The Copernicus Climate Change Service (C3S) and the Copernicus Marine Service (CMEMS) have confirmed that the global sea surface temperature has surpassed the record levels recorded for this time of year in 2023 and 2024. Daily data from C3S exceeded the levels of 2024 on June 21, reaching 20.86 ºC, slightly above the 20.83 ºC observed in both 2023 and 2024. Data from the Copernicus Marine Service also reflected record temperatures on that same June 21, with 21.0 ºC, a value that exceeds the previous records of 2023 and 2024 by 0.1 ºC.
This new global record for sea surface temperature for the date is set against the backdrop of the unprecedented heat wave sweeping across Europe this summer, making 2026 the third year among the last four to surpass this threshold. The difference compared to previous records is small, around 0.1 degrees, but it was expected: with the onset of El Niño conditions in the equatorial Pacific and unusually high sea surface temperatures in other ocean basins in recent months, the World Meteorological Organization (WMO) had announced on June 2, 2026, the initiation of this phenomenon. According to the organizations, new daily records are expected in the coming weeks, with implications for both weather patterns and global climate, as well as marine ecosystems.
Over the past three years, the global ocean outside the polar regions, between latitudes 60ºN and 60ºS, has remained between 0.35 ºC and 0.73 ºC above the historical average, and in June these anomalies reached record levels for this time of year.
C3S, implemented by the European Centre for Medium-Range Weather Forecasts (ECMWF), and the Copernicus Marine Service, implemented by Mercator Ocean International, have jointly announced this unprecedented level of global ocean warming extrapolated for this time of year, a phenomenon that reflects both ongoing climate change and the onset of an El Niño episode whose intensity, according to C3S seasonal forecasting models, could reach levels not seen in decades.
Carlo Buontempo, director of the Copernicus Climate Change Service at ECMWF, pointed out that current conditions suggest the onset of a new phase that could once again lead to unprecedented levels, and added that, with ocean temperatures at these levels and El Niño on the horizon, it is likely that more records will fall in the coming months. For his part, Pierre-Yves Le Traon, scientific director of the Copernicus Marine Service at Mercator Ocean International, emphasized that continuous monitoring of the ocean helps public authorities, the scientific community, and decision-makers understand how the marine environment is changing and design protection policies, highlighting the cooperation between both services: C3S provides the climate perspective of the terrestrial system as a whole, while the Marine Service offers detailed ocean analysis and forecasts.
A warmer ocean has far-reaching effects: it keeps the atmosphere warm for longer, provides additional energy to storms, and increases evaporation, which raises the risk of extreme precipitation and flooding. Ocean warming also contributes to sea level rise and ice melt, and subjects marine ecosystems to greater stress. Higher surface temperatures are also associated with more frequent and intense marine heat waves, which disrupt ecosystems and fishing, impact coastal economies, and can amplify extreme heat events in nearby land areas. Additionally, El Niño acts as an extra source of heat for the atmosphere, raising the global average temperature and altering weather patterns around the planet.
These record values have been observed independently in both the ERA5 reanalysis from C3S, produced by ECMWF, and in the GLO12 system of the Copernicus Marine Service, produced by Mercator Ocean International. ERA5 temperature data can be accessed through the Climate Pulse app, and GLO12 data through the MyOceanHealth platform. Both services combine in situ and satellite observations, including data from the European Space Agency (ESA) and Eumetsat, integrated into Copernicus models to generate high-resolution short-term ocean forecasts and long-term seasonal forecasts of the ocean-atmosphere system.
The phenomenon confirmed by Copernicus was corroborated by ECMWF as a sister institution. Climatologist Kim Cobb stated to CNN that this episode of El Niño is unusually intense for this time of year and occurs in a warmer climate, structurally different from decades past. Scientists predict that 2027 will bring new global temperature records driven by El Niño, with effects that could be unique given the magnitude of this episode.
Warming is not limited to the surface: according to a joint Chinese-American research team published in the journal Advances in Atmospheric Sciences, the deep ocean waters, between 0 and 2,000 meters deep, recorded a new heat content record last year. A related article published in Nature Climate Change by many of the same authors warns that this monitoring depends on the integrity of a global sensor network — the Global Ocean Observing System — supported by numerous countries but heavily reliant on U.S. investment in research. The authors point out that any reduction in this international cooperation, such as the early withdrawal by the Trump Administration from a deep ocean monitoring megaproject valued at $370 million, would reduce the quality of future data on ocean heat content, disproportionately impacting climate research. French oceanographer Sabrina Speich told The Guardian that ocean heat content is the most reliable indicator of climate change available, and warned that losing that monitoring capability would mean losing the ability to track not only ocean warming but the entire climate system.
Scientists from Copernicus continue to monitor the evolution of these records to determine if the current spike is temporary or persistent, in a context where forecasts indicate an intense El Niño episode and the possibility of new temperature records, both in the ocean and in the atmosphere, in the coming months.
