Climate: Arctic sea ice on pace for record meltdown

Arctic sea ice
The image above shows a May 21, 2016 view of Arctic sea ice in the Beaufort Sea from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Credit: Land Atmosphere Near-Real Time Capability for EOS (LANCE) System, NASA/GSFC.

Melt season is 2 to 4 weeks ahead of 2012, which set record for low extent

Staff Report

Arctic sea ice extent continues to track toward a record low, the National Snow and Ice Data Center reported last week, resuming regular updates of sea ice after switching to a new satellite for the measurements.

As of June 7, the sea ice meltdown was ahead of 2012 by two to four weeks. Sea ice extent hit a record low that year and has been near that level every year since. The past two years, it set new record-lows for winter extent.

There was extensive early ice melt in the Beaufort Sea and surging warm air from eastern Siberia and northern Europe are part of what is driving this year’s below-average ice conditions, according the June 7 bulletin from the NSIDC.

The overall sea ice extent for May also set a new record low, at 4.63 million square miles, on the heels of record lows in January through April. May’s ice extent was 224,000 square miles before the previous record low set in 2004, and 537,000 square miles below the 1981 to 2010 long-term average.

During May, the ice melted away at a rate of about 23,600 square miles per day, compared to the average of about 18,000 square miles per day. May air temperatures 4 to 5 degrees Fahrenheit above the 1981 to 2010 average across most of the Arctic Ocean, and even warmer — 7 to 9 degrees Fahrenheit — in parts of the Chukchi Sea, north of Alaska.

The latest satellite readings show ice thicknesses in parts of the Arctic similar to 2015, but thinner overall than during the past five years. Early 2016 readings by York University researchers show thicknesses in the Northwest Passage similar to that in 2015.

Data from the European Space Agency’s CryoSat-2 satellite show that first-year ice in March 2016 is thinner compared to the March 2011 to 2016 average, especially in the Beaufort Sea (20 to 40 centimeters thinner) and the Barents and Kara seas (10 to 30 centimeters thinner). Multiyear ice north of Canada and Greenland is also thinner.

In Barrow, Alaska, researchers recently found widespread signs of early melting, with sea ice much thinner than average, as well as melt ponds that formed early in the season. Local weather observations indicate a winter-long pattern of unusual offshore wind that may have contributed to early melting. Barrow also had its earliest-ever snow melt-out on May 20, with a melt season that began 10 days earlier than the previous record, set in 2002.

The National Oceanic and Atmospheric Administration announced on May 20 that Barrow, Alaska recorded the earliest snowmelt (snow-off date) in 78 years of recorded climate history. Typically snow retreats in late June or early July, but this year the snowmelt began on May 13, ten days earlier than the previous record for that location set in 2002.

Along with melting sea ice, the northern hemisphere also saw record- and near-record low spring snow cover extent from March through May, based on data from the Rutgers University’s Global Snow Lab. April’s snow cover was the lowest at 27.91 million square kilometers (10.78 million square miles), and May was the fourth lowest at 16.34 million square kilometers (6.3 million square miles).

Around Antarctica, sea ice grow slower than average during May, with the total extent dipping below average in the second half of the month. Antarctic sea ice extent for May 2016 averaged 4.13 million square miles, about 35,000 square miles below the 1981 to 2010 long-term average.

Antarctic sea ice has been trending at near-average to below-average levels since June of 2015. In May 2016, extent was particularly low in the Bellingshausen Sea, Fimbul Ice Shelf area, and Wilkes Land Coast, but well above average in the northwestern Weddell Sea near the Antarctic Peninsula.

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