New islands are usually formed by volcanoes erupting from the seafloor, but China is on an island-building spree on a group of low-lying coral atolls and reefs called the Spratly Islands between the Philippines and Vietnam.
U.S. officials say the artificial islands are designed to boost China's power. They include military airstrips, radar installations and barracks. But will these artificial islands last longer than the rhetoric between the West and China?
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The disputed Spratly Islands are often hit by typhoons, rough seas and underwater currents. U.S. satellites and military flights last week showed images of dozens of marine dredging platforms at work around the islands, pulling up tons of sand from the seafloor and dumping it on top of the existing rocky and coral reefs.
A recent U.S. P-8a surveillance flight also showed concrete-making facilities, key to making the islands a permanent part of the remote seascape.
"You can build an island if you do it right," said Robert Dalrymple, professor of civil engineering at Johns Hopkins University. "But it is not clear these islands will be permanent unless they can deal with erosion. They will wash away just like putting sand on East coast beaches."
Artificial islands have been built before in shallow waters off Florida, the Caribbean, Arabian Sea and many other areas for coastal resorts, housing or airports.
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The Chinese operation includes big concrete breakwaters, just like those seen along U.S. coastlines. But sand has a way of moving from one place to another over time and many coastal communities have been fighting to keep their beaches from moving out to sea.
Dalrymple has visited Chinese construction projects in the past and says the nation does have the engineering expertise of dealing with big amounts of sand and sediment from rivers emptying into its Pacific coastline.
Other marine experts worry about the effect on marine life. The Spratlys contain major fishing grounds for several Asian nations, and the local marine biodiversity has already been on the decline for the past two decades, according to a study by Australian and Taiwanese scientists in 2013.
The report in the journal Conservation Biology found that coral abundance has declined from 20 percent percent within the Spratly archipelago the past 10 to 15 years. Climate change has affected these reefs far less than coastal development, pollution, overfishing, and destructive fishing practices.
Greg Mitchell, professor of marine ecology at the Scripps Institution of Oceanography in La Jolla, Calif., has studied Pacific reef ecosystems. He says the dredging and concrete piers are probably destroying what's left of the local ecology.
"If the islands had been left alone, they were probably very diverse," Mitchell said. "But all of the fishing fleets from Asia have been there hunting everything from sea cucumbers and giant clams and sharks for fins. My guess is the biodiversity has been altered already. But now, they are burying the ecosystem and destroying it."
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John McManus, a marine biologist at the University of Miami, spent two decades in the Philippines studying the coral reefs of the Spratly Island area. He says the long-term effects of China's massive island-building will take decades to reverse because coral is such a slow-growing organism. Sand from dredging is also spreading beyond the immediate construction sites, covering nearby coral reefs and killing them.
"This is the worst thing that has happened to coral reefs in our lifetime," McManus said. "We've had massive degradation. Within two years, the amount of coral has declined incredibly in this area and it's significant on a global scale."
Phillipines' foreign minister said last month that China has destroyed 300 acres of coral reefs in the region, and the island-building project threatens $100 million in high-value fisheries.
A Chinese Foreign Ministry spokeswoman said in April that the islands will host "typhoon shelters, navigation aids, search-and-rescue centers, marine meteorological forecasting stations, fishing services and civil administration offices," she said.