NEW YORK — The coral on the sea floor around the Pacific island of Kiritimati looked like a boneyard in November — stark, white and lifeless. But there was still some hope.
This month, color returned with fuzzy reds and browns, but that’s not good news. Algae has overtaken the lifeless coral on what had been some of the most pristine coral reefs on the planet, said a University of Victoria coral reef scientist, Julia Baum, after dozens of dives in the past week. Maybe 5 percent will survive, she estimated.
‘‘What it really looks like is a ghost town,’’ Baum said. ‘‘It’s as if the buildings are standing but no one’s home.’’
Kiritimati is where El Nino, along with global warming, has done the most damage to corals in the past two years, experts said. While dramatic images of unprecedented total bleaching on Australia’s Great Barrier Reef are stunning the world, thousands of miles to the east conditions are even worse.
‘‘This El Nino has its most powerful grip right at this spot,’’ said Georgia Tech climate scientist Kim Cobb in a telephone interview from the island, 2,000 miles south of Hawaii.
About 36 percent of the world’s coral reefs — and 72 percent of US reefs — are in such warm water they are on an official death watch. And that could rise to 60 percent of the world’s coral by July, said Mark Eakin, of the National Oceanic and Atmospheric Administration. Eakin said Kiritimati was the worst he’s seen, with American Samoa a close second. ‘‘It is unprecedented,’’ Baum said.
The island has been on the highest level of alert for coral stress since June. Eakin wasn’t part of the Baum-Cobb team, but when he saw their photos, he e-mailed Baum: ‘‘I was simply aghast at the pictures. I expected the worst, but still wasn’t prepared for those.’’
It’s the heat that’s killing the coral. In December, temperatures at Kiritimati peaked at 88.5 degrees and have been 5 to 7 degrees warmer than normal.
Water temperatures around the island are nearly a degree Fahrenheit warmer than the last big El Nino, in 1997-98, and the damage is far worse.
Nearly half a billion people rely on coral reef marine life for food, Eakin said. ‘‘Coral reefs cover only one-tenth of 1 percent of the sea floor but are home to 25 percent of all marine species,’’ he said.
In the past, El Nino warming didn’t cause such mass bleaching in Australia. But the effects of recent El Ninos have coincided with water that’s already warmer because of manmade climate change, Hughes said. ‘‘The link between bleaching and global warming is incontrovertible,’’ Hughes said.