Human-driven climate change has made wildfires in parts of South America and Southern California many times larger and more destructive this year.

An annual assessment by international experts has cautioned according to climate models, the Los Angeles wildfires in January were twice as likely and 25 times larger, in terms of burned area, in the current climate than they would have been in a world with no human-caused global warming. It also made last year’s burning in the Pantanal-Chiquitano region in South America 35 times larger, while also driving record-breaking fires in the Amazon and Congo.

However, it added it is still too early to tell how much climate change contributed to the impacts of the wildfires.

The new report warned that more severe heatwaves and droughts are making extreme wildfires more frequent and intense worldwide, resulting in increasing threats to people’s lives – through fire and polluting smoke – as well as property, economies and the environment.

The second annual State of Wildfires report has been co-led by the UK Centre for Ecology & Hydrology (UKCEH), the UK Met Office, the University of East Anglia (UEA) and the European Centre for Medium-Range Weather Forecasts (ECMWF). The scientists used satellite observations as well as advanced modelling to identify and investigate the causes of wildfires from the last fire season (March 2024-February 2025) and the role that climate and land use change played.

UKCEH land surface modeller Dr Douglas Kelley, who co-led this year’s report, said: “Our annual reports are building unequivocal evidence of how climate change is increasing the frequency and severity of extreme wildfires. Without human-driven warming, many of these wildfires, in Pantanal and Southern California, for example, would not have been on an extreme scale.”

Report co-lead Dr Francesca Di Giuseppe of ECMWF explained: “Climate change is not only creating more dangerous fire-prone weather conditions, but it is also influencing the rates at which vegetation grows and provides fuel for the fires to spread.

“Our analyses detected the critical role of both extreme weather and fuel in the Los Angeles fires, with unusually wet weather in the preceding 30 months contributing to strong vegetation growth and laying the perfect foundations for wildfires to occur when unusually hot and dry conditions arrived in January.”

The amount and dryness of vegetation also played a critical role during the extreme wildfires in Amazonia and Congo, where abnormally dry forests and wetlands allowed fires to spread faster and further.

The scientists warned whatever global action is taken on climate change, there will still be more wildfires across the world in future due to the warming that has already happened. However, large-scale reductions in greenhouse gas emissions will mean the predicted increases in frequency and severity of fire will be at a much-reduced rate.

Report co-lead Dr Matthew Jones, from UEA’s School of Environmental Sciences, said: “We urge world leaders at COP30 to make bold commitments to cut greenhouse gas emissions rapidly this decade. This is the single most powerful contribution that most developed nations can make to avoiding the worst impacts of extreme wildfires on living and future generations.”

Dr Maria Barbosa, a wildfire scientist at UKCEH and co-author of the report, added: “It is not too late to act to prevent a dramatic escalation in wildfires in regions across the world, and limit the risks to people, property, infrastructure, economies and biodiversity.”