The World Without Us - Alan Weisman (2007)

Part II

Chapter 10. The Petro Patch


HEN HUMANS DEPART, among the immediate beneficiaries of our absence will be mosquitoes. Although our anthropocentric worldview may flatter us into thinking that human blood is essential to their survival, in fact they are versatile gourmets capable of supping at the veins of most warm-blooded mammals, cold-blooded reptiles, and even birds. In our absence, presumably plenty of wild and feral creatures will rush to fill our void and set up house in our abandoned spaces. Their numbers no longer culled by our lethal traffic, they should multiply with such abandon that humanity’s total biomass—which the eminent biologist E. O. Wilson estimates wouldn’t fill the Grand Canyon—won’t be missed for long.

At the same time, any mosquitoes still bereaved by our passing will be consoled by two bequests. First, we’ll stop exterminating them. Humans were targeting mosquitoes long before the invention of pesticides, by spreading oil on the surfaces of ponds, estuaries, and puddles where they breed. This larvicide, which denies baby mosquitoes oxygen, is still widely practiced, as are all other manners of antimosquito chemical warfare. They range from hormones that keep larvae from maturing into adults, to—especially in the malarial tropics—aerial spraying of DDT, banned only in parts of the world. With humans gone, billions of the little buzzers that would otherwise have died prematurely will now live, and among the secondary beneficiaries will be many freshwater fish species, in whose food chains mosquito eggs and larvae form big links. Others will be flowers: when mosquitoes aren’t sucking blood, they sip nectar—the main meal for all male mosquitoes, although vampirish females drink it as well. That makes them pollinators, so the world without us will bloom anew.

The other gift to mosquitoes will be restoration of their traditional homelands—in this case, home waters. In the United States alone, since its founding in 1776, the part of their prime breeding habitat, wetlands, that they have lost equals twice the area of California. Put that much land back into swamps, and you get the idea. (Mosquito population growth would have to be adjusted for corresponding increases in mosquito-eating fish, toads, and frogs—though, with the last two, humans may have given the insects yet another break: It’s unclear how many amphibians will survive chytrid, an escaped fungus spread by the international trade in laboratory frogs. Triggered by rising temperatures, it has annihilated hundreds of species worldwide.)

Habitat or not, as anyone knows who lives atop a former marsh that was drained and developed, be it in suburban Connecticut or a Nairobi slum, mosquitoes always find a way. Even a dew-filled plastic bottle cap can incubate a few of their eggs. Until asphalt and pavement decompose for good and wetlands rise up to reclaim their former surface rights, mosquitoes will make do with puddles and backed-up sewers. And they can also rest assured that one of their favorite man-made nurseries will be intact for, at minimum, another century, and will continue making cameo appearances for many more centuries thereafter: scrapped rubber automobile tires.

Rubber is a kind of polymer called an elastomer. The ones that occur in nature, such as the milky latex extract of the Amazonian Pará tree, are, logically, biodegradable. The tendency of natural latex to turn gooey in high temperatures, and to stiffen or even shatter in cold, limited its practicality until 1839, when a Massachusetts hardware salesman tried mixing it with sulfur. When he accidentally dropped some on a stove and it didn’t melt, Charles Goodyear realized that he’d created something that nature had never tried before.

To this day, nature hasn’t come up with a microbe that eats it, either. Goodyear’s process, called vulcanization, ties long rubber polymer chains together with short strands of sulfur atoms, actually transforming them into a single giant molecule. Once rubber is vulcanized—meaning it’s heated, spiked with sulfur, and poured into a mold, such as one shaped like a truck tire—the resulting huge molecule takes that form and never relinquishes it.

Being a single molecule, a tire can’t be melted down and turned into something else. Unless physically shredded or worn down by 60,000 miles of friction, both entailing significant energy, it remains round. Tires drive landfill operators crazy, because when buried, they encircle a doughnut-shaped air bubble that wants to rise. Most garbage dumps no longer accept them, but for hundreds of years into the future, old tires will inexorably work their way to the surface of forgotten landfills, fill with rainwater, and begin breeding mosquitoes again.

In the United States, an average of one tire per citizen is discarded annually—that’s a third of a billion, just in one year. Then there’s the rest of the world. With about 700 million cars currently operating and far more than that already junked, the number of used tires we’ll leave behind will be less than a trillion, but certainly many, many billions. How long they’ll lie around depends on how much direct sunlight falls on them. Until a microbe evolves that likes its hydrocarbons seasoned with sulfur, only the caustic oxidation of ground-level ozone, the pollutant that stings your sinuses, or the cosmic power of ultraviolet rays that penetrate a damaged stratospheric ozone layer, can break vulcanized sulfur bonds. Automobile tires therefore are impregnated with UV inhibitors and “anti-ozonants,” along with other additives like the carbon black filler that gives tires their strength and color.

With all that carbon in tires, they can be also burned, releasing considerable energy, which makes them hard to extinguish, along with surprising amounts of oily soot that contains some noxious components we invented in a hurry during World War II. After Japan invaded Southeast Asia, it controlled nearly the entire world’s rubber supply. Understanding that their own war machines wouldn’t go far using leather gaskets or wooden wheels, both Germany and the United States drafted their top industries to find a substitute.

The largest plant in the world today that produces synthetic rubber is in Texas. It belongs to the Goodyear Tire & Rubber Company and was built in 1942, not long after scientists figured out how to make it. Instead of living tropical trees, they used dead marine plants: phytoplankton that died 300 million to 350 million years ago and sank to the sea bottom. Eventually—so the theory goes; the process is poorly understood and sometimes challenged—the phytoplankton were covered with so many sediments and squeezed so hard they metamorphosed into a viscous liquid. From that crude oil, scientists already knew how to refine several useful hydrocarbons. Two of these—styrene, the stuff of Styrofoam, and butadiene, an explosive and highly carcinogenic liquid hydrocarbon—provided the combination to synthesize rubber.

Six decades later, it’s what Goodyear Rubber still makes here, with the same equipment rolling out the base for everything from NASCAR racing tires to chewing gum. Large as the plant is, however, it’s swamped by what surrounds it: one of the most monumental constructs that human beings have imposed on the planet’s surface. The industrial megaplex that begins on the east side of Houston and continues uninterrupted to the Gulf of Mexico, 50 miles away, is the largest concentration of petroleum refineries, petrochemical companies, and storage structures on Earth.

It contains, for example, the tank farm behind razor-edged concertina wire just across the highway from Goodyear—a cluster of cylindrical crude-oil receptacles each a football field’s length in diameter, so wide they appear squat. The omnipresent pipelines that link them run to all compass points, as well as up and down—white, blue, yellow, and green pipelines, the big ones nearly four feet across. At plants like Goodyear, pipelines form archways high enough for trucks to pass under.

Those are just the visible pipes. A satellite-mounted CT scanner flying over Houston would reveal a vast, tangled, carbon-steel circulatory system about three feet below the surface. As in every city and town in the developed world, thin capillaries run down the center of every street, branching off to every house. These are gas lines, comprising so much steel that it’s a wonder that compass needles don’t simply point toward the ground. In Houston, however, gas lines are mere accents, little flourishes. Refinery pipelines wrap around the city as tightly as a woven basket. They move material called light fractions, distilled or catalytically cracked off crude oil, to hundreds of Houston chemical plants—such as Texas Petrochemical, which provides its neighbor Goodyear with butadiene and also concocts a related substance that makes plastic wrap cling. It also produces butane—the feedstock for polyethylene and polypropylene nurdle pellets.

Hundreds of other pipes full of freshly refined gasoline, home heating oil, diesel, and jet fuel hook into the grand patriarch of conduits—the 5,519-mile, 30-inch Colonial Pipeline, whose main trunk starts in the Houston suburb of Pasadena. It picks up more product in Louisiana, Mississippi, and Alabama, then climbs the eastern seaboard, sometimes above-ground, sometimes below. The Colonial is typically filled with a lineup of various grades of fuel that pump through it at about four miles per hour until they’re disgorged at a Linden, New Jersey, terminal just below New York Harbor—about a 20-day trip, barring shutdowns or hurricanes.

Imagine future archaeologists clanging their way through all those pipes. What will they make of the thick old steel boilers and multiple stacks behind Texas Petrochemical? (Although, if humans stick around for a few more years, all that old stock, overbuilt back when there were no computers to pinpoint tolerances, will have been dismantled and sold to China, which is buying up scrap iron in America for purposes that some World War II historians question with alarm.)

If those archaeologists were to follow the pipes several hundred feet down, they would encounter an artifact destined to be among the longest-lasting ever made by humans. Beneath the Texas Gulf coast are about 500 salt domes formed when buoyant salts from saline beds five miles down rise through sedimentary layers. Several lie right under Houston. Bullet-shaped, they can be more than a mile across. By drilling into a salt dome and then pumping in water, it is possible to dissolve its interior and use it for storage.

Some salt dome storage caverns below the city are 600 feet across and more than half a mile tall, equaling a volume twice that of the Houston Astrodome. Because salt crystal walls are considered impermeable, they are used for storing gases, including some of the most explosive, such as ethylene. Piped directly to an underground salt dome formation, ethylene is stored under 1,500 pounds of pressure until it’s ready to be turned into plastic. Because it is so volatile, ethylene can decompose rapidly and blow a pipe right out of the ground. Presumably, it would be best for archaeologists of the future to leave the salt caverns be, lest an ancient relic from a long-dead civilization blow up in their faces. But how would they know?

Back above ground, like robotic versions of the mosques and minarets that grace the shores of Istanbul’s Bosphorus, Houston’s petroscape of domed white tanks and silver fractionating towers spreads along the banks of its Ship Channel. The flat tanks that store liquid fuels at atmospheric temperatures are grounded so that vapors that gather in the space below the roof don’t ignite during a lightning storm. In a world without humans to inspect and paint doubled-hulled tanks, and replace them after their 20-year life span, it would be a race to see whether their bottoms corrode first, spilling their contents into the soil, or their grounding connectors flake away—in which case, explosions would hasten deterioration of the remaining metal fragments.

Some tanks with moveable roofs that float atop liquid contents to avoid vapor buildup might fail even earlier, as their flexible seals start to leak. If so, what’s inside would just evaporate, pumping the last remaining human-extracted carbon into the atmosphere. Compressed gases, and some highly inflammable chemicals such as phenols, are held in spherical tanks, which should last longer because their hulls aren’t in contact with the ground—although, since they’re pressurized, they would explode more sensationally once their spark protection rusts away.

What lies beneath all this hardware, and what are the chances that it could ever recover from the metallic and chemical shock that the last century of petrochemical development has wreaked here? Should this most unnatural of all Earthly landscapes ever be abandoned by the humans who keep its flares burning and fuels flowing, how could nature possibly dismantle, let alone decontaminate, the great Texas petroleum patch?

HOUSTON, ALL 620 square miles of it, straddles the edge between a bluestem and grama-grass prairie that once grew belly-high to a horse and the lower piney-woods wetland that was (and still is) part of the original delta of the Brazos River. The dirt-red Brazos begins far across the state, draining New Mexico mountains 1,000 miles away, then cuts through Texas hill country and eventually dumps one of the biggest silt loads on the continent into the Gulf of Mexico. During glacial times, when winds blowing off the ice sheet slammed into warm gulf air and caused torrential rains, the Brazos laid down so much sediment that it would dam itself and as a result slip back and forth across a deltaic fan hundreds of miles wide. Lately, it passes just south of town. Houston sits along one of the river’s former channels, atop 40,000 feet of sedimentary clay deposits.

In the 1830s, that magnolia-lined channel, Buffalo Bayou, attracted entrepreneurs who noticed that it was navigable from Galveston Bay to the edge of the prairie. At first, the new town they built there shipped cotton 50 miles down this inland waterway to the port of Galveston, then the biggest city in Texas. After 1900, when the deadliest hurricane in U.S. history hit Galveston and killed 8,000 people, Buffalo Bayou was widened and deepened into the Ship Channel, to make Houston a seaport. Today, by cargo volume, it’s America’s biggest, and Houston itself is huge enough to hold Cleveland, Baltimore, Boston, Pittsburgh, Denver, and Washington, D.C., with room to spare.

Galveston’s misfortune coincided with discoveries of oil along the Texas Gulf coast and the advent of the automobile. Longleaf piney woods, bottomland delta hardwood forests, and coastal prairie soon were supplanted by drilling rigs and dozens of refineries along Houston’s shipping corridor. Next came chemical plants, then World War II rubber factories, and, finally, the fabulous postwar plastics industry. Even when Texas oil production peaked in the 1970s and then plummeted, Houston’s infrastructure was so vast that the world’s crude kept flowing here to be refined.

The tankers, bearing flags of Middle Eastern nations, Mexico, and Venezuela, arrive at an appendage of the Ship Channel on Galveston Bay called Texas City, a town of about 50,000 that has as much acreage devoted to refining as to residences and business. Compared to their big neighbors—Sterling Chemical, Marathon, Valero, BP, ISP, Dow—the bungalows of Texas City’s residents, mostly black and Latino, are lost in a townscape ruled by the geometry of petrochemistry: circles, spheres, and cylinders—some tall and thin, some short and flat, some wide and round.

It is the tall ones that tend to blow up.

Not all of them, although they often look alike. Some are wet-gas scrubbers: towers that use Brazos River water to quench gas emissions and cool down hot solids, generating white steam clouds up their stacks. Others are fractionating towers, in which crude oil is heated from the bottom to distill it. The various hydrocarbons in crude, ranging from tar to gasoline to natural gas, have different boiling points; as they’re heated, they separate, arranging themselves in the column with the lightest ones on top. As long as expanding gases are drawn off to release pressure, or the heat is eventually reduced, it’s a fairly safe process.

Trickier are the ones that add other chemicals to convert petroleum into something new. In refineries, catalytic cracking towers heat the heavy hydrocarbons with a powdered aluminum silicate catalyst to about 1,200°F. This literally cracks their big polymer chains into smaller, lighter ones, such as propane or gasoline. Injecting hydrogen into the process can produce jet fuel and diesel. All these, especially at high temperatures, and especially with hydrogen involved, are highly explosive.

A related procedure, isomerization, uses a platinum catalyst and even more heat to rearrange atoms in hydrocarbon molecules for boosting fuel octane or making substances used in plastics. Isomerization can get extremely volatile. Connected to these cracking towers and isomerization plants are flares. If any process becomes imbalanced or if temperatures shoot too high, flares are there to bleed off pressure. A release valve sends whatever can’t be contained up the flare stack, signaling a pilot to ignite. Sometimes steam is injected so that whatever it is doesn’t smoke, but burns cleanly.

When something malfunctions, the results, unfortunately, can be spectacular. In 1998, Sterling Chemical expelled a cloud of various benzene isomers and hydrochloric acid that hospitalized hundreds. That followed a leak of 3,000 pounds of ammonia four years earlier that prompted 9,000 personal injury suits. In March 2005, a geyser of liquid hydrocarbons erupted from one of BP’s isomerization stacks. When it hit the air, it ignited and killed 15 people. That July, at the same plant, a hydrogen pipe exploded; in August, a gas leak reeking of rotten eggs, which signals toxic hydrogen sulfide, shut much of BP down for a while. Days later, at a BP plastics-manufacturing subsidiary 15 miles south at Chocolate Bayou, flames exploded 50 feet in the air. The blaze had to be left to burn itself out. It took three days.

The oldest refinery in Texas City, started in 1908 by a Virginia farmers’ cooperative to produce fuel for their tractors, is owned today by Valero Energy Corporation. In its modern incarnation, it has earned one of the highest safety designations among U.S. refineries, but it is still a place designed to draw energy from a crude natural resource by transmuting it into more explosive forms. That energy feels barely contained by Valero’s humming labyrinth of valves, gauges, heat exchangers, pumps, absorbers, separators, furnaces, incinerators, flanges, tanks girdled by spiral stairwells, and serpentine loops of red, yellow, green, and silvery pipes (the silver ones are insulation-wrapped, meaning that something inside is hot, and needs to stay that way). Looming overhead are 20 fractionation towers and 20 more exhaust stacks. A coker shovel, basically a crane with a bucket on it, shuttles back and forth, dumping loads of sludge redolent of asphalt—the heavy ends of the crude spectrum, left in the bottom of the fractionators—onto conveyors leading into a catalytic cracker, to squeeze another barrel of diesel from them.

Above all this are the flares, wedges of flame against a whitish sky, keeping all the organic chemistry in equilibrium by burning off pressures that build faster than all the monitoring gauges can regulate them. There are gauges that read the thickness of steel pipe at the right-angle bends where hot, corrosive fluids smash, to predict when they will fail. Anything that contains hot liquid traveling at high speeds can develop stress cracks, especially when the liquid is heavy crude, laden with metals and sulfur that can eat pipe walls.

All this equipment is controlled by computers—until something exceeds what the computer can correct. Then the flares kick in. Suppose, though, that a system’s pressures exceeded their capacity—or suppose nobody were around to notice the overload. Normally, somebody always is, around the clock. But what if human beings suddenly disappeared while the plant was still operating?

“You’d end up with a break in some vessel,” says Valero spokesman Fred Newhouse, a compact, congenial man with light brown skin and grizzled hair. “And probably a fire.” But at that point, Newhouse adds, fail-safe control valves up and downstream from the accident would automatically trip. “We measure pressure, flow, and temperature constantly. Any changes would isolate the problem so that fire couldn’t ripple from that unit to the next one.”

But what if no one were left to fight the flames? And what if all the power died, because no one was manning any of the coal, gas, and nuclear plants, or any of the hydroelectric dams from California to Tennessee, all of which funnel electrons through a Houston grid connection to keep the lights on in Texas City? And what if the automatic emergency generators ran out of diesel, so no signal tripped the shutoff valves?

Newhouse moves into the shadow of a cracking tower to consider this. After 26 years at Exxon, he really likes working for Valero. He’s proud of their clean record, especially compared to the BP plant across the road, which the EPA in 2006 named the nation’s worst polluter. The thought of all this incredible infrastructure out of control, torching itself, makes him wince.

“Okay. Everything would burn until all the hydrocarbon in the system was gone. But,” he insists, “it’s very unlikely that fire would spread beyond the property. The pipes that connect the Texas City refineries all have check valves to isolate one from another. So even when you see plants explode,” he says, gesturing across the road, “adjacent units aren’t damaged. Even if it’s a huge fire, fail-safe systems are in place.”

E.C. isn’t so sure. “Even on a normal operating day,” he says, “a petrochemical plant is a ticking time bomb.” A chemical plant and refinery inspector, he’s seen volatile light petroleum fractions do some interesting things on their way to becoming secondary petrochemicals. When light-end chemicals such as ethylene or acrylonitrile—a highly inflammable precursor of acrylic, hazardous to human nervous systems—are under high pressure, they often slip through ducts and find their way to adjacent units, or even adjacent refineries.

In the event that humans were gone tomorrow, he says, what would happen to petroleum refineries and chemical plants would depend on whether anybody bothered to flip some switches before departing.

“Supposing there’s time for a normal shutdown. High pressures would be brought down to low pressure. Boilers would be shut down, so temperature isn’t a problem. In the towers, the heavy bottoms would cake up into solid goop. They would be encased in vessels with steel inner layers, surrounded by Styrofoam or glass-fiber insulation, with an outer skin of sheet metal. Between those layers there’s often steel or copper tubing filled with water to control temperatures. So whatever is in them would be stable— until corrosion set in from the soft water.”

He rummages in a desk drawer, then closes it. “Absent any fire or explosion, light-end gases will dissipate into the air. Any sulfur by-product lying around will eventually dissolve and create acid rain. Ever see a Mexican refinery? There’re mountains of sulfur. Americans ship it off. Anyhow, refineries also have big tanks of hydrogen. Very volatile, but if they leaked, the hydrogen would float away. Unless lightning blew it up first.”

He laces his fingers behind his curly, graying brown hair and tilts back in his office chair. “Now that would get rid of lot of cement infrastructure right there.”

And if there were no time to shut down a plant, if humans were raptured off to heaven or another galaxy and left everything running?

He rocks forward. “At first, emergency power plants would kick in. They’re usually diesel. They would probably maintain stability until they depleted their fuel. Then you’d have high pressures and high temperatures. With no one to monitor controls or the computers, some reactions would run away and go boom. You would get a fire, and then a domino effect, since there’d be nothing to stop it. Even with emergency motors, water sprayers wouldn’t work, because there’d be no one to turn them on. Some relief valves would vent, but in a fire, a relief valve would just feed the flames.”

E.C. swivels completely in his chair. A marathoner, he wears jogging shorts and a sleeveless T-shirt. “All the pipes would be conduits for fires. You’d have gas going from one area to another. Normally, in emergencies you shut down the connections, but none of that would happen. Things would just spread from one facility to the next. That blaze could possibly go for weeks, ejecting stuff into the atmosphere.”

Another swivel, this time counterclockwise. “If this happened to every plant in world, imagine the amount of pollutants. Think of the Iraqi fires. Then multiply that, everywhere.”

In those Iraqi fires, Saddam Hussein blew up hundreds of wellheads, but sabotage isn’t always needed. Mere static electricity from fluids moving through pipes can spark ignition in natural-gas wells, or in oil wells pressurized with nitrogen to bubble up more petroleum. On the big flat screen in front of E.C, a blinking item on a list says that a Chocolate Bayou, Texas, plant that makes acrylonitrile was 2002’s biggest releaser of carcinogens in the United States.

“Look: If all the people left, a fire in a gas well would go until the gas pocket depleted. Usually, the ignition sources are wiring, or a pump. They’d be dead, but you’d still have static electricity or lightning. A well fire burns on the surface, since it needs air, but there would be no one to push it back and cap the wellhead. Huge pockets of gas in the Gulf of Mexico or Kuwait would maybe burn forever. A petrochemical plant wouldn’t go that long, because there’s not as much to burn. But imagine a runaway reaction with burning plants throwing up clouds of stuff like hydrogen cyanide. There would be a massive poisoning of the air in the Texas-Louisiana chemical alley. Follow the trade winds and see what happens.”

All those particulates in the atmosphere, he imagines, could create a mini chemical nuclear winter. “They would also release chlorinated compounds like dioxins and furans from burning plastics. And you’d get lead, chromium, and mercury attached to the soot. Europe and North America, with the biggest concentrations of refineries and chemical plants, would be the most contaminated. But the clouds would disperse through the world. The next generation of plants and animals, the ones that didn’t die, might need to mutate in ways that could impact evolution.”

ON THE NORTHERN edge of Texas City, in the long afternoon shadow of an ISP chemical plant, is a 2,000-acre wedge of original tall grass donated by Exxon-Mobil and now managed by The Nature Conservancy. It is the last remnant of what were 6 million acres of coastal prairie before petroleum arrived. Today, the Texas City Prairie Preserve is home to half of the 40 known remaining Attwater’s prairie chickens—considered the most endangered bird in North America until the controversial 2005 spotting in Arkansas of a lone ivory-billed woodpecker, a species hitherto believed extinct.

During courtship, male Attwater’s prairie chickens inflate vivid, balloon-like golden sacs on either side of their necks. The impressed females respond by laying a lot of eggs. In a world without humans, however, it’s questionable whether the breed will be able to survive. Oil industry apparatus isn’t all that has spread across their habitat. The grassland here once ran clear to Louisiana with hardly a tree, the tallest thing on the horizon being an occasional grazing buffalo. That changed around 1900 with the coincidental arrival of both petroleum and the Chinese tallow tree.

Back in China, this formerly cold-weather species coated its seeds with harvestable quantities of wax to guard against winter. Once it was brought to the balmy American South as an agricultural crop, it noticed there was no need to do that. In a textbook display of sudden evolutionary adaptation, it stopped making weatherproof wax and put its energy into producing more seeds.

Today, wherever there isn’t a petrochemical stack along the Ship Channel, there’s a Chinese tallow tree. Houston’s longleaf pines are long gone, overwhelmed by the Chinese interloper, its rhomboid leaves turning ruby red each fall in atavistic memory of chilly Canton. The only way The Nature Conservancy keeps them from shading out and shoving aside the bluestem and sunflowers of its prairie is with careful annual burning to keep the prairie chicken mating fields intact. Without people to maintain that artificial wilderness, only an occasional exploding old petroleum tank might beat back the botanical Asian invasion.

If, in the immediate aftermath of Homo sapiens petrolerus, the tanks and towers of the Texas petrochemical patch all detonated together in one spectacular roar, after the oily smoke cleared, there would remain melted roads, twisted pipe, crumpled sheathing, and crumbled concrete. White-hot incandescence would have jump-started the corrosion of scrap metals in the salt air, and the polymer chains in hydrocarbon residues would likewise have cracked into smaller, more digestible lengths, hastening biodegradation. Despite the expelled toxins, the soils would also be enriched with burnt carbon, and after a year of rains switchgrass would be growing. A few hardy wildflowers would appear. Gradually, life would resume.

Or, if the faith of Valero Energy’s Fred Newhouse in system safeguards proves warranted—or if the departing oilmen’s last loyal act is to depressurize towers and bank the fires—the disappearance of Texas’s world champion petroleum infrastructure will proceed more slowly. During the first few years, the paint that slows corrosion will go. Over the next two decades, all the storage tanks will exceed their life spans. Soil moisture, rain, salt, and Texas wind will loosen their grip until they leak. Any heavy crude will have hardened by then; weather will crack it, and bugs will eventually eat it.

What liquid fuels that haven’t already evaporated will soak into the ground. When they hit the water table, they’ll float on top because oil is lighter than water. Microbes will find them, realize that they were once only plant life, too, and gradually adapt to eat them. Armadillos will return to burrow in the cleansed soil, among the rotting remains of buried pipe.

Unattended oil drums, pumps, pipes, towers, valves, and bolts will deteriorate at the weakest points, their joints. “Flanges, rivets,” says Fred Newhouse. “There are a jillion in a refinery.” Until they go, collapsing the metal walls, pigeons that already love to nest atop refinery towers will speed the corruption of carbon steel with their guano, and rattlesnakes will nest in the vacant structures below. As beavers dam the streams that trickle into Galveston Bay, some areas will flood. Houston is generally too warm for a freeze-thaw cycle, but its deltaic clay soils undergo formidable swell-shrink bouts as rains come and go. With no more foundation repairmen to shore up the cracks, in less than a century downtown buildings will start leaning.

During that same time, the Ship Channel will have silted back into its former Buffalo Bayou self. Over the next millennium, it and the other old Brazos channels will periodically fill, flood, undermine the shopping malls, car dealerships, and entrance ramps—and, building by tall building, bring down Houston’s skyline.

As for the Brazos itself: Today, 20 miles down the coast from Texas City, just below Galveston Island and just past the venomous plumes rising from Chocolate Bayou, the Brazos de Dios (“Arms of God”) River wanders around a pair of marshy national wildlife refuges, drops an island’s worth of silt, and joins the Gulf of Mexico. For thousands of years, it has shared a delta, and sometimes a mouth, with the Colorado and the San Bernard rivers. Their channels have interbraided so often that the correct answer to which is which is temporary at best.

Much of the surrounding land, barely three feet above sea level, is dense canebrake and old bottomland forest stands of live oaks, ashes, elms, and native pecans, spared years ago by sugarcane plantations for cattle shade. “Old” here means only a century or two, because clay soils repel root penetration, so that mature trees tend to list until the next hurricane knocks them over. Hung with wild grapevines and beards of Spanish moss, these woods are seldom visited by humans, who are dissuaded by poison ivy and black snakes, and also by golden orb weaver spiders big as a human hand, which string viscous webs the size of small trampolines between tree trunks. There are enough mosquitoes to belie any notion that their survival would be threatened when evolving microbes finally bring down the world’s mountain ranges of scrap tires.

As a result, these neglected woods are inviting habitats for cuckoos, woodpeckers, and wading birds such as ibises, sandhill cranes, and roseate spoonbills. Cottontail and marsh rabbits attract barn owls and bald eagles, and each spring thousands of returning passerine birds, including scarlet and summer tanagers in fabulous breeding plumage, flop into these trees after a long gulf crossing.

The deep clays below their perches accumulated back when the Brazos flooded—back before a dozen dams and diversions and a pair of canals siphoned its water to Galveston and Texas City. But it will flood again. Un-tended dams silt up fast. Within a century without humans, the Brazos will spill over all of them, one by one.

It may not even have to wait that long. Not only is the Gulf of Mexico, whose water is even warmer than the ocean’s, creeping inland, but all along the Texas coast for the past century, the ground has been lowered to receive it. When oil, gas, or groundwater is pumped from beneath the surface, land settles into the space it occupied. Subsidence has lowered parts of Galveston 10 feet. An upscale subdivision in Baytown, north of Texas City, dropped so low that it drowned during Hurricane Alicia in 1983 and is now a wetlands nature preserve. Little of the Gulf Coast is more than three feet above sea level, and parts of Houston actually dip below it.

Lower the land, raise the seas, add hurricanes far stronger than midsize, Category 3 Alicia, and even before its dams go, the Brazos gets to do again what it did for 80,000 years: like its sister to the east, the Mississippi, it will flood its entire delta, starting up where the prairie ends. Flood the enormous city that oil built, all the way down to the coast. Swallow the San Bernard and overlap the Colorado, fanning a sheet of water across hundreds of miles of coastline. Galveston Island’s 17-foot seawall won’t be much help. Petroleum tanks along the Ship Channel will be submerged; flare towers, catalytic crackers, and fractionating columns, like downtown Houston buildings, will poke out of brackish floodwaters, their foundations rotting while they wait for the waters to recede.

Having rearranged things yet again, the Brazos will choose a new course to the sea—a shorter one, because the sea will be nearer. New bottomlands will form, higher up, and eventually new hardwoods will appear (assuming that Chinese tallow trees, whose waterproof seeds should make them permanent colonizers, share the riparian space with them). Texas City will be missing; hydrocarbons leaching out of its drowned petrochemical plants will swirl and dissipate in the currents, with a few heavy-end crude residues dumped as oil globules on the new inland shores, eventually to be eaten.

Below the surface, the oxidizing metal parts of chemical alley will provide a place for Galveston oysters to attach. Silt and oyster shells will slowly bury them, and will then be buried themselves. Within a few million years, enough layers will amass to compress shells into limestone, which will bear an odd, intermittent rusty streak flecked with sparkling traces of nickel, molybdenum, niobium, and chromium. Millions of years after that, someone or something might have the knowledge and tools to recognize the signal of stainless steel. Nothing, however, will remain to suggest that its original form once stood tall over a place called Texas, and breathed fire into the sky.