TAS: How the oceans will rise, over 2,000 years

AAP General News (Australia)
02-10-2000
TAS: How the oceans will rise, over 2,000 years

By Don Woolford

HOBART, Feb 10 AAP - The world's oceans are likely to rise by seven to eight metres
over the next 1,000 to 2,000 years, according to a leading Australian research institution.

The estimates, released today by the Hobart-based Antarctic Cooperative Research Centre,
contradict popular speculation that there could be a large rise in sea levels over the
next century.

"We want to get away from extremist ideas about changes," Professor Bill Budd, who
led the centre's modelling team on the project, said.

The centre's findings are part of Australia's contribution to the Inter-governmental
Panel on Climate Change, an international body that is reviewing scientific estimates
on long-term climate change.

While the CSIRO and Bureau of Meteorology are also contributing to the study, which
is due to be completed around the end of this year, the centre is Australia's main research
body into polar influences on the climate.

Prof Budd said the centre's earlier work focused on shorter term effects.

The new estimates were based on the "middle road" scenario on greenhouse gas emissions.

This was for emissions to stabilise in about 100 years at about triple the pre-industrial
level. At present emissions are about 1.5 times that level.

The centre said ocean change would be associated with the melting of the two remaining
ice-sheets of Greenland and Antarctica.

The smaller Greenland ice-sheet would, if completely melted, raise ocean levels by six metres.

Calculations suggested that warming by a few degrees might trigger the melting of most
of the sheet, but the process would take 1,000 to 2,000 years.

The much larger Antarctic ice sheet would, if melted, raise the oceans by about 55 metres.

But warming of two to three degrees would not melt it because most Antarctic temperatures
were well below the melting point of ice.

However, a one to two metre rise over the next 2,000 years could occur if glacier flow
into the ocean increased.

The centre said that over the next century or two there would be little melting of
the ice-sheets and ocean levels would be determined by thermal expansion and the melting
of non-polar glaciers.

This could be counteracted by an increase in the volume of Antarctic ice because more
snow was falling as a result of higher evaporation from the warmer oceans.

The best estimate was that the oceans would rise by "several tens of centimetres per century".

Prof Budd said a major point of the findings was that low-level communities would have
plenty of time to adapt to the gradual rise of ocean levels.

He said the Netherlands was aleady working to strengthen its system of dikes.

AAP dw/apm/br

KEYWORD: OCEANS

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