Rising Arctic temperatures melt ice
The temperature is rising again in the Arctic, with the sea ice extent dropping to one of the lowest levels on record, climate scientists have reported.
The new Arctic Report Card "tells a story of widespread, continued and even dramatic effects of a warming Arctic", said Jackie Richter-Menge of the Cold Regions Research and Engineering Laboratory, a US Army Corps of Engineers facility.
"This isn't just a climatological effect. It impacts the people that live there," she added.
Atmospheric scientists concerned about global warming focus on the Arctic because that is a region where the effects are expected to be felt first, and that has been the case in recent years.
There was a slowdown in Arctic warming in 2009, but in the first half of 2010 warming has been near a record pace, with monthly readings over 4C (7.2F) above normal in northern Canada, according to the report card.
Highlighting the immediate consequences of the warming, researchers said last winter's massive snowstorms that struck the Northeast and Mid-Atlantic US states were tied to higher Arctic temperatures.
"Normally the cold air is bottled up in the Arctic," said Jim Overland of the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Seattle. But last December and February, winds that normally blow west to east across the Arctic were instead bringing the colder air south to the Mid-Atlantic, he said.
"As we lose more sea ice it's a paradox that warming in the atmosphere can create more of these winter storms," said Mr Overland at a news briefing.
There is a powerful connection between ice cover and air temperatures, Ms Richter-Menge has explained. When temperatures warm, ice melts. When reflective ice melts it reveals darker surfaces underneath, which absorbs more heat. That, in turn, causes more melting "and on the cycle goes", she said.
In September the Arctic sea ice extent was the third smallest in the last 30 years, added Don Perovich of the Army laboratory. He said the three smallest ice covers have occurred in the last four years.