Daily Global Sea Ice Area and Trend
Context: the average global September sea ice area is about 22.1 million sq. km. On 12 November, 2015 it was 3% (-.6/22.1
(million sq. km)) slightly below the 1979-2008 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 September 2015