IUCN warns 96% of shallow reefs face collapse risk

The International Union for Conservation of Nature classified 96% of the world’s shallow-water coral reef systems as critically endangered, warning that they face an extremely high risk of collapse by 2075 under a projected warming scenario. The assessment, the first global review of its kind, examined 127 tropical and subtropical reef systems spanning 188,362 square kilometres. The classification is a measure of risk, not a finding that 96% of reefs have already collapsed. The IUCN defines collapse as the near or complete loss of living hard corals, leaving an ecosystem unable to sustain itself. Researchers used a middle-of-the-road climate scenario in which global temperatures rise 2.7 degrees Celsius above pre-industrial levels by 2100. The IUCN said that if future climate projections are excluded, 24% of the ecosystems would be classified as critically endangered, compared with 96% when projected warming is included. Climate-driven heat stress was identified as the most consistent threat to reef decline. The IUCN also cited overfishing, pollution, coastal development, tourism and more frequent storms. Overexploitation of parrotfish and other groupers threatens 63 of the...