Record marine heat waves in 2023 covered 96% of oceans, lasted four times longer than average

Heat waves aren't just getting worse on land, the majority of the world's oceans are experiencing record-breaking temperatures too. These marine heat waves are getting longer, more intense and reaching farther than ever before. In particular, 2023's marine heat waves (MHWs) exhibited the longest duration, widest extents, and highest intensities on record—and 2024 wasn't any better.