Nearly 44% of the world's reef-building coral species face an elevated risk of extinction, primarily due to rising ocean temperatures linked to climate change, according to a new study.

The research, published Thursday in the scientific journal Nature, assessed 892 reef-building coral species using the International Union for Conservation of Nature (IUCN) Red List criteria.

Of the 774 species with sufficient data, 340 were classified as threatened, including 33 critically endangered, 251 endangered and 56 vulnerable.

Researchers from institutions including the Australian Institute of Marine Science and the University of Queensland examined coral population trends and projected heat stress, updating a 2008 assessment. The study identified climate-driven heat stress as the main cause of projected population declines.

Reef-building corals are marine animals whose hard skeletons form the foundations of tropical reefs. Rising water temperatures can cause them to expel the algae living in their tissues, which provide nutrients and give corals their color.

The process, known as coral bleaching, leaves corals vulnerable to starvation, disease and death.

Researchers warned that the assessment predates the record ocean heat and global coral bleaching event of 2023-2025, meaning the proportion of threatened species could now be higher.

Coral reefs support diverse marine life and provide food, coastal protection and livelihoods in more than 100 tropical countries.

The researchers stressed that limiting further warming remains essential to preserving coral biodiversity.