So far the entire natural coastline around Tianjin has been eroded away and replaced by an artificial shoreline including dykes and docks. North China's Hebei Province has been losing its coastline at a rate of eight km each year for the past two decades.

"Of China's 84 cities that enjoy a population beyond 500,000, there are 49 located in the coastal areas," said Zheng, adding that coastal erosion has damaged shorefront roads, buildings, farmland and shelterbelts.

Sea level rises worldwide cannot be reversed, so Chinese city officials and planners must take measures to adapt to the change, Zheng said.

The pollution issue

The coastal areas have become the basic industrial belt in China, however, and pollution levels along the coast have also intensified due to unreasonable resource exploitation, inappropriate industrial projects and pollution discharges.

The situation in areas around the Bohai Sea in north China is especially serious, said Liu Rongzi, an official with the SOA. "The north part of the Bohai Sea has seen over-exploitation and the west part is at a level a little lower than that."

The 15 cities around the Bohai Sea have achieved a total production output value of 1,293 billion yuan ($177 billion), 60 percent of which comes from industry, far more than from agriculture and the service industry. In cities like Panjin, Dagang and Dongying, industry makes up an 80 percentage of the economic pattern, according to statistics from the National Ocean Technology Center (NOTC).

Every year the amount of sewage discharge into the Bohai Sea accounts for 32 percent of the country's total waste drainage of major sewage outlets into the sea.

"Bohai is a semi-closed sea for which it will take at least 30 years to complete a water exchange," said Liu. The large amount of pollution discharge and long period of water exchange have contributed to the increasing levels of pollution in areas of the sea.

Liu is worried that the Bohai Sea will become a garbage dump due to population expansion and the rapid growth of heavy industry. Oceanic creatures could degenerate and disappear and the sea become dead, impacting areas around Bohai, including Beijing.

Between 1990 and 2006, there were more than 100 red tides, a higher-than-normal concentration of a microscopic alga (plant-like organisms) in the Bohai Sea, affecting a total area of 40,000 square km and resulted in a considerable economic loss.

Clean oceanic industry

In recent years China has started a national strategy of energy saving and emissions reduction. Tackling coastal pollution has also been included in this long-term plan.

At present China has three major ocean economic zones including the Bohai Rim in the north, the Yangtze River Delta and the Pearl River Delta in the south.

Statistics show that the Bohai Rim, whose oceanic industry output makes up for 32 percent of the gross ocean industry value of the country, is developing its ocean economy according to a healthy pattern. The top three income sources there are ocean fishery, oceanfront tourism and offshore oil and gas resources.

According to Wu Shanshan, an engineer with the NOTC, the ocean industry in the Bohai Rim area has developed in a comprehensive and mature manner. Coastal Shandong Province has the most complete marine industry in the region.

The Bohai Rim also places emphasis on the environmentally friendly salt making and salt chemicals industry. It is the most important base for this industry in the country.

In general, said Wu, China's marine industry has benefited from emerging technologies in more than 20 technical domains, especially for the marine environment, resources prospecting and development, and common marine engineering technologies.

To improve its monitoring techniques, China launched its first marine satellite in 2002. In recent years Chinese scientists have rolled out advanced marine observation instruments and equipment that has noticeably raised the technical level of China's marine industry, and the market competitiveness of home made marine instruments.