The heavy iron anchor and chain tumbled noisily into the water. We lowered two red skiffs from our research vessel, loaded our diving gear, and sped off toward the lagoon. After a five-day sail from Fiji to Kanton island, we were anxious to see if reefs here had survived a rare ocean disaster—a lethal spike in the temperature of local seawater. During the El Niño of 2002-03, a body of water more than 1°C (1.8°F) warmer than usual had stalled for six months around the Phoenix Islands, a tiny archipelago in the central Pacific. We'd heard that the hot spot had severely bleached the region's corals. As I descended toward the lagoon floor, I was hoping things weren't as bad as we'd been told.
Settling down beside the reef, I saw dead coral everywhere. What had been flourishing, overlapping, overflowing brown and auburn plates of corals were now ghostly, broken reminders of their former beauty. When I'd first visited the Phoenix Islands a decade ago, these reefs had supported numerous species of hard corals, as well as giant clams, sea anemones, nudibranchs, and great populations of fish, from blacktip reef sharks to parrotfish to bohar snappers. Because the islands have remained undisturbed for so long, they'd largely avoided overfishing, pollution, and other harmful impacts of modern civilization. But they hadn't been able to avoid climate change, which most scientists believe amplifies El Niños.