Australia faced its most catastrophic bushfire conditions since the 2019-2020 fire season in January, with over 30 blazes scorching 350,000 hectares and destroying more than 300 structures. But the scale of the crisis isn’t just about the intensity of individual fires; a new study reveals a disturbing trend: the conditions for major wildfires are increasingly aligning across different parts of the world simultaneously.
Researchers publishing today in the journal Science Advances report that the ideal conditions for major wildfires are now aligning across the globe at more than double the rate they did nearly 50 years ago. The study, led by Cong Yin of the University of California Merced, analyzed global climate and fire data between 1979 and 2024, tracing a “fire weather index” – a measure of fire danger based on temperature, wind, and moisture. They found a significant increase in days where extreme fire weather conditions occurred in multiple regions at once, like North America, and Europe.
Climate change is a major driver of this trend, accounting for roughly half of the increase, according to the research. This isn’t simply about more frequent wildfires; it’s about more fires happening at the same time, in different places, stretching resources and increasing the risk to both human life and the environment. “They are more difficult to predict or measure,” Yin said. “If we seek to do a better job, we need to measure all these three dimensions.”
The consequences are already being felt. Wildfire smoke is linked to tens of thousands of premature deaths annually in the United States, and recent years have demonstrated its ability to travel vast distances. East Coast residents, for example, vividly remember the amber haze that descended on cities like New York and Philadelphia due to Canadian wildfires, triggering widespread air quality warnings. One study estimated that smoke from those fires contributed to 82,000 deaths.
The increasing frequency of simultaneous wildfires also strains international firefighting cooperation. In recent years, countries have relied on assistance from neighbors and allies to combat major blazes. Canada and Mexico sent teams and equipment to fight wildfires in Los Angeles last year, even as the Netherlands, France, and Italy provided firefighting aircraft to Spain during its summer wildfires. Australia, New Zealand, and the US maintain a standing agreement to share personnel and equipment. However, as more regions experience simultaneous extreme fire weather, the availability of external assistance diminishes.
The study highlights that the boreal regions – forested areas in northern latitudes – are experiencing the highest levels of synchronized fire weather, with extreme heat, little rain, and high winds occurring more frequently at the same time. Conversely, some areas, like Southeast Asia, are seeing fire conditions develop into less aligned, likely due to increasing humidity as temperatures rise.
Researchers constructed a model simulating a world without climate change to isolate its impact. The comparison revealed that human-caused climate change has contributed to about half of the observed increase in synchronized fire weather since 1979. Robert Field, a fire researcher at Columbia University who was not involved in the study, called the findings a “prelude to what’s coming,” noting he hadn’t seen a study of this scale before. Vox
The study also underscores the limitations of current fire risk assessments, which may systematically underestimate the true threats, particularly as temperatures continue to rise and communities expand into fire-prone areas. Beyond firefighting, experts emphasize the need for proactive landscape management, including controlled burns, and, crucially, reductions in greenhouse gas emissions.
As the threat of simultaneous severe fires grows, the question remains whether current international cooperation agreements and resource allocation strategies will be sufficient to address the escalating crisis. The University of East Anglia reported that the rising risk compromises international firefighting efforts, but details on how those efforts will adapt remain unclear.
