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The Arctic and Antarctic May Have a Linked Climate Change Oscillation of 200 Years

First Posted: Apr 30, 2015 06:23 AM EDT
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There may be a link between abrupt temperature changes in Greenland and Antarctica during the last ice age. The researchers have uncovered a highly detailed ice core and found out that there was a clear "lag" between the two changing climates.

Greenland's climate during the last ice age was extremely unstable. It was characterized by a number of large, abrupt changes in mean annual temperature. Each of these changes occurred within just several decades. Caused "Dansgaard-Oeschger events," they took place once every few thousand years during the last ice age. In contrast, temperature changes in Antarctica showed an opposite pattern; when Antarctica cooled, Greenland was warm and vice versa.

The new ice cores revealed that the abrupt climate changes show up first in Greenland, with the response to the Antarctic climate delayed by about 200 years. In fact, there were a total of 18 abrupt climate events during the past 68,000 years.

"The fact that temperature changes are opposite at the two poles suggests that there is a redistribution of heat going on between the hemispheres," said Christo Buizert, lead author of the new study, in a news release. "We still don't know what caused these past shifts, but understanding their timing gives us important clues about the underlying mechanisms."

So what sort of mechanisms may be causing these changes? The 200-year lag suggests that there's an oceanic mechanism involved. The long time lag suggests water since in the atmosphere, the response would have occurred in a matter of just years or decades. It's likely that the Atlantic Meridional Overturning Circulation (AMOC) is involved.

"This ocean circulation rings warm surface waters from the tropics to the North Atlantic," said Buizert. "As these water masses cool, they sink to the bottom of the ocean. This happens right off the coast of Greenland, and therefore Greenland is located in a sweet spot where the climate is very sensitive to changes in the AMOC."

The findings reveal a bit more about abrupt climate change and show that when it comes to Greenland and Antarctica, there may be an oceanic link.

The findings are published in the journal Nature.

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