Almost half of all warm-water species of coral are threatened with extinction -- and climate change is the chief culprit, a new report said on Wednesday. The updated risk assessment from the International Union for Conservation of Nature (IUCN) was announced at the COP29 climate summit in Azerbaijan, which is being skipped by the leaders of many top polluting nations. Oceans have absorbed around 90 percent of the excess heat in the atmosphere due to the release of carbon dioxide and other greenhouse gases.

Rising ocean temperatures have spurred mass bleaching events at coral reefs across the world, threatening crucial ecosystems for marine life as well as the livelihoods of people who rely on them. The updated assessment of the IUCN's Red List of Threatened Species looked at reef-building corals, which live in warm, shallow waters in tropical areas. Its analysis found that 892 reef-building coral species are now considered threatened, representing 44 percent of the total.

This marked a significant increase from the last assessment in 2008, when a third of all species was listed as threatened. The organisation is still assessing the extinction risk for cold-water coral, which lives in deeper, darker ocean waters, making it difficult to study. The IUCN called on negotiators at the COP29 conference to act quickly to reduce planet-heating fossil fuel emissions.

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