Climate change eradicating Arctic’s oldest ice – ‘What was once a refuge for older ice has become a graveyard’

By Randy Boswell, Postmedia News
5 October 2011 The Arctic’s oldest, thickest sea ice — much of which used to survive the year’s warmest months — had all but disappeared by the end of this summer’s near-record meltdown, according to new U.S. analyses that vividly show how the circumpolar region is being transformed by warmer temperatures and other features of climate change. In reports issued this week by NASA and the associated National Snow and Ice Data Center, the respective teams of U.S. scientists offered end-of-season overviews of the state of the northern cryosphere that emphasized not only the severe shrinkage of the ice cover for the fifth straight year, but also the widespread replacement of the Arctic’s most mature ice masses by much younger, thinner and weaker sheets of ice. The trend — reinforced by this year’s loss of about 50 per cent of Canada’s rapidly vanishing, millennia-old Arctic ice shelves along the coast of Ellesmere Island — continues to suggest the likelihood of ice-free Arctic summers in the coming decades, the experts say. “The oldest, thickest ice (five or more years old), has continued to decline,” states the report from the Colorado-based NSIDC, which points to the Beaufort Sea north of the Yukon-Alaska boundary as a prime area for the loss of old-growth ice. “In essence, what was once a refuge for older ice has become a graveyard.” That observation recalls warnings issued two summers ago by one of Canada’s top Arctic scientists, University of Manitoba researcher David Barber, who described how “rotten” ice was becoming prevalent throughout Canada’s northern waters, where thicker and more durable ice previously had been the norm. “The multi-year (ice) continues to decline precipitously, and we have a good handle now on the processes controlling this,” Barber told Postmedia News on Wednesday. “We are on the way to a seasonally ice-free Arctic; in fact, you could have taken an ice-reinforced tanker across the pole in 2010 and again in 2011— so in terms of ship navigation, we have already reached it.” By the time Arctic ice reached its minimum extent of 4.3 million square kilometres on Sept. 9, it had nearly equalled 2007’s record melt to just 4.13 million square kilometres. […] “It looks like the spring ice cover is so thin now that large areas melt out in summer, even without persistent extreme weather patterns,” NSIDC director Mark Serreze said in the centre’s summary of the season’s ice losses. […] “The sea ice is not only declining, the pace of the decline is becoming more drastic,” said Maryland-based NASA scientist Joey Comiso. “The older, thicker ice is declining faster than the rest, making for a more vulnerable perennial ice cover.”

Climate change eradicating Arctic’s oldest ice