A sweeping new report from the Global Coral Reef Monitoring Network warns that coral reefs worldwide are running out of time to recover between increasingly frequent marine heat waves. Published Monday, the assessment found global coral reefs declined by 9.5 percent from 2020 to 2024 compared with 1980 to 2009, with the largest single-year decline on record — affecting 87 percent of reefs — occurring in 2024. Historically, global bleaching events happened roughly once per decade, but since 2010 they have occurred every four to six years.

Bleached corals need time to recover, but rising sea temperatures are narrowing that window. Lead author Manuel Gonzalez-Rivero of the Australian Institute of Marine Science called the findings "dire and serious," noting reefs take decades to regain what they lost. Global average sea surface temperature recently hit a record 21.1 degrees Celsius, according to the Copernicus Climate Change Service.

Scientists like Carlos Duarte of the Coral Research and Development Accelerator Platform say the situation may be worse than reported, citing recent bleaching in Western Australia, mortality in the Red Sea, and 90 percent genetic diversity loss in the Caribbean. With a brewing El Niño likely to trigger another global bleaching event next year, the Intergovernmental Panel on Climate Change predicts 70 to 99 percent coral loss at 1.5 to 2 degrees Celsius warming. Terry Hughes of James Cook University cautioned that coral cover metrics mask declining biodiversity.