After the record-breaking temperatures for the global ocean in 2023 and 2024 (Cheng et al., 2023, 2024; Copernicus Global Climate Highlights 2023, 2024), global warming continues impacting ocean state and variability. 2025 ranked as the third warmest year on record for the global average surface air temperatures going back to 1850 as well as for the extra-polar global-average sea surface temperature (SST) (Copernicus Global Climate Highlights, 2025). The average global temperature for 2023-2025 is the first three-year average above 1.5ºC. SSTs remained high throughout 2025, despite the absence of El Niño conditions which contributed to the warm SSTs in 2024 and 2025. The unprecedented SSTs were associated with marine heatwaves (MHWs) around the globe, in particular in the Mediterranean Sea. In this semi-enclosed sea, climate change brought new records in 2025 for the ocean temperatures, salinity and sea level affecting marine life, coastal communities and industries.
Melanie Juza (Fri,) studied this question.