News•September 12, 2012

Arctic Has Lost Enough Ice to Cover Canada and Texas

The official end of the Arctic Ocean melt season could come any time now, but the sea ice that covers the North Polar region has already smashed the previous record low for end-of-summer ice area set in 2007.

Credit: Alfred Wegener Institute

Back then, a combination of warm temperatures and ice-dispersing winds left just 1.61 million square miles of ice cover — but that meltback was surpassed in late August this year, and by now, the ice extent has dropped by more than 35 percent below the 2007 record, according to the National Snow and Ice Data Center. Since March, according to one calculation, the amount of ice that has disappeared is equal to the areas of Texas and Canada, combined.

This unprecedented melting (unprecedented since we’ve been able to monitor the ice with high accuracy using satellites, anyway, which first became possible in 1979) is extremely worrisome for several of reasons. For one, as Climate Central reported on August 27, sea ice is a powerful reflector that bounces a lot of sunlight back into space rather than letting it warm the Earth.

When that ice melts, it exposes the darker ground or water underneath, turning the region into an energy absorber rather than a reflector. Sea ice is especially vulnerable to melting, and over the past 30 years or so there’s been a downward trend in sea ice coverage in summer. The result is a feedback loop that accelerates global warming, with melting ice leading to more warming of the water below leading to more melting.

For another, a warming Arctic threatens to release carbon dioxide from melting permafrost and methane both from permafrost and from under the seafloor, each of which could accelerate warming as well.

A warming Arctic is also a tempting place to look for energy and mineral resources, and for new shipping routes. Royal Dutch Shell has just begun drilling an exploratory well in the Chukchi Sea north of Alaska, and a Chinese icebreaker is slicing its way through the increasingly thin and brittle ice surrounding the North Pole.

Environmentalists fear that shipping, mining and drilling will expose this formerly inaccessible corner of the world to pollution, oil spills and other ecological disasters.

U. of Washington animation of sea ice volume readings from a computer model.

Finally, a warmer Arctic could throw a monkey wrench into existing weather patterns in other parts of the world, bringing colder winters and more snowfall to the U.S. and Europe, for example.

Arctic experts are quick to acknowledge that the ice rebounded temporarily from its 2007 record low (although that rebound may have been somewhat misleading, since much of the ice that came back was relatively thin, and thus more prone to rapid melting than the thick, multi-year ice that forms over many seasons).

The ice could rebound again — for a while. Over the long term, however, it’s clear that the Arctic could be largely ice-free in late summer within a few decades, and maybe much sooner than that.

That’s true if we’ve already reached an ice minimum for a year. It’ll be even clearer if the ice plummets still more before the winter re-freeze begins.

An earlier version of this story asserted that the area of ice that has melted since March is equal to the areas of Canada and Alaska combined. In fact, the total melt area is equal to that of Canada and Texas combined. Thanks to our readers for pointing out the error.