www.bbc.uk
Sunday, 17 February, 2002, 02:05 GMT
Sea level rises 'underestimated'
By BBC News Online's Jonathan Amos
Scientists may have seriously underestimated the
likely rise in sea levels this century.
The claim comes from a research team that has
examined the rate at which glaciers and ice caps are
melting because of rising temperatures on Earth.
Professor Mark Meier himself has made a study of the
South Cascade Glacier in Washington
They say new data show these areas to be retreating
far faster than previously thought, with the run-off
waters set to lift the height of the oceans well
above that recently predicted by the UN's
Intergovernmental Panel on Climate Change.
"The glacier wastage at the moment is unprecedented,"
Professor Mark Meier of the University of Colorado at
Boulder, told the annual meeting of the American
Association for the Advancement of Science in Boston.
"In some glaciers, like the South Cascade Glacier in
Washington that I have studied for years, we know
that the present rate of melting is greater than it
ever has been for the last 5,000 years."
Latest data
Professor Meier, of the University of Colorado at
Boulder, US, and his colleague Mark Dyurgerov
analysed information about glacier volumes from
several thousand years ago to the present, and
studied the last 40 years in more detail.
Their work suggests glacier wastage will have a much
bigger impact on sea levels than the scientific
"consensus" has accepted.
"The IPCC thinks there will be an increase in sea
levels by 2100 of 5-11 centimetres due to glacier
melt alone. We think it will be nearer 17-27 cm - and
that's a conservative estimate," said Professor
Meier.
He said there were several reasons for the different
assessment. He said the IPCC had not had the benefit
of studying the latest data - especially from Alaska
which has two giant glaciers. It had also not taken
account of the increased sensitivity of glaciers to
rising temperatures.
Many reports
Professor Meier concedes that much of the data on
glaciers is patchy, predominantly from Europe, and
that which does exist has only been fully reported
from the 1960s onwards. Nevertheless, he claimed a
clear picture of behaviour was emerging.
Glacier melting is only one aspect of sea level rise;
increasing temperatures in the oceans is a much
bigger factor.
Overall, the IPCC expects global sea levels to rise
by between 11 and 88 cm this century, and to rise
further after that. These are figures based on
computer modelling.
Currently, measured sea levels are going up by about
0.8 millimetres per year with no apparent
acceleration in that increase.
The IPCC is supposed to represent a broad scientific
consensus on climate change - and it will examine
Professor Meier's evidence, as it will information
from many other research groups. It might accept his
assessment; it could continue to take a different
view.
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