Environment (Commonwealth Union) – Coral reefs have always been a fascinating component of underwater ecosystems. The deterioration of such ecosystems has consequences beyond aesthetics.
The ability of coral reefs to recover from cyclones, coral bleaching and other detrimental occurrences when they are provided enough time, is seen as a positive aspect among environmentalists. However, a new global report warns that climate change and increasingly frequent marine heatwaves are leaving coral reefs with less time to recover.
The Status of Reefs of Coral of the World: 2025 is the most comprehensive assessment of reef coral health and decline ever undertaken globally. The report, published by the Global Reef of Corals Monitoring Network (GCRMN), analyses more than 21 million observations from 90,000-plus coral reef surveys from 600 partners from over 120 nations, territories and economies.
The paper states that the global average hard coral cover declined by 9.5% from 30.2% during the historical reference period of 1980–2009 to 27.3% during 2020 to 2024.
Researchers found the decline in coral cover was primarily driven by four major global coral bleaching events, driven by climate change and marine heatwaves.
The findings highlight growing concerns about the ability of coral reefs to recover from climate-related damage as bleaching events become more frequent and severe. With less time between disturbances, corals may struggle to grow, reproduce and rebuild reef ecosystems before the next major stress event occurs.
Associate Professor Tracy Ainsworth of University of New South Wales of Australia, a co-author of the report and current vice-president of the International Coral Reef Society indicated that we are now living in an era where disruption has become a recurring reality for coral reefs.
In the past, major coral bleaching events typically occurred roughly once every ten years. Since 2010, however, the interval has shortened to around five or six years. This is particularly concerning because many coral species require at least five years to reach maturity and start reproducing.
Associate Professor Ainsworth pointed out that in some regions, reefs are already experiencing severe disturbances every year, while in others, these events are occurring once every few years.
She indicated that the growth and maturity timeline required by corals is at present being overwhelmed by stress as well as disturbance events.
This means mature corals can be lost more quickly than new generations are able to develop and restore the reef.
A/Prof. Ainsworth indicated that the large coral colonies typically found on reefs may be several decades old.
She pointed out that once these corals are lost, it can take decades for the reef’s population structure to be rebuilt.
“But that timeline is now interrupted by more, and increasingly severe, stress events, making it harder for new corals to grow and fill the reef.”
The report also highlights some signs of coral reefs’ ability to recover. Between 2017 and 2019, global hard coral cover rose by 6% after the third worldwide coral bleaching event.
However, these improvements were subsequently wiped out by the unprecedented coral losses linked to the fourth global bleaching event, which began in 2023 and extended through 2025. Significant declines were recorded during the 2024 mass bleaching event on the Great Barrier Reef, followed by extensive bleaching across Western Australian reefs in 2025.
The fourth global bleaching event caused the steepest reduction in hard coral cover recorded over the 45-year monitoring period, although the report does not yet reflect its complete impact.
According to A/Prof. Ainsworth, successful reef recovery relies on maintaining healthy and diverse coral populations that can provide new corals to areas that have been damaged. For this to happen, some reefs must avoid bleaching, severe storms and pollution from land, or at least retain enough surviving corals to reproduce and help replenish affected areas.
