Andreas Späth

The Great Seawall off China

2014-12-01 12:57

Andreas Wilson-Späth

During the last 20 years an enormous system of seawalls has been built along the coast of mainland China. Already longer than its famous inland predecessor, its function is not to keep marauding nomads at bay, but to reclaim land from the ocean and put it to profitable use in the Asian superpower’s ballooning economy.

It’s a classic story of "man" conquering nature. It’s also a tale of short-term benefits versus long-term losses – of sacrificing ecosystems vital for a sustainable future in exchange for material gains in the here and now.

Seawalls now extend along some 11 000km, or approximately 60%, of China’s coastline, and they are getting longer. By enclosing coastal wetlands, intertidal mudflats, swamps and mangrove forests with dykes separating them from the sea and filling them with rocks, sand and soil, valuable new land for human settlement and economic activity is created.

A disproportionate junk of China’s stellar economic growth has happened in its coastal regions which generate some 60% of the nation’s GDP. Making brand new space available for commerce, industry, agriculture, infrastructure, housing and ports here offers massive financial returns.

In the second half of the last century, an average of 24 000 hectares of coastal wetland area were converted to dry land every year. Between 2006 and 2010, the annual reclamation rate skyrocketed to 40 000 hectares, and from 2010 until 2020 it is expected to increase even further, to 60 000 hectare per annum.

It’s an impressive feat of Chinese-style monumental engineering, but last month, a group of scientists rang the alarm bell in an article in the journal Science, suggesting that the environmental harm caused will overshadow any temporary profits.

In purely monetary terms, the researchers estimate that China’s wetlands provided the country with US$200 billion in ecosystem services in 2011 alone. Turning them into parking lots and industrial parks is estimated to result in a loss of US$31 billion per year.

These coast-hugging ecosystems have significant recreational and tourism value, and represent important habitats for many diverse species of plants and animals, including over 230 different types of waterbirds, many of them threatened or endangered and likely to be pushed towards extinction as their breeding grounds dry up.

The disappearance of the wetlands has already contributed to a precipitous decline in the number of migratory waterbirds that use them as stop-over points when travelling along the East Asian – Australasian flyway (a long-distance bird superhighway in the sky that links the southern hemisphere to the arctic).

Wetlands have been shown to provide natural protection against floods, storm surges, typhoons and tsunamis. In fact they do a better job of this than artificial seawalls.

In addition, they are important sites of carbon storage, yield some 28 million tons of fish and seafood products for Chinese consumers annually, and act as spawning grounds for offshore fisheries and a nursery for a myriad of aquatic organism at the bottom of the marine food chain.

When intact, coastal wetlands act as natural sponges, absorbing pollution discharged from the land. Once reclaimed, they turn into sources of pollution from which industrial and agricultural waste pours into the sea.

Sacrificing such crucially important ecosystems for the sake of so-called development is short-sighted and irresponsible. But many people still consider protecting such areas and maintaining them in their natural state akin to a tax on economic growth.

According to Zhijun Ma of Shanghai’s Fudan University, the lead author of the Science article, “in China, even though the central government has realised the importance of wetland conservation, local governments still prefer the construction of seawalls to obtain more land for supplying rapid economic development”.

- Andreas is a freelance writer with a PhD in geochemistry. Follow him on Twitter: @Andreas_Spath
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