ever since. Luckily, it is located in one of the few areas in the Arctic not eroded by continental glaciers, leaving the thick sediment record remarkably undisturbed and continuous. Cores from Lake E reach back in geologic time nearly 30 times farther than Greenland ice cores covering the past 110,000 years....

I assume this is a picture of Martin Melles and Julie Brigham-Grette. From the UMassAmherst website

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