Coral reefs are running out of time to recover between heat waves, global assessment finds

The world's coral reefs are losing living coral and the time they need to recover between marine heat waves, and scientists warn the strengthening El Niño could trigger another global bleaching event, Mongabay reported.

The Global Coral Reef Monitoring Network's "Status of Coral Reefs of the World: 2025" report, released Aug. 31, found average hard coral cover fell from 30.2% in 1980-2009 to 27.3% in 2020-2024, a 9.5% relative decline, and dropped to 25.8% in 2024. It drew on 87,299 surveys in 123 countries and territories.

The fourth global bleaching event, from 2023 to 2025, drove an 8.9% drop in coral cover between 2023 and 2024 alone, the largest single-year decline on record. Bleaching events now occur roughly every four to six years, down from about once a decade, leaving reefs little time to rebound.

"Given current ocean temperatures and the strengthening of El Niño, we may anticipate conditions favouring another global bleaching event," said Manuel González-Rivero, the report's lead author and a researcher at the Australian Institute of Marine Science. Julia Baum, a coral reef ecologist at the University of Victoria in Canada, said the unfolding El Niño "will almost certainly be a death sentence for many of the world's coral reefs."

Losses varied widely by region: coral cover fell 48.7% across the northern Arabian Sea, Persian Gulf and Gulf of Oman, and 43.4% in the Caribbean. Reefs cover less than 0.2% of the ocean floor but support at least a quarter of marine species. Local measures such as sustainable fishing help, researchers said, but rapid cuts in greenhouse gas emissions are essential.

This brief is based on reporting by Autumn Spanne, published Sept. 25, 2026, by Mongabay. Read the original: https://news.mongabay.com/2026/09/global-coral-reefs-get-less-time-to-recover-as-oceans-heat-up-report-finds/