Wednesday, December 14, 2016

Scientists See 'New Arctic' Is More Prone to Melting and Storms

Region's role as climate moderator threatened

Arctic sea ice hangs on through the summer (Credit: Click to Enlarge.
Scientists in a rare and sometimes dangerous study of the Arctic have found that the region's thinning sea ice is more prone to melting and storms, threatening its role as a moderator of the planet's climate.

The researchers reached this conclusion after spending almost half a year, much of it on a ship frozen into the ice, as part of the first wintertime expedition to examine the younger, thinner sea ice that typifies the "new Arctic."  They discussed their findings in the fall meeting of the American Geophysical Union.

"Many things we experienced took us by surprise," said Mats Granskog, a research scientist at the Norwegian Polar Institute and chief scientist of the Norwegian young sea ICE, or N-ICE2015 project.  "We saw that the new Arctic, with much thinner sea ice only three to four feet thick, functions much differently from the Arctic we knew only 20 years ago, when the ice was much thicker."

Global warming is proving to be particularly hard on the Arctic, with late summer sea ice coverage less than half of what it was in the 1970s.  While they can't specifically link their short-term observations to climate change, the N-ICE researchers worry that the reduced sea-ice coverage and thickness will lead to even more melting, the so-called "Arctic amplification." Most of the solar energy that reaches Arctic snow and sea ice gets reflected back into space. But when the snow and ice is replaced by darker, open water, most of the energy gets absorbed and in turn helps melt more ice.

Now, the researchers say, what ice is left is particularly vulnerable.  The thinner and younger ice works differently, said Granskog.  It moves faster, breaks up more easily and is more vulnerable to winds and storms.

Von Walden, a Washington State University professor of civil and environmental engineering, spent a month on the project and helped to document the first observations of how winter storms affect the surface energy balance of the young, thinner sea ice.

Von Walden saw how high winds move the ice, stressing and breaking it.  The winds also transport large amounts of heat and moisture.

One winter storm raised the surface temperature from -40 F to 32 F in less than 48 hours, while the moisture in the air increased by 10 times.  These storms also bring clouds.  All of these factors significantly warm the surface at a time when there is no sunlight, he said.

Read more at Scientists See 'New Arctic' Is More Prone to Melting and Storms

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