By Zou Huilin and Wu Chong (China Daily)
Updated: 2007-04-09 11:54

Shanghai, the pulse of China's economy and a city built on the coast, has a romantic name, which means "go to sea" - shang (going) hai (sea). Now the city faces the risk of actually going under the sea, according to new scientific claims. Scientists say rising sea levels, resulting from global warming, are moving so fast that many island nations and coastal cities will be submerged by 2050. The news has shocked Shanghai, a city of low elevation.

"From the water mark of the creek left on the bank after each downpour, I notice the creek surface is rising up gradually, a result of the sea level rise," said Dai Jian, an office clerk who was brought up in the area near the Suzhou Creek, a tributary of Huangpu River running across the center of Shanghai.

Dai has lived along the creek for 15 years and is only one of a few local people who have noticed the small year-on-year water level variation. But he is not the only one who is noticing the flood risk to the city.

Last Friday, the Intergovernmental Panel on Climate Change (IPCC) of the United Nations published its latest report on climate change, analyzing the impact of greenhouse gas emissions on the world's ecosystem.

It iterates that people who live in least developed countries, small island developing states, Asia's vast river deltas and most of Africa are most vulnerable to possible sea level rises resulting from global warming.

Two weeks ago, a report from the UK-based International Institute of Environment and Development (IIED) named Shanghai and other Asian cities at risk showing a map of the predicted increasing sea levels.

The report, by both British and US scientists, says Asia accounts for two-thirds of the world's urban population and almost three-quarters of total population living in the low elevation coastal zones, which are located less than 10 meters above sea level. If Asian countries fail to act soon, the results could be catastrophic, the authors warn.

A research conducted by the Tianjin-based National Marine Data and Information Service (NMDIS) also reveals that by 2050, the sea level at the Yangtze River Delta, where Shanghai is located, will have risen 20 to 60 centimeters. The Bohai Sea region, where Tianjin is situated, will have risen 30 to 60 centimeters, it claims.

Even the Shanghai municipal government admits there has been an obvious sea level rise in recent years. But it says the sea level increase was not due to the water flowing into the East China Sea.

Because the estuary near Shanghai is wide, the water gushing into the sea will not cause a sudden rise of sea level. Nonetheless, authorities are joining forces with scientists in making preparations.

Chen Manchun, a research fellow with the Tianjin marine information service, said experts in Tianjin, Shanghai, and other coastal cities are conducting more frequent observations on the sea level change, from the previous every one hour reports to the current recordings of every 5 minutes.

And several local experts are putting forward a plan to build a water gate near the Yangtze River estuary to prevent a sea storm in a bid to lower the risk of flooding, according to Zhang Zhenyu, the spokesperson of Shanghai Flood Risk Information Center under Shanghai Water Administration Bureau.

Lu Yongjin, a senior engineer at the Shanghai Engineering Institute, said it is feasible to build an 8.5-meter-high water gate near the Yangtze River estuary to the East China Sea.

He said construction of such a water gate is more efficient than heightening the current dykes of Huangpu River, which lies at the estuary of the Yangtze River, located near the bund of Shanghai.

The planned water gate is believed to be able to withstand the flooding aftermath of a serious storm, which could only occur every 10,000 years. The current 6.9-meter-high dyke can only withstand the storm that could occur every 200 years.

Lu said reinforcing the current dyke to 8.5 meters will cost 6 billion yuan ($780 million), however construction of a new gate will cost 4 billion yuan ($520 million). Building the water gate might cause shipping complications on the Yangtze River, but as far as preventing storms, it was a good solution, the engineer said.

The IIED report also suggests that Asian cities at risk should also consider resettlement strategies away from coastal areas. This concept poses a challenge for China, which has witnessed an obvious population movement towards the coast for decades.

"Coastal settlement, particularly in the lowlands, is likely to expose residents to seaward hazards such as sea level rise and tropical storms, both of which are likely to become more serious with climate change," it says.

Therefore, avoiding policies that favor coastal development, such as the special economic zones in China, and imposing more effective coastal zone management, could make a difference in the longer term in reducing the risks of sea level rise, according to the report.

The Chinese government has encouraged people to migrate west and is also considering a national plan to combat climate change. Details of this plan will be revealed soon.

The IPCC study estimates a 1-meter sea level rise would cost $944 billion, almost half of it in Asia.

Moving away from their beloved city by the sea is not what Shanghai people want. At the same time, they do not want the city to be wiped off the face of the earth.

"As a geologist, I know this (Shanghai being submerged by the sea) will happen one day, just as I know 7,000 years ago there was no Shanghai in the world," said Zheng Hongbo, head of the School of Ocean and Earth Science from Tongji University. "Scientifically, we accept the fact; but personally we cannot, because we have emotional ties with the city.

"We love Shanghai and do not want it disappear from the map."