Daily Global Sea Ice Area and Trend
Context: the average global December
ice area is about 21 million sq. km. On 3 February it was 6% (01/16 (million
sq. km) below the 1979-2000 average for the date. This is well within normal
variation. Not subject to urban heat
island effects, the trend in global sea ice extent is a primary indicator
of climate change, or the lack thereof.
(Source: Department
of Atmospheric Sciences at the University of Illinois).
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Analysis: This is our primary indicator of warming or cooling, but it only goes back to 1979, when satellite sensors and analytical programs could get a handle on measuring sea ice. Even today it has problems, such as dealing with water on ice, as happens after a warm spell. The sensor sees water, not ice, but this does not mean the underlying ice is gone. If the Arctic loses ice, but the global balance is about the same, there is no global warming.
Last reviewed or updated in February 2010