From the Smithsonian Magazine

According to a press release, researchers from the University of Colorado, Boulder’s Earth Lab took a deep dive into the U.S. Forest Service’s Fire Program Analysis-Fire Occurrence Database, analyzing all wildfires recorded between 1992 and 2012. The researchers found that humans caused more than 1.2 million of the 1.5 million blazes in the database.

The cost of those human-induced fires is staggering. The researchers estimate that man-made fires have tripled the average fire season over the past 21 years from 46 days to 154 days. It now costs over $2 billion per year to fight the fires, and that figure does not include the impacts to recreational lands or local economic impact that fires can have.