RYAN BACHOO
Lead Editor – Newsgathering
The world’s coral reefs are running out of time to recover between increasingly frequent marine heatwaves and global bleaching events, with climate change driving a long-term decline in coral cover, a new global assessment has found.
The Status of Coral Reefs of the World: 2025, released by the Global Coral Reef Monitoring Network, draws on more than 40 years of data, including 21.1 million observations from 87,299 surveys covering 36,886 sites across 124 countries, territories and economies.
The report found that every major global coral bleaching event since 1998 has resulted in a decline in global hard coral cover, with reefs only partially recovering before being hit by another marine heatwave.
The first global bleaching event in 1998–1999 resulted in an estimated 6.5 per cent decline in hard coral cover, followed by declines of 9.9 per cent in 2010–2011, 6.6 per cent in 2016–2017 and 8.9 per cent following the 2023–2024 event.
Lead author Dr Manuel González Rivero said the greatest concern was not only the loss of coral, but the diminishing opportunity for reefs to recover.
“Climate change is driving more frequent and severe marine heatwaves, but local pressures such as poor water quality, overfishing and coastal development are making reefs even less able to withstand them,” he said.
González Rivero said reefs that once had decades to recover between major bleaching events were now sometimes getting only five or six years.
He warned that reefs affected by the unprecedented marine heatwaves of 2024 could have had little more than a year to begin recovering before facing another period of heat stress.
The report describes this as a “staircase of decline”, with each successive bleaching event making recovery increasingly difficult.
Despite the overall deterioration, the assessment found evidence that coral reefs can recover when disturbances are reduced and they are given sufficient time.
Following the third global bleaching event, global hard coral cover increased by approximately six per cent between 2017 and 2019, demonstrating that reefs retain the capacity to regain coral cover.
However, global hard coral cover has still declined from an average of 30.2 per cent between 1980 and 2009 to 27.3 per cent between 2020 and 2024 — a relative decline of about 9.5 per cent.
The report identifies climate change-induced heat stress as the primary driver, while warning that local pressures can further weaken reefs.
Coral reefs cover less than 0.2 per cent of the ocean floor but support at least 25 per cent of marine species and underpin food security, livelihoods, tourism, coastal protection and cultural heritage for close to one billion people.
About 104 million people now live within five kilometres of a coral reef, a 46 per cent increase over the past two decades.
David Obura, Chair of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, said the findings should prompt urgent action.
He said the data showed that current efforts have not been sufficient and warned that delayed action could result in irreversible losses to reefs, economies and communities that depend on them.
The report concludes that different futures remain possible. It says ambitious emissions reductions, combined with effective management of overfishing, coastal development and poor water quality, provide the strongest pathway for maintaining coral cover.
Palau’s Permanent Representative to the United Nations, Ambassador Ilana Seid, said local conservation, marine management and the integration of traditional knowledge with scientific innovation had already produced positive results.
“The challenge before us is no longer identifying what needs to be done, but finding the collective will to do it,” she said.
