As the graphic above shows, people cause most wildfires. But lightning-ignited fires burn by far the most territory.
There is a clear link between climate change and wildfires. Increased spring and summer temperatures, along with earlier spring snowmelt, cause the drying of soils and vegetation. Those conditions increase the risk wildfires. In the West there has already been a nearly fourfold increase in large wildfires in recent decades, with greater fire frequency, longer fire durations, and longer wildfire seasons. The graphic below shows the increasing trend in number of acres burned each year.