Sea levels rising at top end of estimates

SEA levels are rising at the top of international estimates, making an increase of between 50cm and 1m possible over the next century.

SEA levels are rising at the top of international estimates, making an increase of between 50cm and 1m possible over the next century.

This is the conclusion of two of Australia's leading climate scientists.

Will Steffen, who has been appointed to the federal government's climate change committee, said this had not been challenged by the Royal Society's revised statement on global warming.

Professor Steffen, of the Australian National University, said the Royal Society had "been extremely measured with its language" but had not changed its view on the science.

Professor Steffen will today open a three-day climate forum in Hobart with an address titled Communicating climate science in a political minefield.

The Royal Society's revised fact sheet on climate change has been interpreted as an attempt to retreat from the heat of politics over the issue. Some people have claimed the report signals an end to claims of a scientific consensus on the warming threat.

But Professor Steffen said he did not think there was any conflict between the Royal Society's latest statement and the Intergovernmental Panel on Climate Change's 2007 update on sea level rises.

The Royal Society's climate change summary said thermal expansion of the ocean made it very likely that for many centuries the rate of global sea-level rise per century would be at least 20cm.

But it said "there is currently insufficient understanding of the enhanced melting and retreat of the ice sheets on Greenland and West Antarctica to predict exactly how much the rate of sea level rise will increase above that observed in the past century for a given temperature increase'.'

Senior CSIRO scientist John Church this week launched a book that says sea levels are rising at about 3mm a year against a long-term average of 2mm a year. "We have been tracking sea level since 1993 and it is now at the upper end of the IPCC projections of 80cm by the end of the century," he said.

Dr Church said 140 million people lived within 1m of high tide and trillions of dollars in infrastructure was vulnerable to rising sea levels.