Burning down the house: Wildfire and the benefits of natural disaster mitigation

For more than a century, government wildfire managers have aggressively suppressed wildfires within western U.S. forests. In that time, our understanding of the ecological benefits of wildfire has improved. Nevertheless, it has been politically difficult for managers to limit suppression effort, even for relatively non-threatening wildfires. As wildfires within the western U.S. become more frequent, more severe, and more costly to manage, it will become increasingly important to allocate responses to wildfire efficiently. Yet we know very little about benefits of wildfire suppression, in part because it is difficult to know how a fire might have spread in absence of suppression. To estimate benefits of wildfire suppression, I adopt a two-step strategy. In the first step, I use a novel spatial duration model, historical fire perimeters, and outputs from a state-of-the-art wildfire simulation tool to estimate the relative contributions of fire suppression effort and physical factors to the probability a wildfire will be extinguished. In the second step, estimates of the model are used to predict fire spread probabilities with and without suppression effort, and these probabilities are used to compute estimates of avoided structure losses due to wildfire suppression. Comparing estimated benefits of wildfire suppression to reported costs, I find that the net benefits of fire suppression vary substantially across fires. While in some cases wildfire suppression generates large net benefits, avoided losses to structures do not justify costs of suppression for many wildfires, especially those that begin in remote areas. In recent years, a series of devastating wildfire events—including the Rim Fire in Yosemite National Park in 2013, the Fort McMurray wildfire in Alberta in 2016, and a cluster of fires in northern California in October 2017—have occurred in the western U.S. and Canada. These wildfires are part of a pattern of increasingly frequent and severe wildfires in the region. Since the ∗Correspondence: Matthew Wibbenmeyer, 2127 North Hall, University of California, Santa Barbara, California 93106. E-mail: [email protected].