Some corals can adapt to warmer oceans, but only under "moderate" warming scenarios that require international efforts to cut carbon emissions, scientists said Wednesday.
In a study published in the U.S. journal Science Advances, researchers looked at genetic adaptation and the likely effects of future warming on a cool-water coral population known as tabletop corals in the Cook Islands in the South Pacific Ocean.
They found some of the corals carry genetic variants that predispose them to heat tolerance.
To test how well the corals could use heat-tolerant genes to adapt to future climate change, the scientists ran computer simulations based on projections by the UN Intergovernmental Panel for Climate Change.
They found coral could survive under the mild and moderate scenarios, where warming does not exceed 1.8 to 2.0 degrees Celsius by 2100.
But under the more severe scenarios, where temperatures rise between 2.0 and 3.7 degrees Celsius, simulations showed adaptation was not fast enough to prevent extinction.
"These corals aren't going to adapt at an unlimited rate," said lead author Rachael Bay, a postdoctoral scholar at the University of California, Davis.
"Keeping these reefs around requires curbing emissions."
This research focused specifically on tabletop corals and scientists said further study is needed to understand the broader implications for other coral species.
"Many existing coral populations have a bank of adaptations that has been evolving for a long time," said co-author Steve Palumbi from Stanford University.
"Those existing adaptations are an asset for them to survive longer and for us humans to benefit longer."
Reef-building corals are among the most vulnerable organisms to rising ocean temperatures.
Over the past three years, coral reefs have experienced the worst bleaching and mortality events in recorded history, largely due to warmer waters.
