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Welcome to the Pyrocene Age

Another autumn, more fires, more refugees and incinerated homes. Free-burning fire is the proximate provocation for the havoc, since its ember storms are engulfing landscapes. But in the hands of humans, combustion is also the deeper cause. Modern societies are burning lithic landscapes, once-living biomass now fossilized into coal, gas and oil, which is aggravating the burning of living landscapes. The influence doesn’t come only through climate change, although that is clearly a factor. The transition to a fossil-fuel civilization also affects how people in industrial societies live on the land and what kind of fire practices they adopt. Even without climate change, a serious fire problem would exist… What were lithic landscapes have been exhumed and no longer only underlie living ones. In effect, once released, the lithic overlies the living and the two different kinds of burning interact in ways that sometimes compete and sometimes collude. Like the power lines that have sparked so many wildfires, the two fires are crossing, with lethal consequences.

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 it claims most of the attention because 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.

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 inspiring 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. 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. Widen the aperture a bit, and we can envision Earth entering a fire age comparable to the ice ages of the Pleistocene, complete with the pyric equivalent of ice sheets, pluvial lakes, periglacial outwash plains, mass extinctions, and sea level changes. It’s an epoch in which fire is both prime mover and principal expression. Even climate history has become a subset of fire history… a particular kind of meddling through our monopoly over fire.

It’s been a stretch to fully include human fire practices within traditional ecology. But industrial fire, unlike landscape fires, is solely a product of human finagling, and so has stood outside the bounds of ecological science. It’s as though the intellectual sink for understanding can no more hold the new realm of burning than nature can its emissions.

This article was originally published by The Conversation. Stephen Pyne has written two books about wildfires, called Between Two Fires and Fire. He is Emeritus Professor, School of Life Sciences, at Arizona State University.