A recent study suggests that prescription burns could effectively lessen the impact of future wildfires by about 16% and reduce smoke pollution by 14%. These controlled burns seem to have greater success outside the wild-urban interface (WUI) — the zones where urban areas meet wild vegetation, according to findings released on Thursday.
Makoto Kelp, a postdoctoral researcher at Stanford University, remarked, “While prescription fires are often touted as a valuable tool against wildfires, our study provides clear evidence that they really work in practice.” Kelp went on to clarify that not every treatment is equally effective, but when applied well, prescribed burns can significantly reduce the damage caused by severe wildfires.
Experts have long viewed prescribed burns as a viable way to manage wildfire risks, with the researchers noting that $2 billion in federal funds have been earmarked for such efforts. However, the uptick in using these controlled fires in the western U.S. has only been modest in recent years. The researchers speculated that this inconsistency might stem from a lack of solid research on effectiveness and differing public opinions on the practice.
To illustrate the benefits of prescribed burns, scientists analyzed high-resolution satellite images, land management records, and smoke emission data to compare treated and untreated areas during the intense fire season of 2020. They specifically focused on regions that underwent controlled burns and adjacent untreated areas from late 2018 through spring 2020.
Their findings indicated that areas subjected to prescribed fire experienced reduced extreme burning and emitted significantly less smoke. This outcome was particularly crucial for the authors, as they highlighted the connection between particulate matter (PM 2.5) from wildfires and health issues such as cardiovascular and respiratory problems. Marshall Burke, an associate professor at Stanford, emphasized that “smoke is a silent threat, and prescription fires may be one of the few tools we have to actually lower smoke exposure.”
Interestingly, their research revealed that controlled burns contribute to only about 17% of the PM 2.5 smoke seen during wildfires in those areas. They projected that if California meets its goal of conducting prescribed burns on 1 million acres annually, the state could reduce PM 2.5 emissions by 655,000 tons over five years—amounting to 52% of the total smoke generated during California’s 2020 wildfire season.
Regarding the effects in WUI versus non-WUI zones, the authors found a reduction in fire severity of 8.5% in WUI areas, and about 20% in non-WUI areas. Typically, WUI zones have favored mechanical thinning over prescribed burns due to concerns about smoke and safety.
While the researchers couldn’t yet fully explain this inconsistency, they emphasized the necessity of further understanding the issue. Noah Defembaugh, a senior author and professor at Stanford’s School of Sustainability, pointed out that rapid population growth in the WUI region, where vegetation is particularly vulnerable to climate impacts, underscores the need for better insights into why prescribed burns in these areas are not as effective.
