[ASC-media] Media Release: Getting into hot water - global warming and rising sea levels

Australian Academy of Science scied at science.org.au
Tue Apr 13 13:50:36 EST 2004

13 April 2004

Getting into hot water - global warming and rising sea levels

The 20th century saw the greatest increase in temperature of any century during the last thousand years, and the 1990s was the warmest decade since records began. As the temperature rises, so does the sea level - with profound consequences for us all. The new Australian Academy of Science Nova: Science in the news topic has the latest information on rising sea levels at http://www.science.org.au/nova.

A warmer world will have a higher sea level because as the land and lower atmosphere of the world warm, heat is transferred into the oceans. When materials are heated they expand. So the heat that is transferred causes seawater to expand, which then results in a rise in sea level. In addition, water from land-based ice such as glaciers and ice sheets may enter the ocean, thus adding to the rise.

On average, it is expected that by 2100 sea levels will have risen in most places by around half a metre. For people living on low-lying islands such as Tuvalu, Kiribati or the Maldives, an extra 50 centimetres could see significant portions of their islands being washed away by erosion or covered by water. Even if some low-lying islands remain above the sea, many island nations will have their supplies of drinking water reduced because seawater will invade their freshwater aquifers. 

While these islands have sizeable populations, they are insignificant compared to the tens of millions of people living in the low-level coastal areas of southern Asia. These include the coastlines of Pakistan, India, Sri Lanka, Bangladesh and Burma. 

Modelling predicts that in Australia, a rise in sea level of one metre could see our coastal beaches recede by about 100 metres, unless some preventative action is taken. CSIRO researchers believe that damage costs associated with coastal flooding would more than double in southern Queensland and northern New South Wales if sea levels were to rise by 40 centimetres. Low-lying coastal ecosystems, such as the freshwater wetlands that make up about 90 per cent of the coastal zone of Kakadu in the Northern Territory, would also be vulnerable.

Future planning should take global warming and consequent sea level rises into consideration. For example, building protective sea walls and restricting coastal development in areas at risk are planning measures that could minimise damage from rising sea levels over the next century.

More about rising sea levels is on the Australian Academy of Science's Nova: Science in the news website at http://www.science.org.au/nova. The topic also includes a glossary; student activities; further reading; and annotated links to relevant websites. The topic was developed with support from the Australian Greenhouse Office.

The principal sponsor of Nova: Science in the news is the Commonwealth Bank Foundation (www.commbank.com.au/foundation).

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