Thanks in large measure to a slow freeze-up this fall in the Barents Sea and Hudson Bay, the extent of Arctic sea ice at the end of November was the third lowest since satellite monitoring began in 1979, according to the National Snow and Ice Data Center.
The extent of the ice at the end of the month was 405,000 square miles below the 1979 to 2000 average for November. That’s an area equal to slightly less than California and Texas combined.
“Compared to our expectations, we are on the fast track of change,” says Mark Serreze, NSIDC’s director. “Things are happening a lot faster than we thought would be the case.”
Unusually warm air over the Hudson Bay kept sea ice from forming there in November. And warm southerly winds helped push ice north out of the Barents Sea during the month. The lack of ice cover there probably allowed heat stored in the ocean to escape into the atmosphere, accentuating the warmer than average temperatures. This is part of a phenomenon known as “Arctic amplification,” in which warming triggers changes that tend to accentuate the warming. Scientists had predicted this phenomenon, and now it appears to have taken hold.
“Has arctic amplification already happened? The answer is absolutely yes,” Serreze says. “Arctic amplification isn’t this thing that will happen 20 from now. It is here.”
Sea ice in the Arctic is now declining at a rate of about 4.5 percent per decade, and if this trend continues, all sea ice could be gone at the end of summer by the year 2050, according to Serreze.
Each year, sea ice reaches a seasonal low in mid-September, right at the end of the warm season. And compared to the extent of sea ice in September 1980, “we’ve really lost a lot of real estate,” Serreze says. By 2005, an area of ice equivalent in size to all the states east of the Mississippi had been lost. By 2007, the year of the record low sea ice extent, an area equivalent to Iowa, North Dakota and South Dakota was added to the decline. Sea ice extent staged a little bit of recovery this September, but it was still the third lowest on record.