The remarks came after Paul Brown, an established environmental journalist with the Guardian, said at a recent meeting in Guangzhou that by 2050 the global temperature would have risen by 2 degrees Centigrade, and that would lead to Shanghai becoming inundated by ocean water.

"It is impossible that Shanghai will be submerged by 2050, because climate change tends to be only periodical, and our defenses will grow accordingly," said Chen Manchun, a research fellow with the Tianjin-based National Marine Data & Information Service.

"But Brown's remarks warn us that if we don't pay enough attention to climate change, our coastal cities will be at risk in the near future," Chen told China Daily yesterday.

Based on his team's research, Chen predicts that by 2050 the sea level at the Yangtze River Delta, where Shanghai is located, will have risen by 20 to 60 centimeters, and that the Bohai Sea region, where Tianjin is located, will have risen by 30 to 60 centimeters.

"In the last decade of the 20th century, China's sea level rose at a rate of 1.8 millimeters a year. Over the next 10 years, that rate will almost double," Chen said.

Chen and his colleagues are now working to classify the country's coastal areas based on how much they will be affected by rising sea levels and to monitor those considered most at most risk.

"In those areas that might be in danger, new construction projects will be strictly controlled," Chen said, adding that Shanghai is exercising a strict screening process for all new projects being built along the coast.

In addition, coastal cities are building higher and stronger sea walls to fend off the advancing tides.

"We are also improving the management of our sea walls," Chen said. "Poor management can lead to disaster. New Orleans taught us a good lesson on that."