Record marine heatwaves will cause mass coral bleaching across the world in the next few years, according to a coral reef scientist from the University of Queensland. The worrying finding comes from an international study led by UQ Professor Ove Hoeg-Huldberg, from the UQ School of the Environment, who is currently attending the COP28 climate change meetings in Dubai. This study was published on: Science.

“We were shocked to find that heat stress conditions began as much as 12 weeks before recorded peaks and persisted for much longer in the eastern tropical Pacific and wider Caribbean,” Professor Hoegh-Guldberg said.

“Historical evidence suggests that current marine heatwaves could herald mass coral bleaching and die-offs globally over the next 12 to 24 months as the El Niño phase of the El Niño-Southern Oscillation, or ENSO, continues.

“July 2023 saw the hottest days on Earth since 1910 and the hottest month ever recorded in terms of sea surface temperatures.

“This puts huge pressure on vital but fragile tropical ecosystems such as coral reefs, mangroves and seagrasses.

“For example, a coral reef in the Florida Keys called Newfound Harbor Key accumulated heat stress nearly three times the previous record, and this occurred 6 weeks before previous peaks.”

Professor Hoeg-Guldberg said the findings come at a critical time for protecting global biodiversity, as many countries are committed to mitigating climate change.

“The latest environmental information suggests that we are not on track for global surface temperatures to reach very dangerous levels by the middle or end of this century,” he said.

“Frankly, we’re running in the opposite direction. “This is compounded by the fact that these devastating impacts are evolving into a massive, record-breaking global event.”

Professor Hoegh-Guldberg said the protection of coral reefs would be under serious threat in the next few decades unless serious and rapid action was taken.

“Our study shows that ENSO is an important driver in the fate of the world’s coral reefs,” he said. “Rising sea temperatures, combined with other stressors such as ocean acidification and pollution, have severely weakened their resilience. “This puts coral reefs and a quarter of the ocean’s biodiversity at serious risk of extinction.”

Professor Hoegh-Guldberg said efforts to introduce heat tolerance genes into natural coral populations were promising, but the reality of scaling these efforts remained logistically challenging.

“Given the complex and interconnected nature of marine ecosystems such as coral reefs, an integrated approach is needed to mitigate the impacts of changing ocean conditions,” he said. “The importance of reducing our emissions is highlighted by our findings that significant changes in ocean warming will destroy coral reefs and many other ecosystems. “With this in mind, there are extremely challenging discussions at the COP28 climate meetings.”