Arctic Melt Ponds

Photo By: Kathryn Hansen / NASA

After a record-setting July, the Arctic melting nearly set another record in August, according to the latest report from the National Snow and Ice Data Center. The Arctic had 28% less ice than average throughout August.

Only in 2007 was there less ice than in any other August on record. Both the Northwest Passage and the Northern Sea route were free of ice.

Air temperatures have already cooled, but warm ocean waters continue to erode ice from the bottom-up, and scientists expect another week or two of melting before the season is finished. Whether or not 2011 sets a new record, it is certain to rank at least second among years with the most melting.

Arctic melting is one of the clearest signs of global warming, as temperatures have risen faster in the Arctic than elsewhere on the globe. Beyond open shipping channels, the melting has major implications for politics and the environment. Russia recently signed an agreement with Exxon to drill for oil, and the U.S. has moved toward approving a permit that would allow Shell to drill off the coast of Alaska. Other nations are jockeying for position to exploit petroleum reserves in the Arctic, too. And the loss of ice could affect weather patterns and climate changes worldwide, triggering feedback loops that make the world warm faster (for instance, as snow-white ice melts, it reveals dark blue water, which absorbs more heat from the sun, which leads to more melting; and as tundra thaws, it releases methane, a potent greenhouse gas).

The melt season ends in September, when the Arctic summer ends. That's when we'll know if 2011's melting will exceed 2007's overall, as this chart shows:

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