Record Low for Arctic Sea Ice
Arctic sea ice was at a record low maximum extent for the second consecutive year, according to scientists at the U.S. National Snow and Ice Data Center (NSIDC) and NASA.
The new record low follows record high temperatures in December, January and February around the globe and in the Arctic. The atmospheric warmth probably contributed to this lowest maximum extent, with air temperatures up to 10 degrees Fahrenheit above average at the edges of the ice pack where sea ice is thin, said Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
The wind patterns in the Arctic during January and February were also unfavorable to ice growth because they brought warm air from the south and prevented expansion of the ice cover. But ultimately, what will likely play a bigger role in the future trend of Arctic maximum extents is warming ocean waters, Meier said.
“It is likely that we're going to keep seeing smaller wintertime maximums in the future because in addition to a warmer atmosphere, the ocean has also warmed up. That warmer ocean will not let the ice edge expand as far south as it used to,” Meier said. “Although the maximum reach of the sea ice can vary a lot each year depending on winter weather conditions, we’re seeing a significant downward trend, and that’s ultimately related to the warming atmosphere and oceans.”
This year’s record low sea ice maximum extent will not necessarily result in a subsequent record low summertime minimum extent, Meier said. Summer weather conditions have a larger impact than the extent of the winter maximum in the outcome of each year’s melt season; warm temperatures and summer storms make the ice melt fast, while if a summer is cool, the melt slows down.
“I’ve never seen such a warm, crazy winter in the Arctic,” said NSIDC director Mark Serreze. “The heat was relentless.” Air temperatures over the Arctic Ocean for the months of December, January and February were 2 to 6 degrees Celsius (4 to 11 degrees Fahrenheit) above average in nearly every region.
Sea ice extent over the Arctic Ocean averaged 14.52 million square kilometers (5.607 million square miles) on March 24, beating last year’s record low of 14.54 million square kilometers (5.612 million square miles) on February 25. Unlike last year, the peak was later than average in the 37-year satellite record, setting up a shorter than average ice melt season for the coming spring and summer.
According to NSIDC, sea ice extent was below average throughout the Arctic, except in the Labrador Sea, Baffin Bay and Hudson Bay. It was especially low in the Barents Sea. As noted by Ingrid Onarheim at the Bjerknes Centre for Climate Research in Bergen, Norway: “A decrease in Barents Sea ice extent for this winter was predicted from the influence of warm Atlantic waters from the Norwegian Sea.”
Scientists are watching extent in this area because it will help them understand how a slower Atlantic Meridional Overturning Circulation may affect Arctic sea ice. “Some studies suggest that decreased heat flux of warm Atlantic waters could lead to a recovery of all Arctic sea ice in the near future,” said NSIDC senior research scientist Julienne Stroeve. “I think it will have more of a winter impact and could lead to a temporary recovery of winter ice extent in the Barents and Kara seas.”
This year’s maximum extent is 1.12 million square kilometers (431,000 square miles) below the 1981 to 2010 average of 15.64 million square kilometers (6.04 million square miles) and 13,000 square kilometers (5,000 square miles) below the previous lowest maximum that occurred last year.
Ice extent increases through autumn and winter, and the maximum typically occurs in mid-March. Sea ice then retreats through spring and summer and shrinks to its smallest or minimum extent typically by mid-September.
“The Arctic is in crisis. Year by year, it’s slipping into a new state, and it’s hard to see how that won’t have an effect on weather throughout the Northern Hemisphere,” said Ted Scambos, NSIDC lead scientist.
NSIDC will release a full analysis of the winter season in early April, once monthly data are available for March.