Unstable Antarctica

The climate of Antarctica has never been stable, and proxy indicators from ice cores show abrupt alterations in atmospheric circulation and temperature over the millennia. One of the most dramatic changes was the intensification of the circumpolar westerly winds between 6000 and 5000 years ago and again between 1200 and 1000 years ago. The ice core temperature records show a much warmer period than today, between 12 and 9 thousand years ago, known as the early Holocene climatic optimum. In recent centuries there have been major changes, in particular a significant cooling between 1700 and 1850 associated with altered atmospheric circulation above the region. Yet over the past 50 years surface temperature and snowfall have barely changed while the atmospheric circulation and total sea ice cover have remained virtually the same.


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