Storm Surges Increase With Warming Oceans

Coastal storm surges will become an increasing threat to life and property, says Dr John Church, a scientist at Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Antarctic Cooperative Research Centre.

Dr Church was a lead author on sea-level rise for the Intergovernmental Panel on Climate Change's assessment approved in Shanghai, China last month.

The Third Assessment Report - Climate Change 2001:The Scientific Basis - was prepared over the past three years by several hundred experts reviewing the published science, and more than 100 scientific authors drawing this together into the final report.

Global average sea level is projected to rise between 9 and 88 cm between 1990 and 2100 for a global average surface temperature rise projected to be between 1.4 and 5.8 degrees Celsius.

Addressing a national conference in Hobart of climate scientists and meteorologists today, Dr Church said computer calculations indicate increasing atmospheric concentrations of greenhouse gases will result in warmer atmospheric and ocean temperatures.

The assessment provides the most comprehensive scientific benchmark for the issue to be managed by future generations.

"For the 21st century, models indicate that ocean thermal expansion will be the largest contributor to sea-level rise, although the melting of non-polar glaciers and ice caps will also contribute.

"During the 21st Century there will be almost no melting of the Antarctic ice cap, and it takes centuries for the flow of ice sheets to respond to changes in climate.

"Beyond 2100, sea level will continue to rise for centuries after greenhouse gas concentrations have stabilised," he says.

After 500 years, sea-level rise from thermal expansion may only have reached half of its eventual level," Dr Church says.

"Changes in the mean sea surface height will increase the frequency of storm surges of a given height. This will have significant impact on populations living in coastal regions."

"Changes in the frequency or intensity of storms could exacerbate the effects of sea level rise on flooding risks," he says.

Dr Church is presenting a joint paper Understanding 20th century sea-level rise and projections for the future to the Australian Meteorological and Oceanographic Society (AMOS) conference being held at the University of Tasmania. The paper was co-authored with Dr Jonathan Gregory, Hadley Centre for Climate Prediction and Research, in the UK.