Science: China's Seawall Construction May Be a Bad Investment

A new "Great Wall" runs along 60% of mainland China's coastlines. But the push to gain more land for economic development could put the country’s coastal wetlands and the services they provide at risk, researchers say.
China's reliance on seawalls to capture land for economic use could devastate the country's remaining coastal wetlands.

China is expected to ramp up construction of its coastal seawalls over the next several years. But the practice, which encloses large swaths of wetlands for agricultural and industrial use, is going to cost the country dearly in the long run, researchers warn.

Traditionally, seawalls have protected shorelines and the people who live on them from erosion, waves, and the tide. However, just a few centuries ago, humans began using seawalls to convert coastal wetlands into farms and factories — a decision that crippled the ecosystem services such as storm protection that are provided by such natural environments.

Many countries around the world have recognized the value of wetlands and have started scaling back their construction of seawalls. By bucking this global trend and building a new "Great Wall," China risks losing all of its coastal wetlands, according to Zhijun Ma from Fudan University in Shanghai and colleagues from around the world.

The authors' Policy Forum appears in the 21 November issue of Science.

"Governments and the public in the rest of the world have gradually realized that coastal wetlands provide many ecological services, which makes wetland conservation mainstream in those countries," said Ma. "But in China, even though the central government has realized the importance of wetland conservation, local governments still prefer the construction of seawalls to obtain more land for supporting rapid economic development."

The authors suggest that this ongoing reclamation of wetlands for agricultural and industrial purposes in China is driven by a lack of national legislation, an overemphasis on economic growth at the local level, and a lack of public appreciation for wetlands in general.

The nation's coastlines host 230 different species of water birds and provide spawning grounds for a myriad of aquatic organisms, they say. These wetlands also absorb pollutants and serve as ecological barriers against extreme weather events.

But China has already lost about half of these coastal wetlands to reclamation projects since 1950, and some studies predict that the country is currently on track to lose $31 billion in ecosystem services each year — approximately 6% of all the money China makes from the sea — as a consequence.

"The central government has recognized this loss of coastal wetlands and it has taken steps to keep some areas intact, by establishing nature reserves and designating Ramsar Sites, for example," Ma explained, referring to sites designated under the 1971 international wetlands convention. "However, many local governments are overemphasizing economic development and various government agencies have conflicting ideas about wetland use."

The authors suggest that the current political climate in China encourages the exploitation of the country's coasts without any significant penalties. To keep some of the wetlands from being converted into ports and aquaculture ponds, Ma and his colleagues suggest that the Chinese government at both the local and national levels needs to establish a minimum range of coastal wetlands to conserve.

They also call for a single agency, operated under the State Council, to coordinate such wetland management and punishments for government officials that are found responsible for ecological losses.

"I think we need outreach and education about ecosystem services and sustainable development so that people appreciate wetlands more," said Ma. "Scientists need to provide solid evidence about the consequences of wetland loss to guide the government in deciding where, when, and how much coastal wetlands can be enclosed without damaging the integrity of our environment."