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Friday, February 6, 2009

More Global Warming Warning Signs From The Ends of the Earth

The trend in Arctic sea ice extent shows a slower-than-normal re-freezing this January, as the Southern Hemisphere summer bakes Australia.
Also see
Stunning Photos of Antarctica.

Arctic Sea Ice Extent - Jan 2009
This map shows the extent of Arctic sea ice in January 2009. The pink line shows the median extent for the month.
Photo: NSIDC

Every summer, the Arctic melts a little, and every winter it re-freezes. That's normal. But global warming continues to melt the Arctic, each summer has seen more melting, and each winter less re-freezing. In 2005, a new record was set for the loss of sea ice in summer, and then in 2007, that record was shattered. Sea ice melting in 2008 fell just shy of the 2007 record, and scientists have worried that even the most dire predictions about the melting of the Arctic may be too conservative.

New data indicates that we do have reason for concern. The re-freezing of the Arctic is going slowly this year. Much less ice has formed than in a normal year, and the amount of ice present is trending near to the extent recorded in 2007, before the record melt. January was the sixth-lowest ice extent on record.

Scientists from the National Snow and Ice Data Center say that there was virtually no increase in ice from Jan. 15 to Jan. 26, a time when winter chill is typically creating new ice.

In January, there were 293,000 square miles less of ice than average. If that area of ocean were a state, it would be slightly larger than Texas, second only to Alaska in size.

Arctic Sea Ice jan 2009

These are just interim observations. The real test will be this summer, when we see if the Arctic offers up another indication of global warming's creeping effects.

Still, even if the summer of 2009 doesn't approach or set a new record, it's hard to ignore the longer trend:

Arctic Sea Ice trend

On the other side of the world, meanwhile, the Southern Hemisphere summer threatens a large ice shelf in Antarctica, and more immediately, has killed several in Australia. A record heat wave -- the second in as many years -- is alarming people there, as the realities of climate change become evident.

Australia heat wave
NASA / This map shows the land surface temperature anomaly across Australia between Jan. 25 and Feb. 1, 2009. The darkest reds and the darkest blues show a 10-degree (C) differential from normal (white).

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