Bleaching casts shadow over Great Barrier Reef

This is a major blow to the World Heritage Site that attracts about A$5 billion ($3.59 billion) in tourism each year. Australian scientists said the coral mortality figure will likely rise if some of the remaining 65 percent of coral in the northern and central reefs fail to recover from bleaching.

The report casts a shadow over the long-term prospects of the Great Barrier Reef against a backdrop of climate change and scientists said UNESCO may reconsider its decision not to put the World Heritage Site on its endangered list. 

Australian scientists said in March that just seven percent of the Great Barrier Reef had avoided any damage as a result of bleaching, and they held grave fears particularly for coral on the northern reef. 

Bleaching occurs when the water is too warm, forcing coral to expel living algae and causing it to calcify and turn white. Mildly bleached coral can recover if the temperature drops, otherwise it may die.