New research on corals in the Pacific islands of Kiribati suggests some reefs are more likely than others to withstand ocean warming.
With tropical sea temperatures forecast to rise by between one and three degrees Celsius by the end of this century, it had been feared that all corals might be at risk of bleaching and death - ruining communities which rely on the reefs' fish or tourism value for their livelihood.
But research by the Australian Nuclear Science and Technology Organisation (ANSTO), the University of British Columbia and the Scripps Institution of Oceanography has found that coral which has survived heat stress is more likely to do so again.
The researchers analysed how corals from different regions of Kiribati responded to two bleaching events - caused when temperatures get too hot - in 2004 and 2009.
Corals on Kiribati's equatorial islands are pounded by El Nino-driven heat waves, while corals on the islands farther from the equator are less affected.
"Until recently, it was widely assumed that as the oceans warm due to climate change, coral will bleach and die off worldwide," said Jessica Carilli from ANSTO's Institute for Environmental Research.
"This would have very serious consequences, as loss of live coral - already observed in parts of the world - directly reduces fish habitats and the shoreline protection reefs provide from storms," Dr Carilli said.
"The research findings give hope that, even though warming of the oceans is already occurring, coral that has previously withstood anomalously warm water events may do so again."
The findings, published on Sunday in the scientific journal PLoS ONE, support previous laboratory and observational studies on the Great Barrier Reef.
Because the reef stretches over a huge distance, with some areas having stable temperatures and others not, the research suggests a mixed result from ocean warming.