Just a few months ago, global warming deniers were trumpeting--falsely it turned out--data they claimed showed that north polar sea ice was at a level not seen in nearly 40 years. This was supposed to show that global warming had stopped, and indeed that we were headed to a new ice age.
The truth is that sea ice at the north pole has been shrinking dramatically, and is poised to set a new record low this summer. Courtesy of "Cryosphere Today" the attached graph shows that the current extent of north polar sea ice is below last year's level, which set a record. If the decline continues at the same pace, by September the Northwest passage will be wide open to shipping and very little sea ice will remain.
Fortunately, the melting of the north polar sea ice does not raise sea levels, as it is all over water, rather than land. However, such melting does contribute to further warming in northern latitudes, as it replaces reflective white ice with heat absorbing dark water. If that in turn accelerates melting of the Greenland ice sheet, it will contribute to rising sea levels.
Those of us on the U.S. east coast are enjoying an unseasonably pleasant summer--so far (and we hope it continues). But don't let that fool you: it may be nice here, but the earth is still running a fever.
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