Global Ocean Temperatures Hit a Record High as El Niño Intensifies

Global ocean temperatures have reached a new record high, as the developing El Niño climate pattern adds extra heat to an ocean already warming because of human-driven climate change.

On Saturday, August 22, global daily mean sea surface temperatures were higher than at any point since satellite records began in 1979, according to the European Union’s Copernicus Climate Change Service.

“This record is another clear sign of an ocean under increasing stress,” Samantha Burgess, Copernicus’ strategic lead for climate change, said in a statement. “El Niño is adding heat to the system on top of decades of human-induced warming. As ocean temperatures continue to rise, the risks to marine ecosystems and coastal communities are also increasing.”

The long-term rise in ocean temperatures is primarily linked to human activities, including the burning of coal, oil and gas. These activities release carbon dioxide and other greenhouse gases into the atmosphere, trapping heat and driving global warming.

El Niño is a naturally occurring climate pattern that begins with unusually warm surface waters in the tropical Pacific Ocean. It can temporarily raise global average temperatures and alter weather patterns around the world. The current event is raising concerns because it is developing on top of record levels of human-caused warming.

Researchers warn that an exceptionally strong El Niño could intensify climate-related risks and place additional pressure on already stressed ecosystems. The combination of natural variability and long-term global warming could push some marine environments closer to critical thresholds.

New Record for Global Sea Surface Temperatures

Copernicus estimates global sea surface temperatures using satellite observations and other climate data. Its measurements showed that average ocean surface temperatures reached 21.1 degrees Celsius (69.98 degrees Fahrenheit) on Saturday, narrowly surpassing the previous record of 21.09 C (69.96 F), set in 2024.

The 2024 record occurred during the previous El Niño event, which came close to the threshold for being classified as a “super” El Niño. The latest record is notable because ocean temperatures typically reach their highest daily levels in March and April, following the Southern Hemisphere summer.

Copernicus representatives said the latest record is consistent with the long-term warming trend and the development of unusually strong El Niño conditions. Monthly average sea surface temperatures in both June and July also reached record highs.

“The ocean is under unprecedented stress,” Copernicus said. The organization warned that continued ocean warming could have far-reaching consequences for the climate system, marine life and coastal communities.

Warmer oceans contribute to thermal expansion and melting ice, both of which drive sea-level rise. They also increase the likelihood of marine heatwaves, which can damage coral reefs, disrupt fisheries and affect marine food webs. Because the ocean stores and transfers vast amounts of heat, rising sea temperatures can also influence storms, rainfall and other weather patterns.

Could This Become a Super El Niño?

El Niño conditions are continuing to strengthen, although the event’s full intensity may not be clear until later this year or in 2027. The National Oceanic and Atmospheric Administration’s Climate Prediction Center has forecast a greater than 90% chance of a very strong El Niño developing during the fall and winter.

The U.K. Met Office has also warned that the event could be among the strongest in modern records and potentially the most powerful since the 19th century.

“We should be clear that this is an unprecedented event. We’ve never seen signs of El Niño this strong in our forecast,” Adam Scaife, head of long-range forecasting at the Met Office, said in an statement published August 21.

A strong El Niño does not guarantee extreme weather in every region, but more intense events generally increase the risk of significant impacts. El Niño can influence the Indian summer monsoon, for example, and some areas have already experienced rainfall well below average.

In the United States, El Niño often brings warmer-than-average winters to northern states, while the southern states may see increased storm activity and wetter conditions. However, every El Niño event is different, and its effects depend on the event’s strength, timing and interaction with other climate patterns.