Earth Report - Rising Tides 1 of 6 - BBC Environmental Documentary, recorded 10.03.2009
Sea levels are likely to rise by about 1.4m (4ft 6in) globally by 2100 as polar ice melts, according to a major review of climate change in Antarctica.
Conducted by the Scientific Committee on Antarctic Research (SCAR), it says that warming seas are accelerating melting in the west of the continent.
Ozone loss has cooled the region, it says, shielding it from global warming.
Rising temperatures in the Antarctic Peninsula are making life suitable for invasive species on land and sea.
The report - Antarctic Climate Change and the Environment - was written using contributions from 100 leading scientists in various disciplines, and reviewed by a further 200.
Rising seas: A tale of two cities
SCAR's executive director Dr Colin Summerhayes said it painted a picture of "the creeping global catastrophe that we face".
"The temperature of the air is increasing, the temperature of the ocean is increasing, sea levels are rising - and the Sun appears to have very little influence on what we see," he said.
SCAR's report comes 50 years to the day after the Antarctic Treaty, the international agreement regulating use of the territory, was opened for signing, and a week before the opening of the potentially seminal UN climate summit in Copenhagen.
High rise
Two years ago, the Intergovernmental Panel on Climate Change (IPCC) projected that the global average sea level would probably rise by 28-43 cm (11-16in) by the end of the century.
But it acknowledged this figure was almost certainly too low, because it was impossible to model "ice dynamics" - the acceleration in ice melting projected to occur as air and water temperatures rise.
Launching the SCAR report in London, lead editor John Turner from the British Antarctic Survey (BAS) suggested that observations on the ground had changed that picture, especially in parts of the West Antarctic ice sheet.
"Warmer water is getting under the edges of the West Antarctic ice sheet and accelerating the flow of ice into the ocean," he said.
Glaciers: If the world's mountain glaciers and icecaps melt, sea levels will rise by an estimated 0.5m
Thermal expansion: The expansion of warming oceans was the main factor contributing to sea level rise, in the 20th Century, and currently accounts for more than half of the observed rise in sea levels
Ice sheets: These vast reserves contain billions of tonnes of frozen water - if the largest of them (the East Antarctic ice sheet) melts, the global sea level will rise by an estimated 64m
By the end of the century, he said, the sheet will probably have lost enough ice alone to raise sea levels globally by "tens of centimetres".
The remainder of the projected rise would come from melting of the Greenland cap, melting of mountain glaciers in the Himalayas and Andes, and the expansion of seawater as it warms.
A number of research teams have come up with similar projections.
But this is the first time that an international body such as SCAR has endorsed the likelihood that sea levels will rise enough to threaten some of the world's biggest cities by the end of the century.
Cold store
The Antarctic Peninsula - the strip of land that points towards the southern tip of South America - has warmed by about 3C over the last 50 years, the fastest rise seen anywhere in the southern hemisphere, according to the report.
But the rest of the continent has remained largely immune from the global trend of rising temperatures.
ANTARCTIC CLIMATE CHANGE
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