The world’s oceans reached their highest recorded temperature on Aug. 22, according to Copernicus, Europe’s Earth observation agency, which has tracked global sea-surface temperature daily since 1979. The global average sea-surface temperature hit 70 degrees that day, surpassing the previous single-day record set in March 2024, Copernicus said.
Scientists attribute the new record to the combination of long-term human-driven climate change and a powerful El Niño forming in the tropical Pacific. Samantha Burgess, strategic lead for climate at Copernicus’ European Center for Medium-Range Weather Forecasts, said El Niño is “adding heat to the system, but it is doing so on top of decades of human-driven warming.” She added that “as ocean temperatures continue to rise, the risks to marine ecosystems and coastal communities also increase.”
According to Copernicus, higher ocean temperatures contribute to sea level rise and increase the likelihood of extreme weather. Warmer water transfers more heat and moisture into the atmosphere, which can intensify storms and heat on land. Warmer oceans also have a reduced capacity to absorb carbon dioxide, the agency noted.
Copernicus said record temperatures have already been measured in isolated parts of the world’s oceans, including the western Mediterranean Sea, as well as at the Earth’s poles, driven mainly by human-made climate change. The agency expects this warming trend to continue, with ocean temperatures now being amplified further by the developing El Niño.
The timing of the August record is notable because global ocean temperatures are typically at their highest in March and April, following the Austral summer, according to Copernicus. A record set in August, outside that usual seasonal peak, is therefore seen as particularly concerning by the agency.
The report does not specify additional details about the scale or expected duration of the current El Niño event, nor does it provide specific projections for how much further ocean temperatures might rise. Copernicus has been the primary source cited for the data and analysis in this report, which was written by Bloomberg’s Millan for the Los Angeles Times.
Key facts
- Global average sea-surface temperature hit a record 70 degrees on Aug. 22, according to Copernicus.
- Copernicus has tracked global sea-surface temperature daily since 1979.
- The previous single-day record was set in March 2024.
- The record is attributed to a combination of long-term climate change and a forming El Niño in the tropical Pacific.
- Ocean temperatures are typically highest in March and April, making the August record notable, per Copernicus.
- Record temperatures have also been measured in the western Mediterranean Sea and at the Earth’s poles.