Kiribati, an island nation in the middle of the Pacific Ocean, is one of the earliest clear-cut victims of climate change. The highest points on the main island are no more than two meters above sea level. Earlier this year, the president of Kiribati made headlines for spending $8.7 million on a piece of land in Fiji as a place to send climate refugees when waters rise.

But the whole story is more complicated, as Christopher Pala reported in the Atlantic after making a visit. When sea levels rise, some islands may actually rise with them.

“The islands that people live on in Kiribati are made of essentially sand and gravel, which is generated from the surrounding coral reef,” explained Paul Kench, head of the University of Auckland’s School of Environment. “Waves deposit that sediment to form an island. When sea levels go up, there’s a perception that islands are static and they can’t move. But in fact…the islands can build vertically.”

As sea levels rise and more waves hit the low-lying islands in Kirbati, researchers like Kench expect that some of island material will be washed to higher elevations, helping raise the island’s height. Other material will probably be washed to other islands in the chain, building them up. It’s a process that has actually been happening for some time.

“When we look at satellite images for the last 30 to 40 years, and couple that with old aerial photographs from WWII, we can see that some islands have effectively migrated on their reef platforms,” says Kench. “We know that islands are starting to move, essentially, on the reef platform.”

That process, of course, is being amplified by climate change–and the fact that Kiribati’s tiny main island now has a population density approaching Tokyo or Hong Kong.

“One of the difficulties in having islands that move around a lot is that you have people living on them,” says Kench. “On the island of South Tarawa, 50,000 people live on a very small land area. When the island starts to change in places where you have very dense population pressures, that causes problems.”