Past the precipice? Projected coral habitability under global heating

A variety of corals form an outcrop on Flynn Reef, part of the Great Barrier Reef near Cairns, Queensland, Australia.

Coral reefs are rapidly declining due to local environmental degradation and global climate change. In particular, corals are vulnerable to ocean heating. Hotter oceans can kill corals via expulsion of their food-producing algae and eventual starvation, or by cooking them to death.

As of 2021, we estimate that over 91% and 79% of reef locations will experience bleaching conditions at least once per 10 years and 5 years, respectively, suggesting that widespread long-term coral degradation is no longer avoidable.

We project that 2%-5% of reef locations avoid bleaching every 5 years at 1.5°C of mean global heating, but 0% remain at 2.0°C.