Severe coral bleaching worsens in most pristine parts of Great Barrier Reef

Expert blames global warming, as coral bleaches when water temperatures go above a certain threshold for an extended period of time

Damage to parts of the Great Barrier Reef has worsened, leading authorities to raise the alert to the second-highest level, indicating severe local coral bleaching.

Related: Devastating global coral bleaching event could hit Great Barrier Reef next