Coral reefs are at significant risk due to rising ocean temperatures and marine heatwaves, and according to a global team of scientists, swift action to cut greenhouse gas emissions is essential for their survival.
Coral reefs are at significant risk due to rising ocean temperatures and marine heatwaves, and according to a global team of scientists, swift action to cut greenhouse gas emissions is essential for their survival.
Led by Dr. Liam Lachs from Newcastle University, the research indicates that corals can adapt to increasing temperatures through natural selection, but this is only possible if countries meet their commitments under the Paris Agreement and limit global warming to below two degrees Celsius.
Dr. Lachs noted, “Marine heatwaves are causing widespread coral bleaching and death in tropical reef ecosystems, and the increasing frequency and severity of these events are projected to worsen with climate change.”
“While new research shows that corals might adapt their heat tolerance, a crucial question remains: can natural selection help them keep up with rising global temperatures? Our findings suggest adaptation will likely be outpaced by moderate to high levels of warming.”
The international research team focused on the corals in Palau, western Pacific, using an eco-evolutionary simulation model to analyze coral populations.
This model includes information about the thermal limits and evolutionary characteristics of thermally vulnerable corals and their ecological context. The study, published today in Science, predicts the outcomes of various scenarios for global development and fossil fuel consumption based on assessments from the Intergovernmental Panel on Climate Change.
Prof. Peter Mumby, a co-author from The University of Queensland, stated, “If we do not meet Paris Agreement targets, global temperatures could rise by 3-5 degrees by the end of this century. At such temperatures, natural selection may not be enough to help sensitive coral species survive.”
“While we can envision a future with relatively healthy coral reefs, achieving this demands significant reductions in global emissions and strategic management of coral habitats,” he added.
Dr. Lachs remarked, “With current climate policies, we are on track for a middle-ground emissions outcome—approximately 3 °C of warming—where natural selection for heat tolerance will play a critical role in the survival of some coral populations.”
“From this emissions scenario, we anticipate severe declines in reef health and an increased risk of local extinction for heat-sensitive coral species. Nonetheless, there is considerable uncertainty regarding the evolutionary potential of coral populations.”
Co-author Dr. James Guest, who leads the Coralassist Lab, emphasizes the urgent need to develop management strategies adapted to climate changes for coral reefs.
“We must implement management practices that enhance the natural ability of corals to adapt genetically, while also investigating ways to boost the chances of adaptation in wild populations,” Dr. Guest explained.
One promising method, still in experimental phases, involves targeted assisted evolution, which could enhance heat resistance through selective breeding, as mentioned in a separate study by the Coralassist Lab.
Coral reefs are vital, diverse marine ecosystems. “Overall,” Dr. Lachs concludes, “the findings of our models suggest that genetic adaptation could mitigate some of the anticipated declines in coral reef health and diversity throughout the 21st Century, provided that urgent climate actions are implemented.”
