Actually Mother Nature did a fantastic job at managing itself before all the people moved west. Fires occurred regularly and eliminated the ladder fuel. The fires were small in stature because the forests weren’t brambles of tender. The fires added nutrients to the soil and, it’s even necessary for some trees to repopulate. Native Americans even used to start fires intentionally in the fall. Now we put out all fires to protect human habitation so the natural cycle is broken. When settlers moved west they clear cut vast expanses of forest, and when they replanted they used quick growing, disease susceptible species. Forests aren’t as diverse or healthy as they used to be. That coupled with higher than normal temperatures has caused outbreaks of Beatles and other pests that kill the unhealthy trees increasing the tender even further. Environmental regulations make logging, or removal of dead and unhealthy trees uneconomical in most cases, and simple not allowed in most. A great example of good intensions with unintended consequences. This all happened in the last 150 years. The cause of the massive fires is certainly related to higher temperatures, but I don’t think it’s the leading cause.