by Sam Kean
But the source of the speed and energy with which these gases rise is still the subject of intense speculation. Potter, of the Pacific Wildland Fire Sciences Laboratory, has found some surprising possible answers. They arise, in part, from some of those old military fire experiments—these particular ones conducted in the aftermath of World War II by a U.S. government that feared the devastation of Hamburg might represent the future of modern warfare.
In the wrinkled, sage-covered mountains of Nevada near the California border, 30 miles east of Mono Lake, there is a meadow that seems to lie in shadow even on sunny days. Spread across it are hundreds of dark patches, where the soil is mixed with charcoal. These spots lay row upon row, like the ghostly foundations of a dead city. In a sense, that is exactly what they are.
In 1967, workers with the Forest Service and the Department of Defense stacked 342 piles of juniper and piñon logs in this place—20 tons of wood per pile, spaced 25 feet apart. Then, at 8 a.m. on September 29, they set fire to them.
Project Flambeau comprised some two dozen experiments like this one, meant to simulate an American suburb under nuclear attack—specifically, the many small fires that would merge into a storm, as happened not only in Hamburg but also in Hiroshima and Nagasaki.
Lengthy reports describe how helium balloons released near the fire here rose several hundred feet, then swooped down into the flames, revealing strong downdrafts feeding the fire from its sides. But what drew Potter’s interest was the water. Concentrations of water vapor rose 10 to 20 times higher than the surrounding air.
Water is a major product of combustion, second only to carbon dioxide. It forms as oxygen binds to the hydrogen atoms in wood, gasoline, or just about any other fuel—creating hydrogen oxide, otherwise known as H2O. Burning four pounds of perfectly dry wood releases a pound or two of water.
Exhale onto a car window and you will see another form of the same phenomenon, fogging the glass: water produced from the oxidation of food you have eaten. This vapor is familiar and mundane; it hardly seems like a violent force.
And yet water vapor fuels the strongest updrafts in nature, says Potter, from thunderstorms to tornadoes to hurricanes. As moist air rises during these storms, the water vapor condenses into cloud droplets, releasing a small amount of heat that keeps the air slightly warmer than its surroundings, so it continues to rise. “Water,” he says, “is the difference between a weak updraft and a really powerful updraft.”
Potter wondered if the water vapor released from combustion might infuse extra energy into wildfire plumes. By condensing and giving off heat, it might allow some plumes to rise higher and faster, accelerating the fire on the ground.
Through a bit of serendipity, this theory actually led to Clements’s first fire experiment—the prescribed prairie burn back in 2005. It was Potter, who happened to know Clements’s Ph.D. adviser, who suggested it. Neither the results of Clements’s experiment nor those of Flambeau were conclusive about the importance of this pulse of water vapor. Still, some people have latched onto the theory.
Michael Reeder, a meteorologist at Monash University in Australia, is one of them. He believes that water was pivotal in fueling the firestorm that swept through the suburbs of Canberra, the Australian capital, on January 18, 2003.
The fire consumed 200,000 acres of drought-stricken territory that day, isolating the city under a glowing haze of Halloween orange. Remote infrared scans suggest that during a single 10-minute period, it released heat equivalent to 22,000 tons of TNT—50 percent more than the energy unleashed by the atomic bomb dropped on Hiroshima.
A series of four pyrocumulonimbus clouds rose into the stratosphere that afternoon. These fire-fueled, anvil-shaped thunderheads lofted black, sooty hail up to six miles away. One of them spawned a tornado that snapped the tops off pine trees as it plowed a path of destruction 12 miles long and a quarter mile wide.
The tornado and the height of the clouds “point to something extraordinary,” says Reeder. “[They] require moisture—and the question is: how do you get that much moisture over eastern Australia during drought conditions?”
Combustion provides a plausible source for it. Reeder estimates that the fire incinerated over 2 million tons of wood and vegetation that day, liberating at least a million tons of water vapor into the sky.
The temperature and density differences that drive such cataclysmic power can seem deceptively minuscule. When N2UW flew through the plume of the Pioneer Fire in 2016, its instruments registered updrafts of 80 to 100 mph. Yet at that elevation, 8,000 feet above the flames, the interior of the plume was only 3 to 6 degrees Fahrenheit warmer than the surrounding air, meaning that its buoyant stampede through the atmosphere was powered by a density difference of just about 1 percent.
In other words, given the right atmospheric conditions, a few degrees of warmth and extra buoyancy could spell the difference between a plume that pushes 40,000 feet up, into the stratosphere, powering a vicious blaze on the ground—as Pioneer did—and one whose smoke never escapes the top of the boundary layer at 3,000 feet, leaving the fire stunted, like a weather-beaten dwarf tree gasping for life at timberline.
N2UW made two more passes through the plume of the Pioneer Fire on August 29. During that third and final pass, static electricity roared through the cockpit radio. Concerned that lightning from the plume might strike the plane, the pilot turned off his antenna.
That flight yielded far more than the first direct measurement of a plume’s updraft. Days later, Clements found himself looking at a portrait of the fire’s plume unlike any that has existed before: a vertical MRI slice of sorts cut along the path of the plane—captured by its fine-tuned scientific radar, aimed straight down.
Color-coded by the velocity of its air currents, the blotchy mass resembled a hovering spirit—large-headed, legless, and deformed. Clements’s trained eye began to pick out some basic structures: a 40 mph downdraft next to a 60 mph updraft signified a turbulent eddy on the edge of the plume. Hot air pushing up past cooler, stationary air had set in motion a tumbling, horizontal vortex—the sort of thing that could easily have accounted for the plane’s brief freefall. Those blotchy radar pictures may finally allow us to see through wildfire’s impulsive, chaotic veneer—and perceive the more predictable, underlying forces that guide its behavior. “We didn’t even know this would work,” said Clements. “This is the most exciting thing I think I’ve ever seen in my career.”
Simply seeing can be transformative. Not until people saw microbes could they comprehend and fight diseases like malaria—once blamed on foul spirits or miasmas. And not until Earth’s colorless, odorless magnetic field became visible could people appreciate how it shaped the planet’s environment.
While the smoke plume of the Pioneer Fire was apparent to the naked eye, the violent forces within it were also deceptively invisible. As the plane first approached it on August 29, the pilot’s standard weather console showed the plume as nothing but a swath of cool blue—a seemingly gentle updraft, with no hint of what lay in wait.
J. B. MACKINNON
Tragedy of the Common
from Pacific Standard
White-rumped vultures were one of the most common large birds on the planet. There were an estimated 40 million of them in India alone. One famous bird sanctuary, Keoladeo National Park, had 30 vulture nests per square mile. Even in Delhi, India’s capital city and the second-largest urban agglomeration in the world, they averaged 8 per square mile.
Biologist Vibhu Prakash found it captivating to see hordes of the hungry scavengers feeding, their backs like a phalanx of shields that heaved with the rhythm of beaks tugging flesh. In just 20 minutes, the birds could pick a cow carcass clean.
“They were in so big a number, villagers would be scared passing near the congregation,” said Prakash, a principal scientist with the Bombay Natural History Society. “When they are feeding on a dead body and all, they look a little scary.”
In 1997, Prakash headed into Keo
ladeo, a small UNESCO World Heritage site 100 miles south of Delhi, in order to update a count of white-rumped vultures that he had carried out a decade earlier. He was about to become the principal witness to an accelerating vanishment that, even in this age of extinctions, retains its power to shock.
When his tally was complete, Prakash had recorded a 58 percent drop in the Keoladeo vulture population. “I saw the dead vultures almost everywhere,” he said. “We saw dead birds inside the park, and then we also saw dead birds outside the park.” Local villagers, who relied on vultures to keep rotting livestock carcasses from spreading disease and sold the cleaned bones to be ground into fertilizer, confirmed that there were far fewer of the birds around. Prakash began to investigate further, ultimately launching a 7,000-mile road survey that uncovered a 90 percent decrease in vultures nationwide.
Years of study finally determined that a veterinary drug, diclofenac, was persisting in livestock carcasses and poisoning vultures after so much as a single exposure. Though the drug is now banned, illegal use remains a problem. The white-rumped vulture die-off has now reached 99.9 percent, and the species has joined the dismal roster of more than 5,000 life-forms assessed as critically endangered by the International Union for Conservation of Nature.
Today, Prakash said, many Indians under the age of 25—roughly half the population—don’t believe him when he describes the birds’ recent omnipresence. “They’ve not actually seen a vulture,” he said. “They think I’m telling stories.”
Nature is like granola: the list of ingredients is long, but the bowl is mostly filled with just a few of them. Take England, for example, which is small and critter-obsessed enough to count its wildlife nearly one by one. Population estimates for 58 species of land mammals in that country, ranging from the familiar to the obscure, total about 173 million animals. But just three species—the common shrew, rabbit, and mole—account for half of those individuals. All told, the most common 25 percent of English mammal species add up to 97 percent of all the individual animals. Similar patterns play out on land and at sea, in your local park or across whole continents, and whether you’re counting beetles, shellfish, or tropical trees. The most common land bird in the United States and Canada is the American robin, harbinger of spring. Robins alone are as numerous as the two countries’ 277 least common bird species combined.
That species of such incredible abundance can decline as quickly as the white-rumped vulture did points to a counterintuitive idea in conservation: that common species may need protection just as much as rare ones do.
The first scientist to propose the conservation of the common was, almost too perfectly, the author of a book called Rarity. But after 20 years of studying what made some species rare, Kevin Gaston, an ecologist at the University of Exeter, in England, started to wonder why other species are widespread and abundant. He soon came to a seemingly contradictory conclusion: “The state of being common is rare.” While any given common species is made up of many individuals, only a small fraction of species are common.
Gaston’s work culminated in “Common Ecology,” a paper published in the journal BioScience in 2011 that found that commonness was not a well-studied phenomenon, and that “many common species are as poorly studied as many rare ones.” The work triggered a quiet surge of research. A study from 2014 hints at the scale of what’s been overlooked. Its authors found that the number of birds nesting in Europe has dropped by 421 million—fully one-fifth of the continent’s bird population, gone—since 1980, and that this decline in sheer birdiness is accounted for almost entirely by common species, among them such household names as the skylark.
Industrial agriculture carries much of the blame for Europe’s disappearing birds. “They’ve been taking out hedgerows, taking out trees, making fields bigger, increasing inputs of insecticide, pesticides—just essentially squeezing out the opportunities for wild organisms to live in those kinds of environments,” Gaston told me. “We’re talking just massive losses.”
But even the most human-adapted and urban of birds, such as starlings and house sparrows, have steeply decreased—in fact, those two very common birds were among the top five birds experiencing population declines. Most of the rarest birds in Europe are actually increasing at present, due to successful conservation efforts, although they remain uncommon; meanwhile, most of the common birds are declining toward scarcity. “The inevitable place you end up,” said Gaston, “is that everything is rare.”
In the annals of extinction and near-extinction, many of the most infamous cases involved species that were once incredibly common: the plains bison, the passenger pigeon, the Carolina parakeet. The pattern continues today. Consider the radiated tortoise, one of the world’s most beautiful tortoises, its carapace a geodesic dome roofed with elaborate parquet tiles.
The tortoise is capable of extraordinary plenitude—a survey from the year 2000 estimated 10 tortoises per acre in the most pristine redoubts of the species’ range on the African island of Madagascar. But after millennia of coexistence with Malagasy peoples (many of whom considered eating the tortoises fady, or taboo), the species began to fade. Local traditions broke down, the human population shot up, and tortoise hunting and collection for the pet trade surged (one biologist followed a local transit bus as it stopped 11 times in 10 miles to let passengers capture every shuffling shellback they saw). In 2000, researchers declared the prospects for the radiated tortoise “worrisome.” A decade later, the species had leaped to critically endangered status, one step away from extinction in the wild.
Other recent examples include the saiga (an Asian antelope that looks like something out of Star Wars, which has plummeted from almost a million to 50,000—a 95 percent drop—since the end of the Soviet era); the European horse chestnut; sharks in general; and, of course, the white-rumped vulture.
And yet, formerly common species make up only a small fraction of the living things that are threatened with near-term extinction today. The vast majority of critically endangered species are those that were relatively rare to begin with, for the simple reason that it’s much easier to drive a species with low numbers or very limited distribution to the brink.
To focus only on that final moment of total extinction, however, is to downplay the breadth of the extinction crisis. A far more frequent occurrence is extirpation, or local extinction—the disappearance of a species from one or another place where it used to live. Tigers, for example, have vanished from 93 percent (and counting) of their former habitat, including 10 entire nations in Asia. The Pashford pot beetle, on the other hand, is thought to be extinct but was never known to live beyond certain bogs in east-central England. One species is gone but was never abundant in the first place; the other is still with us but has experienced staggering losses.
The authors of one recent study found that the rate of population loss among terrestrial vertebrates is extremely high, even in “species of low concern.” They wrote that “beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations” and used the term “biological annihilation” to describe the magnitude of the crisis. Remarkably, they characterized the wave of local extirpations as a “much more serious and rapid” decline than mass extinctions.
The current estimate among population biologists is that the planet has lost half the individual animals, plants, and other living things that make up our visible world. Most of these accumulated deaths have come at the expense of common species. They are the animals killed most often by hunters, the creatures most likely to end up as roadkill, the trees and plants that die in large numbers each time land is cleared for a farm or a housing development. Even birdwatchers dismiss the most familiar species as “dirt birds.” The term derives from the saying “common as dirt.”
Widespread and abundant species are often seen as natural resources, like copper or oil, rather than as living things. Of all the fish in the oceans, just 10 species account for almost a third of the global catch�
��Alaska pollock, chub mackerel, Atlantic herring, yellowfin tuna, and Japanese anchovy among them. The United Nations’ Food and Agriculture Organization classifies every one of these fish stocks as either “fully fished” or “overfished.” Similarly, the 10 most common tree species in any given nation will, on average, provide 76 percent of the wood and pulp production. In the United States, home to sprawling forests and more than a thousand native tree species, just three—Douglas fir, loblolly pine, and western hemlock—account for one-quarter of the timber harvest. It has been the lot of common species to be mistakenly thought of as infinite in number. Until, one day, it turns out that they aren’t.
Despite all this doom and destruction, even protectors of the environment have tended to overlook the plight of common species. Conservation biology is forever scrambling to pull yet another species back from the void. One result has been the paradox witnessed among nesting birds in Europe, where rarer species are generally increasing while common species have declined by the tens of millions.
Two humble species of newt illustrate how this kind of situation can arise. The great crested newt, which looks like a tiny dragon carrying fire in its belly, is endangered in Belgium. The smooth newt, itself decorated with polka dots and a mini dinosaur crest, is a common species.
Researchers looked at 74 farmland ponds in Belgium; crested newts turned up in just 12 of them, while smooth newts were found in 33. One way to save the endangered crested newt is obvious: protect its dozen ponds. Yet if the remaining ponds are polluted, drained, or otherwise destroyed, then eventually the smooth newt, too, will have only 12 ponds to dwell in. That trend again: everything ends up rare.
To conserve the commonness of smooth newts, you must preserve a larger number of ponds, which will have the parallel effect of conserving the crested newt as well. All of which sounds manageable when you’re talking about a scattering of water holes. But setting aside habitat to save a species no longer works at the scale of, say, a continent.
