Forest fires seem to be more numerous and larger, and the forest fire season is getting longer. Some of these fires are caused by arson. For example, from USA Today:
The man suspected of igniting the Holy Fire in Southern California was charged on Thursday with three counts of felony arson, among other offenses.
The Carr Fire, another large 2018 fire, was caused accidentally by a spark from a motor vehicle. According to CNN:
... on one road near Redding, California, when a tire failed last month on a trailer and its rim scraped the asphalt, the result was catastrophic for an entire region.
The sparks that shot out July 23 from that minor incident, California fire officials said, ignited what is now the sixth-most destructive wildfire in state history.
Improperly attended campfires have caused major forest fires, although my limited search did not turn up a campfire as the cause of a major forest fire in 2018.
In the past few years, what have been the immediate causes of major forest fires in the US and Canada? Suggested breakout: arson, vehicles, campfires, other human causes, lightning, other natural causes (if any). Canada and the US should probably be listed separately.
"Several years" is intentionally vague; it depends on what data is available. Let's say several years means two to ten. "Major forest fires" is also vague. I suggest Class F and Class G fires, or perhaps just Class G fires, as defined by The National Wildfire Coordinating Group:
◦Class E - 300 acres or more, but less than 1,000 acres;
◦Class F - 1,000 acres or more, but less than 5,000 acres;
◦Class G - 5,000 acres or more**
If someone has a better definition for a major fire, please use it.
Note that I am not asking about what may be the ultimate causes such as climate change or fire management policies.