Arctic Sea ice is growing, but summer heat persists: National Snow and Ice Data Center
Above average air temperatures still found over nearly all of the Arctic Ocean
The coming of winter over the Arctic Ocean means a season of diminishing sunlight, falling temperatures and rapid growth of sea ice.
But the low sea ice extent at the start of this cooler season now also means there’s still a lot of heat flowing into the air from open water areas.
These keep the Arctic warmer than usual, said the National Snow and Ice Data Center in its recent update on ice conditions in the Arctic.
Through summer, heat from the sun is absorbed within expanding areas of dark, open water.
Then, when the sun sets, this heat stored in the uppermost layers of the Arctic Ocean is released upwards, keeping the air above the Arctic unusually warm.
This warming effect has been especially pronounced during the early autumn of 2012, the data centre said.
Air temperatures averaged over the most recent 30 days of data are above average over nearly all of the Arctic Ocean, it said.
A scientists with the Colorado-based centre, Walt Meier, has described the impact of this warmth as “like leaving the fridge door open.”
Many climate scientists say Arctic sea ice, which is now thinner and covers less of the Arctic Ocean, is wreaking havoc on weather far to the south.
Some suggest the warming of the Arctic Ocean contributed to the development of the recent mega-storm Sandy, which caused flooding and widespread damage along the United States’ eastern coastline this past week.
Despite the increase in Arctic warmth, freeze-up remains in high gear, the data centre notes: as of Oct. 15, sea ice extent stood at 5.18 million square kilometres.
Arctic sea ice extent is increasing rapidly, at about 100,000 sq. km. per day, expanding southward at the ice edge, as well as northward from the Arctic coasts.
But this ice cover is still 3.49 million sq. km. below the 1979 to 2000 mean for this time of year, and 70,000 sq. km. below that recorded on Oct. 15, 2007.
Sea ice extent was still at record low levels in mid-October, compared to the 33-year satellite measurement period (1979 to 2012).
This past September, sea ice extent fell to the lowest recorded since 1979.