Arctic Sea Ice Hits New and Early Summer Low for Satellite Era

ORIGINAL: NYTimes

By ANDREW C. REVKIN 

August 27, 2012

Sunsets started to tease the Arctic horizon as scientists on board the U.S. Coast Guard Cutter Healy headed south in the Chukchi Sea during the final days collecting ocean data for the 2011 ICESCAPE mission.  The ICESCAPE mission, or "Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment," is a NASA shipborne investigation to study how changing conditions in the Arctic affect the ocean's chemistry and ecosystems. The bulk of the research took place in the Beaufort and Chukchi seas in summer 2010 and 2011. Credit: NASA/Kathryn Hansen

NASA/GSFC The extent of sea ice on the Arctic Ocean has reached a new low for the satellite era.

11:44 p.m. | Updates from several scientists below |

The planet is warming and the Arctic is warming the most, as long foreseen by scientists in a climate system pushed out of balance through the rapid buildup of heat-trapping greenhouse gases in the atmosphere. One result is greater loss of Arctic sea ice in the annual summer warmup.

Today, the National Snow and Ice Data Center announced that the annual summer retreat of Arctic Ocean sea ice had reached a new low for the 33-year satellite era of careful monitoring (1.58 million square miles, or 4.1 million square kilometers), and there is still another week or two of melting before the typical summer ice minimum occurs.

This quote in the release from Walt Meier of the ice center efficiently encapsulates the context:

"By itself it’s just a number, and occasionally records are going to get set. But in the context of what’s happened in the last several years and throughout the satellite record, it’s an indication that the Arctic sea ice cover is fundamentally changing."

The animated sea-ice imagery above — from one of two autonomous cameras set on ice near the North Pole each spring — gives a close-focus view of the slushy conditions that develop on the shifting ice when the summer sun is at its peak. (This is part of the annual North Pole Environmental Observatory project that I reported on in 2003; the cameras drift with the ice through the summer and are currently over the shoulder of Greenland. You can track their position here.)

¶Justin Gillis has more on this development over on the news side of The Times. This excerpt echoes the thinking of quite a few ice researchers I’ve interviewed over recent years:

¶“It’s hard even for people like me to believe, to see that climate change is actually doing what our worst fears dictated,” said Jennifer A. Francis, a Rutgers University scientist who studies the effect of sea ice on weather patterns. “It’s starting to give me chills, to tell you the truth.”

¶Still, there are many other veteran sea-ice scientists (this is not false balance) who note that the complexity of this system has consistently defied predictions in either direction (see this year’s Sea Ice Outlook forecasts to get the range of forecasts).

¶There’s plenty of year-to-year, and even decade-to-decade variability to complicate things, as both modeling and observations have shown. And variations in the thickness and extent of sea ice cloaking the Arctic Ocean are driven by yet another set of complicating factors, ranging from long-term shifts in atmospheric pressure patterns to events as close-focus as the potent Arctic superstorm I reported on earlier this month.

¶That’s one reason that, even with today’s announcement that the sea ice reached a new low extent for the satellite era, I wouldn’t bet that “the Arctic is all but certain to be virtually ice free within two decades,” as some have proposed. I’d say fifty/fifty odds, at best. [See the update below including a sea-ice scientist's take on such wagers.]

¶But I will bet that profound changes are well under way that virtually guarantee the Arctic described in history books — an ice-locked and forbidding frontier for everyone except the Inuit — will not resemble the Arctic of the second half of this century. There will be problems and opportunities, as I and other Times reporters chronicled in detail in our 2005 series “The Big Melt” and as I wrote in my book, “The North Pole Was Here.”

¶But is this a situation that is appropriately described as a “death spiral”? Not by my standards.

¶11:44 p.m. | Postscript | Cecilia Bitz of the University of Washington, one of the authors of “Future abrupt reductions in the summer Arctic sea ice,” an important 2006 paper projecting ice trends in this century, sent this reaction (edited very slightly for e-mail shorthand):

¶It surprises me to say that the observed trend is still not as fast as the threshold we placed on an rapid ice loss events in our 2006 paper…. Thus, even though models are thought to not lose ice fast enough, every one of the old CCSM3 runs had a “RILE” (rapid ice loss event) at some point in the 21st century that beat the current streak. None did so before 2012 though, and we know that the model trends speed up as the ice thins.

¶As far as bets go, I agree with you — a 50-50 chance it will take a few decades is about right. The current rate of loss each year is about 0.2 million square km. Starting from 4 million square km, at this rate it would take 20 years. Models say it should accelerate, so decrease by a few years maybe.

¶The RILES we found were due in part to ocean heat flux pulses on the Atlantic side. I don’t think we can say if one has happened lately. This year we can’t claim a large unusal high pressure occurred like 2007. My best guess is that the ice just started out very thin in the spring. The IceBridge indicates this was true especially north of Banks Is, where the ice melted out first.

AUG. 28, 2:48 P.M. Update

¶Jennifer Francis of Rutgers University sent this additional thought after I sent a batch of ice researchers an e-mail last night seeking broader context for this year’s ice retreat:

¶The fact that the ice is so dramatically thinner now than it was only 20 years ago means that it is vulnerable to any abnormal weather event or fluctuation in ocean currents. If the “perfect storm” of atmospheric and oceanic conditions that led to the 2007 record, or the patterns that reduced ice this summer, happened back in the thick-ice era, sea-ice loss would not be making headlines. Following this summer’s new record ice loss, the Arctic will enter a winter with even less ice than ever before, leading to even thinner ice, which barring any monumental external events like a major volcanic eruption, will likely perpetuate the trend in sea ice decline.

¶We are all trying to understand a system that has entered territory never seen before, and I think scientists are naturally cautious in their interpretations and predictions of what’s to come. Models were formulated with understanding of the familiar system, which may explain why some model simulations lag observations in losing ice.

¶Hajo Eicken, an ice researcher at the University of Alaska, Fairbanks, sent this note on the importance of tracking regional conditions as well as the overall picture:

¶Following up on Jennifer’s comments, and with my regional blinkers on, it’s important to point to the expected increases in interannual variability in total ice extent, but also keep in mind that at the regional level, the thickness distribution of sea ice plays an important role in determining how a particular summer or even specific weather events like storms or stretches of calm sunny weather play out. This has been obvious this year in the Chukchi and East Siberian Seas where you had a stretch of thicker sea ice linger well into summer (in fact, some of the ice remnants — though rotten — still show up in the satellite data from the region).

¶Earlier this year, a number of research groups was able to coordinate thickness measurements (airborne, surface based and associated deployment of buoys) to help us better understand the ice thickness evolution in this sector of the Arctic. More detail is available on this here.

¶While the goal of this campaign was to improve seasonal ice prediction, the work also showed two important processes at work:

¶(i) Older, thicker multiyear ice continues to flush out of the high Canadian Arctic and depending on winter surface circulation, some of this ice may reach very close to the coast. In fact, this winter not just old sea ice but also some glacial ice fragments were spotted in northern Alaska inshore waters. This thicker multiyear ice takes longer to melt back (both because of greater thickness and higher albedo than first-year ice) and so in conjunction with the weather it is responsible for more extensive ice in the late summer in this region. At the same time, it represents a potential hazard to operations in the region, of which – as you are aware – there is quite a bit this year.

¶(ii) Even subtle year-to-year changes in the thickness of first-year ice and its snow cover can play an important important role in determining interannual and seasonal variations in ice extent with an overall thinner ice cover. This is what may have contributed in part to lingering ice in this region as a result of thicker first-year ice (due to a more severe winter and higher winter ice growth) as well.

¶This is not to detract from the large-scale picture discussed by Jennifer and Cecilia, but under conditions of an overall diminished ice cover, such remnants become very important from a marine ecosystems perspective (e.g., walrus hauling out on such ice) while at the same time continuing to play a role as a hazard to marine operations.

¶J. Michael Wallace of the University of Washington, someone whose views I’ve tracked closely for decades, had this sobering assessment (I’ve asked him to clarify what he means by “irreversible” given various papers (e.g., 1, 2, 3) cutting against that idea and will add an update when it comes):

¶I view the question of whether the minimum sea ice extent sets a new record this year as secondary. The important news is that in five summers the sea ice concentration over the Arctic has not recovered from its precipitous decline in 2007. This is one of the clearest examples of a regime shift in the recent historical record. I think we still need to be open to the possibility that natural variability has played a role in the recent warming of the Arctic, but with each year that goes by without a return to the pre-2007 summertime Arctic climatology it seems more likely that the remarkable change that we have witnessed will prove to be irreversible. [After reading my query about "irreversible" he sent a slightly adjusted version of this comment which you canread in the comment stream by clicking here.]

¶Ignatius Rigor, a climate and ice researcher at the University of Washington (who’s been heard from here quite a lot in recent years), added this note (in the group exchange with Francis, Eicken and others):

¶What really strikes me is how vulnerable the thinner ice pack is. In 2007 we had a persistent high sitting over the Canadian Arctic, which contributed significantly to the export of sea ice out of the Arctic. This year, that deep low in August may have may have been the trigger. In the past (pre-1990s) this low would have just spread the ice pack out and increased sea ice extent, but with how thin the ice is, this just allows heat to melt the scattered ice from all sides and have a bigger impact on sea ice extent.

4:52 P.M. Update

¶This afternoon, I asked Marika Holland, a climate and ice modeler at the National Center for Atmospheric Research, to consider recent ice trends in light of her work with Jennifer E. Kay and Alexandra Jahn on a paper findinglikely periods of ice recovery on the way to an ice-free Arctic in summer. This relates to differing views (see comment discussions) on the merits of the phrase “Arctic death spiral.” As I’ve said, and told Holland, that phrase would be fine with me if it were stressed that there will be “loop the loops” on the way down. Here’s her note:

¶The work pointing to periods of recovery on the way to a largely ice-free summer later in the century is still valid…. Basically the message is that natural variability is large for sea ice. When this reinforces the anthropogenic change, it can cause RILEs [rapid ice loss events] — but it can also counter that change and cause brief periods of near-stability (or even small increases on a decadal scale). So, given the research, I think that loop-the-loops are to be expected. This in no way means that the ice loss is not large, important, and likely to result in near ice-free Septembers later this century though!

¶I found a nice recent YouTube presentation by Holland on climate model projections of Arctic ice loss that makes a nice closer here for now: