However, it took more than $130 million and a lot of man-hours to drain and seal the arsenal’s lake, in which ducks once died minutes after landing and the aluminum bottoms of boats sent to fetch their carcasses rotted within a month. In a world with no one left to bury the bad stuff, decaying chemical containers would slowly expose their lethal contents. Places like the Indian Point nuclear power plant, 35 miles north of Times Square, would dump radioactivity into the Hudson long after the lights went out.
Old stone buildings in Manhattan, such as Grand Central Station or the Metropolitan Museum of Art, would outlast every modern glass box, especially with no more acid rain to pock their marble. Still, at some point thousands of years hence, the last stone walls—perhaps chunks of St. Paul’s Chapel on Wall Street, built in 1766 from Manhattan’s own hard schist—would fall. Three times in the past 100,000 years, glaciers have scraped New York clean, and they’ll do so again. The mature hardwood forest would be mowed down. On Staten Island, Fresh Kills’s four giant mounds of trash would be flattened, their vast accumulation of stubborn PVC plastic and glass ground to powder. After the ice receded, an unnatural concentration of reddish metal—remnants of wiring and plumbing—would remain buried in layers. The next toolmaker to arrive or evolve might discover it and use it, but there would be nothing to indicate who had put it there.
Before humans appeared, an oriole could fly from the Mississippi to the Atlantic and never alight on anything other than a treetop. Unbroken forest blanketed Europe from the Urals to the English Channel. The last remaining fragment of that primeval European wilderness—half a million acres of woods straddling the border between Poland and Belarus, called the Bialowieza Forest—provides another glimpse of how the world would look if we were gone. There, relic groves of huge ash and linden trees rise 138 feet above an understory of hornbeams, ferns, swamp alders, massive birches, and crockery-size fungi. Norway spruces, shaggy as Methuselah, stand even taller. Five-century-old oaks grow so immense that great spotted woodpeckers stuff whole spruce cones in their three-inch-deep bark furrows. The woods carry pygmy owl whistles, nutcracker croaks, and wolf howls. Fragrance wafts from eons of mulch.
High privilege accounts for such unbroken antiquity. During the 14th century, a Lithuanian duke declared it a royal hunting preserve. For centuries it stayed that way. Eventually, the forest was subsumed by Russia and in 1888 became the private domain of the czars. Occupying Germans took lumber and slaughtered game during World War I, but a pristine core was left intact, which in 1921 became a Polish national park. Timber pillaging resumed briefly under the Soviets, but when the Nazis invaded, nature fanatic Hermann Göring decreed the entire preserve off limits. Then, following World War II, a reportedly drunken Josef Stalin agreed one evening in Warsaw to let Poland retain two-fifths of the forest.
To realize that all of Europe once looked like this is startling. Most unexpected of all is the sight of native bison. Just 600 remain in the wild, on both sides of an impassable iron curtain erected by the Soviets in 1980 along the border to thwart escapees to Poland’s renegade Solidarity movement. Although wolves dig under it, and roe deer are believed to leap over it, the herd of the largest of Europe’s mammals remains divided, and thus its gene pool. Belarus, which has not removed its statues of Lenin, has no specific plans to dismantle the fence. Unless it does, the bison may suffer genetic degradation, leaving them vulnerable to a disease that would wipe them out.
If the bison herd withers, they would join all the other extinct megafauna that even our total disappearance could never bring back. In a glass case in his laboratory, paleoecologist Paul S. Martin at the University of Arizona keeps a lump of dried dung he found in a Grand Canyon cave, left by a sloth weighing 200 pounds. That would have made it the smallest of several North American ground sloth species present when humans first appeared on this continent. The largest was as big as an elephant and lumbered around by the thousands in the woodlands and deserts of today’s United States. What we call pristine today, Martin says, is a poor reflection of what would be here if Homo sapiens had never evolved.
“America would have three times as many species of animals over 1,000 pounds as Africa does today,” he says. An amazing megafaunal menagerie roamed the region: Giant armadillos resembling armor-plated autos; bears twice the size of grizzlies; the hoofed, herbivorous toxodon, big as a rhinoceros; and saber-toothed tigers. A dozen species of horses were here, as well as the camel-like litoptern, giant beavers, giant peccaries, woolly rhinos, mammoths, and mastodons. Climate change and imported disease may have killed them, but most paleontologists accept the theory Martin advocates: “When people got out of Africa and Asia and reached other parts of the world, all hell broke loose.” He is convinced that people were responsible for the mass extinctions because they commenced with human arrival everywhere: first, in Australia 60,000 years ago, then mainland America 13,000 years ago, followed by the Caribbean islands 6,000 years ago, and Madagascar 2,000 years ago.
Yet one place on Earth did manage to elude the intercontinental holocaust: the oceans. Dolphins and whales escaped for the simple reason that prehistoric people could not hunt enough giant marine mammals to have a major impact on the population. “At least a dozen species in the ocean Columbus sailed were bigger than his biggest ship,” says marine paleoecologist Jeremy Jackson of the Smithsonian Tropical Research Institute in Panama. “Not only mammals—the sea off Cuba was so thick with 1,000-pound green turtles that his boats practically ran aground on them.” This was a world where ships collided with schools of whales and where sharks were so abundant they would swim up rivers to prey on cattle. Reefs swarmed with 800-pound goliath grouper, not just today’s puny aquarium species. Cod could be fished from the sea in baskets. Oysters filtered all the water in Chesapeake Bay every five days. The planet’s shores teemed with millions of manatees, seals, and walrus.
Within the past century, however, humans have flattened the coral reefs on the continental shelves and scraped the sea grass beds bare; a dead zone bigger than New Jersey grows at the mouth of the Mississippi; all the world’s cod fisheries have collapsed. What Pleistocene humans did in 1,500 years to terrestrial life, modern man has done in mere decades to the oceans—“almost,” Jackson says. Despite mechanized overharvesting, satellite fish tracking, and prolonged butchery of sea mammals, the ocean is still bigger than we are. “It’s not like the land,” he says. “The great majority of sea species are badly depleted, but they still exist. If people actually went away, most could recover.”
Even if global warming or ultraviolet radiation bleaches the Great Barrier Reef to death, Jackson says, “it’s only 7,000 years old. New reefs have had to form before. It’s not like the world is a constant place.” Without people, most excess industrial carbon dioxide would dissipate within 200 years, cooling the atmosphere. With no further chlorine and bromine leaking skyward, within decades the ozone layer would replenish, and ultraviolet damage would subside. Eventually, heavy metals and toxins would flush through the system; a few intractable PCBs might take a millennium.
During that same span, every dam on Earth would silt up and spill over. Rivers would again carry nutrients seaward, where most life would be, as it was long before vertebrates crawled onto the shore. Eventually, that would happen again. The world would start over.
The wilds of New York
If humans were to vanish from New York, how soon would nature take over? Scientists predict that within . . .
10 years: Sidewalks crack and weeds invade. Hawks and falcons flourish, as do feral cats and dogs. The rat population, deprived of human garbage, crashes. Cockroaches, which thrive in warm buildings, disappear. Cultivated carrots, cabbages, broccoli, and brussels sprouts revert to their wild ancestors.
20 years: Water-soaked steel columns supporting subway tunnels corrode and buckle. Bears and wolves invade Central Park.
50 years: Concrete chunks tumble from buildings, whose steel foundations beginto crumble. Indian Point nuclear reactors leak radioactivity into the Hudson River.
100 years: Oaks and maples re-cover the land.
300 years: Most bridges collapse.
1,000 years: Hell Gate Bridge, built to bring the railroad across the East River, finally falls.
10,000 years: Indian Point nuclear reactors continue to leak radioactivity into the Hudson River.
20,000 years: Glaciers move relentlessly across the island of Manhattan and its environs, scraping the landscape clean.