Surviving the Rising Seas Islands can adapt to changing conditions, study finds


In recent years, leaders and inhabitants of many small-island nations such as Kiribati and Tuvalu have warned that extreme weather poses a threat to their homelands. They fear their nations could disappear under rising seas. 

Research published in June 2020, however, concludes that small, low-lying islands in the Pacific and the Caribbean — often seen as the places most vulnerable to extreme weather — can naturally adapt and rise to elevations above encroaching waves. 

A three-year study led by Britain’s University of Plymouth, which looked at coral reef islands such as the Maldives and the Marshall Islands, found that tides move sediment to create elevation, a process that may keep the islands habitable. “The dominant discourse is that of an island drowning, and the outcome of that is coastal defences and relocation. … We think there are more trajectories for the islands,” said lead author Gerd Masselink, professor of coastal geomorphology at the University of Plymouth. 

Conventional wisdom has held that low-lying island states are at greatest risk from increasingly powerful storms and rising oceans. Some such nations are preparing to resettle their people within decades. Many are already building sea walls, moving coastal villages to higher ground, appealing for international aid or setting up projects to repair damage caused by climate impacts. 

Although mostly uninhabited, the world’s tens of thousands of coral reef islands are home to about 1 million people who largely rely on fishing or tourism for a living, Masselink said. 

Varying weather and wave patterns create islands with different structures, but they tend to be relatively small, low-lying, sandy or gravel platforms atop a living reef. The islands were formed hundreds of thousands of years ago by waves piling up reef material or sediment, which is a natural defense mechanism that continues, he noted. 

For the study published in the journal Science Advances, scientists built a model coral reef and island in a laboratory tank with rising water levels and used computer simulations to replicate how such islands respond to higher seas. 

The results suggest that by opting for climate-resilient infrastructure that allows for occasional flooding, such as buildings on stilts and movable houses, islanders with enough space could adapt to their shifting environment, Masselink said. Dredging coral sand and sediments found in island lagoons and moving it to beaches could also aid the natural process of raising the islands, he said.

Sea walls, however, are compromising the islands’ natural abilities to adjust to rising sea levels: “If you stop the flooding of the islands, you also stop the movement of the sediment on top of the island,” he said. Most coral islands do not depend on agriculture and import food and fresh water, making saltwater contamination during flooding less of an issue.

Hideki Kanamaru, natural resources officer with the United Nations Food and Agriculture Organization in  the Indo-Pacific, said the study provided a new perspective on how island nations could tackle the challenge of sea- level rise.  Reuters

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