WASHINGTON — The warmth of the Arctic this year, featuring temperature departures many degrees above normal, has scientists floored. They used words such as ‘‘absurdly’’ or ‘‘ridiculously’’ to describe how warm the region has been.
That warmth has major consequences for key Arctic systems, including vulnerable sea ice, whose melting leaves many darker patches of ocean exposed — patches that then absorb the sun’s radiation, rather than reflecting it away as sea ice does. Thus, loss of sea ice further warms the whole system, in a process known as ‘‘Arctic amplification.’’
According to data from the National Snow and Ice Data Center, Arctic sea ice extent is running not only well below average, but also below levels seen during 2012, which eventually set the all-time record for lowest Arctic ice extent (which occurs in the late summer or early fall).
Arctic sea ice saw a record low level for its average extent in January, according to the center: more than over a million square kilometers smaller than the average ice extent seen from 1981-2010. And now, February has set another record monthly low, the center said Wednesday. ‘‘Arctic sea ice was at a satellite-record low for the second month in a row,’’ it noted.
‘‘It’s not a good start to the year,’’ said Julienne Stroeve, a senior research scientist with the center.
The average extent in February was 5.48 million square miles, or 200,000 square miles lower than the previous record low February, which occurred in 2005, the group said. That was 1.16 million square miles below average for the month.
This is happening amid a dramatically warm start to the year. Recent satellite data suggest that February was the warmest month ever recorded in this particular record of the planet’s atmosphere.
Stroeve cautions, however, that just because sea ice levels are at record lows at the start of this year — a phenomenon that may be influenced by the strong El Nino event that we’ve been witnessing — that doesn’t mean that in the summer, when sea ice reaches its annual low, there will also be a new record.
‘‘Those regions of the ice cover that are low right now, they’re going to melt out anyways in summer,’’ Stroeve explained. What remains in September is therefore something of a separate issue. The all-time record low point for Arctic sea ice occurred in September of 2012.
‘‘The trends are negative everywhere, of course they’re stronger in the summer time, but they’re in the winter as well,’’ Stroeve said.
Meanwhile, there’s another possible record in the offing, although this one is a tad more complicated to explain as well as less certain to occur. It’s called a new ‘‘low maximum’’ for winter sea ice, which may sound like a contradiction in terms, but it isn’t.
In general, ice extent grows throughout the winter toward an annual peak, and then declines toward a low in late summer or early fall. Thus, the moment when it peaks is the ‘‘maximum’’ and when it reaches its lowest extent, the ‘‘minimum.’’ And in general, as Arctic sea ice has declined, its maximum extent has also declined — last year set a new record low, at just 14.54 million square kilometers.
This year, in contrast, ice has not even reached that extent, though it was extremely close Tuesday, March 1, at 14.472 million square kilometers, and appeared to be leveling off.
Thus, the coming week or more will tell whether the stunning warmth of the Arctic will continue to set new records.
Declining sea ice won’t be the only consequence of the extremely warm Arctic this winter. For instance, the outbreak of a second early season wildfire this year in Alaska — in February — hints at how this early season warmth could set the stage for other major problems in the Arctic as the year advances.
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