WASHINGTON (May 16, 2023)—A pioneering study published today in Environmental Research Letters links the area burned by forest fires and increases in drought and fire-prone conditions to heat-trapping emissions from the largest global carbon producers.

Since the mid-1980s, 53 million acres of forested land in the western United States and southwestern Canada has burned—an area larger than the state of Idaho.
Since the mid-1980s, 53 million acres of forested land in the western United States and southwestern Canada has burned—an area larger than the state of Idaho. Credit: UCS

The findings of “The Fossil Fuels behind Forest Fires,” an analysis led by experts at the Union of Concerned Scientists (UCS), are particularly relevant to California where wildfires have grown larger and more severe. The seven largest blazes on record in the state have all occurred since 2018.

The report found that 19.8 million burned acres—37% of the total area scorched by forest fires in the Western United States and southwestern Canada since 1986—can be attributed to heat-trapping emissions traced to the world’s 88 largest fossil fuel producers and cement manufacturers. Emissions from these companies also contributed nearly half of the observed increase in conditions that raise the risk of large, severe forest fires across the region since 1901, the study found.

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California’s own catastrophic wildfires have come at great cost. Between 2017 and 2021 alone, the state’s emergency fire suppression costs exceeded $4 billion and economic damages from wildfires surpassed a staggering $21 billion, according to CalFire. A California factsheet associated with this study says those totals underestimate the true cost of wildfire because they represent the value of lost property and possessions, but fail to incorporate damages like business interruptions, lost wages, health impacts and premature deaths, and supply chain disruptions.

“Over the last several decades, human-caused climate change has turned routine Western wildfires into exceptionally destructive events. Towns are turning to ash and livelihoods are being destroyed,” said Kristina Dahl, report author and principal climate scientist at UCS. “Our study offers scientifically backed answers to questions of who bears the responsibility for this gut-wrenching destruction. We’re hopeful that with new evidence in hand, policymakers, elected officials, and legal experts will be better equipped to truly hold fossil fuel companies accountable in public, political, and legal arenas.” 

UCS scientists who conducted the study used vapor pressure deficit (VPD)—a measure of air’s ability to draw water out of plants and soils—to demonstrate how emissions traced to major fossil fuel producers have had a direct hand in the steep increases in the area burned by forest fires and the rise of fire-danger conditions. The authors also assessed the latest science on how changes in VPD have contributed to increases in the number of large fires, the length of the fire season, the severity of forest fires, and a prolonged megadrought. 

José Pablo Ortiz Partida, UCS senior bilingual water and climate scientist, summarized recent scientific research in a recent blog that finds nearly all of the increase in the area burned by summer forest fires in California from 1972 to 2018 was due to increased VPD. With rising VPD closely tied to rising temperatures fueled by human-caused climate change, Ortiz Partida wrote that the trend is a particular problem for California’s forests and agricultural industry because of its impact on drought conditions, tree mortality and wildfire risk.

Communities of color and low-income communities face disproportionate public health risks from wildfire due to systemic socioeconomic injustices and are less able to recover.

“While the impacts of increasingly dangerous wildfires are pervasive, it’s crucial to acknowledge the disproportionate devastation faced by communities of color,” saidOrtiz Partida, who is based in California’s Central Valley. “As we turn to solutions—both restorative and preventative— the needs of underserved and other vulnerable communities must be front and center.”  

The report suggests that the fossil fuel industry is not only responsible for emissions from its operations and the use of its products, but also for the increased emissions associated with wildfires, which emit large amounts of heat-trapping carbon dioxide, particularly during extreme fire years like California experienced in 2020. Failing to curtail global fossil fuel use would likely result in increased wildfires and emissions, making the state’s ambitious goals of achieving carbon neutrality by 2045 more difficult to achieve.

Holding fossil fuel companies accountable for the harm they have caused and continue to cause is critical to wildfire resilience-building efforts, according to the study. Also crucial are programs and policies that rapidly reduce heat-trapping emissions, reduce human-ignited wildfires, increase resources for forest health, protect community health and safety, and coordinate equitable investments in fire preparedness and recovery. 

Additional Resources:

  • A UCS blog by José Pablo Ortiz Partida, “California’s Thirsty Future: The Role of Vapor Pressure Deficit in Our Changing Climate and Drought.” 
  • A UCS blog by Mark Specht, “Both Utilities and Fossil Fuel Companies Are to Blame for Western Wildfires” 

The Union of Concerned Scientists puts rigorous, independent science to work to solve our planet’s most pressing problems. Joining with people across the country, we combine technical analysis and effective advocacy to create innovative, practical solutions for a healthy, safe, and sustainable future. For more information, go to www.ucsusa.org.