Press

The Global Coral Reef Monitoring Network (GCRMN) has released its most comprehensive assessment of the world’s coral reefs to date. Status of Coral Reefs of the World: 2025 brings together 21.1 million observations from 87,299 surveys at 36,886 reef sites, contributed by 600 partners across more than 120 countries, territories, and economies. The result is the largest global coral reef assessment ever produced—and Reef Check data are part of that picture.

The report’s findings underscore the growing pressure on coral reefs. Global hard coral cover averaged 30.2% during the 1980–2009 reference period, compared with 27.3% from 2020–2024—a relative decline of 9.5%. In 2024, global hard coral cover stood at 25.8%. Between 2023 and 2024 alone, coral cover fell by a relative 8.9%, the largest single-year decline on record. 

Climate-driven marine heatwaves are the primary driver of the global decline. Since 1998, four global coral bleaching events have each been associated with relative losses of 6.5–9.9% in global hard coral cover. Since 2010, these large-scale disturbances have been occurring every four to six years in many regions, leaving reefs with less time to recover before the next event.

Yet the report also makes clear that the story is not the same everywhere—and that recovery is still possible. Following the third global bleaching event, global hard coral cover increased by approximately 6% between 2017 and 2019. Across the 10 GCRMN regions, four show long-term declines in hard coral cover, four show no evidence of net long-term change, and two have increased relative to their reference periods. These regional differences highlight the importance of reducing local pressures such as pollution, coastal development, overfishing and unsustainable resource use while addressing climate change globally.

Reef Check Data Help Build the Global Picture

Reef Check-collected monitoring data contributed to all 10 regional chapters of the report: Australia, Brazil, the Caribbean, East Asian Seas, the Eastern Tropical Pacific, the Pacific, the Red Sea and Gulf of Aden, the ROPME Sea Area, South Asia, and the Western Indian Ocean. Several Reef Check coordinators also served as co-authors of their respective regional chapters. The report specifically acknowledges the Reef Check Foundation and the countless hours contributed by Reef Check volunteers to collecting these data.

That contribution speaks directly to one of the report’s central messages: sustained, long-term monitoring is essential to effective coral reef conservation. Consistent monitoring allows scientists and managers to establish baselines, identify long-term trends, connect changes in reef condition with their causes, measure recovery, and determine whether conservation strategies are working. Without those data, it is far more difficult to know where reefs are improving, where they are declining, and where limited conservation resources can have the greatest impact.

For nearly 30 years, Reef Check scientists, coordinators, partners and volunteer citizen scientists have helped build this kind of long-term record. The new GCRMN report demonstrates why that work matters: individual surveys, repeated year after year and shared across borders, become part of the evidence base used to understand the health of an entire global ecosystem.

The situation for coral reefs is urgent, but their fate is not predetermined. As the report concludes, limiting global warming is fundamental to their future, while reducing local stressors, strengthening reef protection, adapting management and investing in monitoring can improve resilience and recovery. Actions taken now can improve outcomes for coral reefs—and for the communities, economies and biodiversity that depend on them.

Coral bleaching is changing reefs around the world, so this September, we’re giving up our color to bring attention to what reefs are facing.

In recognition of the fourth annual Coral Bleaching Awareness Month, Reef Check has joined the Coral Reef Alliance, the International Coral Reef Initiative (ICRI) and hundreds of partners around the world in “bleaching” our logo on social media.

For Reef Check, the campaign is closely connected to the work we have been doing for three decades: getting people into the water to observe, measure and document changes occurring on reefs.

Reef Check was founded in 1996 to address a critical gap in our understanding of coral reef health. The following year, trained volunteer divers and scientists carried out the first-ever global survey of coral reefs using a standardized monitoring protocol. Today, Reef Check’s Tropical Program includes citizen scientist teams in more than 40 countries, conducting more than 600 surveys each year. Since 1997, Reef Check EcoDivers have completed more than 17,000 coral reef health surveys worldwide.

That long-term perspective is particularly important now.

On August 22, 2026, the daily global average sea surface temperature reached 21.10°C (69.98°F), the highest recorded since the Copernicus Climate Change Service dataset began in 1979. At the same time, El Niño is strengthening, with NOAA forecasting a greater than 90% chance that it will become a very strong event during the Northern Hemisphere fall and winter.

For coral reefs already facing increasing heat stress, these conditions are cause for concern—and make consistent monitoring more important than ever.

When corals experience prolonged heat stress, they can expel the symbiotic algae living within their tissues that provide much of their color and energy. Without them, corals become pale or white, a phenomenon known as coral bleaching.

Bleaching does not necessarily mean a coral has died. If stressful conditions subside, corals can recover. But severe or prolonged bleaching leaves corals more vulnerable to disease and mortality, while other pressures—including poor water quality and overfishing—can further reduce a reef’s ability to withstand and recover from heat stress.

This is where long-term monitoring makes a difference.

Reef Check EcoDivers use a globally standardized scientific protocol to document coral cover, fish and invertebrate populations, and other indicators of reef health. By returning to reefs and collecting comparable data over time, our teams help create a record of how these ecosystems are changing.

During periods of extreme ocean heat, those observations allow us to put what divers are seeing today into a much larger context—comparing reef conditions before, during and after bleaching events and helping identify not only where reefs are declining, but also where they may be demonstrating resilience and recovery.

Three decades of monitoring have shown us that the story of coral reefs is not only one of loss. Reef Check data also document reefs that recover and communities taking action to protect the ecosystems they depend upon. That is why continuing to monitor reefs through this period of unprecedented change matters.

Bleaching our logo for the month of September is a small symbol of what reefs around the world are experiencing. Keeping trained divers in the water, collecting the data needed to understand those changes, is the work that comes next.

You can be part of it. Your support helps Reef Check train and mobilize EcoDivers, maintain long-term monitoring sites and collect the data needed to understand how reefs respond to extreme heat and bleaching. Please consider making a donation to help keep our teams in the water and ensure that changes happening on reefs around the world do not go undocumented.

Thank you to all who came to our recent fundraiser and showing of the documentary Holdfast Together. A big shout-out to our fantastic Q&A panel, moderated by Reef Check’s Annie Bauer-Civiello, which included Reef Check’s Dan Abbott and True Barnes, Alec Welsh (SeaTrees/Filmmaker), and Jennifer Kimberly (P.U.R.P.), who all did an amazing job talking about the importance of kelp monitoring and restoration. Also, a big thank you to Faction Brewery in Alameda, which hosted the event. In total, we raised $1,000! There will be another screening of Holdfast Together in conjunction with the CA Seaweed Festival in Monterey in October. If you are local, don’t miss out!

Submitted by Biosphere Expeditions

Reef Check partner and international wildlife conservation organization Biosphere Expeditions has published its 13th annual Maldives coral reef conservation report, detailing critical marine monitoring conducted during the Reef Check EcoExpedition in October 2025 across Ari, South Malé and Vaavu atolls.

While the archipelago escaped a mass coral bleaching event in 2025 following severe thermal stress in 2024, the findings reveal a starkly uneven recovery landscape across the central atolls. 

The report’s release comes at a crucial moment as escalating ocean temperatures, an approaching El Niño cycle and localized human impacts threaten tropical coral ecosystems worldwide.

Global Context: Approaching El Niño and Coral Reef Trajectories

The report highlights that the primary threats to Maldivian reefs (climate breakdown, ocean acidification, overfishing, coastal sedimentation and substandard waste management) persist unabated.

Current projections by the Intergovernmental Panel on Climate Change (IPCC) warn that 70–90% of global tropical coral reefs may succumb by 2050 under a 1.5°C global warming scenario.

With thermal anomalies and an approaching El Niño threat looming, the survival of lagoonal inner reefs remains precariously fragile. The report emphasizes that without immediate enforcement of local environmental regulations, sustainable fisheries management and systemic global climate governance, recovery windows for coral reef conservation will continue to close.

From Citizen Science to Top-Notch Global Research

The release of the 2025 report also underscores the pivotal role played by citizen scientists in coral reef conservation.

Biosphere Expeditions’ marine dataset from the Maldives and Oman was recently featured and recognized in Nature Communications, demonstrating how volunteer-collected data, if collected properly by credible organizations such as Biosphere Expeditions and Reef Check, meets the highest scientific standards and feeds directly into peer-reviewed research on global coral reef degradation.

Furthermore, long-term monitoring data gathered by Biosphere Expeditions volunteers and Reef Check EcoDivers directly enabled the scientific publication Pancrazi et al. (2025). This study formally validated the “inner/outer reef dichotomy” paradigm first identified in Biosphere Expeditions’ field reports, proving that post-bleaching recovery on inner lagoonal reefs is stunted compared to cooler outer slopes.

“All this shows that our citizen scientists are active contributors to globally significant research,” says Dr. Matthias Hammer, Founder and CEO of Biosphere Expeditions and co-author of the report. “When conducted with scientific rigor, citizen science provides the robust, multi-year datasets needed to inform international climate policy and drive local conservation action.”

To prevent further ecological collapse, Dr. Hammer and expedition scientist Dr. Simon Harding are calling for “stringent enforcement of dredging license conditions, immediate implementation of sustainable fisheries management and well-managed, enforced and expanded local marine protected areas”.

Over a Decade of Conservation Achievements in the Maldives

Since launching its first Maldives research expedition in 2011, Biosphere Expeditions has built an enduring legacy of community-based conservation:

Long-Term Scientific Monitoring: Biosphere Expeditions provides one of the few continuous, independent long-term datasets tracking coral health, reef fish populations and human impacts across central Maldivian atolls.

Educational Outreach: In partnership with local organizations, Biosphere Expeditions published a dedicated reef educational booklet for Maldivian children, distributing 2,000 copies to the Ministry of Education to embed marine conservation into local schools.

Empowering Local Conservationists: Through its ongoing placement scheme, Biosphere Expeditions provides full scholarships to Maldivian nationals to train as certified Reef Check EcoDivers alongside international volunteers.

Grass-Roots Leadership: Placement alumni have gone on to achieve major national conservation successes. Notably, former placement recipient Shaha Hashim spearheaded community-based reef monitoring across the Maldives, organized the first-ever all-Maldivian Reef Check survey and now leads local marine NGO initiatives fighting against destructive fishing practices and unmanaged coastal dredging.

Next Steps

The success in the Maldives marks the latest milestone in Biosphere Expeditions’ 25-year legacy of global citizen science achievements.

The next Biosphere Expeditions coral reef and whale shark survey in the Maldives will take place from 17 to 23 October 2026. Qualified divers wishing to join the expedition as citizen scientists can find further details at www.biosphere-expeditions.org.

August 6, 2026
6:00PM – 8:00 PM
Faction Brewing 2501 Monarch St. Alameda, CA 94501