Jason Momoa has warned that coral reefs are nearing extinction as scientists document the unprecedented scale of the fourth global coral bleaching event. The warning lands in the middle of a planetary failure that’s been measured, counted and confirmed by the same institutions that keep tallying the damage while the oceans cook.
Momoa, the actor and United Nations Environment Programme Advocate for Life Below Water, has made ocean protection a central part of his public work, from portraying the ocean superhero Aquaman to advocating for marine conservation. He says coral reefs support marine biodiversity, coastal communities and cultural traditions. In Hawai‘i, Momoa says reefs help feed families, protect coastlines and remain closely connected to Hawaiian traditions. That’s the human cost sitting underneath the scientific language.
Who Pays for the Damage
The National Oceanic and Atmospheric Administration confirmed the fourth global coral bleaching event on 15 April 2024. NOAA Coral Reef Watch said bleaching-level heat stress affected approximately 84.4% of the world's coral reef area between 1 January 2023 and 30 September 2025. Mass bleaching was documented in at least 83 countries and territories across the Pacific, Atlantic and Indian oceans. Those numbers don’t describe a distant environmental abstraction. They describe a system-wide collapse hitting coastlines, fisheries and communities far from the boardrooms and ministries where the causes keep piling up.
In an update published on 2 June 2026, NOAA said the global event likely ended in mid-2025, while noting that identifying the beginning and end of global bleaching events is becoming increasingly difficult as coral reefs experience heat stress more frequently. That’s the bureaucratic language of a planet under pressure. The apparatus can measure the wreckage, but it can’t stop the machinery driving it.
Momoa also identified plastic pollution, coastal development, agricultural runoff and overfishing as additional sources of damage. Plastic waste can injure coral colonies, while sediment and pollutants from construction and farming can reduce water quality. Overfishing can disrupt marine food webs and affect species that play important roles in maintaining reef health. Measures such as reducing pollution, protecting coastal habitats and improving fisheries management can help strengthen reef resilience, but local conservation efforts must be supported by action to reduce global greenhouse gas emissions.
What the Science Says
An opinion article published by The Guardian on 17 April 2026 and republished by UNEP said up to 90% of coral reefs could disappear by 2050 under 1.5°C of global warming, while losses could reach 99% at 2°C. The Intergovernmental Panel on Climate Change has warned that reef-building corals face substantial losses even at 1.5°C of global warming above pre-industrial levels. The projections cited by UNEP describe the potential decline of reef ecosystems rather than a fixed date when all corals will disappear. The numbers are grim enough without dressing them up.
Coral bleaching occurs when corals experience prolonged environmental stress, particularly unusually warm seawater. Corals live in a relationship with microscopic algae called zooxanthellae. These algae provide energy through photosynthesis and give corals much of their colour. When ocean temperatures rise beyond a coral's tolerance level, the coral may expel the algae and turn white. Bleaching does not automatically mean a coral has died. Some colonies can recover if temperatures return to normal conditions, but prolonged stress can cause starvation, disease and death. The extent of the damage depends on the duration of heat exposure, coral species and local environmental conditions. Repeated bleaching can leave reefs with insufficient time to recover between heatwaves.
A study published in Coral Reefs in January 2026 examined coral heat stress between 1985 and 2025. Researchers found that an uninterrupted period of global coral heat stress from 2018 to 2025 affected 87% of reef areas worldwide, the highest proportion recorded in the study. They also reported that median heat stress accumulation across reef areas was nearly 50% greater than during the previous global bleaching event record. The study said coral reefs are entering an era of more frequent bleaching, reducing the recovery time between major disturbances.
What’s Left to Save
Conservation organisations and scientists are working on coral restoration, reef monitoring and research into heat-tolerant coral species. Projects include coral nurseries, restoration programmes and efforts to identify colonies that may withstand warmer conditions. Restoration can support damaged reefs in suitable locations, but its success depends on water quality, the level of destruction and future environmental conditions. Protecting healthy reefs remains essential because established ecosystems may be more resilient than severely degraded ones.
The future of coral reefs will depend on how effectively governments, organisations and communities address rising temperatures and local environmental pressures. That’s the official framing. The reality underneath is harsher: reefs are being asked to survive the consequences of decisions made far above the waterline, while the people who depend on them are left to absorb the fallout.