New research shows human activity now triggers 85% of wildfires across the United States
Every time someone tosses a cigarette from a car window or leaves a campfire unattended, they’re playing with one of nature’s most destructive forces. Scientists have discovered that humans now cause a staggering 85% of all wildfires in the United States, with only 15% sparked by lightning or volcanic activity.
What makes this even more alarming is that human-caused fires burn faster, spread farther, and destroy more property than natural blazes. In 2024 alone, wildfires caused $1.8 billion in damage nationwide, and the problem is getting worse every year.
1. Campfires and cigarettes start thousands of blazes every year
Unattended campfires and carelessly discarded cigarettes are among the leading causes of human-sparked wildfires, turning simple outdoor activities into potential disasters. A single cigarette butt thrown from a car window can smolder for hours before igniting dry grass or leaves.
Even properly built campfires can escape their rings when people fail to fully extinguish them with water and dirt. Park rangers report finding “cold” campfires that still have hot embers buried underneath, capable of reigniting hours or even days later when wind conditions change.
2. Power lines and electrical equipment spark massive fires
Faulty power lines, transformers, and electrical equipment cause some of the most devastating wildfires, often during high-wind events when equipment fails or power lines snap. California’s deadliest fire, the 2018 Camp Fire that killed 85 people, was caused by a worn power line.
Utility companies now face billions in liability for fire-related damages, leading to controversial “public safety power shutoffs” that leave millions without electricity during dangerous weather conditions. These planned outages aim to prevent equipment from sparking fires but create their own safety and economic problems.
3. Arson accounts for a shocking number of intentional fires
Deliberate fire-setting represents one of the most disturbing causes of human-sparked wildfires, with arsonists responsible for thousands of blazes annually. Some arsonists target specific properties, while others simply enjoy watching fires burn and destroying natural areas.
Law enforcement agencies have developed specialized units to investigate wildfire arson, using everything from surveillance cameras to DNA evidence found on incendiary devices. The psychological profiles of wildfire arsonists often reveal people seeking attention, revenge, or the thrill of destruction.
4. Vehicle accidents and mechanical failures create roadside infernos
Cars with dragging chains, overheated engines, or flat tires scraping on asphalt can shoot sparks into roadside vegetation, starting fires that quickly spread to nearby forests and grasslands. Mechanical failures account for thousands of wildfires each year.
Hot catalytic converters and exhaust systems can ignite dry grass when vehicles park in tall vegetation. Even something as simple as a car backfiring or a motorcycle with a modified exhaust can provide enough heat to start a fire in drought conditions.
5. Construction and industrial activities generate dangerous sparks
Welding, grinding, and other construction activities produce showers of sparks that can travel surprising distances and ignite fires in nearby vegetation. Construction sites often lack proper fire safety protocols, especially in wildland-urban interface areas.
Industrial facilities, mining operations, and manufacturing plants create multiple fire risks through hot machinery, chemical processes, and waste disposal. Workers using power tools in dry conditions have started numerous fires that grew into major blazes threatening entire communities.
6. Fireworks and explosives cause seasonal fire spikes
Fireworks celebrations, particularly around July 4th, create predictable spikes in wildfire activity as pyrotechnics land in dry vegetation or malfunction. Gender reveal parties using explosive devices have caused several massive fires, including California’s 2020 El Dorado Fire.
Even legal fireworks can start fires when used improperly or during dry conditions. Fire departments across the country report dramatic increases in wildfire calls during holiday weekends when fireworks use peaks.
7. Agricultural activities like controlled burns often escape control
Farmers and ranchers conducting controlled burns or crop residue burning sometimes lose control of their fires when weather conditions change unexpectedly. Agricultural burning accounts for a significant portion of human-caused wildfires, especially in rural areas.
Debris burning, brush clearing, and slash pile burning can escape containment when wind picks up or spreads embers beyond firebreaks. Even experienced land managers sometimes miscalculate weather conditions or fire behavior, leading to escaped burns that threaten neighboring properties.
8. Human-caused fires burn in more dangerous locations
Unlike lightning strikes that typically occur in remote wilderness areas, human activities concentrate fire risks near populated areas where the damage potential is much higher. Human-caused fires often start along roads, near homes, and in recreational areas.
This proximity to development means human-sparked fires destroy more structures and threaten more lives than natural fires. The wildland-urban interface, where homes meet wild vegetation, has become a particularly dangerous zone for human-caused fire ignition.
9. Fire suppression costs have skyrocketed to over $3 billion annually
The cost of fighting wildfires has exploded as human-caused fires have increased, with annual suppression costs now exceeding $3 billion according to recent data. The five-year average cost to the Forest Service alone is over $2 billion annually.
These enormous costs reflect both the increasing number of fires and their complexity, as firefighters must protect homes and infrastructure rather than just letting natural fires burn in wilderness areas. The 2021 fire season cost nearly $4.4 billion to suppress, the highest on record.
10. Prevention efforts focus on changing human behavior
Fire prevention campaigns now target specific human behaviors like proper campfire extinguishing, safe equipment use, and awareness during high-risk weather conditions. “Only You Can Prevent Wildfires” has evolved into detailed education about everyday fire risks.
Technology solutions include spark arresters on equipment, improved power line safety systems, and real-time fire danger alerts sent to smartphones. However, experts say the most effective prevention remains changing human behavior and increasing awareness of how easily everyday activities can start devastating fires.