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How will the Arctic sea ice cover develop this summer?
July 10, 2008cent probability, below that of the year 2005 - the year with the second lowest sea ice extent ever measured. Chances of an equally low value as in the extreme conditions of the year 2007 lie around eight per cent. Climate scientists from the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association come to this conclusion in a recent model calculation. They participate with their prognosis in an international scientific contest, in which some of the most renowned institutes on climate research want to fathom out possibilities for seasonal predictions on Arctic sea ice cover by means of different methods and climate models.
"After the strong decrease of the Arctic ice during the last summer, climate scientists all around the world are constantly asked: how will the ice develop in the next years?" describes Prof. Dr. Rüdiger Gerdes from the Alfred Wegener Institute his motivation. "To answer this question, we did not want to guess, but to rely on sound calculations." The scientists' problem: scenarios of the long-term development of sea ice clearly indicate a de-creased ice cover - exact prognoses for the following summer, however, are not yet possible. This is mainly due to the fact that the short-term development of sea ice depends strongly on the actual atmospheric conditions, namely the weather and in particular wind, cloud cover and air temperatures.
Because the exact atmospheric conditions which determine the weather patterns in the Arctic Ocean during the coming months are not predictable, Rüdiger Gerdes and his team have entered atmospheric data of the last twenty years into an ocean sea ice model developed at the Alfred Wegener Institute. "Through this, we are still not able", says Gerdes, "to make a definitive statement on sea ice cover in September. However, this 'trick' enables us to compute the bandwidth of possible ice covers, and to quantify the probability of extreme events." Apart from the variability of atmospheric quantities during the melting season, ice thickness at the beginning of the season determines the new ice minimum. Accordingly, computations of ice thickness enter the models of the researchers from Bremerhaven. Start conditions from June 27th 2008 were used for their current prognosis.
Different from long-term prognoses, the researchers' forecasts can quickly be checked by reality. This is all right by Rüdiger Gerdes and his team. "It is a first test, and all participating researchers are eager to know how their prognosis has fared at the end of the summer. In the end, this small competition serves the optimisation of our models, so that we are able to improve our predictions concerning short-term seasonal fluctuations. It has to be added, however, that even perfect models would not be able to rule out a component of chance regarding the atmosphere. These forecasts will always be about probability, and not exact prognoses."
Helmholtz Association of German Research Centres
Different from long-term prognoses, the researchers' forecasts can quickly be checked by reality. This is all right by Rüdiger Gerdes and his team. "It is a first test, and all participating researchers are eager to know how their prognosis has fared at the end of the summer. In the end, this small competition serves the optimisation of our models, so that we are able to improve our predictions concerning short-term seasonal fluctuations. It has to be added, however, that even perfect models would not be able to rule out a component of chance regarding the atmosphere. These forecasts will always be about probability, and not exact prognoses."
Helmholtz Association of German Research Centres
Sea Ice Current Events and Sea Ice News RSSArctic sea ice hits second-lowest extent, likely lowest volume, say CU-Boulder researchers
Arctic sea ice extent during the 2008 melt season dropped to the second-lowest level since satellite measurements began in 1979, reaching the lowest point in its annual cycle of melt and growth on Sept. 14.
Arctic sea ice annual freeze-up underway
After reaching the second-lowest extent ever recorded last month, sea ice in the Arctic has begun to refreeze in the face of autumn temperatures, closing both the Northern Sea Route and the direct route through the Northwest Passage.
NASA data show Arctic saw fastest August sea ice retreat on record
Following a record-breaking season of arctic sea ice decline in 2007, NASA scientists have kept a close watch on the 2008 melt season. Although the melt season did not break the record for ice loss, NASA data are showing that for a four-week period in August 2008, sea ice melted faster during that period than ever before.
Arctic sea ice reaches lowest extent in 2008, second lowest ever recorded
The Arctic sea ice cover appears to have reached its minimum extent for the year, the second-lowest extent recorded since satellite record-keeping began in 1979, according to the University of Colorado at Boulder's National Snow and Ice Data Center, or NSIDC.
Curbing coal emissions alone might avert climate danger, say researchers
An ongoing rise in atmospheric carbon dioxide from burning of fossil fuels might be kept below harmful levels if emissions from coal are phased out within the next few decades, say researchers.
NASA study illustrates how global peak oil could impact climate
The burning of fossil fuels -- notably coal, oil and gas -- has accounted for about 80 percent of the rise of atmospheric carbon dioxide since the pre-industrial era. Now, NASA researchers have identified feasible emission scenarios that could keep carbon dioxide below levels that some scientists have called dangerous for climate.
Bad sign for global warming: Thawing permafrost holds vast carbon pool
Permafrost blanketing the northern hemisphere contains more than twice the amount of carbon in the atmosphere, making it a potentially mammoth contributor to global climate change depending on how quickly it thaws.
Arctic ice on the verge of another all-time low
Following last summer's record minimum ice cover in the Arctic, current observations from ESA's Envisat satellite suggest that the extent of polar sea-ice may again shrink to a level very close to that of last year.
Successful series of measurements in Arctic sea ice
The German Research Vessel Polarstern had to prove its ice breaking capabilities in Arctic waters to gain data on two series of long-term research measurements. After working in regions up to latitude 82° N, Polarstern of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association will enter port in Reykjavik (Iceland) on August 10th.
Wilkins Ice Shelf hanging by its last thread
The Wilkins Ice Shelf is experiencing further disintegration that is threatening the collapse of the ice bridge connecting the shelf to Charcot Island. Since the connection to the island in the image centre helps to stabilise the ice shelf, it is likely the break-up of the bridge will put the remainder of the ice shelf at risk.
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