The climate crisis inflamed deadly wildfires that left 23 people dead in Chile and devastated forests in Argentina that host some of the world’s oldest trees, scientists have found.

The hot, dry and windy conditions that enabled the fires to blaze across huge areas in January were made about three times more likely by global heating, researchers from the World Weather Attribution (WWA) consortium found.

Parts of Chile and Argentina are experiencing significantly drier summers as a result of human-caused carbon emissions, with rainfall now 25% lower in early summer in Chile and 20% lower in the affected region of Patagonia.

Severe wildfires left the Chilean regions of Biobío and Ñuble in a “state of catastrophe” in mid-January and killed 23 people, destroyed more than 1,000 homes and forced 52,000 people to flee. The fires were driven by temperatures exceeding 37C and strong winds.

In Argentina, wildfires broke out in early January, affecting the Unesco-listed Los Alerces national park in Patagonia, home to ancient alerce trees that can live for more than 3,000 years. The damage is thought to have been worsened by large budget cuts to fire management services by the government led by Javier Milei, who has called the climate crisis a “socialist lie”.

Dr Juan Antonio Rivera, of the National Scientific and Technical Research Council in Mendoza, Argentina, who is part of the WWA team, said: “Ancient forests were devastated, as was the unique biodiversity in the area. These are ancient giants that have stood undisturbed for thousands of years.

“Unfortunately with a government that does not understand climate change and its connection to human activities, and where nature is secondary in terms of priorities, wildfires end up having greater impacts than they should. The drying of our landscapes is no longer a projection but a crisis that needs an urgent response to protect our unique biodiversity and the people of our region.”

Dr Clair Barnes, of Imperial College London, who is also part of the WWA team, said: “Our analysis shows a clear and dangerous fingerprint of climate change on these fires. By burning fossil fuels, we have essentially loaded the dice, making the conditions for these devastating blazes more likely.”

The scientists said the supercharging of extreme weather would continue to increase until humanity stops burning fossil fuels.

The study used peer-reviewed methods and data from weather records and climate models to determine how much more likely the hot, dry and windy conditions were as a result of global heating.

The situation in Chile was worsened by non-native tree plantations that are more flammable than native trees. “These plantations are located directly next to settlements, as was seen in Valparaíso in 2024,” said Mauricio Santos-Vega, of the Red Cross Red Crescent Climate Centre. Wildfires ravaged Valparaíso and other nearby regions in 2024, leaving at least 131 people dead.