Global ocean temperatures have reached their highest daily average ever recorded, a development scientists attribute to the escalating Super El Niño and ongoing human-driven warming. On August 22, sea surface temperatures outside of polar regions registered 21.1°C (69.98°F), surpassing the previous record set in March 2024, according to the Copernicus Climate Change Service.
This August 22 also marked the hottest August day for the world's oceans since records began, exceeding the prior record from 2023. The current surge is linked to a developing Super El Niño in the tropical Pacific, which is causing a significant accumulation of warm water.
Experts emphasize that the El Niño phenomenon is adding heat to an ocean system already warming over decades due to climate change. Temperatures in the key El Niño region are approximately 2.6°C (4.7°F) above the long-term seasonal average, with projections suggesting further increases. The Met Office predicts Pacific warming could reach 3°C (5.4°F), and some reports indicate a potential rise as high as 4°C (7.2°F).
Samantha Burgess, Strategic Lead for Climate at the European Centre for Medium-Range Weather Forecasts, stated that the record is a clear indication of an ocean under stress, with El Niño amplifying existing human-induced warming. The timing of this record is particularly concerning, as sea surface temperatures typically peak in March or April following the Southern Hemisphere summer. The late August record underscores the immediate impact of El Niño on global weather patterns.
The El Niño Southern Oscillation (ENSO) is a natural climate cycle that alternates between warm El Niño and cool La Niña phases every two to seven years. During an El Niño phase, the trade winds that normally push warm water across the Pacific weaken or reverse, hindering the upwelling of cooler deep-ocean water and causing warm water to pool near the surface off the coast of South America.
This collected warm water then disperses, raising global average temperatures and disrupting weather patterns worldwide. The current warming is described as reaching "unprecedented" levels, with El Niño building on a scale not seen since the 19th century. While most of the heating is concentrated in the Equatorial Pacific, its effects are being felt globally.
Last month was the hottest July on record for oceans outside polar regions, with temperatures at 20.96°C (69.7°F). Coastal regions in Europe have also experienced a series of marine heatwaves.
The combination of El Niño and long-term ocean warming poses significant risks. Warming oceans contribute to sea level rise as water expands when heated, and increase the likelihood of extreme weather events such as tropical storms and hurricanes. Burgess noted that rising ocean temperatures heighten risks for marine ecosystems and coastal communities, with the number of global marine heatwave days tripling since the early 1990s.