Global sea surface temperatures reach a record high, again

Global sea surface temperatures have reached a record high, according to new data from the European Union’s Copernicus Climate Change Service (C3S). On August 22, the average temperature, excluding polar regions, hit 21.1° Celsius (69.98° Fahrenheit), surpassing the previous record set in March 2024. Even modest increases in temperature translate to significant heat energy in the vast ocean, as highlighted by the 2025 European state of the climate report.

In the same year, the global ocean heat content, the total heat stored in the ocean, also set a new record high. The rising ocean temperatures are causing widespread repercussions. The report emphasizes how sea surface temperatures contribute to sea-level rise, heighten the risk and intensity of marine heatwaves, strain critical ecosystems like coral reefs and seagrass, and jeopardize fisheries and food security.

Samantha Burgess, strategic lead for climate with C3S, explained that increased sea surface temperatures also heighten the potential for extreme weather events, putting coastal communities at risk while reducing the ocean's capacity to act as a carbon sink for the planet. Over 90% of the excess heat produced by global warming has been absorbed by the world's oceans.