Large wildfires require a cocktail of conditions, such as favourable wind speed and direction, fuel, terrain and, of course, ignition, which can be as simple as a trailer throwing up sparks by scraping on a road.
Broadly speaking, however, climate change is making conditions more favourable for wildfires in the American west. Of the 20 largest wildfires in California’s recorded history, 15 have occurred since 2000, at a time when forests have become drier and warmer.
