The map reflects the locations of thermal stress (i.e., abnormally high sea surface temperatures) on coral reefs between 1998 and 2007 based on coral bleaching observations (in purple) and severe thermal stress from satellite detection (defined as a degree heating week ≥ 8, shown in orange). As many occurrences of coral bleaching are unobserved or unreported, the satellite-detected thermal stress serves as a means of filling in gaps in the observational data.