The Pyrocene How We Created an Age of Fire, and What Happens Next

Fire can be considered one of our oldest tools, long used to shape whole landscapes. But our burning of fossil fuels presents a clear break from what has come before. Riffing on the concept of the Anthropocene, environmental historian Stephen J. Pyne calls ours the Pyrocene: an age of fire. Drawing on a long career writing about and working with fire, The Pyrocene is a short book that overflows with interesting ideas.

Pyne is one of the few people who can reasonably call himself a fire historian. Now a Professor Emeritus at Arizona State University, he was a firefighter in the Grand Canyon for 15 years and has written some 35 books, most of them on fire and its history. He coined the term Pyrocene in a 2015 essay in Aeon, not so much to propose a new geological epoch, but more as a shorthand to organise his thinking on the long history of humans and fire. He calls the current book "an interpretive essay, or argued analogy, not a monograph" (p. 163). In other words, this is a book of ideas rather than data. Three of these stood out for me.

First, Pyne discerns three types of fire. First-fire is the oldest, its history stretching back some 420 million years. The study of fossil charcoal shows that lightning sparked fires as soon as plants developed on land. Second-fire was wielded by our hominin ancestors. It has long been considered our first tool, allowing us to cook our food which resulted in lasting morphological changes. Pyne argues it could also be considered our first domesticate. Unlike a tool, "it could not be put on a shelf and ignored until it was next needed. Once kindled, it had to be tended" (p. 60). This is the fire that indigenous people used for millennia to shape the landscapes they inhabited. Third-fire is the much more recent burning of fossil fuels.

Second is just how influential the switch to fossil fuels has been. In an example of inspired writing, Pyne calls it the pyric transition, a move from burning living landscapes to burning lithic landscapes. And there are some notable differences between the two. While second-fire could exist without us, third-fire could not. More importantly, "living landscapes had ecological boundaries and internal checks and balances" (p. 85). Weather, seasons, and the cycle of plant growth meant that we "could coax and cajole only so much [fuel] out of a landscape". Being mined rather than grown, "lithic landscapes knew no such boundaries [...] their fires did not recycle carbon but transferred it across deep time" (p. 86). That last statement refers to the fact that most of the world's coal reserves were laid down during the Carboniferous.

Third were the various ramifications of this pyric transition. Naked flame disappeared from our daily lives, as "industrial transformation [...] stuffed it in machines" (p. 126). In the countryside, farmers wanted the ecological benefits of fire without the actual fire. Nutrients were provided by artificial fertilizers rather than burned vegetation; weeds and pests were removed by tractors and chemicals rather than fire and smoke. Whereas "an integrative process like fire does a score of things, none of them maximized" (p. 97), the goal of industrial agriculture became to select and mimic only those fire processes that would maximize productivity, making farms more like factories. Wildfires were suppressed at all costs by relying, ironically, on petrol-powered machines – in a sense fighting fire with fire. This disastrous policy allowed kindling to build up over decades, resulting in ever-fiercer conflagrations. Only after the birth of fire ecology in the 1950s did prescribed burns become an acceptable management tool. Pyne favours incorporating traditional ecological knowledge in future solutions. Cautiously, he concludes that "fire isn't ecological pixie dust that sprinkled willy-nilly over the landscape will magically restore or make everything right. But it can help bring what exists into a working whole" (p. 143).

The concept of the Pyrocene is very powerful. Nevertheless, I have some minor niggles. The reader will have to do some sieving to get at the interesting ideas. Though the chapter titles suggest a clear narrative, I found the book slightly lacking in structure. I had to disentangle the many ideas Pyne throws out to write this review. One tangent is a chapter in which he argues that the Pyrocene is of a similar magnitude to the Pleistocene ice ages. Some impacts are similar (e.g. sea-level changes, mass extinctions, permafrost freezing and now thawing), though he admits it not a perfect analogy. Whereas ice is a substance that moves slowly, fire is a reaction that devours living matter. Similarly, Pyne's analogy between the pyric transition and humanity's current demographic transition feels forced. His bold proposal to leave fossil fuels in the ground – and burn them in a distant future to ward off the next ice age – is not further developed here and veers into the realm of maverick geoengineering.

As with the Anthropocene, the question of when the Pyrocene started naturally arises. Pyne proposes both a long and a short version. In the former, "the narrative of humanity's career as keeper of the planetary flame is continuous and unbroken". In the latter, "the pivot to fossil biomass marks a phase change in kind, not just quantity". The latter also avoids lumping "all the more or less judicious uses of fire in living landscapes with the global rupture sparked by burning lithic landscapes" and does not "condemn all of humanity when only a small fraction was responsible for unleashing the combustion cascade that has washed over the planet" (p. 146). Remarkably, Pyne prefers the long interpretation, which seems at odds with both the nature of his pyric transition and with the book's flap text announcing that the "ancient relationships between humans and fire broke down when people began to burn fossil biomass".

I might be mistaken, but I think both criticisms stem from a common root. Pyne's biography mentions how his career largely unfolded in "extraordinary isolation" without "students, research assistants, or colleagues". As he kept writing about fire history, the intellectual edifice he constructed grew, each book making "harder the cost of entry [...] for someone else". The Pyrocene has no acknowledgements section, though his Author's Note thanks a few people. Without wanting to psychoanalyse Pyne, nor wishing to downplay his extraordinary body of work, intellectual ideas do not grow in a vacuum and academic peers can provide useful sounding boards.

Overall, The Pyrocene is a pleasantly brief book. Pyne is an inspired author who mints novel terms and employs creative writing to make his point. His argument that we have transitioned into a fire age is thought-provoking and worth reading.