ABC News Online, Posted 3 hours 8 minutes ago
http://www.abc.net.au/news/stories/2008/08/28/2349041.htm
The Arctic ice cap keeps melting under the effects of global warming and in August, saw its second largest summer shrinkage since satellite observations began 30 years ago, US scientists say.
Measurements on August 26 showed an ice cap of 5.26 million square kilometres, just below the 5.32 million square kilometres observed on September 21, 2005, making it the second biggest summer Arctic ice-cap melt in history, said the National Snow and Ice Data Centre (NSIDC).
Since the start of August, the Boulder, Colorado-based centre said, the Arctic polar cap shrank by 2.06 million square kilometres.
The melting is so fast and extensive it could shrink the ice cap to below the 4.25 million square kilometres reached in the summer of 2007, the smallest it has ever been observed by satellites, the centre said.
Since the end of the Arctic summer and the start of the freezing autumn is several weeks away, it said, the ice cap could dwindle even more than it did in 2007.
At the end of northern hemisphere summer 2007, the Arctic ice cap was 40 per cent smaller than the average 7.23 million square kilometres observed in 1979-2000, the NSIDC said.
The North Pole melting season begins in mid-June. The ice cap shrinks to its smallest area by mid-September and grows the most in winter by mid-March.
"The bottom line, however, is that the strong negative trend in summer time ice extent characterising the past decade continues," NSIDC said in a report.
The North Pole itself could even become free of ice by September for the first time in modern history, setting a new milestone in the effects of global warming on the Arctic ice shelf, NSIDC glaciologist Mark Serreze said in late June.
"We could have no ice at the North Pole at the end of this summer. And the reason here is that the North Pole area right now is covered with very thin ice, and this ice we call 'first-year ice,' the ice that tends to melt out in the summer," he explained.
Dr Serreze said the possibility the ice cap could vanish stood at 50 per cent.
If it does happen in September, he added, "it's possible that ships could sail from Alaska right to the North Pole".
The Arctic has been free of ice in the geologic history of the Earth, but never in modern history, Dr Serreze said.
"Clearly, if you look over what we have seen in the past three years and where we were headed, we are in... this long-term decline and we may have no ice at all in the Arctic Ocean in summer by 2030 or so," he added.
Not long ago, he said, the summer disappearance of the Arctic ice was predicted to happen between 2050 and 2100.
The NSIDC said the receding North Pole ice sheet was chiefly caused by the melting of ice in the Chukchi Sea, off the Alaskan coast, and the East Siberian Seas, off the coast of eastern Russia.
The Chukchi ice sheet is one of the natural habitats of the polar bear, where it hunts for seals, and its disappearance is a direct threat to the animal's survival.
The vanishing summer polar ice cap, however, also opens up the fabled Northwest Passage that winds through the northern Canadian islands and links the Atlantic and Pacific oceans.
Shipping routes using the Northwest Passage would spare very long detours through the Panama Canal and around South America's Cape Horn.
An ice-free North Pole would also expose untold wealth of natural resources, including oil and natural gas, locked up beneath the Arctic Ocean waters, which Canada and Russia are already eagerly preparing to exploit.
- AFP
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