Scientists said 2025 was one of the three hottest years on record and that human-caused climate change worsened extreme weather during the year. The analysis was released in Europe by the World Weather Attribution group on Tuesday, as people across the world faced dangerous heat, drought and flooding.
The WWA researchers said climate change worsened by human behavior made 2025 one of the three hottest years on record. They said it was also the first time the three-year temperature average broke through the threshold set in the 2015 Paris Agreement of limiting warming to no more than 1.5 degrees Celsius (2.7 Fahrenheit) since preindustrial times.
WWA scientists said they identified 157 extreme weather events as the most severe in 2025, using criteria including causing more than 100 deaths, affecting more than half an area’s population or having a state of emergency declared. Of those events, the researchers closely analyzed 22.
In the analysis, the group said dangerous heat waves were the world’s deadliest extreme weather events in 2025. The researchers said some of the heat waves they studied this year were 10 times more likely than they would have been a decade ago due to climate change. Friederike Otto, a co-founder of World Weather Attribution and an Imperial College London climate scientist, told The Associated Press, “The heat waves we have observed this year are quite common events in our climate today, but they would have been almost impossible to occur without human-induced climate change.” Otto added, “It makes a huge difference.”
The WWA analysis also said temperatures remained high despite La Nina, an occasional natural cooling of Pacific Ocean waters that influences weather worldwide. The researchers cited continued burning of fossil fuels—oil, gas and coal—which send planet-warming greenhouse gases into the atmosphere. Otto warned, “If we don’t stop burning fossil fuels very, very, quickly, very soon, it will be very hard to keep that goal” of warming, and said, “The science is increasingly clear.”
WWA described other extremes from 2025, including drought and floods. It said prolonged drought contributed to wildfires that scorched Greece and Turkey. The group said torrential rains and flooding in Mexico killed dozens of people and left many more missing. It also cited Super Typhoon Fung-wong, saying it forced more than a million people to evacuate in the Philippines, and it said monsoon rains battered India with floods and landslides.
The analysis said increasingly frequent and severe extremes threatened the ability of millions of people to respond and adapt to those events with enough warning, time and resources, which the scientists called “limits of adaptation.” As an example, it pointed to Hurricane Melissa, saying the storm intensified so quickly it made forecasting and planning more difficult and pummeled Jamaica, Cuba and Haiti so severely that it left the small island nations unable to respond to and handle extreme losses and damage.
The report also described climate diplomacy and policy developments. It said this year’s United Nations climate talks in Brazil in November ended without any explicit plan to transition away from fossil fuels, and said that while more money was pledged to help countries adapt to climate change, those efforts will take more time.
Officials, scientists and analysts have conceded that the Earth’s warming will overshoot 1.5 degrees Celsius, the analysis said, though some said reversing that trend remains possible. The report described uneven progress across countries, saying China is rapidly deploying renewable energies including solar and wind power but is also continuing to invest in coal. It said some European nations, despite calls for climate action, cite limits on economic growth. It also said the Trump administration steered the United States away from clean-energy policy toward measures that support coal, oil and gas.
Otto said policymakers have prioritized fossil-fuel industry interests over public needs, telling AP: “The geopolitical weather is very cloudy this year with a lot of policymakers very clearly making policies for the interest of the fossil fuel industry rather than for the populations of their countries.” She also said there was “a huge amount of mis- and disinformation that people have to deal with.”
Andrew Kruczkiewicz, a senior researcher at the Columbia University Climate School who was not involved in the WWA work, said places are facing disasters they are not used to. He told AP that extreme events are intensifying faster and becoming more complex, requiring earlier warnings and new approaches to response and recovery. Kruczkiewicz added that “On a global scale, progress is being made,” but that “we must do more.”