Human-caused climate change has been the main driving force behind coral bleaching risk over the past four decades, a new research finds.
The research, led by the global climate research organisation Climate Central, points out that El Niño is often mistakenly viewed as the cause of widespread coral bleaching events, such as those in 1998, 2010, 2014-2017 and 2018-2025. Rather, fossil fuel-driven ocean temperature is the main force behind bleaching and coral mortality.
Titled ‘Quantifying the role of climate change in driving mass coral
bleaching’, the research was published in ‘Oceanography’.
Multi-model attribution method
For the research, “scientists used a multi-model extreme event attribution method to assess the influence of climate change on sea surface temperatures”, says Climate Central in a release on the research. “They
then applied those results to the bleaching risk model developed by NOAA’s Coral Reef Watch and found a clear climate change influence on coral bleaching risk,” it adds.
The research suggests that there would have been essentially no coral bleaching and certainly no global-scale event without human-caused climate change. The attribution method used indicated that of
71 regions where coral bleaching was observed, “only one region would have had a moderate risk of bleaching in a world without climate change”, says Climate Central.
For all other global events, it was found that climate change was necessary to push temperatures over the bleaching risk
threshold.
Carbon pollution damaging coral reefs
“Our study shows that without climate change, coral bleaching would be a rare and isolated event, and global mass coral bleaching simply would not occur,” said Andrew Pershing, chief programme officer, Climate Central, and lead author of the study.
“Millions of people and entire countries rely on healthy coral reefs for livelihoods and food security. But our emissions of
carbon pollution are causing increasingly widespread damage and death to these vital and vibrant ecosystems,” Pershing added. “Without immediate emissions reduction, coral reefs as we know them will disappear.”
Extinction threat
Scientists, using the same methodology, looked at the risk of coral bleaching during the 2026-2027 El Niño event now underway. “While natural El Niño-driven warming may lead to low levels of bleaching risk in a few regions, human-caused climate change is likely to drive coral bleaching across the globe, particularly in the southern Caribbean, the Central and South American coasts and the coasts of Eastern Asia,” said Climate Central. Historically, global coral bleaching events had been attributed more to El Niño than to climate-change related ocean warming. The research found that at the rate of current global warming rates, the impact of rising temperatures due to human-caused climate change will outweigh the impact from El Niño in all coral-containing regions by 2028.The findings add to the evidence that coral reefs worldwide are growing increasingly vulnerable despite their ability to adapt to rising temperatures. Scientists warn that without intervention and a reduction in greenhouse gases, further warming could threaten coral reef ecosystems with extinction.