Industrial Fire. Contemporary Fire

Yet, limits still remained. Anthropogenic fire was only as powerful as the fuels that fed it. The cultivator could, within bounds, make and break biomass to fashion fuel, but the cultivator could not evade the cycles of growth and decay that oversaw how much living biomass was available for converting into combustibles.

Humans could hope to transcend this profound cycle only if they could tap another source of combustibles. With fossil biomass, they did precisely that. The combustion of coal, gas, and petroleum launched a new epoch in the Earth's fire history, the era of industrial fire.

Thus began the Big Burn. Combustion now extends through geologic time as well as across geographic space. The competition between lightning and torch over biomass continues, but both now face a combustion competitor for whom the source fuel is, over several centuries, unbounded. Rather, the problem is one of sinks, the capacity of the plant to absorb combustion's byproducts. Industrial fire burns without regard to ecological context. The Earth is awash in its effluent, the pollution of combusted fossil biomass. The Big Burn has inspired a Big Dump.

Steadily, and on a vast scale, industrial fire has substituted for previous pyrotechnologies. In their built environment, industrial societies have all but extinguished open flame. In fields, fossil fallow has replaced living (typically, with a subsequent loss of biodiversity). Even in wild-lands, industrial societies have actively sought to suppress all expressions of open flame.

This complex competition has bequeathed an Earth that is fissuring into two great combustion realms, one dominated by biomass burning, the other by industrial fire. There are few points of overlap, and these are likely transitional.

In effect, a kind of pyric version of the familiar demographic transition occurs. Fire births boom, while fire deaths slow. The old traditions of fire survive, even as new burning proliferates. The population of fires explodes, like a plague of locusts. Eventually substitutions and outright suppression quench the old or drive the flames into nature preserves. The process lingers longest in places like India and Mexico that hold rich deposits of fossil biomass and stubbornly planted rural societies. Beyond such vague observations, however, the dynamics of industrial fire and its curious ecology remain unknown.

Contemporary Fire. Today the trends in fire are these: a boom in industrial combustion, a revival of natural fire, and a collapse in anthropogenic burning. How these interact, however, is the vexing three-body problem of fire science. Over-all, the Earth seems to suffer a vast maldistribution of burning. There are places, mostly in the developing world, that have too much fire; places, largely in the developed world, that have too little fire; places along exurban (beyond city suburbs) frontiers that have volatilely mixed fires.

There is too much of the wrong kind of fire and too little of the right. Probably the planet has too much combustion and too little fire. The crisis over global warming is, finally, a crisis over combustion.

These are separate problems, amenable to distinctive analyses and solutions. The need to limit the Big Bum is obvious, although how to bolster carbon sinks and shrink combustion-released carbon sources is less so. It is an easy matter, technically, to keep houses from burning. It is trickier—a cultural call—to decide what to do with natural fire in wilderness preserves. In fire-prone landscapes, fire will enter, and in places long subject to burning, the abrupt removal of fire (or a sudden shift in its regime) may be as upsetting as its untoward introduction. It is as though a forest that received 90 centimeters of rain evenly distributed over the year got only 13 centimeters and that in two months.

The most profoundly disrupted biotas are those that had experienced regular surface burning two or more times a decade. Paradoxically, the chief fire crisis in the nature reserves of industrial nations traces to fire's attempted abolition.

The real quagmire, however, concerns the oldest of human fire practices. What is the proper place for anthropogenic fire? Removing fires from areas that have adapted to human-tended fire regimes can be as ecologically disruptive as thrusting fires into places lacking such history. Reinstating fire that has been stripped out of biotas is not a simple process of reversal. Fire is not ecological pixie dust that, sprinkled over degraded lands, renders them hale and lovely.

Fire will take its character from its context: It will synthesize its surroundings. Rather, fire's return must more resemble the reintroduction of a lost species, like a wolf. To thrive, fire must have a suitable habitat. All this is to state one of the truisms of fire history: There is no neutral position. Fire deleted may be as ecologically powerful as fire inserted.

Still, there are reasons to lump these various expressions of contemporary combustion together. They interact, they share a history, and they rely on Homo sapiens as a fire creature. In this sense, fire is less a tool or even an ecological process than a relationship, and less a technical problem than a cultural negotiation. One form of combustion does not exist autonomously from the others.

They compete for biomass, they compete for space in the atmosphere, they shape very different, even antagonistic ecosystems. Yet, they have one common element. How they appear on Earth will depend on humans, who remain, however disdainful their sense of mission and slovenly their practice, the keepers of the planetary flame.