Wildfire risk in the United States is expected to increase and seasons will lengthen due to climate change, according to a study involving DRI, Argonne National Laboratory and the University of Wisconsin-Madison. By examining past wildfire data and future climate models, the research provides important insights for effective wildfire management.
Scientists studied multiple fire danger indices across the contiguous United States to assess the impact of climate change on future wildfire risk and seasonality.
Wildfires are one of the most devastating natural disasters in the United States, threatening lives, destroying homes and infrastructure, and causing air pollution. To properly predict and manage wildfires, managers need to understand wildfire risk and allocate resources accordingly. A new study lends scientific expertise to the effort.
Assessing future fire risks
In the study, published in the November issue of the journal Earth's Future, researchers from the Desert Research Institute (DRI), Argonne National Laboratory and the University of Wisconsin-Madison teamed up to assess future fire risks. They looked at four fire danger indices used to predict and manage wildfire risk in North America to see how risk correlated with observed wildfire size between 1984 and 2019. They then looked at how wildfire risk would change under projected future climates and found that both the likelihood of fires and the extension of wildfire seasons are likely under climate change.
comprehensive risk assessment
"We used several of these fire danger indices to assess fire risk in the contiguous United States," said Dr. Guo Yu, an RI assistant research professor and lead author of the study. "But previous studies have used only one of these indices to examine how climate change will alter wildfire risk, and only a few have looked at how fire risk translates into the size or characteristics of actual wildfires. We wanted to rigorously assess both in this paper."
The fire danger index uses information about weather conditions and fuel moisture (or how dry the ground vegetation is). The most commonly used fire danger indices in North America are the U.S. Geological Survey Fire Severity Index, the Canadian Forest Fire Weather Index, and the Energy Release Component and Burning Index of the National Fire Danger Rating System.
Correlations and climate predictions
First, scientists used satellite remote sensing data from 1984-2019 to study how potential fire risk from more than 13,000 wildfires (excluding controlled burns) correlated with final wildfire size. They found that higher wildfire risk tended to lead to larger wildfire sizes, with this relationship being stronger over larger areas.
By plugging the fire danger index into future climate projections, the study found that the risk of extreme wildfires in the continental United States will increase by an average of 10 days by the end of the century, driven primarily by rising temperatures. Some areas, such as the southern Great Plains (including Kansas, Oklahoma, Arkansas and Texas), are expected to experience an increase of more than 40 days of extreme wildfire danger per year. The annual wildfire risk season is expected to decrease in some small areas, including the Pacific Northwest and mid-Atlantic coasts, due to increased rainfall and humidity.
Regional differences and seasonal changes
In the Southwest, the extreme wildfire season is expected to increase by more than 20 days per year, with most of those occurring in the spring and summer. Fire season is also expected to extend into winter, particularly in the Texas-Louisiana Coastal Plain.
"In future climate warming, we could see even higher fire dangers in winter," Yu said. "It surprises me because it feels counterintuitive, but climate change is going to change the landscape in many ways."
Impact on fire management
The study authors hope the study will help fire managers understand the size of potential wildfires so they can prepare accordingly, and understand how fire seasonality will shift and lengthen under climate change.
Reference: "Performance of the Fire Danger Index and Its Role in Predicting Future Wildfire Danger in the Continental United States," November 20, 2023, The Future of the Planet.
doi:10.1029/2023ef003823
Compiled source: ScitechDaily