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Last year was the third-hottest on record, according to an analysis of temperature data released Wednesday by three independent agencies. That puts 2025 just behind the second-hottest year, 2023, and the hottest, 2024.
What makes this result extraordinary, scientists say, is that 2025 saw a cooling phase in the equatorial Pacific Ocean, or La Nina, that suppresses global temperatures. In other words: Heat from greenhouse gases countered that cooling influence enough that the year still landed among the very warmest.
It’s more evidence that “human-caused warming is now really overwhelming inter-annual natural variability” in weather, said Daniel Swain, a climate scientist in the University of California’s Agriculture and Natural Resources division.
The notable 2025 heat is in line with what many scientists say is a recent speeding up of the pace of global warming. “The warming spike observed from 2023-2025 has been extreme, and suggests an acceleration,” wrote researchers with Berkeley Earth, a scientific nonprofit that maintains one of the temperature databases.
Several factors are likely contributing to the acceleration, they wrote, including declines in reflective low-hanging clouds and in sulfur pollution from shipping that has a cooling effect.
The EU’s Copernicus Climate Change Service, the U.K. Met Office and Berkeley Earth found that 2025 was hotter than the 1850-1900 average by 1.47 degrees Celsius, 1.41 C and 1.44 C, respectively.
According to Copernicus, the three-year warming average is now for the first time above 1.5 C — the threshold that countries pledged not to breach in the 2015 Paris Agreement. The group estimates that the world might fully surpass the 1.5 C mark by mid-2029, 13 years sooner than was projected when countries signed the pact. (Exceeding the Paris limit itself doesn’t mark a step-change in worsening climate impacts; it’s more of a diplomatic target.)
Humans burning fossil fuels is the overwhelming cause of global warming and provides a long-term push on the planet’s temperature. Because worldwide emissions continue to rise, the past 11 years have all been among the 11 hottest, and the hottest 25 years have all occurred since 1998.
At least half the globe’s land in 2025 faced a higher-than-average number of heat-stress days, or conditions that feel like at least 32 C. Greenland warmed in May more than 12 C above average in some places. The ice there melted 12 times faster than usual on May 19.
The extra heat makes extreme weather worse. More than 400 people died in wildfires in Los Angeles in January, and the area saw $40 billion in insured losses alone. Climate change made the fire weather 35% more likely, according to World Weather Attribution, a scientific group that analyzes weather events shortly after they occur to determine the role that climate change may have played.
Year to year, fluctuations in the average temperature reflect short-term weather conditions as much as climate change. The presence of a warming El Nino or cooling La Nina phase in the equatorial Pacific Ocean is usually the controlling factor in where any year ranks among the most recent several.
Considering that the Pacific last year was in either a neutral phase or a slight tilt toward La Nina, 2025 was hot. It was only negligibly cooler than 2023, a year that saw an El Nino emerge in the summer. In fact, last year was hotter than every El Nino year before 2023.
Lower temperatures in the tropics offset surging heat elsewhere in 2025. It was Antarctica’s hottest-ever year and the second hottest for the Arctic. February set a new record low for global sea ice, according to Copernicus.
Total precipitation was more or less average, a fact that belies destructive flooding in many parts of the world.
(Left) Residents look out from their homes surrounded by high floodwaters in Hat Yai, in Thailand’s southern Songkhla province, on Nov. 26. (Right) An aerial view of a home surrounded by water in Kangar in northern Malaysia’s Perlis state, on Nov. 27.
| AFP-JIJI / Getty Images / Bloomberg
In central Texas in early July, flash flooding killed more than 135 people, including 27 children and counselors at Camp Mystic in Kerr County. Pakistan saw a near-repeat of its deadly 2022 floods during its monsoon season. More than 1,750 people perished in Sri Lanka, Indonesia, Malaysia, Vietnam and Thailand in late November, when three cyclones engulfed a region not known for them.
Jamaicans, accustomed to hurricanes, watched Melissa approach in early October. It rapidly intensified into a Category 5 storm with the strongest wind gust ever measured — 252 miles per hour (405 kilometers per hour). Melissa did $8.8 billion of damage to the island, or 41% of its 2024 GDP, and claimed more than 100 lives across Jamaica, Haiti, the Dominican Republic and Cuba.
“If such a storm just hits you face-on, there is just not much that you can do,” said Friederike Otto, co-founder of World Weather Attribution. Greenhouse gas pollution is making storms more powerful and “the change in intensity really makes a difference.”
WWA found that climate change made the high ocean temperatures that fueled Melissa about six times more likely.
Berkeley Earth expects a 2026 global average temperature similar to last year’s, ranking perhaps 4th on record, with the current La Nina giving way to a neutral phase. It’s too early to predict the next El Nino, which — when it comes — now usually brings a new global temperature record, too.
The 2025 heat analysis comes after the U.S., long the world’s anchor of climate science and diplomacy, has moved to abandon that role. The administration has dismissed hundreds of scientists, removed authoritative reports and risk tools from the internet and earlier this month pledged to exit both the foundational 1992 U.N. climate treaty and the U.N.’s scientific advisory, the Intergovernmental Panel on Climate Change.
Florian Pappenberger is director general of the European Centre for Medium-Range Weather Forecasts, which operates Copernicus. “Data and observations are essential to our efforts to confront climate change and air-quality challenges,” he said, “and these challenges don’t know any borders.” Pappenberger called the Trump administration’s stance toward climate data “concerning.”
Despite wild growth in clean-energy technologies, greenhouse gas emissions are at an all-time high and the world consequently is choosing to remain on “a very bad climate trajectory,” Swain said.
“We still have the ability to manage this, but we’re not managing it,” he said. A “period of global cooperation, for many different types of things, seems to have at least for now ended.”
