Scientists report abnormal sea level rises off Western Australia-英语点津

Scientists say that along the coast of Western Australia sea levels are rising at a rate double that of the world average.

Statistics from Australia's National Tidal Center show sea levels have increased by 8.6 millimeters a year off Perth and by 8.1 off the tropical Kimberley region over the past two decades. The global average is a rise of just over three millimeters.

For much of the past century there were average global increases of 1.7 millimeters a year, but that rate doubled between 1993 and 2007. Some regions, notably Western Australia have suffered more than others, partly, scientists say, because of how gravitational pull affects tides.

Scientists at CSIRO, Australia's government-funded scientific research institute, say that climate change has played a role in the increase. Warmer temperatures cause water to expand, a phenomenon called thermal expansion, and cause glaciers and polar ice caps to melt.

Climatologists say that greenhouse gas emissions, such as carbon dioxide from burning oil and coal, contribute significantly to global warming.

John Church is a researcher at CSIRO.

"I think the fact that sea levels are rising is a major reason for concern and it's a combination of the global average rise together with the natural variability leading to larger regional rises over certain periods and extreme events as in storm surges which will have the most impact," Church said.

About 90 percent of Australians live in coastal areas. There are fears that some low-lying communities may have to be abandoned in years to come because of flooding and erosion. And with higher sea levels, heavy rains and massive tides known as storm surges, which often accompany tropical storms, can do unexpected damage.

There are increasing demands that future development be more sensitive to rising sea levels and the threat of storm surges.

Some climate scientists think the Australian continent is particularly susceptible to a shifting climate and predict a greater incidence of droughts, floods and storms as the Earth warms.

Next month, global climate change talks will be held in Copenhagen. Nations hope to reach an agreement on ways to reduce greenhouse gas emissions and reduce the damage from global warming.