Makoto Kelp, Marshall Burke, Minghao Qiu, Iván Higuera-Mendieta, Tianjia Liu, Noah S Diffenbaugh

Prescribed fire is increasingly proposed as a policy strategy to reduce wildfire risks, but evidence of its effectiveness in lowering fire severity and smoke emissions remains limited in the western US. We empirically demonstrate that areas treated with prescribed fire and subsequently burned during California’s extreme 2020 wildfire season showed a -14% net reduction in smoke emissions, though these treatments were less effective near populated areas. Our findings suggest that expanding prescribed fire use can meaningfully reduce smoke emissions, even when factoring in smoke from the prescribed fires themselves. The proposed policy of treating one million acres annually in California could reduce overall smoke emissions by 655,000 metric tons over the next five years—equivalent to 52% of the emissions from 2020 wildfires. Our results also suggest that broader application of prescribed fires can provide benefits in mitigating severe wildfire impacts and improve air quality in fire-prone regions worldwide.