Atolls and Rising Seas

The atoll is the final stage of an island's life: once the volcanic rock sinks beneath the waves, only a coral ring around a lagoon is left. The Maldives and the Marshall Islands are whole nations built on coral atop sunken volcanoes.

That history carries a sharp risk today. Coral atolls sit just meters above sea level, which makes them the nations most exposed to rising oceans. The slow geology that built them could be undone by a few centuries of warming.