IUCN's first global coral reef assessment finds 96% of reef ecosystems critically endangered

Almost all of the world's warm, shallow-water coral reef ecosystems are at an extremely high risk of collapse within the next 50 years, according to the first global coral reef assessment under the IUCN Red List of Ecosystems.

The International Union for Conservation of Nature (IUCN) said on October 22 that 96 per cent of the reef ecosystems assessed are Critically Endangered, the highest threat category. The study covered reefs in 127 tropical and subtropical ecoregions, spanning more than 188,000 square kilometres, and drew on over 250 experts working in more than 80 countries and territories.

Heat stress the main driver

The IUCN said heat stress caused by climate change is the most consistent driver of decline, triggering mass bleaching and coral die-offs. Based only on changes observed over the past 50 years, about 24 per cent of the ecosystems would already be Critically Endangered. The figure rises sharply once projected ocean warming is included.

Overfishing of reef fish such as parrotfish and grouper, which help reefs recover, affects about 63 per cent of the ecosystems, the assessment found. Pollution, coastal development, tourism pressure and more frequent storms add to the strain.

Famous reefs on the list

The Great Barrier Reef, the Coral Triangle, the Mesoamerican Barrier Reef and the Red Sea reefs were all classed as Critically Endangered. One ecosystem, in the western Galapagos Islands, is considered to have already collapsed after the 1982-83 El Nino. IUCN Director General Grethel Aguilar said it is "not too late" to give reefs a chance to recover.

Separately, the IUCN said a reassessment of 892 reef-building coral species found that 44 per cent are threatened with extinction.

Why it matters for India

India's reefs in the Gulf of Mannar, the Gulf of Kachchh, Lakshadweep and the Andaman and Nicobar Islands support fisheries, tourism and coastal protection for many communities. The assessment's authors say cutting greenhouse gas emissions, along with local action on fishing and pollution, is the most important step to slow the decline.