Lightning strikes and human activity are the two primary causes of forest fires,

 

Lightning strikes and human activity are the two primary causes of forest fires, with their dominance varying significantly by region. 

• Human Activity: Globally, humans are responsible for the vast majority of wildfire ignitions, with estimates ranging from 85% to 90% in the United States and Canada.  Common human causes include discarded cigarettes, unattended campfires, debris burning, equipment malfunctions (such as sparks from engines or power lines), and intentional arson. 
• Natural Causes: Lightning is the most common natural ignition source, accounting for nearly half of all wildfires in Canada and up to 60% in British Columbia.  While lightning starts fewer total fires than humans in some populated areas, it is responsible for a disproportionate amount of the total land area burned because these fires often occur in remote locations. 
• Other Natural Causes: Volcanic eruptions and spontaneous combustion of dry organic matter are rare but documented natural causes. 

Climate change is the primary driver behind the increased frequency and severity of forest fires in both Canada and the United States, creating conditions of extreme heat, prolonged drought, and reduced snowpack that act as fuel. 

• Fuel Accumulation: Decades of aggressive fire suppression and a lack of controlled burns have allowed dry vegetation to accumulate on forest floors, turning natural ecosystems into tinderboxes ready to ignite. 
• Geographic Scale: Canada’s vast, remote boreal forests are often impossible to contain once ignited, while U.S. western states face "perfect storms" of record heat, snow droughts, and low humidity that extend fire seasons and intensify blazes. 

 Canada has a long-standing reciprocal agreement with the United States to assist with wildfire suppression, dating back to 1982.  This mutual aid involves sharing personnel, aircraft, and equipment across borders to manage large-scale fire events. 

Recent and historical examples of Canadian support include:

• California (January 2025): Canada deployed resources including CL-415 waterbombers from Quebec and Ontario, Type 1 wildland firefighters from Alberta and British Columbia, and incident command personnel to help battle devastating wildfires in Southern California. 
• 2023 Historic Season: During a record-breaking fire year in Canada where over 45 million acres burned, the U.S. deployed 2,774 wildland firefighters to Canada. In return, Canada provided aid to U.S. states affected by wildfires, reinforcing the "shared challenge" dynamic. 
• Ongoing Coordination: Resources are mobilized through the Canadian Interagency Forest Fire Centre (CIFFC) and the U.S. National Interagency Coordination Center (NICC).  This includes sending specialized crews, airtankers, and overhead staff to U.S. states like California and others during peak fire seasons. 

Despite political tensions over smoke drift in 2026, officials from both countries emphasize that fire does not know borders and that cross-border cooperation remains a critical component of wildfire management in North America. 

 Canada has also invested $12 billion since 2020 in forest sustainability and fire prevention to mitigate future risks.