Coral reefs nearing irreversible decline, scientists warn

Coral reefs worldwide are bleaching so frequently that they can no longer recover between events, pushing global coral cover well below historical norms and toward irreversible decline, according to a landmark report released Monday by the Global Coral Reef Monitoring Network.

The report, drawing on more than 40 years of monitoring data from nearly 37,000 reef sites across 120 countries and territories, found that the gap between mass bleaching events has shrunk from decades to an average of just five or six years, according to Reuters. Hard coral cover fell 9.5% below its historical average during the 2020–2024 period, part of what lead author Manuel Gonzalez-Rivero described as a "staircase of decline."reuters+1

A Shrinking Window for Recovery

"If we give them enough time, they have the capacity to recover," Gonzalez-Rivero said. "But we haven't seen that amount of time being allowed. In fact, the frequency of those bleaching events has pretty much doubled."reuters

The world's first mass bleaching event was recorded in 1998, and three more have followed since 2010. Between 2017 and 2019, reefs regained 6% coral cover, nearly offsetting a 6.6% loss from the 2016 bleaching. But the most recent event, beginning in 2023, was the most extensive on record, affecting 77% of the world's coral reef areas. That event, which ran from early 2023 to mid-2025, subjected 84% of reef areas to bleaching-level heat stress across all three ocean basins, according to NOAA's Coral Reef Watch.gcrmn+2

Rising Temperatures Threaten New Bleaching

With ocean surface temperatures reaching a record high of 21.1 degrees Celsius on August 22 and El Niño patterns intensifying, Gonzalez-Rivero warned another bleaching event could strike this year. "It is very likely given the temperatures," he said.reuters

The report's release was timed to coincide with the opening of the 55th Pacific Islands Forum in Palau, where leaders from across the region are gathering through September 4 to coordinate climate priorities ahead of the COP31 climate conference later this year.reuters+1

Calls for Urgent Action

The report urged rapid emissions cuts alongside management of local threats, including unsustainable fishing and excessive coastal development. David Obura, chair of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, said in a statement: "We must act now to halt this decline and invest in solutions that reduce pressures and build resilience. Delayed action risks locking in irreversible losses."wmbdradio