Tropical waters are the scene of a growing ecological crisis. Nearly 50% of reef-building coral species are now at risk of extinction, according to a report by the International Union for Conservation of Nature (IUCN) published this Wednesday, November 13. By comparison, the IUCN’s previous assessment in 2008 estimated that only a third of coral species were at risk of extinction

According to this latest report, 892 coral species that inhabit the warm, shallow waters of the tropics are at risk. Corals in deeper, colder waters, meanwhile, remain difficult to study and are still being assessed by the IUCN.

“Climate change, a major threat”

This update of the “red list” of threatened species is published in parallel with the COP29 climate conference, currently underway in Baku, Azerbaijan. On the sidelines of this conference, IUCN is urging negotiators to speed up action to reduce greenhouse gas emissions. As the organization points out, coral reefs play a crucial role for mankind: they provide food resources, protect coastlines and contribute to carbon storage.

In October, the U.S. Ocean Observing Agency had already warned of an unprecedented global bleaching episode due to abnormally high ocean temperatures. Currently, more than two-thirds of the world’s coral reefs have been lost.

Today, more than two-thirds of coral reefs in the Atlantic, Pacific and Indian Oceans are exposed to thermal stress, posing a serious threat to these ecosystems, which are true reservoirs of biodiversity at the heart of the marine life cycle.