Your link proves nothing either. That and I find it odd you don't count the sun as a external heat source. But beyond that there are enough sources indicating

Your link proves nothing either. That and I find it odd you don't count the sun as a external heat source. But beyond that there are enough sources indicating it can happen... - https://sciencestruck.com/what-causes-forest-fires https://sciencestruck.com/what-causes-forest-fires - https://www.natural-hazards.ch/home/dealing-with-natural-hazards/forest-fire/danger-levels-forest-fire.html https://www.natural-hazards.ch/home/dealing-with-natural-haz... - https://en.m.wikipedia.org/wiki/Spontaneous_combustion https://en.m.wikipedia.org/wiki/Spontaneous_combustion - https://www.dosomething.org/facts/11-facts-about-wildfires https://www.dosomething.org/facts/11-facts-about-wildfires It seems I could go on and on of people describing how it can happen and some how it has happens.