By Christopher Pala

Off the palm-fringed white beach of Butaitari, Kiribati, the view underwater is downright scary. Corals are being covered and smothered to death by a bushy seaweed that is so tough even algae-grazing fish avoid it. It settles in the reef's crevices that fish once called home, driving them away.

Dead coral stops supporting the ecosystem and, within a couple of decades, will crumble into rubble, allowing big ocean waves to reach the beach during storms and destroy the flimsy thatched huts of the Micronesians.