For a wildfire to ignite and burn sufficient of the following three elements need to be present in combination:
- Fuel in the form of live or dead trees, vegetation and other organic matter;
- Oxygen in the air around us;
- Heat to ignite and burn, from lightning or human sources.
The cause of a wildfire depends on the source of the heat that ignited a fuel source.
The vast majority of naturally-caused wildfires are ignited by lightning. When lightning strikes, it can create enough heat to ignite a tree or other fuel source. Lightning strikes cause approximately 60% of wildfires in the Province in an average year. While lightning-caused wildfires cannot be prevented, the severity of wildfires may be reduced through land management activities such as fuels management, prescribed burning and landscape fire management planning.
Theoretically, there are other causes that could fall into the natural wildfire category, including rock fall, meteorite or volcano, but the likelihood of non-lightning caused natural wildfires is extremely rare in British Columbia.
There are numerous ways human activity can start wildfires, either accidentally or intentionally. On average 40% of wildfires in British Columbia are person-caused by activities such as open burning, the use of engines or vehicles, dropping burning substances such as cigarettes, or any number of other human-related activities that can create a spark or a heat source sufficient to ignite a wildfire. The most important factor of person-caused fires is that they are preventable.
Fires Under Investigation
All wildfires in British Columbia are investigated for fire origin and cause. The origin and cause of lightning-caused wildfires with an obvious strike tree can be relatively straightforward to determine, while other wildfire causes can involve extensive and complex investigation. Until the cause of a wildfire has been investigated and confirmed, the BC Wildfire Service will report its cause as ‘under investigation’.