On Sunday, by an area about the size of Texas, Arctic sea ice extent shrunk below the previous record low established September 18, 2007.
The National Snow and Ice Center (NSIDC) today reports the sea ice extent bottomed out at 1.32 million square miles, about 293,000 square miles below the prior 2007 record. Arctic sea ice extent has been monitored by satellite since 1979.
“This year’s minimum is 18% below 2007 and 49% below the 1979 to 2000 average,” NSIDC wrote in its release on the minimum, noting these numbers are preliminary.
This year’s record low extent follows a long-term decline. The 6 lowest extents on record have all occurred in the last 6 years.
“We are now in uncharted territory,” said Mark Serreze, NSIDC director. “While we’ve long known that as the planet warms up, changes would be seen first and be most pronounced in the Arctic, few of us were prepared for how rapidly the changes would actually occur.”
Animation of Arctic sea ice in 2012 versus daily average (1979-2000) from NOAA
The 2012 sea ice extent had already dropped below the 2007 record on August 26, three weeks before Sunday’s minimum. NOAA reported the ice loss during August occurred at the fastest clip on record for the month, shrinking at the rate of 35,400 square miles per day.
“Climate models have predicted a retreat of the Arctic sea ice; but the actual retreat has proven to be much more rapid than the predictions,” said Claire Parkinson, a climate scientist at NASA.
NASA says a large Arctic storm in early August played a role in the record low extent.
“The storm cut off a large section of sea ice north of the Chukchi Sea and pushed it south to warmer waters that made it melt entirely,” NASA wrote. “It also broke vast extensions of ice into smaller pieces more likely to melt.”
NASA animation showing interaction between Arctic storm and sea ice in early August
But NASA Parkinson’s said the same storm wouldn’t have had the same effect decades ago.
“[The storm] likely wouldn’t have had as prominent an impact, because the ice wasn’t as vulnerable then as it is now,” Parkinson said.
Environmental advocates were quick to connect the dots between the sea ice decline and human-caused global warming, calling for emissions reductions.
“These data represent an urgent call to act now to reduce short-lived climate pollutants, especially methane and black carbon, which are much more potent warming agents than CO2,” said Ellen Baum with Clean Air Task Force.
A number of other organizations which monitor Arctic sea ice have documented record low ice levels in addition to NSIDC. The Arctic Sea Ice blog is running a series of posts highlighting them.
For example, a model from University of Washington’s Polar Science Center estimates Arctic sea ice volume dropped below the record set last year. This model estimates sea ice volume incorporating data from satellites, Navy submarines, moorings, and field measurements as well as atmospheric information.
Sea ice volume is important because, unlike extent, it provides information on ice thickness, offering a deeper picture of what’s happening to the ice. Independent volume data from the CryoSat-2 satellite indicate about 560 cubic miles of summer sea ice have vanished over the past year according to an article in the Guardian.
Arctic sea ice is viewed as a critical player in the northern hemisphere’s climate. It serves as a refrigerator which, when opening its door, sends blasts of cold air southward, triggering storms. The long term decline in this cold air source is likely already affecting weather patterns according to researchers.
A 2012 study by Jennifer Francis of Rutgers University and Stephen Vavrus of the University of Wisconsin proposes Arctic sea ice loss is adding sufficient heat to the atmosphere to change the course of the jet stream, the river of air at high altitudes along which storms track poleward and equatorward. It suggests the jet stream is slowing down and becoming more wavy - meaning extreme weather patterns may be becoming more persistent.
“Slower progression of upper-level waves would cause associated weather patterns in mid-latitudes to be more persistent, which may lead to an increased probability of extreme weather events that result from prolonged conditions, such as drought, flooding, cold spells, and heat waves,” the study concluded.
But this year’s record low sea ice extent doesn’t necessarily mean an extreme winter looms. Climate Central’s Andrew Freedman corresponded with Vavrus on this matter, who qualified the implications of the study.
“[Vavrus] cautioned that people should view their study as a “launching point” for more research, and not interpret it as having any predictive value for the upcoming winter,” Freedman wrote.