Climate Corner
Wildfires and climate
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To provide a better understanding of what climate change means for Montanans, we are hosting a new monthly series, entitled Montana Climate Matters. Each month, you’ll hear from experts knowledgeable about climate science, impacts, and solutions. Our goal in this endeavor is to facilitate understanding, promote discussion, and help provide a roadmap for action on this critical issue. We hope you’ll follow the series and consider it an opportunity to stay informed.
With record-breaking fire seasons devastating communities across Montana and the West, the search for factors driving the increase in large, destructive fires becomes more urgent. Studies show that fire sizes have increased dramatically over the past two decades, and when ignitions coincide with strong winds and desiccated fuels, fires spread in ways that are nearly impossible to control using traditional firefighting methods. Preparing communities for wildfires requires a coordinated effort, investment in mitigation strategies and a recognition of the risks caused by a warming climate driven by human-caused increased greenhouse gases in the atmosphere.
Large wildfires, as well as urban conflagrations, are clearly linked to warm, dry conditions. Between 1950 and 2015, daily minimum, maximum, and average temperatures in Montana rose by 2–3°F. Unprecedented heat waves and drought in the West have dried fuels, creating an environment primed for explosive wildfire. Researchers have found that human-caused warming accounted for a 55% increase in fuel aridity from 1979 to 2015 in the western US, nearly doubling the annual acreage burned between 1984 and 2015. Across the American Southwest, 2000 to 2018 was the driest span since the late 1500s.
In Montana, the 2020 Bridger Foothills fire grew from less than 100 acres to over 8,000 acres in a matter of hours, this despite an intensive firefighting effort. Seven of the largest fires in Montana in the past century have occurred since 2000, including the state’s largest fire on record—the Lodgepole Complex, which burned 271,000 acres. Along with the Rice Ridge and Lolo Peak fires, these three fires contributed to a total destruction of over 1.3 million acres in 2017, the worst fire season since the Big Burn of 1910. An average of over 300,000 acres have burned annually in Montana since 2000, in stark contrast to the less than 30,000 acres that burned per year on average in the preceding 90 years. This dramatic increase in wildfire activity corresponds with a sharp rise in annual temperatures.
Historically, the West experienced a defined fire season lasting several months, but wildfires can now occur any time of year. A fire swept through Denton, Montana, in December 2021, and the Marshall Fire raged in late December 2021 and early January 2022 in Colorado. The growing year-round wildfire risk escalates the costs of wildfire response. The 2017 fire season was the first time Montana’s wildfire-related costs surpassed $1 billion.
Even when vegetation around communities is managed through fuel reduction efforts, firebrands or embers from wildfires miles away can still ignite homes. Once individual homes catch fire, strong winds drive flames from house to house, creating fires that spread without the need for vegetation, causing widespread destruction in urban areas.
Numerous strategies have been proposed to mitigate the negative impacts of the increasing incidence of large wildfires, beginning with efforts to reduce greenhouse gas emissions. A comprehensive approach is needed, incorporating traditional burning practices and prescribed burns to reduce woody fuel loads—particularly where homes are built near forests. Other key measures include home hardening and managing fuels within the home ignition zone (0–300 feet around the home). Preparing communities for wildfires also involves improving access for emergency responders, designating safe zones, and pre-fire coordination among multiple agencies and organizations.
Ultimately, a warming climate will continue to lead to larger, more frequent, and costlier wildfires across the West. As more people move to and recreate in Montana and the region, the number of communities facing wildfire risk increases. Effective strategies for wildfire preparedness and response must acknowledge and anticipate the unavoidable impacts of climate change on the future of wildfires in the West.
Dave McWethy Ph.D., is an Associate Professor in the Department of Earth Sciences at MSU-Bozeman. The opinions expressed herein are his alone.
