2 February 2007The Australian
The study, co-authored by a leading Australian researcher, found sea levels could rise by as much as 88cm by 2100 - about 30cm higher than previous highest forecasts.
Published in the journal Science, the research comes ahead of the UN's Intergovernmental Panel on Climate Change (ICPP) report which is expected to find humans are the likely cause of climate change.
The IPCC report, to be released in Paris tonight, will deliver the UN climate panel's strongest warning yet, that human activities are causing global warming that may bring more drought, heatwaves and rising sea levels.
The new report on rising ocean levels found the climate system overall - but sea levels in particular - could be responding more quickly to rising carbon emissions than scientists estimated in their current climate models.
One of the report's authors, CSIRO's John Church, said the greatest underestimation appeared to be the contribution of melting ice sheets to rising sea levels.
He said the rapidly melting ice was playing a more significant role, with glaciers now flowing into the ocean faster than previously thought.
"Models of the potential contribution of the Greenland and Antarctic ice sheets need to be improved to include the potential of a relatively dynamic response," Dr Church said.
The international team from six institutions cautioned against suggestions that the IPCC had previously overestimated the rate of climate change, saying the situation could, in fact, be quite the opposite.
They reviewed observations of carbon dioxide, temperature and sea level from 1990 to 2006 and compared them with projected changes for the same period.
Researchers warned the relatively short review period of 16 years meant it was premature to conclude that all sea levels would continue to rise at the same rate in the future. However, they said their findings showed previous projections had not exaggerated the rate of change and may have underestimated it.
Delegates said IPCC scientists agreed it was "very likely" that human activities were the main cause of warming in the past 50 years.
The panel, grouping 2500 scientists from 130 countries, is also expected to say that oceans will keep rising for more than 1000 years even if governments stabilise greenhouse gas emissions.
A UN draft projected that Arctic ice would shrink, and perhaps disappear in summer by 2100, while heatwaves and downpours would become more frequent.
Sea levels were likely to rise by between 28 and 43cm this century.
Temperatures are predicted to rise by three degrees Celsius over pre-industrial levels by 2100.
The IPCC report is due to be released at 7.30pm (AEDT).
