Coral reefs are among the most species-rich, productive and economically valuable
ecosystems on Earth but increasingly frequent pantropical coral bleaching events are
threatening their persistence on a global scale. The 2015–2016 El Niño led to the hottest
sea surface temperatures on record and widespread bleaching of shallow-water corals.
However, the causes of spatial variation in bleaching are poorly understood, and near-
surface estimates of heat stress, such as those inferred from satellites, cannot be …