A global assessment of reef-building corals, released at the ongoing COP29 UN climate conference in Azerbaijan, reveals that 44% of these species are at risk of extinction. The IUCN Red List of Threatened Species highlights the urgency of protecting coral ecosystems. These ecosystems are essential to marine biodiversity and human livelihoods.
The reassessment, which included 892 warm-water coral species, shows a dramatic increase in the proportion of threatened corals. In 2008, one-third of coral species were classified as threatened. Today, that number has risen to nearly half of all reef-building corals.
CLIMATE CHANGE: THE LEADING THREAT TO CORAL REEFS
The primary driver behind the decline of coral species is climate change. Rising global temperatures lead to more frequent bleaching events. These intense events occur when corals expel the algae (zooxanthellae) that give them nutrients. This also provides their vibrant colors. Without these algae, corals are unable to survive for long.
The IUCN report incorporates the most recent data from the Global Coral Reef Monitoring Network (GCRMN). It also includes projections from the Intergovernmental Panel on Climate Change (IPCC) on future warming scenarios. These projections show that warming events will continue to threaten coral reefs. They will add to the damage already caused by pollution, agricultural runoff, and unsustainable fishing practices.
STRUGGLING CORAL SPECIES
The report highlights species such as Staghorn coral (Acropora cervicornis). Elkhorn coral (Acropora palmata) has also seen significant declines in the Caribbean. These species are classified as Critically Endangered due to a combination of ocean warming, water pollution, hurricanes, and coral diseases.
Other species around the world face various threats, especially true in the Atlantic and Indo-Pacific regions. They are dealing with annual bleaching events and disease outbreaks. In the Indo-Pacific, the majority of coral species are found. Yet, Coral species in the Atlantic face even greater challenges. This is due to the frequency of bleaching and local environmental stressors.
THE CALL FOR ACTION: REDUCING EMISSIONS AND LOCAL THREATS
To mitigate coral extinction, the IUCN stresses the need for immediate and significant reductions in greenhouse gas emissions. Cutting emissions is the most effective way to slow ocean warming. It gives corals a greater chance to adapt to changing conditions. At the same time, local threats, such as pollution and unsustainable fishing, must be addressed. This approach gives coral species the best possible chance of survival.
Beth Polidoro, IUCN Species Survival Commission Coral Red List Authority Coordinator, stressed, “By acting now, we can slow the pace of ocean warming and broaden the window of opportunity for corals to potentially adapt and survive in the long term.” She emphasized that coral reefs are not only critical for biodiversity but also for coastal fishing communities, shoreline stabilization, and carbon storage.
ONGOING RESEARCH AND ADAPTATION EFFORTS
While there is limited evidence that corals can adapt to warmer waters, there is still hope. The IUCN recommends further research into coral adaptation and restoration efforts to strengthen coral resilience. Coral ecosystems have been on the frontline of climate change for decades. This new assessment reinforces the urgency of continued conservation and restoration efforts.
Dr. David Obura, Co-Chair of the IUCN SSC Coral Specialist Group, warned, “Without relevant decisions from those with the power to change this trajectory, we will see the further loss of reefs and the progressive disappearance of coral species.”
THE ROLE OF CORAL REEFS IN MARINE ECOSYSTEMS
Coral reefs are among the most biodiverse marine ecosystems on the planet. They play a crucial role in supporting marine species and human communities. Reef-building corals rely on a symbiotic relationship with zooxanthellae, algae that give corals their color and provide essential nutrients. When water temperatures rise, corals expel the algae, resulting in bleaching. If prolonged, this leads to coral mortality.
Without healthy coral reefs, marine biodiversity would decline. Millions of people depend on reefs for their livelihoods, food security, and coastal protection. They would suffer without healthy reefs.
CONSERVATION EFFORTS AND THE FUTURE OF CORAL SPECIES
The MSC Foundation is actively involved in efforts to protect coral species. They collaborate with the IUCN Red List. Their initiatives include research and restoration. “This Global Coral Assessment raises the alarm for urgent collective action,” said Daniela Picco, Executive Director of the MSC Foundation. “It will continue to be a vital resource for our family-led foundation for generations to come.”
The foundation is focused on finding resilient coral genotypes. These efforts aim to enhance restoration activities. They also support the long-term survival of coral reefs. As Professor David Smith, MSC Foundation Chief Science Advisor, notes, “An ocean without functioning coral reefs would be a bleak reality. This highlights the urgent need to find solutions to the climate crisis. We must address today’s coral crisis.”
URGENCY OF COLLECTIVE ACTION
This global coral assessment provides a sobering reminder of the fragility of coral ecosystems. These ecosystems play a critical role in marine and human health. Over 340 species are now at risk of extinction. Bold climate action is more urgent than ever. Local conservation efforts are also needed immediately.
Significant efforts to cut greenhouse gas emissions and tackle local threats are crucial. Without these efforts, the world faces the progressive disappearance of coral reefs. This also threatens the vital species they support. Coral ecosystems provide irreplaceable benefits. These include biodiversity and coastal protection. They also contribute to carbon storage. Their conservation is essential for both nature and humanity.
