Great Barrier Reef coral bleached by underwater heatwave
Scientists say an underwater heat wave in Australia's Great Barrier Reef has led to devastating coral bleaching - the worst in history - which has damaged or killed 95pc of the northern reefs.
An aerial survey of 520 sites across the 2,400km stretch of delicate coral reefs in north-east Australia found that the most pristine sections had been "fried" and were facing some of the worst bleaching in recorded history.
Long stretches of the famously colourful reef, which is world heritage-listed and one of the country's top tourist destinations, have turned "snow-white" following bleaching which began six months ago, according to the researchers.
"This will change the Great Barrier Reef forever," Professor Terry Hughes, from James Cook University, told ABC News.
"We're seeing huge levels of bleaching in the northern thousand-kilometre stretch of the Great Barrier Reef. It's too early to tell precisely how many of the bleached coral will die, but judging from the extreme level even the most robust corals are snow white, I'd expect to see about half of those corals die in the coming month or so."
Scientists believe the bleaching was triggered by a temperature spike due to the El Niño weather pattern, which added to already warmer waters caused by climate change. Warmer temperatures can kill the tiny marine algae which are required to maintain the health of coral and give it colour.
It is the third and worst bleaching phenomenon since 1998 but there is no evidence of any other events in history. "The north has fried," said Professor Hughes. "This is an ongoing, slow-motion train wreck."
The bleaching has affected virtually all species of the reef's coral. Cloudy weather is believed to have kept temperatures down and prevented heavy damage in the southern parts of the reef.
The damage has raised fresh questions about whether Unesco may list the marine park as "in danger".