Climate Change: Polar Regions

Authored by: Roger G. Barry

Encyclopedia of Natural Resources

Print publication date:  July  2014
Online publication date:  June  2014

Print ISBN: 9781439852583
eBook ISBN: 9781351043847
Adobe ISBN:

10.1081/E-ENRA-120047632

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Abstract

The record of climatic changes in the Cenozoic era is briefly discussed. The Antarctic ice sheet formed approximately 33 million years ago (Ma), whereas perennial Arctic sea ice was not established until 14 Ma and the Greenland ice sheet formed approximately 3 Ma. Glacial/interglacial cycles from 2.6 to 0.43 Ma had a 41,000-year periodicity, which then switched to 100,000 years. Long-term changes in the climates of the polar regions were largely in phase. During the last glacial cycle, however, there was a bipolar seesaw on a millennial scale. The late-glacial Younger Dryas cold event was absent in the Antarctic region. During the last millennium the Medieval Warm Period and the Little Ice Age (LIA) were concentrated around the North Atlantic sector. In the twentieth century the Arctic warmed to the 1930s and then substantially more than the global average from 1980. Arctic sea ice declined dramatically in the 2000s. Arctic glaciers and ice caps have retreated and thinned with a recent acceleration in this trend. In the 2000s, Greenland outlet glaciers have retreated and thinned. Permafrost temperatures have risen recently. Temperatures have risen sharply over the last five decades in the Antarctic Peninsula and the ice shelves there are disintegrating. The Antarctic sea ice expanded slightly over the last three decades, although the mechanisms are uncertain.

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