World’s coral reefs are losing recovery time between marine heatwaves, major global report warns

The world’s coral reefs have ever-shorter windows to recover between marine heatwaves, according to the most comprehensive assessment of reef health yet published. The report, published by the Global Coral Reef Monitoring Network (GCRMN) on Monday (31 August), is based on more than 21 million observations from 36,886 reef sites in 124 countries and territories, gathered over more than 40 years. The proportion of reef surface covered by living coral (so-called hard coral) has fallen by 9.5 percent compared with the 1980–2009 average. It fell from a little over 30 percent during the 2009 to 2020 period to 25.8 percent in 2024, which the report’s researchers attribute primarily to climate-driven heat stress. Source: Australian Institute of Marine Science LTMP Heat stress causes bleaching. And bleaching happens when abnormally warm sea temperatures cause corals to expel algae (which gives them their colour) living in their tissue. If the heat persists for long enough, the corals die. This has happened four times since 1998, in ever shorter intervals. To read this story, log in or subscribeEnjoy access to all articles and 25 years of archives, comment and gift articles. Become a subscriber for as low as €1,75 per week.Read without limitsAlready a subscriber? Login