Coral Atolls Rise With the Seas

The plight of Pacific Islanders has been the center of the debate over the human toll of climate change. Last month, the Federated States of Micronesia filed an objection against one the dirtiest power plants in Europe, arguing that unchecked carbon emissions could eventually drown this nation of 600 islands. Another low-lying nation, Tuvalu, which sits halfway between Hawaii and Australia, has long claimed that its entire population may need to be evacuated in the next few decades.

But a new study by Arthur Webb at the South Pacific Applied Geoscience Commission in Fiji and Paul Kench at the University of Auckland in New Zealand throws some cold water on these tropical predictions. Webb and Kench examined satellite images of 27 Pacific islands dating back to the 1950s. Although sea levels have risen 120 millimeters in that time, most of those islands, including seven in Tuvalu, have either stayed the same size or gotten bigger. Their resiliency against rising seas comes from the fact that they are made up of chunks of coral reef that break off during storms and are deposited on their shores.

“It has been thought that as the sea level goes up, islands will sit there and drown,” Kench told New Scientist, “But they won’t. The sea level will go up and the island will start responding.”

The findings may be good news for island residents, but it doesn’t mean they can’t stop worrying. The rate of sea level rise could accelerate in the next century, and it’s not clear whether the coral atolls can keep up. Finally, even though the islands change shape, it doesn’t mean that they will all remain habitable. Then again, I wouldn't have thought they were habitable some 2000 years ago, when the first island-hoppers arrived from Tonga and Samoa.

Much thanks to Brendan Borrell for guest blogging this month. He lives in New York and writes about science and the environment; for Smithsonian magazine and Smithsonian.com, he has covered the ecology of chili peppers, diamonds in Arkansas and the world's most dangerous bird.