"As the untrammeled burning of fossil fuels perturbs the atmosphere, it is clear that even that grandest of physical controls, the climate, no longer lies outside the reach of a fire-tinkering humanity. We need a better understanding of how this has happened, and what, ecologically, it means."

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[Note: Portions of this essay derive from the author's new book, "Tending fire: Coping with America's wildland fires," to be published by Island Press in September 2004.]

What is the fire ecology of industrial combustion? Of automobiles, of coal-fired and gas-turbine power plants, of leafblowers and woodchippers? The concept seems nonsensical. If it means anything, fire ecology refers to the study of real flames crackling through prairie, chaparral, woodlands, the crowns of close-packed conifers. It means understanding how a biota works before and after flame passes through, the effects that fire catalyzes in the living world. Lightning, torch, furnace; smoking snag, flaming fallow, combusting coal -- these are distinct phenomena, connected only through the most tenuous chemistry of hydrocarbon oxidation.

Surely, to suggest that the disembodied combustion that occurs within closed chambers fed by ramjets and carburetors enjoys a shared ecology with free-burning flame is to indulge in fanciful metaphors; surely, to propose that the two "combustions", one of living biomass and the other of fossil biomass, are, in fact, linked as part of a plenum of historical fire ecology is to pass into delusion. Yet that is exactly the case. Without understanding such a connection one cannot understand how fire -- the flames land managers seek and the conflagrations they dread -- operates on the land. The failure to find their unity is one of the grand lapses in the imagination of fire scholarship.

Humanity's firepower has its limits. The power of fire derives from its power to propagate. Starting fires does not guarantee that they will spread. Where conditions are favorable, aboriginal burning can move continents, but it needs a suitable context to leverage spark into broadcast flame. One way to overcome this constraint is to manipulate fuels along with ignition. Biotas can be slashed, drained, browsed, cultivated, dried such that they can carry flame when, left to nature, they would not do so; this is, for fire history, the meaning of agriculture. But this direct use of fire, too, has limits. One can only coax or coerce so much biomass from the land. To burn more fuels than can be restored is to snuff out cultivated flame, not stoke it. If humanity craves more firepower, it has to find another source of fuel, which it has done in the form of fossil biomass. In effect, people are now excavating whole landscapes from the geologic past, kindling a new world of combustion.

Fire thus unshackled its fuel fetters and became more or less unbounded ecologically, even as it became more detached from the land and intensely confined within special chambers. Combustion was no longer limited by its sources (fuels) but by its sinks (the capacity of the environment to absorb its byproducts). The ecological, economic, and social effects of this upheaval have been enormous. Industrial burning quickly substituted for most domestic hearth and manufacturing furnaces and even agricultural fallow, and then pursued open flame into the bush through the leveraged power of machines, vehicles, and tools fed by fossil fuels. This, for fire history, is the meaning of the industrial revolution. By 1990 it was estimated that 60% of the global emissions from burning derived from industrial fire; and because industrial societies suppress open flame, that proportion must grow. The burning of fossil fuels is the deep driver of contemporary combustion, the great biological rearranger of burning, the dark attractor of Earthly fire.

The planet is segregating into two master combustion realms -- one fed by living biomass, the other by fossil biomass. The two rarely coexist, and when they do -- in places like Mexico and India, where rural villages stubbornly persist next to plentiful reserves of coal and oil -- they are likely transitional. Evening satellite photos depict an Earth fissioned into electric lights and fire lights. We have barely begun to understand, in any systematic way, what this means; how industrial fire cascades through a trophic chain of combustion ecology. There is some consideration of how the outpouring might affect the atmosphere, particularly how it contributes to greenhouse gases and global warming. But there is no coherent assessment of how industrial fire shapes the patterns of fire in living biotas, or even a general recognition that the two share a common combustion history. The fact is, industrial, anthropogenic, and natural fires compete with each other. How they do so may be the most fundamental three-body problem in fire scholarship.

The mechanisms behind this transformation are not well understood. The primary process seems to be one of technological substitution. Fire as a tool -- combustion as a source of heat and light -- is amenable to flameless replacements. Domestic fire goes, followed by manufacturing fires and agricultural burning. Yet industrial societies typically extend the reach of their contained combustion into wildlands as well. Here, where open fire behaves more as an ecological process than as a mechanical implement, the substitution takes the form of an active suppression of any and all flames, a practice whose consequences are paradoxical and often deleterious.

This pyric transition itself is immensely significant. The fire problems of the developed nations are largely those inherited from their passage through this transition. So, too, knowledge about what such a passage involves holds considerable meaning for developing nations as they maneuver through the same transition. What institutions do they need to manage fire? What policies are useful, which misguided, which irrelevant? Which historical or traditional fire practices should be preserved, at some cost if necessary, and which should be gratefully discarded as a country moves from a context of rural fire to one dominated by industrial fire? Does the pyric transition itself reveal patterns -- offer suggestions about how to seize and slip through the opportunities and obstacles?

It does. There seems to exist a demographic transition in fire similar to that for humans. Initially, the old fire practices remain while new ones proliferate, with the upshot that the population of fires explodes. Eventually, industrial fire snuffs out the old versions, and the population of "old fire" fails to replace itself. Early industrializing nations thus have a surplus of fires, including many abusive ones. Mature industrialized nations, in contrast, may lack those live burns they need for biotic purposes. During their early industrial evolution, nations seek to suppress the excess fires; later, they try to overcome the shortfall. Fire agencies have little direct control over these processes. Rural fire vanishes, ultimately, because rural populations depart along with the economy that sustained them. Fire did not disappear from much of the United States, for example, because Smokey Bear, the U.S. Forest Service mascot, hectored adults and persuaded children to prevent forest fires. It disappeared because society found combustion alternatives to open fire as a tool and because a rural economy, which had relied on open burning, withered away.

Societies dependent on industrial fire have their combustion maladies. The removal of fire from a biota may be as ecologically powerful as its introduction; many such countries suffer a fire deficit in nature reserves. The metropolitan recolonization of rural landscapes by city dwellers, ardently accompanied by an abolition of open flame, has slammed the wild and the urban together, a collision with frequent explosions. In fire-prone lands, industrial societies have often discovered they have exchanged an annoying domesticated fire for a demonic feral one. Fire, they have learned, is not simply a tool to be handled or discarded by people at will. It is also an ecological process whose suppression or extinction by humans can unravel the tapestry of landscapes, so that even as flame vanishes from everyday life, it reappears in episodic and frequently catastrophic eruptions.

The field for flame is odd, and narrowing. At the cellular level oxidation is carefully confined within molecular machinery. There is no prospect for combustion to propagate wildly through mitochondria and protoplasm. Cellular chemistry breaks fire into its constituent parts and prescriptively channels each into its proper position. Similarly, in the industrial world humanity has likewise fractured combustion into its separate component processes and confined each within prescribed chambers. Oxygen may be abstracted from air; fuel refined into its most volatile fraction; and the broth mixed in precise proportions within closed chambers. Engineering labors mightily to prevent the ensuing reaction from escaping this confinement.

Where fire -- fire, in the vernacular sense -- flourishes is in that vast realm between. The fire-field for free-burning flame thrives within that largely open cauldron in which the active agents are diffused among earth, air, and life, in which plains and ravines, winds and droughts, layered air masses, and Darwin's "entangled bank" of plants and creatures decide the properties of burning. Fire spreads, constrained loosely only by gross features of its environment; escapes are common.

The American West burns because it holds a vast landscape that, by political will, has been removed from settlement, which is to say, shielded from the pyric transition. America has extensive wildland fires because it has extensive wildlands, the outcome of a peculiar history of settlement in which the indigenous peoples were largely removed and, before a new wave of colonizers could fix themselves, the land was set aside as a public domain. Countries with similar fire histories -- Australia, Canada, and Russia -- possess similar national estates for similar reasons. In such lands industrial fire manifests itself through attempts at active suppression. These estates remain the prime habitat of free-burning fire. Their future will largely determine fire's.

Interestingly, at the two polar realms of combustion -- the cellular and the industrial -- biological parameters dominate. (The latter only appears paradoxical because we so often refuse to see ourselves as fire creatures, as ecological agents who deal with fire as moles do with soil or elephants with trees.) As yet, however, we have continued to imagine fire as a chemo-physical phenomenon subject to geophysical controls. A physical force, it must be met with physical counter-forces: water, dirt, retardant, delivered to the free-burning fire by the machinery of internal combustion.

A broader conception, however, suggests that biological controls might also apply. What burns is not abstracted carbon bullion but living ecosystems, whose shapes determine the character of fire and whose processes can be tweaked to yield more benign burns. It is worth an attempt.

Such a reimagining must begin with the biological nature of fire, and with the realization that through humans -- Earth's uniquely fire creature, holding a species monopoly -- there exists a continuum of combustion; that the fire in the machine shares an ecology with the fires of the hunt, the garden, and the wild. As the untrammeled burning of fossil fuels perturbs the atmosphere, it is clear that even that grandest of physical controls, the climate, no longer lies outside the reach of a fire-tinkering humanity. We need a better understanding of how this has happened, and what, ecologically, it means.