Global warming will cause sea levels to rise up to 34 centimeters (11 inches) by the end of the century, causing increased flooding and coastal erosion, according to a new study by Australian researchers.
The study — published in this month's issue of the journal Geophysical Research Letters — said global warming was expected to further heat up the world's oceans and cause glaciers in the Himalayas and ice sheets in Greenland to melt.
The study estimated sea levels would increase between 28 centimeters (11 inches) to 34 centimeters (13 inches) by 2100.
"What we found is that sea levels are rising and increasing with time," said John Church, a co-author of the study by the Commonwealth Scientific and Industrial Research Organization, the Australian government main research body.
"It means there will be increased flooding of low-lying areas when there are storm surges," he said. "It means increased coastal erosion on sandy beaches. We're going to see increased flooding on island nations."
Most scientists believe greenhouse gases from human activities like coal-burning power plants cause global warming by trapping solar heat in the atmosphere.
Greenhouse gas emissions should be reduced by 50 percent by 2050, Church said.
"If not, climate change will continue and increase in magnitude," he said. "I think governments around the world, including Australia, have started the process, but there is a long ways to go and I would argue that it's urgent."
Clive Wilkinson, coordinator of the Global Coral Reef Monitoring Network, a nongovernment group that follows closely developments on rising seas, said the findings were in line with what many scientists have predicted about global warming.
"It fits a pattern that everyone is coming up with," Wilkinson said. "It means we are in real trouble. If you add another meter [yard] over coral reefs, it won't notice it. But the rising water would flood any low-lying areas. Coral island like Tuvalu, Maldives and Kiribati will become uninhabitable."
By examining tidal data, Church said sea levels rose by 19.5 centimeters (7.7 inches) between 1870 and 2004. The increases accelerated with time, averaging 1.7 millimeters (0.07 inches) a year in the 20th century and 1.8 millimeters in the past 50 years.
Church said sea increases were previously estimated based on climate change models. He said his team's research was the first to document rises based on extensive historical tidal data, allowing predictions on sea-level increases to be made with greater precision.
Many island nations are already feeling the impact of rising seas. In Vanuatu and Papua New Guinea in the southwest Pacific, increased sea levels have forced hundreds of islanders to abandon vulnerable coastal homes for higher ground, according to the United Nations and news reports.
The 1997 Kyoto Protocol mandates specific reductions in emissions of carbon dioxide and five other gases by 2012 in 35 industrialized countries that are blamed for causing the warming of earth's atmosphere. The U.S. and Australia rejected the treaty in part because they feared mandatory cuts would cause economic hardship.
Church said containing greenhouse gas emissions would help stem increases, but added sea levels would rise nonetheless.
"We do have to reduce our emissions but we also have to recognize climate change is happening, and we have to adapt as well," Church said.