Arctic sea ice decline 'unprecedented' in last 1,400 years

Nov 23, 2011

By Doyle Rice, USA TODAY

CAPTION

By Martin Jeffries, Associated Press

Arctic sea ice continues to dwindle each summer to some of the lowest levels on record, according to the National Snow and Ice Data Center, with this year's ice loss the second-lowest ever. However, the record only goes back to 1979, when satellites began tracking sea ice. This is admittedly a tiny sample set, especially when dealing with long-term climate changes that last hundreds or thousands of years.But a new study released today in the British journal Nature finds that "both the duration and magnitude of the current decline in sea ice seem to be unprecedented for the past 1,450 years," the study authors report, also calling the declines "unparalleled" in relation to previous patterns of natural variation.
The study was led by Christophe Kinnard of the Center for Advanced Studies in Arid Zones in La Serena, Chile.

Kinnard and his colleagues used proxy data -- such as ice core records, tree ring data, lake sediments and historical evidence -- to reconstruct past sea ice cover in the Arctic. They found that unusually warm Atlantic Ocean water flowing into the Arctic is the cause of the recent sea ice decline.
Whether the observed decline in Arctic sea ice of the past few decades is due to natural variability is difficult to determine, the scientists, admit. However, they conclude it is consistent with human-caused global warming.

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