The International Union for Conservation of Nature (IUCN) classified 96% of assessed shallow-water reef systems as critically endangered, as climate projections point to collapse risk by 2075, AFP reported.
The first global ecosystem review of coral reefs covered 127 tropical and subtropical systems across 188,362 square kilometers. Researchers used a middle-range pathway from the United Nations climate panel, which projects global temperatures reaching 2.7 degrees Celsius above preindustrial levels by 2100. Looking only at observed changes over the previous 50 years and setting projections aside, 24% of the systems would fall into the highest-risk category, IUCN said.
The review identified climate-related heat stress as the most consistent pressure on reefs. Excessive fishing of parrotfish and groupers threatens 63% of the systems; coastal development, pollution, tourism and more frequent storms add to the strain. Warming oceans also increase the frequency and intensity of damaging bleaching events, AFP reported.
The category measures the risk that a reef ecosystem will collapse, rather than the extinction risk of an individual species. Collapse occurs when reef-building hard corals largely give way to algae, rubble and sponges, according to the AFP report. A separate Oct. 15 assessment of reef-building coral species found 340 of 774 species with enough data for assessment, or 44%, threatened with extinction based on information through 2020.
Reefs also support food supplies and livelihoods and help protect coastlines in more than 100 tropical countries, as EconoTimes previously reported. The assessment was released during the United Nations' COP17 biodiversity summit in Yerevan, Armenia, as governments sought progress on a global agreement to stop biodiversity decline and reverse it by 2030.
Mishal Gudka, scientific lead of the assessment, said some reefs have recovered after severe bleaching, showing that recovery remains possible even as the broader collapse risk grows. IUCN Director General Grethel Aguilar said progress depends on limiting emissions and ocean warming, restoring and protecting reefs, and supporting resilient coastlines and the communities that rely on them.
