El Nino's super warm water has turned what had been one of the world's most lush and isolated tropical marine reserves into a coral graveyard, US federal scientists said on Wednesday.
Researchers finishing an emergency undersea expedition found 95 per cent of the coral dead around Jarvis Island in the Pacific Remote Island Marine National Monument. In November, much of the coral had bleached white but was alive.
"There's hardly anything left on the bottom in terms of the coral. It basically looks like a graveyard," said the expedition chief scientist Bernardo Vargas-Angel of the National Oceanic and Atmospheric Administration. "The skeletons are still there but they are covered with algae."
The algae was red, the colour of blood or wine, and below it was a sea of dead coral, he said, returning from a 10-day diving expedition to the region along the equator.
Scientists say the area around Jarvis Island is a special place that normally looks like something out of a technical colour movie, vibrant with coral, plankton, fish and sharks.
The coral can normally survive short bouts of warm water but the water just got too warm for too long, scientists said.
Scientists measure how warm the water is for coral in something called degree weeks. The record had been 18 degree Celsius weeks in 2014. This maxed out at 31.3, said NOAA coral reef co-ordinator Mark Eakin. It has been over 20 degree Celsius weeks for almost eight months, worse than anywhere else, Eakin said.
That warmer water is mostly from El Nino - the natural warming of parts of the Pacific that changes weather worldwide - assisted by man-made warming, Eakin said.
