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By
Matthew Denholm
THE world's worst fears about global warming and rapid
sea-level rise will be realised or exceeded, according
to two new reports.
Australian climate change research published yesterday
found the average level of the oceans had risen 19.5cm
since 1870 and the rate was increasing.
The study provides the first evidence of a 20th-century
acceleration in sea-level rise and supports predictions
the world's oceans will rise 31cm above 1990 levels by
2100.
A separate report released in Britain paints an ever
more alarming picture, suggesting ice sheets may be melting,
raising the prospect of sea levels rising by 5m over several
centuries.
British Prime Minister Tony Blair said the research clearly
showed that "the risks of climate change may well
be greater than we thought".
"It is now plain that the emission of greenhouse
gases, associated with industrialisation and economic
growth from a world population that has increased six-fold
in 200 years, is causing global warming at a rate that
is unsustainable," Mr Blair writes in a foreword
to the research.
Published in the report Avoiding Dangerous Climate Change,
it warns of large-scale disruption if temperatures rise
above 3C - within the range of climate change models for
this century.
The author of the Australian research, internationally
renowned CSIRO chief research scientist John Church, said
it was now clear there would be significant sea-level
rise without major changes to human behaviour.
"Clearly, sea-level rise will be reported in metres
unless we have a substantial decrease in greenhouse gas
emissions," Dr Church told The Australian.
He said his study, conducted with CSIRO scientist Neil
White using data from tide gauges and satellite measurements,
vindicated sea-level rise projections by the UN's Intergovernmental
Panel on Climate Change.
"Although predicted by models, this is the first
time a 20th-century acceleration has actually been detected."
The study concludes that sea levels rose an average 16cm
during the 20th century, with a rough year-on-year increase
of 1.7cm.
It finds that sea level rise began during the first half
of the 19th century, when global sea level was about 20cm
below current levels. A comparison of sea-level benchmarks
carved in rock on the Isle of the Dead, near Port Arthur
in Tasmania in 1840, and the height of ancient Roman fish
tanks, indicated little sea level increase until 1800.
The study, part of Australia's Climate Change Science
Program, is likely to be considered at the IPCC's global
climate change assessment next year.
The British research, based on a forum of scientists
at Exeter last February, includes a warning from British
Antarctic Survey head Chris Rapley that the West Antarctic
Ice Sheet may be starting to melt.
Scientists believe the melting of the ice sheet would
eventually raise sea levels around the world by 5m.
"The last IPCC report characterised Antarctica as
a slumbering giant in terms of climate change. I would
say it is now an awakened giant," Professor Rapley
writes. "There is real concern."
The report warns a delay of even five years in reducing
greenhouse gas emissions "could be significant".
The Federal Opposition said the findings highlighted
the need for Australia to sign the Kyoto Protocol.
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News.com.au
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