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Low-intensity fires reduce the risk of catastrophic wildfires by 60 percent 

Low-intensity fires can significantly mitigate the risk of devastating wildfires, according to new research from Columbia University Mailman School of Public Health and Stanford University. 

The study reveals that practices like controlled burns, managed wildfires, and tribal cultural burning can decrease the risk of catastrophic fires by 60 percent.

Study significance 

The analysis was focused on over 100,000 square kilometers of California forests. This research is particularly relevant, as it comes five years after California’s deadliest wildfire, the Camp Fire. 

The study also aligns with Congress’s reassessment of the U.S. Forest Service’s wildfire strategy during the reauthorization of the Farm Bill.

Goal of the research

“The goal of this paper is to provide a unified analysis of fire dynamics across California’s forests, based on 20 years of continuous, satellite-based monitoring of wildfires. We consider data from all fires detected by satellite monitoring in California’s conifer and hardwood forests during our study period,” wrote the study authors. 

“Using these data, we seek to measure whether areas that burn at low intensity are less likely to experience high-intensity wildfire in the future – and how long any such protective effect lasts.”

Broader focus 

“It’s no secret that wildfire-prone regions need to shift from a single-minded focus on suppression to one that includes much more controlled burning and forest resilience,” said study lead author Xaio Wu.

“However, until now, studies assessing the beneficial effects of prescribed and low-intensity fires have been limited to relatively small areas, such as a single wilderness area or watershed.”

Unique approach 

To measure the protective effect of low-intensity fires, the team used a method that assembled unburned areas into a synthetic landscape closely resembling the burned landscapes’ attributes – such as weather patterns, elevation, vegetation type, and disturbance history. 

According to the experts, this approach allowed them to assess how these burned landscapes might have evolved had they not burned in that same year.

Key insights

The experts found that low-intensity fire in mixed conifer forests in California initially provides a 60 percent reduction in risk of catastrophic fire. This reduced risk lasts at least six years but diminishes over time.

A significant discovery was that low-intensity fire in mixed conifer forests in California offers a substantial reduction in the risk of catastrophic fire. While the effect is smaller in oak-dominated forests, it remains significant.

Useful results

According to the researchers, policymakers could use the study’s results as a foundation for future evaluation of wildland fuel treatments by comparing the quantified benefits to potential costs and risks associated with its implementation. 

The U.S. Forest Service has proposed treating nearly 200,000 square kilometers over the next decade, and California plans to increase its land treatment for wildfires to 2,000 square kilometers annually.

Wildland fuel treatments 

The study emphasizes that for wildland fuel treatments to be effective, they must be ongoing and periodic, especially for forests near communities or critical infrastructure. 

“The purpose of fuel treatments is not to exclude all future fires, but rather to increase the likelihood that, upon the inception of a fire within a designated area, the fire remains low to moderate intensity and exhibits a reduced rate of spread,” explained the researchers.

“This mitigation strategy provides windows of opportunity for control through the allocation of additional suppression resources and reduces the potential for the fire to develop into a high-intensity fire.”

Practical solutions

The risk mitigation benefit of low-intensity burning depends on careful selection and targeting of the intervention to maximize protection for people, communities, and ecosystems.

“This study exemplifies how data science can contribute to climate mitigation through a highly multidisciplinary collaboration,” said Wu. “Wildfires present substantial threats to both our ecosystems and human well-being. As scientists, our constant goal is to find practical solutions.”

Study implications

“I’m hopeful that policymakers will rely on this work as motivation and support for the scale-up of beneficial fire as a key strategy in preventing wildfire catastrophes,” said study co-author Michael Wara, director of the Climate and Energy Policy Program at the Stanford Woods Institute for the Environment. 

“Beneficial fire is not without its own risks – but what our study shows is just how large and long-lasting the benefits are of this crucial risk reduction strategy.”

The study was funded by the National Institutes of Health and Stanford Data Science.

The research is published in the journal Science Advances.

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