Overview
- An analysis published in Advances in Atmospheric Sciences draws on work by more than 50 scientists across roughly 30–31 institutions using Copernicus Marine, NOAA/NCEI, IAP-CAS data and a CIGAR-RT reanalysis.
- About 16% of the global ocean surface set record heat content in 2025, and roughly 33% ranked among their three warmest values on record.
- The most pronounced warming emerged in the South and tropical Atlantic, the North Pacific, the Southern Ocean, the Mediterranean, and the northern Indian Ocean.
- Researchers link the accumulated ocean heat to rising seas from thermal expansion and to intensified marine heatwaves, heavy rains, droughts and stronger storms documented in 2025.
- Global sea-surface temperatures ranked third warmest in 2025 as the Pacific shifted from El Niño toward La Niña, even as subsurface heat content reached a new high.