Abstract
Four global mass coral bleaching events have now been recorded. The first, in 1998, was associated with that year’s strong El Niño. Subsequent global-scale bleaching occurred in 2010 and then over the periods 2014–2017 and 2018–2025 (and likely ongoing). All these events also coincided with El Niños for at least part of the period. While El Niño is an important factor, each event has also occurred during a period of rising global temperatures. Here, we use attribution of daily sea surface temperatures to show that the most recent global coral bleaching event is entirely due to human-caused warming. Furthermore, all previous events, including the original one in 1998, had strong fingerprints of anthropogenic climate change. Our analysis shows that global warming is the main driver of bleaching and that global coral bleaching simply would not occur without human-caused climate change.