Low-lying island atolls–which are home to half a million people around the world–are some of the places most immediately threatened by rising sea levels. Now an unsettling new study from the U.S. Geological Survey shows that these vulnerable places could disappear at rates almost double what scientists had previously realized.
These islands, especially ones surrounded by shallow coral reef, are vulnerable to rising waters in several ways. First, sea level rise itself will eat into their coastline. Many have a maximum elevation of four meters, and recent models predict that the world will have experienced a two-meter sea level increase by the end of the century.
But even more importantly, bigger waves and surges will cause more flooding. Previous models hadn’t taken into account the interaction between sea level rise and wave action for these islands. The new paper demonstrates that sea level rise will cause even larger waves along island shorelines–and twice as much land to be flooded.
The study looked at data from several atolls from the Northwestern Hawaiian Islands, including Laysan Island and Midway Atoll’s Sand, Spit, and Eastern Islands. But the results applied more generally to atolls in the Indian and Pacific Oceans. The tropical Pacific, where many of the world’s low-lying atolls are located, is where sea level is rising the fastest currently.
“It appears that many atoll islands will be flooded annually, salinizing the limited freshwater resources and thus likely forcing inhabitants to abandon their islands in decades, not centuries, as previously thought,” the paper, published in Nature Scientific Reports, says.
That’s one of many moral dilemmas that the whole world will be asked to address when it meets for international climate talks in Paris this December. The questions are becoming harder to put off.