Lowest ice on record for the Chukchi Sea

November saw the lowest sea ice extent recorded for that month in the Chukchi Sea since satellite sea-ice observations began in 1979, the National Snow and Ice Data Center has reported. On the other hand, the Beaufort Sea had completely iced over by the end of the month, NSIDC said.

The various factors that have contributed to the extent of Chukchi Sea open water this November probably extend back into last year, when warm conditions resulted in persistent open water in the Chukchi into December. Then, strong winds in late March and early April broke up the winter sea ice, driving the ice southward, with some of the ice even entering the Bering Sea through the Bering Strait. During the summer a researcher operating on a research vessel found evidence for the early flow of warm water north through the strait - this early flow resulted in ocean temperatures in June 5 degrees F above average, NSIDC said.

The ocean temperature plays a critical role in the timing of the formation of winter sea ice, because heat remaining in the top layer of the ocean needs to be lost to the atmosphere and outer space before the winter ice cover can complete, NSIDC said. Hence, presumably, this year’s late freezeup in the Chukchi.

Across the Arctic Ocean as a whole, the November sea ice cover was the third lowest recorded for that month. At an average of 3.65 million square miles, the ice extent area was consistent with a continuing downward trend of 5.14 percent per decade, NSIDC said.

- ALAN BAILEY