Arctic Sea Ice Extent Improves From Last Year; Still Part of Decade-Long Decline

After a particularly cold arctic winter and a shortened summer, the Arctic Sea ice has shown significantly less melting than it did last year, according to a news release.

In a study conducted by the National Snow and Ice Data Center (NSIDC) and the University of Colorado (UC) at Boulder, researchers said the sea ice extent is an improvement, but still part of a downward trend.

This time last year, the Arctic Sea ice extent was reported to be 1.32 square miles, the smallest figure recorded in the satellite era. It was also about half of the average from 1981 to 2010. This summer's ice extent figure was a big improvement, but still scored in the six smallest numbers recorded and was more than 400,000 square miles below the average of the past two decades.

This year's figure is not an outlier from a decade-by-decade downward trend since the 1970s and it did not surprise NASA scientists.

"I was expecting that this year would be higher than last year," said Walt Meier, a glaciologist at NASA's Goddard Space Flight Center in Greenbelt, Md. "There is always a tendency to have an uptick after an extreme low; in our satellite data, the Arctic sea ice has never set record low minimums in consecutive years."

Every summer, the Arctic Ocean's ice cap shrinks, and every winter, it expands. The longer and colder the winter, the shorter the summer and the less shrinkage that can occur.

"The trend with decreasing sea ice is having a high-pressure area in the center of the Arctic, which compresses the ice pack into a smaller area and also results in clear skies, which enhances melting due to the sun," said Richard Cullather, an atmospheric scientist at Goddard and at the Earth System Science Interdisciplinary Center of the University of Maryland. "This year, there was low pressure, so the cloudiness and the winds associated with the cyclones expanded the ice."

Joey Comiso, a Goddard senior scientist, cautioned that the Arctic ice has become thinner and will continue to melt more rapidly.

"Thinner ice melts completely at a faster rate than thicker ice does, so if the average thickness of Arctic sea ice goes down, it's more likely that the extent of the summer ice will go down as well," he said. "At the rate we're observing this decline, it's very likely that the Arctic's summer sea ice will completely disappear within this century."