|
Arctic ice at record low maximum; March 24 extent beats 2015 record
This year’s annual Arctic sea ice maximum winter extent is the lowest on record since satellite observations of the sea ice began in 1979, the National Snow and Ice Data Center has reported. At 5.607 million square miles, recorded on March 24, the extent was 5,000 square miles lower than the previous record low recorded last winter. The maximum extent is 431,000 square miles less than the 1981 to 2010 average of 6.04 million square miles. However, although this year’s maximum has occurred 12 days later than the 1981 to 2010 average date for the maximum, it is still possible that there could be a late-season surge in ice growth, NSIDC said.
NSIDC attributes this year’s below average ice extent in part to the higher than average temperatures seen in the Arctic all winter. From December through February temperatures were above average across the Arctic, with hot spots near the North Pole and from the Kara Sea towards Svalbard exceeding 11 degrees F above average. In the first two weeks of March air temperatures reached levels 11 degrees F above average in a region from the North Pole to northern Greenland, and up to 22 degrees F above average north of Svalbard, NSIDC said.
In addition to the relatively high temperatures observed this year, southerly winds in the Kara and Barents seas have helped move the ice edge northward of its more typical position. And this area has also seen an influx of warm Atlantic water from the Norwegian Sea, NSIDC said.
Below average The sea ice extent has been below average across the Arctic, except in the Labrador Sea, Baffin Bay and Hudson Bay, and has been especially low in the Barents Sea. During the past few years, the Kara and Barents seas have seen below average winter sea ice coverage, while the Bering Sea has tended to a slight increase in its coverage, NSIDC said.
NSIDC cautioned against using the maximum winter ice extent as a predictor of the likely minimum extent at the end of the summer. The timing of the annual ice melt forms a particularly critical factor in the late summer minimum - if that melt starts earlier than normal, the exposure of dark ice below the snow increases the capture of solar heat, thus causing more ice to melt. Given the warm winter, the Arctic ice cover is likely to be thinner than normal, so that an early surface melt would probably lead to a reduced summer ice cover, NSIDC said.
- ALAN BAILEY
|
