Fire is a Shapeshifter Too

September 7, 2019

At night, viewed from space, the cluster of lights looks like a supernova erupting in North Dakota. The lights are as distinctive a feature of night-time North America as the glaring swathe of the northeast megalopolis. Less dense than those of Chicago, as expansive as those of Greater Atlanta, more coherent than the scattershot of illuminations that characterises the Midwest and the South, the exploding array of lights define both a geographic patch and a distinctive era of Earth’s history.

Nearly all the evening lights across the United States are electrical. But the constellation above North Dakota is made up of gas flares. Viewed up close, they resemble monstrous Bunsen burners, combusting excess natural gas released from fracking what’s known as the Bakken shale, named after the farmer Henry Bakken, on whose land the rock formation was first discovered while drilling for oil in the 1950s. In 2014 the flares burned nearly a third of the fracked gas free. They constitute one of the most distinctive features of the US nightscape. We might call them the constellation Bakken.

While the flares rise upward, the firefront is actually burning downward into the outgassing drill holes as surely as a candle flame burns down its tallow stalk. The flames are descending as rapidly as their fuels are rising. They are burning through deep time, combusting lithic landscapes from the geologic past and releasing their effluent into a geologic future. Eerily, the Bakken shale dates to the Devonian, the era that records the first fossil charcoal, our first geologic record of burnt material. Its gases will linger through the Anthropocene.

In 1860 the English scientist Michael Faraday gave a series of public lectures in which he used a candle to illustrate the principles of natural philosophy. Fire was an apt exemplar because it integrates its surroundings, and it was apt, too, because in Faraday’s world, fire was everpresent.

Every nook and cranny of the human world flickered with flames for lighting, heating, cooking, working, and even entertaining. But that was starting to change. By then, Britain had 10,000 miles of railways and the US had 29,000. Those locomotives demanded more fuels than the living landscape could supply. Engineers turned to ancient landscapes – to fossil biomass, notably coal – and they simplified fire into combustion.

Today, a modern Faraday would not use a candle – probably couldn’t because the lecture hall would be outfitted with smoke detectors and automated sprinklers, and his audience wouldn’t relate to what they saw because they no longer have the lore of daily burning around them. For a contemporary equivalent he might well turn to a fracking flare, and to illustrate the principles behind Earthly dynamics he might track those flames as they burn down through the deep past of fire and humanity.

Among the ancient elements, fire is the odd one out. Earth, water, air – all are substances. Fire is a reaction. It synthesises its surroundings, takes its character from its context. It burns one way in peat, another in tallgrass prairie, and yet another through lodgepole pine; it behaves differently in mountains than on plains; it burns hot and fast when the air is dry and breezy, and it might not burn at all in fog. It’s a shapeshifter.

The intellectual idea of fire is a shapeshifter, too. The other elements have academic disciplines behind them. The only fire department on a university campus is the one that sends emergency vehicles when an alarm sounds. In ancient times, fire had standing with the other elements as a foundational axiom of nature. In 1720, the Dutch botanist Herman Boerhaave could still declare that: ‘If you make a mistake in your exposition of the Nature of Fire, your error will spread to all the branches of physics, and this is because, in all natural productions, Fire… is always the chief agent.’

By the end of the 18th century, fire tumbled from its pedestal to begin a declining career as a subset of chemistry and thermodynamics, and a concern only of applied fields such as forestry. Fire no longer had intellectual integrity: it was considered a derivation from other, more fundamental principles. Just at the time open fire began retiring from quotidian life, so it began a long recession from the life of the mind.

Fire’s fundamentals reside in the living world. Life created the oxygen fire needs; life created the fuels. The chemistry of fire is a biochemistry: fire takes apart what photosynthesis puts together. When it happens in cells, we call it respiration. When it occurs in the wide world, we call it fire.

As soon as plants colonised land in the Silurian period about 440 million years ago, they burned. They have burned ever since. Fires are older than pines, prairies and insects. But nature’s fires are patchy in space and time. Some places, some eras, burn routinely; others, episodically; and a few, only rarely.

The basic rhythm is one of wetting and drying. A landscape has to be wet enough to grow combustibles, and dry enough, at least occasionally, to allow them to burn. Sand deserts don’t burn because nothing grows; rainforests don’t burn unless a dry spell leaches away moisture. Biomes rich in fine particles such as ferns, shrubs and conifer needles can burn easily and briskly. Landscapes laden with peat or encumbered with large trunks burn poorly, and only when leveraged with drought.

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