In a heart-breaking story Thursday, The New York Times reported that large swaths of the reef already are dead.
The rapidity of the die-off shocked scientists, who said that the devastation has already hit the point not expected to be reached for 30 years.
The process begins with "bleaching" of the sensitive coral, as shown in the accompanying New York Times photo. Sometimes the coral can recover from this stage, but large portions of northern sections of the reef near Cairns, Australia, are already dead, the newspaper said. Bleaching is advancing into Southern areas.
Australia has taken action to counter threats to the reefs from human activity such as agricultural runoff and pollution. But the rising ocean temperatures require action against global climate change.
Through eco-tourism and fishing, the Great Barrier Reef supports 70,000 jobs in Australia and provides billions to the economy.
The loss of the world's coral will destroy the fishing industry and food source for millions.