Scientists in Australia have revealed the “tragic” extent of coral bleaching across the Great Barrier Reef, releasing maps which show damage to 93 per cent of the famous 1,500-mile stretch of reefs following a recent underwater heatwave.

Warning that the reef is now in a “precarious position”, scientists released aerial survey maps which show that the mass bleaching event is the worst in history and far more severe than previous such events in 1998 and 2002.

“We’ve never seen anything like this scale of bleaching before,” said Professor Terry Hughes, who convened a team of 300 scientists to study the bleaching.