Most Great Barrier Reef coral studied this year was bleached

A diver swims past coral on the Great Barrier Reef in Australia in 2016 (M. Curnock/GBRMPA/AP)

More than 90% of Great Barrier Reef coral surveyed this year was bleached in the fourth such mass event in seven years in the world’s largest coral reef ecosystem, Australian government scientists said.

Bleaching is caused by global warming but this is the reef’s first bleaching event during a La Nina weather pattern, which is associated with cooler Pacific Ocean temperatures, the Great Barrier Reef Marine Authority said in its annual report released late on Tuesday that found 91% of the areas surveyed were affected.