Scientists map reefs with best chance of survival

Coral bleaching. | Newsreel
Coral reefs around the globe face the risk of year-round bleaching events. | Photo: Rainer von Brandis (iStock)

Year-round coral bleaching on some global reefs is inevitable, with the Great Barrier Reef particularly vulnerable, according to new research.

Researchers from James Cook University and the University of Adelaide believe that by 2080 coral bleaching would be likely to start in spring, rather than summer.

James Cook University Professor Scott Heron said by then year-round bleaching for some reefs was almost inevitable.

“This is regardless of any action taken to mitigate climate change,” Professor Heron said.

A co-author of a study which analysed when and where coral bleaching was likely to take place in the future, Professor Heron said scientists were looking for the most likely places for coral to survive so environmental efforts could be concentrated there.

“Even with substantial mitigation of greenhouse gasses almost all of the world’s coral reefs are likely to be exposed to more than three months of severe bleaching risk by 2080, with 20 percent of these reefs being exposed to severe bleaching conditions for more than nine months of the year,’’ he said.

“These numbers get even worse if we make little or no effort to curb climate change, but that in itself should inspire us toward concerted efforts to reduce emissions.”

Professor Heron said the most biodiverse rich coral regions, including the Great Barrier Reef, were the most vulnerable to heat stress and corals in these regions were least likely to benefit from efforts to mitigate climate change.

“There is much lower than average bleaching risk on the northern coasts of Venezuela and Colombia. Other less impacted areas include Socotra Island opposite the Gulf of Aden and Alor Kecil in Indonesia.

“There’s variability in risk in the Coral Triangle, roughly from Indonesia to the Philippines to the Solomon Islands, but the future looks bleak for reefs in the Great Barrier Reef and Hawaii,” Professor Heron said.

Lead author Dr Camille Mellin, from the University of Adelaide, said it was also expected longer exposure to heat stress in coming decades would weaken coral.

“By identifying Earth’s reef regions that are at lowest risk of accelerated bleaching, our work will show where we can prioritise efforts to limit future loss of coral reef biodiversity.

“Interventions involving assisted evolution, coral translocation, or coral restoration should be maximised in coral refuges with lower risk of bleaching,” Dr Mellin said.

Read the full study.