Contributions of human-caused climate change and individual emitters to global coral bleaching
Abstract
Coral bleaching is among the most infamous climate impacts 1,2 . Yet the extent of bleaching due to human-caused climate change, as opposed to natural El Niño variability, and the contributions of individual countries and carbon majors (fossil fuel and cement producers) remains unquantified. Here, we leverage coral monitoring globally across 4,479 sites from 1985–2024 3,4 to link specific emitters to marine heat stress and bleaching. For events with >10% of corals bleached at a site, we find that 99% (95% CI: 88–100%) were attributable to human-caused climate change. Even during major El Niños, 97–100% of bleaching events were attributable to human-caused climate change and the extent of damage increases over time from 23% of sites bleached (95% CI: 3–35%) during 1998 to 71% of sites (95% CI: 37–85%) during 2023–2024. Emissions of the United States, the largest historical emitter, contributed to 51% (95% CI: 39–65%) of bleaching events. Emissions linked to Chevron, Saudi Aramco, Gazprom, and ExxonMobil each contributed to 14% (95% CI: 11–19%) of bleaching events—roughly double the contribution of the 39 countries of the Alliance for Small Island States. It is virtually certain emissions of China, the United States, and Indonesia caused bleaching in their coastal waters. Strong inequalities exist where countries with high socioeconomic dependence on coral reefs experienced 54% of bleaching yet contributed only 5% to bleaching. As global warming rapidly nears levels…
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