Recent global climate report fails to capture the reality of the changing Arctic seascape, researchers say

Aug 11, 2011 By Emily Finn
Taken from the Canadian Research Icebreaker CCGS Amundsen, in the Beaufort Sea in September 2009. Credit: V. Dansereau

The Arctic — a mosaic of oceans, glaciers and the northernmost projections of several countries — is a place most of us will never see. We can imagine it, though, and our mental picture is dominated by one feature: ice.

Yet the sea is changing dramatically, and its presence shouldn’t be taken for granted, even over the course of our lifetimes.

According to new research from MIT, the most recent global climate report fails to capture trends in Arctic sea-ice thinning and drift, and in some cases substantially underestimates these trends. The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, released in 2007, forecasts an ice-free Arctic summer by the year 2100, among other predictions. But Pierre Rampal, a postdoc in the Department of Earth, Atmosphere, and Planetary Sciences (EAPS), and colleagues say it may happen several decades earlier.

It’s all in the mechanics

Established in 1988 by the United Nations, the IPCC issues reports that represent an average of many findings, and is sometimes criticized for forecasting according to the “lowest common denominator” of climate research. Still, many policymakers put large stock in its predictions, so Rampal says it is important to continuously evaluate and improve their accuracy.

After comparing IPCC models with actual data, Rampal and his collaborators concluded that the forecasts were significantly off: Arctic sea ice is thinning, on average, four times faster than the models say, and it’s drifting twice as quickly.

The findings are forthcoming in the Journal of Geophysical Research – Oceans. Co-authors are Jérôme Weiss and Clotilde Dubois of France’s Centre National de la Recherche Scientifique/Université Joseph Fourier and Centre National de Recherches Météorologiques, respectively, and Jean-Michel Campin, a research scientist in EAPS.

Part of the problem, Rampal says, may be inadequate modeling of mechanical forces acting on and within the ice in the Arctic basin. Thus far, the IPCC models have largely focused on temperature fluctuations, which are one way to lose or gain ice. But according to Rampal, mechanics can be just as important: Forces such as wind and ocean currents batter the ice, causing it to break up. Ice that’s in small pieces behaves differently than ice in one large mass, which affects its overall volume and surface area.

“If you make a mistake at this level of the model, you can expect that you are missing something very important,” Rampal says.

The seasonal tug of war

Rampal says mechanical forces can play a significant role in winter, when little melting occurs but when strong winds and ocean currents can wreak drastic effects on the ice’s shape and movement.

Traditionally, in winter, most of the Arctic Ocean was covered with a thick sheet of ice. But today’s winter ice cover is thinner, meaning it breaks up more easily under the influence of winds and currents. It eventually looks like an “ensemble of floes,” Rampal says, instead of one large mass. In summer, natural melting due to warmer temperatures opens the door to even more breakup. (Scientists refer to these patches of floes as “pancake ice,” because the small circular pieces look like — yes — pancakes on a griddle.)

During both seasons, ice in this state is prone to escaping from the Arctic basin, most commonly through the Fram Strait, a wide swath of ocean between Greenland and the Norwegian archipelago of Svalbard. The smaller the floes, the more likely they are to be lost through the Fram Strait, where they melt on contact with warmer waters to the south.

So, several factors are connected in a positive feedback loop: Thinner ice breaks more easily; smaller chunks of ice drift more quickly; and drifting ice is more prone to export and melting at lower latitude. But Rampal also cites examples of negative feedback loops, which may counteract some of the ice loss. For example, large cracks in winter’s ice cover help create new ice, since the extremely cold air in contact with the liquid ocean promotes refreezing, which leads to a sheet with greater surface area than before.

‘You’d better start now’

Because “everything is coupled” in these intricate feedback loops, “it’s hard to predict the future of Arctic sea ice,” Rampal says. Doing so will require more thorough modeling and real-world observations, especially of mechanical forces and other ice phenomena that have been poorly understood. Rampal is now working on a project with researchers at MIT and NASA’s Jet Propulsion Laboratory, whose goal is to combine models and observations for a more accurate picture of the state of the world’s oceans.

Bruno Tremblay, an associate professor in the Department of Atmospheric and Oceanic Sciences at McGill University, agrees that “the dynamic of sea ice is really important,” and inadequate modeling of mechanical forces is “part of the reason [the IPCC report] can’t predict correctly the future of decline.” Still, he cautions against jumping to overly grim conclusions, citing a need to consider subtle changes in the Arctic atmosphere: At some point, for instance, “maybe the wind no longer aligns itself with the Fram Strait, and that reduces ice export,” he says.

Although it’s impossible to say for sure when we might see an ice-free Arctic, the IPCC itself has acknowledged that its 2007 report may have painted too rosy a picture. “If you look at the scientific knowledge things do seem to be getting progressively worse,” said Rajendra Pachauri, IPCC chair, in an interview reported by The New York Times shortly after the report’s release. “So you’d better start with the interventions even earlier. Now.”


This story is republished courtesy of MIT News (web.mit.edu/newsoffice/), a popular site that covers news about MIT research, innovation and teaching.

Explore further: Quakes destroy or damage 83 houses in Philippines

add to favorites email to friend print save as pdf

Related Stories

A new insight into the decline of the Arctic sea ice cover

May 14, 2009

The mechanical behavior of the Arctic sea ice cover appears to favor its rapid decline. Scientists from INSU-CNRS, Université J. Fourier and Université de Savoie, France, have analyzed the trajectories of drifting ...

NASA Sees Rapid Changes in Arctic Sea Ice

Sep 13, 2006

NASA data shows that Arctic perennial sea ice, which normally survives the summer melt season and remains year-round, shrunk abruptly by 14 percent between 2004 and 2005. According to researchers, the loss of perennial ice ...

Recommended for you

NASA sees Tropical Depression Polo winding down

19 minutes ago

Infrared satellite imagery from NASA's Aqua satellite showed only a swirl of low-level clouds some deep clouds around Polo's weakening center on Sept. 22 as the storm weakened to a depression.

TRMM satellite tallies Hurricane Odile's heavy rainfall

1 hour ago

During the week of Sept. 15, Hurricane Odile and its weakened remnants produced heavy rainfall that caused dangerous flooding over Mexico's Baja California peninsula and southwestern United States. NASA's ...

Arctic sea ice helps remove CO2 from the atmosphere

3 hours ago

Climate change is a fact, and most of the warming is caused by human activity. The Arctic is now so warm that the extent of sea ice has decreased by about 30 pct. in summer and in winter, sea ice is getting ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

Techno1
1 / 5 (2) Aug 11, 2011
...it may happen several decades earlier


I agree. A couple weeks ago I came across some data I had never quite seen before, and was interested, so I played around with several simple regressions relating to the melting of ice, and how that changes average albedo, which then further melts ice.

Of course, my regressions were overly simplistic, but I ignored CO2, and I ignored negative feedbacks, such as the fact "most" extra heat radiates back away during the winter, etc.

Still, I came to the conclusion that even if CO2 remains constant, the Arctic will be ice-free no later than 2053, and possibly in the most extreme case, as early as 2026.

Even if negative feedbacks cut the rate of melting in half, that would only push the upper and lower bounds back to 2095 and 2041 respectively...again, even if you ignore any increases in CO2 levels...

Moreover, this did not even consider other positive feedbacks...continued...
Techno1
1 / 5 (2) Aug 11, 2011
When I did this regression, I ONLY considered positive feedbacks from changes in albedo caused by melting of ARCTIC SEA ICE.

I did not consider positive feedbacks from changes in albedo caused by melting of mountain glaciers, snow packs, and permanent ice caps on greenland and antarctica, nor positive feedbacks caused by melting of sea ice in the southern hemisphere. For simplicity, I treated those things as static, even though I know in reality they would be melting as well...

Of course, CO2 is increasing with a slope of 2.1 PPM per year, so 15 years from now that would be an extra 31.5PPM, or 42 years from now, that would be an extra 88PPM, assuming the average rate of CO2 increase doesn't go up any more (even though population and standards of living will both presumably go up, thus again a ridiculous assertion...)

IMO, the only way you'd get CO2 increase below a slope of 2PPM per year within the next 30 years would be if Rossi's E-Cat is real...
Techno1
1 / 5 (2) Aug 11, 2011
Further, I considered what would happen during the first few years after the first complete arctic sea ice meltdown occurs. This does NOT require Greenland to melt, though Greenland's ice cap provides somewhat of a buffer due to the heatsink of the heat of fusion, and the albedo it provides.

Over the long term, the average minimum extent of sea ice occurs on September 10 or 11. But in the past 10 years, the date of the minimum keeps getting pushed back farther and farther.

What I found is the first complete meltdown will likely occur sometime between Septermber 25 and October 5 of the year, because the melting will be so severe during the first part of the season that it will keep pushing the date of the minimum farther and farther back due to positive feedback.

Now once you have one complete meltdown, the amount of ice you get back for the next year will be significantly less. This will cause the second meltdown to happen MUCH earlier in the year...
Techno1
1 / 5 (2) Aug 11, 2011
The second complete meltdown will happen around September 1 of the following year, and the artic will STAY melted down completely, and well into mid or late October.

The excess heat build up during this time will make re-freezing even harder than the previous year, and will heat the northern hemisphere by several degrees celsius during the hottest parts of late summer and early autumn. This will make the third meltdown slightly worse, but will probably begin to level off a TAD since negative feedbacks, such as loss of heat through radiation, will help prevent some of this heat from sticking around.

During the third meltdown, the SST at the North pole could easily reach 5C in late September or early October.

What this will do to ocean currents is anyone's guess, but it will definitely not be a good thing for the atlantic hurricane season. England, Spain, and Portugal may start getting hit by category 3 to 5 hurricanes, because there will be no cooling on the east atlantic.