Icebergs provide new global warming alert
Two massive icebergs — one as large as Jamaica — have broken away from Antarctica's Ross Ice Shelf, again drawing attention to warnings that human-induced global warming and its potentially catastrophic consequences will become unstoppable unless governments take immediate action.
Researchers at the University of Wisconsin Madison's Antarctic Meteorological Research Center discovered the first iceberg, 295 kilometres long and 37 kilometres wide, on March 17 using satellites. A second iceberg was discovered on March 30, 130 kilometres long and 20 kilometres wide.
The formation of the huge icebergs — which combined account for more than 13,500 square kilometres of the Ross Ice Shelf — means that the ice shelf has retreated 40 kilometres south.
In October 1998, an iceberg measuring more than 150 kilometres long by 35 kilometres wide broke from Antarctica's Filchner-Ronne Ice Shelf.
The Ross Ice Shelf — floating ice nearly the size of New South Wales — and the similarly sized Filchner-Ronne Ice Shelf on the opposite side of the frozen continent prevent the huge land-based Western Antarctic Ice Sheet from flowing into the sea. The Western Antarctic Ice Sheet — the smaller of Antarctica's two land ice sheets — contains 3.2 million cubic kilometres of ice, about 10% of the world's total.
In January 1999, Peter Barrett from New Zealand's Victoria University in Wellington told politicians visiting McMurdo Station, Antarctica, that he believed the Western Antarctic Ice Sheet is near the point of beginning irreversible melting.
If that happened, it would result in a six-metre rise in sea levels in less than a century. More than half the world's people live in areas that would be inundated.
There is good cause for concern. Antarctica has warmed by an average 2.5 degrees Celsius — about three times the global average — since the 1940s, and winter temperatures have jumped almost 5 degrees. According to research conducted by the US Geological Survey, Antarctica is now hotter than at any time in the past 4000 years.
A report released in January by a panel of scientists organised by the US National Academy of Science declared that global warming is "undoubtedly real". The panel concluded that over the last century the world's temperature rose between 0.4 and 0.8 degrees Celsius — a 30% increase from earlier projections.
Further evidence was published last December in the journal Science. Researchers studying satellite measurements of sea ice in the Arctic taken since 1978 found a decline in ice area larger than South Australia.
A report published in the December 1 edition of Geophysical Research Letters also found that, based on sonar readings from US submarines, the average thickness of Arctic ice floes had decreased by about 40% between 1958 and 1997.
Human-induced global warming is caused by rising concentrations of greenhouse gases in the atmosphere, primarily carbon dioxide from the burning of fossil fuels. These gases trap heat.
According to the 2500 scientists from 80 countries who make up the Intergovernmental Panel on Climate Change (IPCC), unless greenhouse gas levels are stabilised the Earth's average temperature will rise 1.5-4.5 degrees Celsius during the 21st century.
To achieve stabilisation, global greenhouse emissions must be rapidly cut by at least 60%. It is estimated that critical levels of atmospheric carbon dioxide will be reached within 30 years at the current levels of greenhouse gas emissions.
North America, Europe, Japan, Australia and New Zealand are responsible for more than 80% of past emissions and 75% of current ones. The US is the worst offender. With around 4.5% of the world's population, in 1990 the US emitted 36.1% of all greenhouse gases. Greenhouse gas emissions in the US are predicted to increase 30% from 1990 levels by 2010.
In Kyoto three years ago, leaders of the rich capitalists countries agreed to reduce their greenhouse gas emissions by a token 5.2% of 1990 levels by 2010. US President Bill Clinton signed the Kyoto treaty which committed the US to reduce its emissions by 7%.
However, US Congress has refused to ratify the agreement at the behest of a coalition of US car manufacturers and mining and oil companies.
Satellite images of the icebergs can be viewed at <http://uwamrc.ssec.wisc.edu/amrc/iceberg.html>.
BY NORM DIXON