The World Without Us

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.