This year’s winter extent likely to be one of the lowest on record
By Summit Voice
FRISCO — With just a few more days to go before Arctic sea ice starts its annual retreat, it looks like this year’s maximum extent will be one the lowest on record. Sea ice extent has been tracking below average nearly all winter and dropped below previous record low levels in early February, staying there ever since.
The extent generally peaks in mid-March before it starts to give way to warmer air temperatures and longer days with more hours of sunlight. This year, temperatures in the Arctic have been distinctly higher than average, resulting in a slower than average expansion of the winter ice cover. Overall, sea ice grew at a rate about 26 percent slower than the 1981 to 2010 average.
Less ice also contributes to higher air temperatures by allowing transfer of heat from the relatively warmer ocean, according to the National Snow & Ice Data Center. Temperatures at the 925 mb level in the central Arctic averaged ranged between 7 to 14 degrees Fahrenheit above average for the month.
For February, sea ice extent averaged 5.58 million square miles, the fourth-lowest extent on record, about 350,000 square miles below the 1981 to 2010 average. The lowest February in the satellite record was in 2005. According to the NSIDC, there were even periods of declining sea ice extent during the month.
Bering Sea ice cover has been below average throughout winter, in contrast to the last several winters. Ice extent also remains below average in the Barents Sea and the Sea of Okhotsk, helping to keep the Arctic ice extent two standard deviations below the 1981 to 2010 average.
Sea ice extent was particularly low in the Barents Sea, following a trend of recent years. While the Barents and Kara seas normally have close to 772,000 square miles of ice in February, recent years have just 193,000 square miles of ice extent or lower.
Because of records kept by whalers and fishermen, the sea ice extent record dates farther back than for many other areas. A recent research project suggests that variations in sea ice in the Barents Sea may be related to natural climate variability, specifically, a 60- to 90-year cycle linked to the Atlantic Multidecadal Oscillation.