Attribution of Extreme Fire Weather under Climate Change: Insights from the 2024–2025 Fire Seasons

Wildfires are among the most significant natural hazards, posing growing threats to ecosystems, human health, and infrastructure worldwide. In recent years, extreme wildfire events have occurred with increasing frequency across multiple regions, raising concerns that conditions once associated with exceptional fire seasons are becoming more common. The 2024–2025 fire year reflects this pattern, with particularly severe impacts in the Americas, including infrastructure and economic losses in western North America and major ecological, carbon, and air-quality impacts in the Amazon and Pantanal, alongside extremes in the Congo Basin. Understanding the role of human-induced climate change in driving these changes is essential for robust attribution and effective risk communication.

Here, the study presents an attribution analysis of individual extreme wildfire events that occurred between March 2024 and February 2025, as part of the State of Wildfires 2024-2025 report. Extreme fire-weather conditions were quantified using the Canadian Fire Weather Index (FWI; based on climate variables of temperature, precipitation, relative humidity, and wind speed), drawing on both observational datasets (ERA5) and the latest generation of global climate model ensembles (CMIP6). An established probabilistic event attribution framework is employed to evaluate the influence of anthropogenic climate change on the likelihood of high fire weather conditions, utilising simulations from the HadGEM3-A large ensemble to compare historical and present-day climates. A new empirical-statistical method was applied to project changes in risk under future global warming levels by using a set of CMIP6 models. Results indicate at least a threefold increase in the probability of extreme fire weather for three selected events from the past to the present period, with a further 1.5-6.4 times more likely to occur under future scenarios, underscoring the growing influence of climate change on wildfire hazards and the need for forward-looking fire management.