While the trend to more extreme fire weather days is well understood for many regions worldwide, a new study has identified the rising incidence of widespread concurrent extreme fire weather days across multiple global regions. The increased risk of concurrent fires poses significant social and ecological consequences and may complicate the global sharing of fire suppression and other resources.

Researchers from the University of California, the Chinese Academy of Sciences, and other institutions looked into trends of synchronous fire weather to identify the risks it poses to communities and fire response. Previous studies found that the increasing trends intensify the demands on fire suppression efforts, worsen air pollution, and adversely impact human health, but these researchers hoped to provide a more comprehensive understanding of the phenomenon.

The researchers analyzed trends of synchronous fire weather in 14 regions defined by the Global Fire Emissions Database and explored the relationships between the weather, climate variability, and air pollution exposure. They found “significant” positive increases in synchronous fire weather across most of the world’s regions over the past 50 years, including the western US, Europe, and Australia, along with South America and Southern Africa, both recognized as major global carbon emission hotspots.

Matt Jones, a scientist at the Tyndall Centre for Climate Change Research and one of the study’s authors, said the increase in fire weather will strain the numerous wildfire response resource-sharing agreements that numerous countries rely on.

“If one country is already managing a high-risk situation at home, sending support elsewhere may simply not be possible,” Jones said. “In effect, rising synchrony increases competition for finite firefighting resources.”

Jones also said the trends identified by the study signal the need for a further focus on how the increasing pattern of synchronous fire weather may evolve under future climate change and closer collaboration among fire management agencies in workforce planning and mutual aid agreements.

Click here to read the full study in Science Advances.