Half Australia's Great Barrier Reef coral 'dead or dying' - scientists

Peter Gash (L), owner and manager of the Lady Elliot Island Eco Resort, snorkels with Oliver Lanyon and Lewis Marshall, Senior Rangers in the Great Barrier Reef region for the Queensland Parks and Wildlife Service, during an inspection of the reef's condition in an area called the 'Coral Gardens' located at Lady Elliot Island in Queensland, Australia, June 11, 2015. REUTERS/David Gray/File Photo

SYDNEY (Reuters) - Australian scientists said on Wednesday that just seven percent of the Great Barrier Reef, which attracts around A$5 billion (2.71 billion pounds) in tourism every year, has been untouched by mass bleaching that is likely to destroy half the coral.

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.