Earth's oceans reached their hottest temperature ever recorded on August 22, 2026, hitting an average sea-surface temperature of 21.10 degrees Celsius (69.98 degrees Fahrenheit), according to the European Union's Copernicus Climate Change Service (C3S). The new record edges past the previous high of 21.09 degrees C set in March 2024.
A Record Built on Warming and El Nino
The record reflects the combined effect of decades of human-caused climate change and the emergence of an exceptionally strong El Nino event. The cyclic climate pattern, marked by unusually warm Pacific Ocean temperatures, is expected to intensify in the coming months, meaning this record is unlikely to stand for long.
"As a climate scientist, this is not surprising to me at all," says Zachary Labe, a climate scientist at Climate Central. "It's consistent with decades of research showing how our climate is changing as the planet warms. And without reductions in the burning of fossil fuels, this warming will only continue."
Consequences for the Planet
The implications of rising ocean temperatures extend far beyond the water itself:
- Sea-level rise: Warmer water expands thermally, directly contributing to rising seas that threaten coastal communities worldwide. - Coral reef collapse: Elevated temperatures trigger mass coral bleaching events. The existing El Nino-related coral bleaching story in today's issue documents how ancient coral records show El Nino events are now 36 percent stronger than pre-industrial levels. - Extreme weather: Hotter oceans fuel more intense hurricanes, typhoons, and atmospheric rivers, increasing the risk of catastrophic flooding and wind damage. - Marine ecosystems: Shifting temperatures force species to migrate, disrupting food chains and fisheries that billions of people depend on for protein.
What Comes Next
The Met Office has predicted an unprecedented sea-surface temperature rise of up to 3 degrees Celsius above the 1991-2020 average during the current El Nino event. Samantha Burgess, strategic lead for climate at the European Center for Medium-Range Weather Forecasts, called the record "another clear signal of an ocean under growing stress."
Climate scientist Labe warns this record will likely be broken again in coming months. "This won't be the last time we say this, and unfortunately, it's very possible we could break this record again," he says.
The data comes from the C3S ERA5 reanalysis, which combines satellite observations with ground-based measurements to produce daily global sea-surface temperature estimates.
Sources: Scientific American, The Guardian, Washington Post, Al Jazeera, Copernicus Climate Change Service.
