A new Nasa-led study found a 23% loss in the extent of the Arctic's thick, year round sea ice cover during the past two winters. This drastic reduction of perennial winter sea ice is the primary cause of this summer's fastest-ever sea ice retreat on record and subsequent smallest-ever extent of total Arctic coverage.
From the 1970s through the 1990s, prennial ice declined by about 500,000 square kilometers (193,000 squares miles) each decade. Since 2000, that amount of decline has nearly tripled. Between winter 2005 and winter 2007, the perennial ice shrunk by an area the size of Texas and California combined.
The minimum ice extent reached in September 2007 shattered the previous record for ice withdrawal set in 2005, of 5.32 milliion square km.
The long-term average minimum, based on data from 1979 to 2000, is 6.74 million square km.
In comparison, 2007 was lower by 2.61 million square km, an area approximately equal to the size of Alaska and Texas combied or the size of 10 United Kingdoms.
The Arctic saw another milestone in the summer of 2007. The ice cap shrank so much this summer that waves briefly lapped among two long-imagined Arctic shipping routes, the Northwest Passage over Canada and the Northern Sea Route over Russia. In August 2007, the Northwest Passage had almost no floating ice. It was the first time the Passage had been completely open to shipping since people started keeping records in 1972. Scientists say that the lack of ice represents clear proof that the planet is warming.
Experts say the ice retreat is likely to be ecen bigger next summer because this winter's freeze is starting from such a huge ice deficit. Professor Maslowski's group, which includes co-workers at Nasa and the Institute of Oceanology, Polish Academy of Science (PAS), is well known for producing modelled dates that are in advance of other teams. He projects a blue Arctic Ocean in summers by 2013. "In the end, it will just melt away quite suddenly. It might not be as early as 2013 but it will be soon, much earlier than 2040." Other teams have variously produced dates for an open summer ocean that, broadly speaking, go about 2040 to 2100.
Discussing the possibly for an open Arctic ocean in summer months, he told the meeting: "A few years ago even I was thinking 2050, 2070, out beyond the year 2100, because that's what our models were telling us. But as we've seen, the models aren't fast enough right now; we are losing ice at a much more rapid rate."
Ice re-forms during winter, but due to warmer waters the amount of re-formed ice appears to be decreasing. Ice that was previously considered "permanent" is now melting. That leaves an ever-decreasing base of ice at the beginning of each melting season.
Sea ice plays an important role in keeping temperatures down around the world. Whereas sea ice reflects 80% of sunlight back into the atmosphere, ocean water absorbs 90 percent of sunlight. As melting ice exposes more ocean to direct sunlight, scientists expect water temperatures to rise, accelerating the ice melt.
This record pace of Arctic ice melt has scientists concerned about rising sea levels, diminished habitats for polar bears and other animals and an impending rush for fossil fuels in the region. Increased traffic through the Northwest Passage and the Northeast Passage (which runs by Siberia) may increase pollution in the area. Experts estimate that 25% of the world's remaining fossil fuel reserves lies under the Arctic seabed. Commentator Jeremy Rifkin noted with irony that it's the burning of fossil fuels and the subsequent rise of global temperature that has made it possible to access these long-blocked stores of oil and gas.
Scientist call this rush for fossil fuels and the melting of permafrost in Siberia and other areas a "ticking time bomb". If Siberia's vast permafrost continues to melt, massive amout of methane, now trapped beneath the ice, may be released. Methane is a highly potent greenhouse gas, more than 2o times stronger than carbon dioxide. Scientists fear that the release of so much methane may initiate a sort of feedback loop, wherein methane release increase the rate of global warming. In turn spurring more permafrost melt and more methane release.
One of the most visible effects of Arctic ice melt is the calving of large pieces of ice from glaciers and ice shelves. In 2005, the Ayles Ice Island, a 30-square mile chuck of ice broke away from Canada's Ayles Ice Shelf and began drifting through the Arctic.
The faster the Arctic melts and the closer our planet comes to catastrophic climate change. "The Arctic may have another ace up her sleeve to help the ice grow back," Dr. Eicken said. "But from all we can tell right now, the means for that are quite limited."
Melting Artic Ice
From the 1970s through the 1990s, prennial ice declined by about 500,000 square kilometers (193,000 squares miles) each decade. Since 2000, that amount of decline has nearly tripled. Between winter 2005 and winter 2007, the perennial ice shrunk by an area the size of Texas and California combined.
The minimum ice extent reached in September 2007 shattered the previous record for ice withdrawal set in 2005, of 5.32 milliion square km.
The long-term average minimum, based on data from 1979 to 2000, is 6.74 million square km.
In comparison, 2007 was lower by 2.61 million square km, an area approximately equal to the size of Alaska and Texas combied or the size of 10 United Kingdoms.
The Arctic saw another milestone in the summer of 2007. The ice cap shrank so much this summer that waves briefly lapped among two long-imagined Arctic shipping routes, the Northwest Passage over Canada and the Northern Sea Route over Russia. In August 2007, the Northwest Passage had almost no floating ice. It was the first time the Passage had been completely open to shipping since people started keeping records in 1972. Scientists say that the lack of ice represents clear proof that the planet is warming.
Experts say the ice retreat is likely to be ecen bigger next summer because this winter's freeze is starting from such a huge ice deficit. Professor Maslowski's group, which includes co-workers at Nasa and the Institute of Oceanology, Polish Academy of Science (PAS), is well known for producing modelled dates that are in advance of other teams. He projects a blue Arctic Ocean in summers by 2013. "In the end, it will just melt away quite suddenly. It might not be as early as 2013 but it will be soon, much earlier than 2040." Other teams have variously produced dates for an open summer ocean that, broadly speaking, go about 2040 to 2100.
Discussing the possibly for an open Arctic ocean in summer months, he told the meeting: "A few years ago even I was thinking 2050, 2070, out beyond the year 2100, because that's what our models were telling us. But as we've seen, the models aren't fast enough right now; we are losing ice at a much more rapid rate."
Ice re-forms during winter, but due to warmer waters the amount of re-formed ice appears to be decreasing. Ice that was previously considered "permanent" is now melting. That leaves an ever-decreasing base of ice at the beginning of each melting season.
Sea ice plays an important role in keeping temperatures down around the world. Whereas sea ice reflects 80% of sunlight back into the atmosphere, ocean water absorbs 90 percent of sunlight. As melting ice exposes more ocean to direct sunlight, scientists expect water temperatures to rise, accelerating the ice melt.
This record pace of Arctic ice melt has scientists concerned about rising sea levels, diminished habitats for polar bears and other animals and an impending rush for fossil fuels in the region. Increased traffic through the Northwest Passage and the Northeast Passage (which runs by Siberia) may increase pollution in the area. Experts estimate that 25% of the world's remaining fossil fuel reserves lies under the Arctic seabed. Commentator Jeremy Rifkin noted with irony that it's the burning of fossil fuels and the subsequent rise of global temperature that has made it possible to access these long-blocked stores of oil and gas.
Scientist call this rush for fossil fuels and the melting of permafrost in Siberia and other areas a "ticking time bomb". If Siberia's vast permafrost continues to melt, massive amout of methane, now trapped beneath the ice, may be released. Methane is a highly potent greenhouse gas, more than 2o times stronger than carbon dioxide. Scientists fear that the release of so much methane may initiate a sort of feedback loop, wherein methane release increase the rate of global warming. In turn spurring more permafrost melt and more methane release.
One of the most visible effects of Arctic ice melt is the calving of large pieces of ice from glaciers and ice shelves. In 2005, the Ayles Ice Island, a 30-square mile chuck of ice broke away from Canada's Ayles Ice Shelf and began drifting through the Arctic.
The faster the Arctic melts and the closer our planet comes to catastrophic climate change. "The Arctic may have another ace up her sleeve to help the ice grow back," Dr. Eicken said. "But from all we can tell right now, the means for that are quite limited."
Melting Artic Ice
Artic Ice Abrupt Withdrawl - Present - 2040
copyrighted © Andrew C Revkin (The New York Times), Jacob Silverman, Jonathan Amos (BBC News), NASA
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