The report, released to coincide with the World Ocean Conference in Manado, Sulawesi, warns that a do-nothing scenario will lead to a steady rise in sea temperatures and the death of the coral reefs.

Far better, some say, to turn old RIGS into coral reefs.

The scientists warned that the recovery of coral cover is expected to take a decade or longer, but it would take much longer to regain the largest and oldest corals that have died.