“The minimum ice extent was the fourth lowest in the satellite record, and reinforces the long-term downward trend in Arctic ice extent,” the center said in a statement. The lowest extent this year, reached on September 11, was 1.7 million square miles. That’s quite low, but still 394,000 square miles above the low extent that occurred Sept. 17, 2012, when ice only covered 1.31 million square miles at the top of the world.
“The nine lowest extents in the satellite era have all occurred in the last nine years,” added NSIDC — yet another clear indicator that declining sea ice is very likely part of a trend tied to global climate change. Indeed, this year’s low sea ice extent was nearly 700,000 square miles less than the average from 1981-2010. (Satellite records began in 1979.)
The center warned that this is a preliminary announcement — it is still possible that ice extent could drop further, though this is the “likely” minimum extent for 2015.
The amazing thing about this year, says Ted Scambos, who heads the NSIDC science team, is that it wasn’t particularly extraordinary in an atmospheric sense — unlike 2012, when storms broke up a great deal of ice. And yet still, it was the fourth lowest extent on record. “It’s showing us that the Arctic is truly evolving from a different state, and far from recovering, even relatively typical summers in the Arctic lead to relatively low sea ice extents,” he says.
“The sea ice decline has accelerated since 1996,” added NASA in a discussion of the annual low. The agency, which funds NSIDC, went even further in noting how low ice has plunged in recent years, noting that “The 10 lowest minimum extents in the satellite record have occurred in the last 11 years.”
The consequences of less sea ice in the Arctic are myriad, ranging from potentially better navigability through sea routes like the Northwest Passage (although recent research suggests that that remains quite challenging) to the loss of habitat for iconic organisms like walruses. Tens of thousands have clustered on the Alaskan coast this year until the sea ice starts to grow again.
“Dwindling sea ice is a stark reminder of the destruction climate change wages on our most vulnerable wildlife and communities,” said Margaret Williams, managing director for Arctic programs at the World Wildlife Fund, in a statement. “Recent images of 35,000 walrus literally climbing onto Alaska’s shores, paint a dramatic visual of our rapidly unraveling Arctic.”
There are also increasingly prominent theories about how the melting Arctic may be influencing mid-latitude weather — perhaps through its effect on the northern hemisphere jet stream. “Having the white cap on the ocean essentially almost disappear for a few weeks in the summer, the fact that it nearly disappears, has to have an impact on atmospheric circulation, and therefore weather,” says NSIDC’s Scambos, although he says precisely how that is playing out remains debated.
Following the 2012 all-time sea ice low, there had appeared to be something of a rebound — while 2012 saw only 1.3 million square miles of sea ice extent, 2013 saw 1.95 and 2014 saw 1.94. So the drop back down to 1.7 million in 2015 is noteworthy in this respect. The fact that the 9 lowest extents have all occurred in the last 9 years, adds Scambos, “just tells you the Arctic isn’t going to recover, is heading in another direction.”
Scientists have long predicted that Arctic sea ice decline would be a key manifestation of a warming planet — and further, that it would be self-reinforcing, as less ice cover allows for more absorption of solar energy by the darker sea surface, trapping still more heat.
This is 2015’s second time on the Arctic sea ice record books — and perhaps not its most significant entry. In February, the time of year when there is the most ice over the Arctic, there was nevertheless the lowest maximum extent of ice on record, according to NSIDC.