Problem statement
In the western United States, human activities have accounted for 63% of wildfire ignitions in recent decades, and tend to occur in different locations and seasons than lightning-caused wildfires. There is increasing need to identify effective strategies for preventing different classes of human-caused ignitions and minimizing the extent of the resulting wildfires. We propose to clarify the contributions of biological, physical, and social factors to ignition likelihoods and wildfire extents across the 11 conterminous western states, thereby informing development of prevention strategies that can be targeted to different ignition sources, weather and climate conditions, ecoregions, and human populations.

We propose to focus on three classes of human-caused ignitions -- powerlines, debris burning, and campfires -- and the wildfires they cause. These classes span a gradient of development from suburban to exurban to wildlands, and are associated with different primary stakeholders, such as utilities, local governments, and state and federal resource agencies, respectively. Powerlines, debris burning, and campfires collectively accounted for 24% of the human-caused wildfire ignitions and 20% of the area burned by human-ignited wildfires from 1992-2015 across the western United States.