Since 2001, each wildfire season has averaged almost 73,000 ignitions and over 6.5 million acres burned in the U.S. Interestingly, the vast majority of these ignitions are human-caused, but the total acreage burned is mostly accredited to lightning-starts.
Annually-collected statistics on ignitions show that 85% of all wildfire starts this century have been classified as human-caused. Wildfire modeling studies point to higher ignitions due to predictable patterns of human activity along transportation routes, in recreation areas, and during certain times of year. Arson, automobile brakes, campfires, engine sparks, and escaped debris fires are the most frequent types of human-caused ignitions.
RedZone’s compilation of 2015 Wildfires Igntions
Though lightning and other natural causes make up most of the other 15% of annual ignitions, they cause 62% of the total acreage burned. This discrepancy is due to the fact that fires that start naturally often occur in large forested areas with more fuel and limited accessibility, and are likely given less suppression effort since naturally-occuring fire helps maintain ecosystem health.
All statistics are based on fires and acres reported to the National Interagency Coordination Center at NIFC.