Ocean Surface Temperatures Are Setting New Records Again

Amidst a record-setting summer heat wave in Europe, the EU-sponsored Copernicus Marine Service has released a familiar message: a new record global sea surface temperature, making 2026 the third year in the last four that this threshold has been passed.

The incremental difference is small, about 0.1 degrees C over the previous records for the date of June 21, and it was expected. With El Nino conditions arriving in the Pacific, and high heat events observed in other ocean basins, the average was predicted to rise - and more daily records are expected in the weeks to come.

The new daily record was confirmed by a sister institution, the European Centre for Medium-Range Weather Forecasts (ECMWF).

“With ocean temperatures at these levels and El Niño on the horizon, we are likely to see more temperature records fall in the coming months. That Copernicus Marine data reaches the same conclusion through independent methods speaks to the strength of European science — and to why open, robust data matters now more than ever,” said Carlo Buontempo, Copernicus Climate Change Service Director at ECMWF.

El Nino events cause surface temperatures to soar in the equatorial Eastern Pacific, affecting weather patterns around the world. Increased average global air temperature and more extreme weather events (droughts, storms and heat waves) typically accompany El Nino years. Climate scientists expect 2027 to bring record global temperatures, driven by El Nino conditions - and the effects could be unique this time, given the size of this year's event.

"This El Niño is unusually large for this early in the year, and it is occurring in a warmer climate that is fundamentally different than past decades," climate scientist Kim Cobb told CNN.

Sea surface temperatures are an important part of the picture for weather, but the rest of the ocean is getting warmer too. Last year, deep ocean waters from 0-2,000 meters of depth set a new record for heat content, a joint Chinese-U.S. research team wrote in Advances in Atmospheric Sciences.

In a related paper in Nature Climate Change penned by many of the same authors, researchers suggested that this work depends on the integrity of a global network of sensors, created by many nations but underpinned by U.S. research investments. Any reductions in this international partnership, known as the Global Ocean Observing System - for example, the Trump administration's early removal of a $370 million deep ocean monitoring megaproject - will reduce future data quality on ocean heat content. This will have an outsize impact on climate research, experts in the field say.

"Ocean heat content is the most robust indicator of climate change we have - not just of what is happening in the ocean, but of the entire climate system," French oceanographer Sabrina Speich told The Guardian. "Lose them, and you lose your ability to track not just ocean warming but the climate system as a whole."