Scientists in Australia have uncovered widespread damage to coral in the Great Barrier Reef, warning that “we are entering uncharted territory,” after surveys showed consecutive years of bleaching for the first time.

Following aerial surveys this week between the coastal cities of Cairns and Townsville, researchers said warmer ocean temperatures had caused widespread bleaching. This followed severe bleaching along the 1,500-mile stretch of reefs last year – the worst on record – caused by warm sea temperatures in March and April.

“This is the first time we have ever seen bleaching in back-to-back summers,” said Dr Neal Cantin, from The Australian Institute of Marine Science.