Rapid Arctic warming has in the past shifted Southern Ocean winds

ScienceDaily | 1/10/2017 | Staff
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A dramatic pattern in our planet's climate history involves paroxysms in Arctic temperatures. During the last ice age, tens of thousands of years ago, Greenland repeatedly warmed by about 10 degrees Celsius over just a few decades and then gradually cooled. Meanwhile the Southern Hemisphere climate stayed fairly stable, with only weak and long-delayed echoes of the temperature chaos up north.

But new University of Washington research shows the fierce winds circling Antarctica -- an important lever on the global climate -- shifted quickly in response to the Northern Hemisphere temperature spikes.

Changes - Northern - Hemisphere - Southern - Hemisphere

"It's most surprising that we can see these really abrupt changes in the Northern Hemisphere making it very quickly to the Southern Hemisphere," said first author Bradley Markle, a UW doctoral student in Earth and space sciences. "The atmospheric circulation is tightly connected across the globe during these events."

The study is published in the January issue of Nature Geoscience.

Researchers - Evidence - West - Antarctic - Ice

Researchers used evidence from a 2-mile-long West Antarctic ice core. That ice core's thick annual layers provide precise dating that allows scientists to match its climate history with those in distant Greenland ice records. The wild northern temperature swings, known as Dansgaard-Oeschger events, are thought to be natural oscillations in the climate system. They have been reproduced in the most sophisticated climate models covering the ice age period. These same models also show a shift in Southern Hemisphere winds.

The new study is the observational support for this shift in the winds.

Antarctic - Ice - Core - Southern - Ocean

The Antarctic ice core shows that Southern Ocean winds shifted at the same time, or at most within a few decades, of each rapid Greenland warming event. Antarctic air temperatures, on the other hand, are connected through the slower-moving oceans and took about two centuries to respond.

"We'd never found anything in our ice cores before that show the Southern Hemisphere responding so...
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