As a historian of fire, I know that no single factor drives it. Flames synthesize their surroundings. Fire is a driverless car that barrels down the road integrating whatever is around it.
Sometimes it confronts a sharp curve called climate change. Sometimes it’s a tricky intersection where townscape and countryside meet. Sometimes it’s road hazards left from past accidents, like logging slash, invasive grasses or postburn environments.
Climate change acts as a performance enhancer, and understandably, it claims most of the attention because it’s global and its reach extends beyond flames to oceans, mass extinctions and other knock-on effects. But climate change is not enough by itself to account for the plague of megafires. Climate integrates many factors, and so does fire. Their interplay makes attribution tricky.
Instead, consider fire in all its manifestations as the informing narrative. The critical inflection in modern times occurred when humans began to burn fossilized rather than living biomass. That set into motion a “pyric transition” that resembles the demographic transition which accompanies industrialization as human populations first expand, then recede. Something similar happens with the population of fires, as new ignition sources and fuels become available while old ones persist.
In the U.S., the transition sparked a wave of monster fires that rode the rails of settlement – fires an order of magnitude larger and more lethal than those of recent decades. Land clearing and logging slash fed serial conflagrations, which blew up in the late 19th and early 20th centuries, the waning decades of the Little Ice Age.
It was a period of flame-catalyzed havoc that inspired state-sponsored conservation and a determination to eliminate free-burning flame. Led by foresters, the belief spread that fire on landscapes could be caged, as it was in furnaces and dynamos.
Eventually, as technological substitution (think of replacing candles with lightbulbs) and active suppression reduced the presence of open flame, the population of fires fell to the point where fire could no longer do the ecological work required. Meanwhile, society reorganized itself around fossil fuels, adapting to the combustion of lithic landscapes and ignoring the fire latent in living ones.
Now the sources overload the sinks: Too much fossil biomass is burned to be absorbed within ancient ecological bounds. Fuels in the living landscape pile up and rearrange themselves. The climate is unhinged. When flame returns, as it must, it comes as wildfire.