Biologists blame climate change for the damage

Corals reefs are suffering a severe underwater heat wave this year for the third time on record, including a mysterious warm patch in the Pacific known as "The Blob", scientists said on Thursday.

The bout of record high temperatures in parts of the oceans, stoked by climate change, is expected to kill more than 12,000 sq kms of reefs, or about five percent of the global total, they said.