by Malte Humpert Studies by the Massachusetts Institute of Technology and the National Center for Atmospheric Research (NCAR) have fueled an ongoing debate about the severity and pace of Arctic sea-ice decline.
Andrew Revkin, writing for the NY Times, cites the NCAR study in support of his view that up and downward fluctuations in ice extent over short time horizons are not very meaningful when determining the overall fate of the Arctic ecosystem. Furthermore he rejects the notion of the system being in a "death spiral" and refers to an article in this month's issue of Science to bolster his position:
There have been large fluctuations in the amount of summer sea ice during the last 10,000 years. During the so-called Holocene Climate Optimum, from approximately 8000 to 5000 years ago, when the temperatures were somewhat warmer than today, there was significantly less sea ice in the Arctic Ocean, probably less than 50% of the summer 2007 coverage, which is absolutely lowest on record. [...] Our studies show that there are great natural variations in the amount of Arctic sea ice. [...] The good news is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return: a level where the ice no longer can regenerate itself even if the climate was to return to cooler temperatures.
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| Arctic Ice Volume 1975-2010 and exponential trend |
In support of his position he cited an article in Nature from December 2010 which showed sea ice extent crashing by two thirds over the next two decades and then collapsing entirely after 2030. Romm criticizes both studies for basing their best-case scenarios on "the implausible assumption" of a GHG emission reduction rate between 50-70 percent by 2030. According to Romm:
You can devise a theoretical scenario of emissions reductions that might — might — stabilize the Arctic, but such a scenario is all but impossible in the face of implacable opposition by the deniers and their political allies, and it is precisely the kind of emissions reduction scenario Revkin himself constantly dismisses. [...] The Arctic will have under half the ice it has today by 2020, thus equaling or surpassing the lowest level identified in this Science paper. The death spiral continues.
While climate experts and scientific continue to debate the past, present, and future of Arctic ice the National Snow and Ice Data Center has released the latest figures on see ice extent. The year 2011 set a new all-time low for July ice extent. This year's minimum is forecasted to occur around September 23rd.
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