People Cause Most US Wildfires
University of Colorado scientist Jennifer Balch and several colleagues came to their conclusion after analyzing reports of 1.6 million wildfires from a comprehensive’s fire occurrence database maintained by the U.S. Forest Service. As shown by the map above, almost all (84 percent) of the fires in the Mediterranean ecosystems of central and southern California, the temperate forests of the eastern United States, and the temperate rainforests of the Pacific Northwest are caused by humans.
The researchers also found that human-ignited fires tripled the length of the wildfire season. Though lightning-ignited fires were clustered in the summer, human-ignited fires occurred in the spring, fall, and winter as well, times when forests tend to be moist. During these seasons, people added more than 840,000 fires - a 35-fold increase over the number of lightning-started fires.
- Drought duration by U.S. county (2010 - 2016)
- Drought severity and duration in the United Sates (2010 - 2016)