A NASA image shows the amount of summer sea ice...

A NASA image shows the amount of summer sea ice in the Arctic on Sept. 16, 2012, at center in white, and the 1979 to 2000 average extent for the day shown, with the yellow line. Scientists say sea ice in the Arctic shrank to an all-time low of 1.32 million square miles on Sunday, Sept. 16, 2012, smashing old records for the critical climate indicator. That's 18 percent smaller than the previous record set in 2007. Records go back to 1979 based on satellite tracking. Credit: AP

That's how few square miles of Arctic Ocean ice were left after this summer's melt -- compared to 1.61 million in 2007, the previous low.

Less white ice means more dark water exposed to the sun, causing our warming planet to absorb more heat. That can lead later to higher sea levels. It raises questions of how to regulate increased fishing and drilling in ice-free waters. The UN Convention on the Law of the Sea is guiding discussions of mineral rights. Our nation hasn't signed it; the melting ice is another reason we should.

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