Under a White Sky: The Nature of the Future

by Elizabeth Kolbert

Someone wonders if we’ll encounter any Chicago River whitefish, local slang for used condoms.

At the meeting of the waters, there’s a V-shaped park, featuring picturesque waterfalls. Like just about everything else on our route, the waterfalls are manufactured.

Before it was dug, all of the city’s waste—the human excrement, the cow manure, the sheep dung, the rotting viscera from the stockyards—ran into the Chicago River, which, in some spots, was so thick with filth it was said a chicken could walk from one bank to the other without getting her feet wet.

The canal, which was planned in the closing years of the nineteenth century and opened at the start of the twentieth, flipped the river on its head. It compelled the Chicago to change its direction, so that instead of draining into Lake Michigan, the city’s ordure would flow away from it, into the Des Plaines River, and from there into the Illinois, the Mississippi, and, ultimately, the Gulf of Mexico. WATER IN CHICAGO RIVER NOW RESEMBLES LIQUID, ran the headline in The New York Times.

In total, forty-three million cubic yards of rock and soil were gouged out, enough, one admiring commentator calculated, to build an island more than fifty feet high and a mile square. The river made the city, and the city remade the river.

reversing the Chicago didn’t just flush waste toward St. Louis. It also upended the hydrology of roughly two-thirds of the United States.

We have become the major driver of extinction and also, probably, of speciation. So pervasive is man’s impact, it is said that we live in a new geological epoch—the Anthropocene.

“What happens is, the fish is swimming in, and its nose is experiencing one electrical voltage, and its tail is experiencing another. That’s what makes the current actually flow through the body. It’s the current flowing through a fish that will shock them or electrocute them. So a big fish has a big voltage difference from its nose to its tail. A smaller fish doesn’t have that much distance for the voltage to cover, so the shock is smaller.”

The Corps considered more than a dozen possible approaches, including: dosing the canal with poison, irradiating it with ultraviolet light, zapping it with ozone, using power-plant effluent to heat the water, and installing giant filters. It even looked into loading the canal with nitrogen to create the sort of anoxic environment typically associated with raw sewage.

The round goby is a native of the Caspian Sea and an aggressive consumer of other fishes’ eggs. It had established itself in Lake Michigan, and the fear was it would use the Sanitary and Ship Canal to swim out of the lake and into the Des Plaines River. From there, it could swim into the Illinois River and on to the Mississippi. But, as Shea put it to me, “Before the project could be activated, the round goby was already on the other side.” It became a case of electrifying the canal after the fish had bolted.

Though people often talk about Asian carp as if it were a single species, the term is a catchall for four fish.

Each of the famous four has its own special talent, and when they join forces, they are, like the Fantastic Four, pretty much unstoppable. Grass carp (Ctenopharyngodon idella) eat aquatic plants. Silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) are filter feeders; the two fish suck water in through their mouths and then rake out the plankton using comb-like structures in their gills. Black carp (Mylopharyngodon piceus) eat mollusks, like snails.

Throw farm clippings into a pond and the grass carp will eat them. Their waste will promote algae growth. The algae will then feed silver carp and also tiny aquatic animals, like water fleas, the preferred diet of bighead carp. This system has allowed the Chinese to harvest immense quantities of carp—almost fifty billion pounds in 2015 alone.

The four famous fish ended up in the Mississippi, at least in part, owing to Silent Spring—another Anthropocene irony. In the book, whose working title was The Control of Nature, Rachel Carson denounced the very idea.

An alternative Carson particularly recommended was setting one biological agent against another. For instance, a parasite could be imported to feed on an unwanted insect.

“In that book the problem—the villain—was the broad, almost unrestricted use of chemicals, particularly the chlorinated hydrocarbons, like DDT,” Andrew Mitchell, a biologist at an aquaculture research center in Arkansas who’s studied the history of Asian carp in America, told me.

The idea was to use the carp, much as Carson had recommended, to keep aquatic weeds in check. (Weeds like Eurasian watermilfoil—another introduced species—can clog lakes and ponds so thoroughly that boats or even swimmers can’t get through.)

Three years later, biologists at the station succeeded in getting one of the carp—now grown—to spawn. Thousands more fingerlings resulted. Pretty much immediately, some escaped. Baby carp made their way into the White River, a tributary of the Mississippi.

Later, in the 1970s, the Arkansas Game and Fish Commission found a use for silver and bighead carp. The Clean Water Act had just been passed, and local governments were under pressure to comply with the new standards. But a lot of communities couldn’t afford to upgrade their sewage-treatment plants. The Game and Fish Commission thought that stocking carp in treatment ponds might help. The carp would reduce the nutrient load in the ponds by consuming the algae that thrived on the excess nitrogen.

Where the tyrannosaurus’s navel would be, if tyrannosauruses had had navels, was a channel linking the lake to the Illinois River. This arrangement accounted for the carp. Carp need moving water to reproduce—either that or injections of hormones—but once they’re done spawning, they like to retreat to slack water to feed.

Silver carp are equally voracious; they’re such effective filter feeders that they can strain out plankton down to four microns across—a quarter of the width of the finest human hair. Just about wherever they show up, the carp outcompete the native fish until they’re practically all that’s left.

The ecological damage, meanwhile, extends beyond fish; black carp, which feed on mollusks, are, it’s feared, pushing already-threatened freshwater mussels over the edge.

The Mississippi River’s drainage basin is the third largest in the world, exceeded in area only by the Amazon’s and the Congo’s. It stretches over more than 1.2 million square miles and encompasses thirty-one states and slices of two Canadian provinces. The basin is shaped a bit like a funnel, with its spout sticking into the Gulf of Mexico.

The two great basins abut each other, but they are—or were—distinct aquatic worlds. There was no way for a fish (or a mollusk or a crustacean) to climb out of one drainage system and into the other. When Chicago solved its sewage problem by digging the Sanitary and Ship Canal, a portal opened up, and the two aquatic realms were connected.

For most of the twentieth century, this wasn’t much of an issue; the canal, loaded with Chicago’s waste, was too toxic to serve as a viable route. With the passage of the Clean Water Act and the work of groups like the Friends of the Chicago River, conditions improved, and creatures like the round goby began to slip through.

According to the Corps’ assessment, reimposing “hydrologic separation” would, indeed, be the most effective way to keep carp out of the Great Lakes. It would also, in the Corps’ estimate, take twenty-five years—three times as long as the original digging of the canal had—and cost up to $18 billion.

They pointed out that each of the two drainage basins has its own roster of invasives, some, like the carp, brought over intentionally, but most introduced accidentally, in ballast water. On the Mississippi side, these include: Nile tilapia, Peruvian watergrass, and convict cichlid from Central America.

On the Great Lakes side are: sea lamprey, threespine stickleback, fourspine stickleback, spiny waterflea, fishhook waterflea, New Zealand mud snail, European valve snail, European ear snail, greater European pea clam, humpbacked pea clam, Henslow pea clam, red swamp crayfish, and bloody red shrimp.

What people really notice about Asian carp—what literally leaps out at them—is that silver carp jump.

Mills was one of several people I met in Illinois who, for reasons that were not always entirely clear to me, had decided to throw themselves into the fight against Asian carp.

A few years ago, when a group of U.S. scientists visited Shanghai to learn more about the fish, the China Daily ran an article headlined ASIAN CARP: AMERICANS’ POISON, CHINESE PEOPLE’S DELICACY.

On one side of the box was printed THE ASIAN CARP SOLUTION and, under that, CAN’T BEAT ’EM, EAT ’EM! Inside were fish cakes that resembled giant meatballs.

In some places, I could see the outlines of what were once fields and now are rectilinear lakes. Great white clouds, billowing above the plane, were mirrored in the black pools below.

Plaquemines has the distinction—a dubious one, at best—of being among the fastest-disappearing places on earth. Everyone who lives in the parish—and fewer and fewer people do—can point to some stretch of water that used to have a house or a hunting camp on it.

And what’s happening to Plaquemines is happening all along the coast. Since the 1930s, Louisiana has shrunk by more than two thousand square miles.

A variety of factors are driving the “land-loss crisis,” as it’s come to be called. But the essential one is a marvel of engineering. What leaping carp are to Chicagoland, sunken fields are to the parishes around New Orleans—evidence of a man-made natural disaster.

This vast system, built to keep southern Louisiana dry, is the very reason the region is disintegrating, coming apart like an old shoe.

Except for those that have been imported to shore up the levees and reinforce the roads, there are no rocks in southern Louisiana.

A version of the Mississippi has been flowing for millions of years, and all the while it has carried on its broad back vast loads of sediment—at the time of the Louisiana Purchase some four hundred million tons’ worth annually.

Because the Mississippi is always dropping sediment, it’s always on the move. As the sediment builds up, it impedes the flow, and so the river goes in search of faster routes to the sea. Its most dramatic leaps are called “avulsions.” Over the last seven thousand years, the river has avulsed six times, and each time it has set about laying down a new bulge of land.

The Mississippi fan, an enormous cone of sediment deposited during the ice ages, now lies under the Gulf; it’s larger than the entire state of Louisiana and in some places ten thousand feet thick.

The delta’s soft, Jell-O-like soils tend to dewater and compact over time. The newest layers, which are wetter, lose bulk most rapidly, so as soon as a lobe ceases to grow, it starts to sink. In southern Louisiana, to borrow from Bob Dylan, any place that is “not busy being born is busy dying.”

Their strategy for dealing with the river’s vagaries, as far as archaeologists have been able to determine, was one of accommodation. When the Mississippi flooded, they sought higher ground. When it shifted quarters, they did, too.

Pierre Le Moyne d’Iberville, the fort’s commander, had been assured by a Bayogoula guide that the site was a dry one. Whether this represented a purposeful misstatement or just a misunderstanding—“dry” in southern Louisiana being a relative term—the place soon flooded out.

Bienville went on to found New Orleans in 1718, in spite of his cold, wet feet. The new city was called, in honor of its watery surroundings, L’Isle de la Nouvelle Orléans. Not surprisingly, the French chose to build where the land was highest. Counterintuitively, this was right up against the Mississippi, on ridges built by the river itself.

During floods, sand and other heavy particles tend to settle out of the water first, creating what are known as natural levees. (Levée in French simply means “raised.”)

Rather than retreat again, the French dug in. They raised artificial levees atop the natural ones and started cutting drainage channels through the muck. Most of this backbreaking labor was performed by African slaves.

These early levees, made of earth reinforced with timber, failed frequently. But they established a pattern that endures to this day. Since the city wasn’t going to move to suit the river, the river would have to be made to stay put.

At the center’s center is a 1:6,000 replica of the delta, from the town of Donaldsonville, in Ascension Parish, to the tip of the Bird’s Foot. The model is made from high-density foam that’s been machined to mimic the region’s topography and all that’s been added to it—the levees, the spillways, the floodwalls. The size of two basketball courts, it’s sturdy enough to stand on.

Prominently displayed on one of the walls of the center is a maxim attributed to Albert Einstein: “We cannot solve our problems with the same thinking we used when we created them.”