Thursday, December 18, 2014

Persistent Warming Driving Big Arctic Changes

Arctic Ocean temperatures in August 2014. (Credit: Click to Enlarge.
Not every year can be a record setter in the Arctic.  But records are only one small piece of a larger puzzle that shows persistent change in the Arctic.  And that change hasn’t slowed according to this year’s Arctic Report Card released at the American Geophysical Union’s Fall Meeting on Wednesday.

Long-term trends in rising temperatures, spiraling sea ice loss, and ecosystem shifts paint a picture of a region in transition due to climate change that is transpiring at a much faster rate than the rest of the globe.
The Arctic has warmed twice as fast as the lower latitudes due to the buildup of heat-trapping greenhouse gases.  This year’s Arctic Report Card shows the average temperature in the past year for the region ran 1.8°F above the 1981-2010 average.

That increase was driven by extreme heat in the winter when the polar vortex dipped into the continental U.S., which in turn, allowed warm air to leak into the Arctic.  Temperatures skyrocketed to 18°F above normal in Alaska and up to 16°F above normal in parts of Greenland for January.

The long-term warming of the Arctic has contributed to a chain reaction of impacts on other parts of the Arctic climate system.  The most notable impact is on the loss of sea ice, which hit its sixth-lowest extent on record in 2014.

While some have pointed to it as a sign of recovery compared to 2012’s record-low, the reality is that the September sea ice minimum has decreased by 13 percent per decade since 1979, when satellite records began.  Ocean waters in parts of the Arctic were also extremely warm at times this year, with temperatures up to 20°F above normal in August.
With the U.S. taking over the chair of the Arctic Council — a group of eight governments with territory in the region — in 2015 for the next two years, 
Martin Jeffries, a science advisor at the Office of Naval Research, said it was a chance to show the public that the U.S. is an Arctic country and not just because of Alaska.

“The Arctic does matter to the Lower 48,” he said.

One of those areas of importance is understanding if the drop in sea ice and rising temperatures are also steering extreme weather toward the continental U.S. and other parts of the lower latitudes.  Some research has tied the rapid changes in the Arctic, known as Arctic amplification, to creating a wavier jet stream that can stall weather patterns.

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