Saturday, November 10, 2007

From Ice To Water

"Rising seas would severely impact the United States and scientists have projected a 1.5m sea-level rise by 2100. This increase would inundate some 22,400 square miles of land along the Atlantic and Gulf coasts of the United States, primarily in Louisiana, Texas, Florida and North Carolina." - A U.S. Environmental Protection Agency 2001 Report.

Quite simply, as a result of global warming, the polar ice caps are melting and at a rate faster than previously thought. A study, published by the journal Science last year, suggests that sea levels worldwide will rise by several metres by the end of this century leading to catastrophic consequences to huge swaths of low-lying regions from Florida, Bangladesh, Lagos to Shanghai.

A recently released UNEP report in June this year said that a 1 metre rise in sea level would inundate over 800 sq km of low-lying lands in Asia with an estimated displacement of more than 100 million people. Coastal and island tidal gauge data indicated that sea levels rose by just 20cm over a 130 years period from 1871 to 2001, at an average rise of 1.7mm per year. But from 1993 to 2006, a mere 7 years, global measurements by satellite altimeters shows that worldwide average sea level rose by more than 3mm per year.

With the world's only two continental ice sheets, Antarctic and Greenland, containing more than half of the world's total amount of freshwater and around 99 per cent of freshwater ice on Earth, the potential for global catastrophe is clear. The rise in global temperatures over the last 50 years, has contributed to the rapid shrinking and melting of both our polar ice caps, especially the Arctic continent.

Arctic Continent.
Greenland is much more susceptible to global warming than Antarctica because it's climate is strongly affected by its proximity to other land masses and to the North Atlantic ocean. Its ice sheet is also smaller and much less thicker, with a volume about one-ninth that of the Antarctic ice sheet. Average temperatures in the Arctic region are rising twice as fast as they are elsewhere in the world and its ice sheets are shrinking rapidly, melting and rupturing. The largest single block of ice in the Arctic, the Ward Hunt Ice Shelf, which had been around for 3,000 years, started cracking in 2000. Within two years it had split all the way through and is now breaking into pieces.

Summer melting now occurs over half of the surface of Greenland's ice sheet, particularly near the coast, with much of the water flowing into the sea. "As the surrounding temperatures rose, the total loss from the ice sheet more than doubled from a few tens of billions of tonnes per year in the early 1990s to about 100 billion tonnes in 2000, with a likely further doubling by 2005," said the UNEP report. Recent images from NASA satellites show that the ice cover is contracting at a rate of 9 percent per decade. If this trend continues, summers in the Arctic could become ice-free by the end of the century.

The "Frozen Continent", an area larger than Europe, is totally covered in ice, some as thick as 10,000 feet. While the rate of melting of its ice sheets is nowhere as fast as in the Arctic, some ice shelves in the northernmost part of Antarctica—the Antarctic Peninsula—have been collapsing in recent years, in line with the rapid warming trend there since 1945.

In Jan 1995, the 1,994 km2 Larsen A ice shelf disintegrated suddenly and in March 1998, after more than 400 years, more than 2,978 km2 of the Larsen B ice shelf collapsed. This was followed by the disintegration of the Wilkins ice shelf in March 1999. The dramatic disintegration of the ices shelves in such a short time period has been attributed to the rise in global temperatures.

Results from a 2005 study by researchers at British Antarctic Survey and U.S. Geological Survey, showed that over the last 50 years, 87% of 244 glaciers studied have retreated and that average retreat rates have accelerated. "On average, the glaciers retreated by 50 metres per year in the last five years, faster than at any time in the last fifty years," the report said. Overall, seven ice shelves have between them, declined in area by about 13,500 km2 since 1974.

Besides contributing to rising sea levels, the rapid shrinking of the ice sheets have tremendous impact on the ecosystem and its native people. Polar bears, seals, whales and walruses in the Arctic are changing their feeding and migration patterns, the natives are finding it difficult to hunt them and along the coastlines, entire villages has been uprooted. The very cultural identity and survival of the native people and the many denizens of the ecosystem are being threatened. In Antarctic, the population of Adelie Penguin have shrunk by 33% during the past 25 years as a result of the disappearance of their winter sea ice habitat.

The retreat of the ice caps is also accelerating global warming due to the loss of the reflective and protective nature of the ice sheets. The melting will expose more land to the sun and the earth will absorb more sunlight and gets even hotter, thus hastening the rise in global temperatures.

Other than governmental and world bodies initiatives in tackling global warming, like the Antarctic tour that Mr.Ban Ki Moon, the United Nations secretary-general is embarking on this week, it is imperative that companies and citizens worldwide adopt clean energy alternatives and green practices to drastically reduce the amount of greenhouse gases emissions. Failure to do so would result in serious repercussions and we might find the price to high to pay for our children.

*Resources :
- Natural Resources Defence Council
- Science Daily
- Climate Hot Maps

*Related post : A Planet In Peril

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