title: Incorporating Anthropogenic Influences into Fire Probability Models: Effects of Human Activity and Climate Change on Fire Activity in California.
abstract: The costly interactions between humans and wildfires throughout California demonstrate the need to understand the relationships between them, especially in the face of a changing climate and expanding human communities. Although a number of statistical and process-based wildfire models exist for California, there is enormous uncertainty about the location and number of future fires, with previously published estimates of increases ranging from nine to fifty-three percent by the end of the century. Our goal is to assess the role of climate and anthropogenic influences on the state's fire regimes from 1975 to 2050. We develop an empirical model that integrates estimates of biophysical indicators relevant to plant communities and anthropogenic influences at each forecast time step. Historically, we find that anthropogenic influences account for up to fifty percent of explanatory power in the model. We also find that the total area burned is likely to increase, with burned area expected to increase by 2.2 and 5.0 percent by 2050 under climatic bookends (PCM and GFDL climate models, respectively). Our two climate models show considerable agreement, but due to potential shifts in rainfall patterns, substantial uncertainty remains for the semiarid inland deserts and coastal areas of the south. Given the strength of human-related variables in some regions, however, it is clear that comprehensive projections of future fire activity should include both anthropogenic and biophysical influences. Previous findings of substantially increased numbers of fires and burned area for California may be tied to omitted variable bias from the exclusion of human influences. The omission of anthropogenic variables in our model would overstate the importance of climatic ones by at least 24%. As such, the failure to include anthropogenic effects in many models likely overstates the response of wildfire to climatic change.
authors.affiliation: Department of Geography, The George Washington University, Washington, DC, United States of America.|Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, United States of America.
authors.forename: Michael L
authors.identifier: 0000-0002-6268-6867
authors.initials: ML
authors.lastname: Mann
authors.affiliation: CEMFOR-CTFC, InForest Joint Research Unit, CSIC-CTFC-CREAF, Solsona, E-25280, Spain.|CREAF, Cerdanyola del Vallès, E-08193, Spain.
authors.forename: Enric
authors.initials: E
authors.lastname: Batllori
authors.affiliation: Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, United States of America.
authors.forename: Max A
authors.initials: MA
authors.lastname: Moritz
authors.affiliation: U.S. Geological Survey, Western Geographic Science Center, Menlo Park, CA, United States of America.
authors.forename: Eric K
authors.initials: EK
authors.lastname: Waller
authors.affiliation: Department of Agriculture and Resource Economics, University of California Berkeley, Berkeley, CA, United States of America.
authors.forename: Peter
authors.initials: P
authors.lastname: Berck
authors.affiliation: US Geological Survey, California Water Science Center, Sacramento, CA, United States of America.
authors.forename: Alan L
authors.initials: AL
authors.lastname: Flint
authors.affiliation: US Geological Survey, California Water Science Center, Sacramento, CA, United States of America.
authors.forename: Lorraine E
authors.initials: LE
authors.lastname: Flint
authors.affiliation: Department of Geography, The George Washington University, Washington, DC, United States of America.
authors.forename: Emmalee
authors.initials: E
authors.lastname: Dolfi
mesh_terms: D000883:Anthropology / Q000706:statistics & numerical data*; D002140:California; D002980:Climate; D057231:Climate Change / Q000706:statistics & numerical data*; D004190:Disasters / Q000706:statistics & numerical data; D005390:Fires / Q000706:statistics & numerical data*; D006802:Human Activities / Q000706:statistics & numerical data*; D006801:Humans; D008962:Models, Theoretical; D011336:Probability