Saturday, August 13, 2011

Arctic Ice Thinning 4 Times Faster Than Predicted by IPCC Models, Semi-Stunning M.I.T. Study Finds

By Joe Romm on Aug 11, 2011 at 10:45 pm

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….

After comparing IPCC models with actual data, [lead author Pierre] 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.


But it’s very safe to say that two-dimensional analyses of sea ice trends — ones that don’t model ice thickness and hence ice volume — are going to miss crucial feedbacks and dynamic changes. That is the central point of this new MIT study, which will be stunning only to those who don’t follow either this blog or the recent scientific literature.

Recent statements that we are seeing an “Arctic Death Spiral” focused on volume. In the words of National Snow and Ice Data Center (NSIDC) director Mark Serreze, who is most associated with that phrase:

Serreze (9/10): “There are claims coming from some communities that the Arctic sea ice is recovering, is getting thicker again. That’s simply not the case. It’s continuing down in a death spiral. Every bit of evidence we have says the ice is thinning. That means there’s less energy needed to melt it out than there used to be.”

Serreze (7/11): “The extent [of the ice cover] is going down, but it is also thinning. So a weather pattern that formerly would melt some ice, now gets rid of much more. There will be ups and downs, but we are on track to see an ice-free summer by 2030. It is an overall downward spiral.“

This new study, “IPCC climate models do not capture Arctic sea ice drift acceleration: Consequences in terms of projected sea ice thinning and decline,” (subs. req’d) adds to our understanding of how the two-dimensional models go astray. Here’s an extended excerpt from the news release:

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.


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.”


Since computer models have been underestimating the effects of climate change, the following may turn out to be overly optimistic. It will be interesting to see what happens. Of course, if we do get these temporary stabilizations, the fossil fuel industry will claim them as evidence against climate change.

ScienceDaily (Aug. 11, 2011) — Although Arctic sea ice appears fated to melt away as the climate continues to warm, the ice may temporarily stabilize or somewhat expand at times over the next few decades, new research indicates.

The computer modeling study, by scientists at the National Center for Atmospheric Research, reinforces previous findings by other research teams that the level of Arctic sea ice loss observed in recent decades cannot be explained by natural causes alone, and that the ice will eventually disappear during summer if climate change continues.

But in an unexpected new result, the NCAR research team found that Arctic ice under current climate conditions is as likely to expand as it is to contract for periods of up to about a decade.


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