Can atolls survive sea-level rise?

Across the Indian and Pacific oceans, tiny atolls — islands formed atop ancient coral reefs — are facing an existential crisis.

Unchecked sea-level rise could all but wipe them out in the coming century.

Rising seas have already made their mark on these islands, having forced the relocation of some South Pacific villages, and even claiming two small islands in Kiribati.

But not all islands are equally vulnerable, reports Lisa S. Gardiner for Yale Environment 360 — in fact, scientists are finding that the ability of islands to persist depends on ecosystem health: “To protect islands most at risk of disappearing,” Gardiner writes, “some researchers now propose using nature-based solutions — like restoring and protecting coral reefs and native forests — to boost their odds of survival.”

Critical to the effort to save these islands is, well, bird poop. Seabirds’ droppings help boost coral growth and can create sediment that over time adds to the islands’ soil. The problem, though, is that most atolls now have little habitat for nesting seabirds, as many of the islands’ native broadleaf forests have been lost, swept aside for a lucrative invader: coconut trees.

Coconuts were introduced to the islands in the 1800s as a cash crop. Humans love coconuts, but birds don’t, finding it difficult to nest in their single-trunk trees, Gardiner writes. Another island invader — rats — is the bane of seabird nests, and any effort to help the islands has to focus on them, too.

In some places, scientists are doing just that. Gardiner reports:

Conservationists working to restore ecosystems and enhance resilience at Tetiaroa Atoll, in French Polynesia, are also aiming to bring back seabirds, says Frank Murphy, director of programs at the Tetiaroa Society. So far, rats have been eradicated on all but one small island, and there are plans to eliminate 80 to 90 percent of the coconut palms.

With the rats gone, island wildlife is starting to change. “We’re getting birds nesting in places where they hadn’t nested before,” says Murphy. Coconut crabs are now abundant, and there has been a huge increase in the number of young sea turtles, which had in the past risked being eaten by rats as they emerged from nests.

Time will tell if even healthy atolls can withstand the sea-level rise to come. Researchers, at the least, are determined to give them a fighting chance.

Read the full story here.

Bruno Vander Velde is the managing director of storytelling at Conservation International. Want to read more stories like this? Sign up for email updates. Also, please consider supporting our critical work.