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Sea Ice Loss 2012: What Do The Records Mean?
Labor Day 2012 was celebrated—if that is the word—with new record lows for the Arctic sea ice in virtually every sea ice dataset, be it ice extent, area, or volume; be it satellite or re-analysis-based; be it Danish, American, or Japanese. And those lows have kept getting lower.
Actually, the new record lows had begun to appear on August 17th, when the University of Bremen sea ice extent chart dipped below its previous all-time low. August 17th is shockingly early; the annual minimum typically falls somewhere in mid-September, and that is naturally when records are set. To see records fall a month earlier than that gave many observers serious pause.
The shock has generated some headlines—probably less than merited, but still more than enough to puzzle many folks. After all, the Arctic Ocean is very far away from most of us; how can the exact amount of ice covering it matter?
Put another way, do the new records really mean anything?
It helps to know a bit of the history. The sea ice has been declining since 1979, when we began to use satellites to monitor it. The decline was relatively slow at first, but by 2005 had become more pronounced; in that year, the minimum reached a surprising low of about 5.3 million square kilometers. Compare that to the lowest extent in the first ten years—6.4 million, observed in 1984.
Still, projections were that there would be Arctic sea ice year-round at least for the balance of the 21st century, if not longer.
Then came the minimum of 2007. That year turned out to be a 'perfect storm' for ice melt—warm temperatures, frequent clear skies to allow in lots of solar energy, and wind patterns favorable for moving ice out into the North Atlantic, all combined to shatter the record low extent of 2005, with an unprecedented 4.25 million square kilometers.
Scientists studying the ice were stunned. Dr. Walter Serreze, shaken out of scientific reticence, spoke of a sea ice "death spiral." Dr. Jay Zwally pointed out that such a rate of annual loss, if continued year on year, would result in an ice-free Arctic by 2012!
But Dr. Zwally did not predict that such a rate would necessarily be sustained—and it wasn’t. 2007 remained the 'record low minimum' year—until now.
(2011 was a partial exception. There are several organizations measuring the ice, using different combinations of satellite sensors, definitions, and software "algorithms" to arrive at their numbers, and one metric had 2011 slightly lower than 2007. Call it a “split title” for that year.)
The persistence of the 2007 record encouraged some people to believe that the ice was 'recovering.' 2007, they argued, was a fluke, a 'one-off' event that would not be repeated. All the ice needed was some time, and things would be back to normal.
Others pointed out that while 2007 was indeed exceptional, it was not an isolated event, but part of a clear longer-term trend of declining sea ice. Weather strongly affects sea ice extents each year, so there will always be a strong ‘randomness’ in the extents. It was not to be expected, then, that every single year would set a new record, and the gains in minimum extent following 2007 were not large enough to provide evidence of real recovery.
One could spend many words on the back-and-forth arguments between the two camps. But this year it became moot. The world saw records set--dramatically lower ones. The old marks from 2007 were not just eclipsed, they were (metaphorically) obliterated. The extent as of this writing is just over 3.6 million square kilometers—about half of typical values in the early 1980s—and still falling. No sane mind can argue any longer that the decline stopped in 2007.
The acceleration of the melt this year was aided somewhat by an exceptional Arctic cyclone which, as one amateur observer pointed out, 'put the ice in a blender.' Some have attempted to blame this year’s stunning decline on that storm and not on the long-term trend. But others have pointed out that the storm, though it did accelerate the decline, did not change the overall slope on the season’s sea ice trend graphs. In fact, you would be hard pressed to tell when the storm occurred by looking at those graphs.
What, then, was responsible for the decline? Not the weather. The weather patterns seen in 2012 were not like the ‘perfect storm’ conditions of 2007. Several times in the season, weather patterns occurred which in the past had slowed melt considerably, leading to predictions of reduced ice loss rates. Yet in 2012, the melt continued quite unhindered. Why?
The answer is not yet clear. But it may well be simple thinning of the Arctic ice. Sensing the ice extent or area from orbit is not simple, but sensing its thickness is harder still. Yet what information on ice thickness we do have suggests a persistent trend toward thinner ice. Thinner ice transmits more energy and is mechanically more fragile than thicker ice. Both factors make it more susceptible to melt. And of course there is simply less of it to melt in the first place. In 2012, the theory goes, a great deal of ice had simply thinned enough that adverse melting weather was not enough to save it.
In any case, the dramatic new records are a powerful indication that the 'alarmists' were correct. The ice has not been recovering in any meaningful way. Dr. Serreze's "death spiral" continues.
So, the records matter because they demonstrate—powerfully!—the continuing decline of the sea ice. And the numbers are getting closer and closer to zero. (For more detail on how sea ice is measured see A Love Story And A Clearance Sale.)
But this raises another question: what does the sea ice decline itself mean? What consequences are likely to follow from an ice-free Arctic? If we are to mourn the loss of the sea ice, for whom and what does the mourning bell toll?
Most obvious are the consequences for the Arctic environment. The sea ice is in itself a wildlife habitat. Its loss will be devastating for polar bears and seals, as well as less charismatic creatures depending on it. We cannot yet predict everything that a serious population crash of bears and seals will do, but consequences there will be.
As an analogy, no-one expected that bringing wolves back to Yellowstone would restore the riverbank vegetation of the area—which means that, even today, we could not predict that the loss of the wolf populations would lead to serious degradations of the riverbanks and their vegetation. Yet it did. Wolves, like polar bears, are 'top predators' in their respective environments. So what will the loss of the bears do?
A crash of bear and seal populations is a bad thing in itself. But it is also bad news for the indigenous population, currently about 150,000 strong in North America, with 50,000 more in Greenland, and possibly another 140,000 in Eurasia.
Speaking to the North American case, food imported from the South is extremely expensive—for example, four liters of milk cost $12.95 (Canadian) in Nunavut in June 2012, nearly three times the price in Southern Canada. Unsurprisingly, many Northerners still rely on 'country food' as much as possible. And hunting is also an important source of both cash income and cultural meaning. So loss of seal populations, or loss of practical access to them due to deteriorating ice conditions, would be a devastating economic and cultural blow.
The bell tolls for Inuit, Yupiat, and other Arctic peoples.
The physical environment is already being degraded, too. The warming already seen has brought serious problems with coastal erosion—problems serious enough to threaten the relocation of entire communities.
And permafrost—formerly an excellent foundation for buildings of all sorts—is increasingly melting, destabilizing or destroying existing buildings and raising design and construction costs for new ones. As we shall see in a moment, ice loss will reinforce the existing warming trend, worsening both of these problems.
Update 1/11/14: Inuit Mental Health Study
- Climate change rattles mental health of Inuit in Labrador - Technology & Science - CBC News
Researchers studying the mental health and well-being of Inuit populations in coastal Labrador say rising temperatures are having damaging psychological effects on people in traditional communities.
But ice loss will also affect southerners. It means more warming not only over the Arctic, but over the whole northern hemisphere, at least. Less ice to melt means that heat coming into the Arctic can raise temperatures more markedly. More exposed sea water means more sunlight absorbed to warm the oceans, and more evaporation to increase water vapor in the air. (Since water vapor is an excellent greenhouse gas, more of it translates to more warming.) And warmer air can hold more water vapor.
Arctic greenhouse gases are not limited to water vapor, though. The melting permafrost mentioned above often liberates significant amounts of methane. Methane has also been observed bubbling up from numerous Arctic lakes, and even from the waters of the Arctic Ocean itself. Arctic methane concentrations have risen markedly in recent years, and now exceed 1,000 parts per billion. Since methane is a potent greenhouse gas, further methane increases will heighten the warming observed already.
In short, sea ice loss means warming both in the Arctic, and beyond it.
The mourning bell, then, also rings for the climatic status quo. But not only in its thermal aspect. Arctic warming also changes circulation—as Dr. Jennifer Francis of Rutgers University recently asked rhetorically, "How can it not?"
Yet it is easier to be confident that it will change circulation, than it is to predict just how. Still, preliminary answers may be emerging in research by Dr. Francis and others—and emerging, perhaps, not only in scientific papers, but in headlines, the greater economy, and ultimately in people's lives.
For it seems likely that the lessening of the difference between Arctic temperatures and those at lower latitudes brings a weakening of the Jet Stream. This, in turn, makes the Jet Stream 'meander' more widely, bringing cold air further south and warm air further north than was typical in the past. Cold outbreaks in temperate zones—such as the cold winters experienced in Europe and Eastern North America in 2009 and 2010—seem to belie the overall warming trend, even as the Arctic sees 'heatwaves' beyond what the trend would lead one to expect.
Dr. Francis, interviewed by Radio Ecoshock
In the scientific language of Overland et al. (2011):
Winter 2009/10 and December 2010 showed a unique connectivity between the Arctic and more southern weather patterns when the typical polar vortex was replaced [leading to] record snow and low temperatures, [and] a warm Arctic-cold continents pattern.
Further, the more meandering Jet Stream seems to have ridges and troughs that move more slowly. Weather conditions become more persistent. Lows keep raining over the same areas, bringing floods—an effect heightened by the global increase in atmospheric water content observed over the last couple of decades. Highs sit over the same regions for weeks, bringing warm dry weather that bakes soils and shrivels crops—just as the American Midwest experienced in 2012.
This connection is not yet confirmed. But if it is correct, then the decline of the sea ice may mean that you pay more for food—insured crop losses to US agriculture as a result of the 2012 drought are estimated at around $20 billion, and corn and soy prices have more than doubled. Further increases are expected over the coming months, and may be global in scale, according to some analysts.
So the mourning bell may be ringing for everyone’s food budget.
If so, it is appropriate; the primary threat of climate change generally is not just to exotic fauna, to built infrastructure, or even to agriculture—it is to food security itself. The Arctic has been described as the ‘canary in the coal mine’ for climate change, because the long-known phenomenon of "Arctic amplification" has meant that warming there far exceeds warming elsewhere.
So if the quintessentially Arctic phenomenon of sea ice loss turns out to be increasing food prices in 2012, it would be a fitting omen of the food security effects we expect increasingly extreme weather to produce.
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