Eventually, when its roof blows away, radioactive rainwater inside and in adjacent cooling ponds could evaporate, leaving a new lode of radioactive dust for the burgeoning Chernobyl menagerie to inhale.

After the explosion, the radionuclide count was high enough in Scandinavia that reindeer were sacrificed rather than eaten. Tea plantations in Turkey were so uniformly dosed that Turkish tea bags were used in Ukraine to calibrate dosimeters. If, in our wake, we leave the cooling ponds of 441 nuclear plants around the world to dry and their reactor cores to melt and burn, the clouds enshrouding the planet will be far more insidious.

Meanwhile, we are still here. Not just animals but people too have crept back into Chernobyl’s and Novozybkov’s contaminated zones. Technically, they’re illegal squatters, but authorities don’t try very hard to dissuade the desperate or needy from gravitating to empty places that smell so fresh and look so clean, as long as no one checks those dosimeters. Most of them aren’t simply seeking free real estate. Like the swallows who returned, they come because they were here before. Tainted or not, it’s something precious and irreplaceable, even worth the risk of a shorter life.

It’s their home.

CHAPTER 16

Our Geologic Record

1. Holes

ONE OF THE largest, and probably longest-lasting, relics of human existence after we’re gone is also one of the youngest. As the gyrfalcon flies, it lies 180 miles northeast of Yellowknife, Northwest Territories, Canada. If you flew over it today, it would be the very round hole half a mile wide and 1,000 feet deep. There are many huge holes here. This is the dry one.

Though, within a century, the rest may be, too. North of the 60th parallel, Canada contains more lakes than the rest of the world combined. Nearly half of Northwest Territories isn’t land at all, but water. Here, ice ages gouged cavities into which icebergs dropped when the glaciers retreated. When they melted, these earthen kettles filled with fossil water, leaving countless mirrors that sequin the tundra. Yet the resemblance to an immense sponge is misleading: because evaporation slows in cold climates, little more precipitation falls here than in the Sahara. Now, as the permafrost thaws around these kettles, glacial water held in place by frozen soil for thousands of years is seeping away.

Should northern Canada’s sponge dry out, that would also be a human legacy. For now, the hole in question and two recent smaller ones nearby comprise Ekati, Canada’s first diamond mine. Since 1998, a parade of 240-ton trucks with 11-foot tires, owned by BHP Billiton Diamonds, Inc., has lugged more than 10,000 tons of ore to a crusher 24 hours a day, 365 days a year, even at —60°F. The daily yield is a handful of gem-quality diamonds, worth well over $1 million.

They’re found in volcanic tubes that formed more than 50 million years ago, when magma bearing pure, crystallized carbon pushed up from deep below the surrounding granite. Even rarer than these diamonds, however, is what fell into the craters left by these lava pipes. This was the Eocene, when today’s lichen-covered tundra was a coniferous forest. The first trees that toppled in must have burned, but as everything cooled, others were buried in fine ash. Sealed away from air, then preserved by cold Arctic dryness, the fir and redwood trunks that diamond miners discovered weren’t even fossilized, but simply wood: intact, 52-million-year-old lignin and cellulose, dating back to when mammals were just expanding into niches vacated by dinosaurs.

One of the oldest mammal species on Earth still lives there, a Pleistocene relic that managed to survive because it was extraordinarily equipped to brave weather that ice-age humans preferred to escape. The chestnut pelage of the musk ox is the warmest organic fiber known, with eight times the insulating factor of sheep’s wool. Known in Inuit as qiviut, it renders musk oxen so impervious to cold that they’re literally invisible to infrared satellite cameras used to track caribou herds. Yet qiviut was nearly their downfall in the early 20th century, when they were all but exterminated by hunters who sold their hides in Europe for carriage robes.

Today, the few thousand that remain are protected, and the only legally harvested wild qiviut comes from wisps found clinging to tundra vegetation, a laborious undertaking that contributes to the $400 price a sweater made from ultrasoft musk ox fleece can command. If the Arctic becomes progressively balmier, however, qiviut may again be this species’ undoing—although, if humans (or at least their noisy carbon emitters) vanished, the musk ox might still get a break from the heat.

If too much of the permafrost itself is undone, it would thaw deeply buried ice that forms crystalline cages around methane molecules. An estimated 400 billion tons of these frozen methane deposits, known as clathrates, lie a few thousand feet beneath the tundra, and even more are found beneath the world’s oceans. All that very- deep-freeze natural gas, estimated to at least equal all known conventional gas and oil reserves, is both enticing and frightening. Because it’s so dispersed, no one has come up with an economical way to mine it. Because there’s so much of it, if it all floats away once the ice cages melt, that much methane might ratchet global warming to levels unknown since the Permian extinction, 250 million years ago.

For now, until something cheaper and cleaner comes along, the only other still-abundant source of fossil fuel we can count on will leave an even bigger signature on the surface than a mere open-pit diamond mine—or copper, iron, or uranium mines, for that matter. Long after those fill with water or with their own windblown tailings, this one is good to endure a few more million years.

2. Heights

“It can only be appreciated—if that’s the word—from above,” says Susan Lapis, a cheerful redheaded pilot who volunteers for the North Carolina-based nonprofit organization SouthWings. From the window of her single- engine, red, white, and blue Cessna 182, you look down at a world sliced as flat as any mile-high ice sheet ever managed. Only this time, the glacier was us, and the world was once West Virginia.

Or Virginia, Kentucky, or Tennessee, because several million acres of Appalachia in all those states now look identically amputated, sheared away by coal companies that, in the 1970s, discovered a trick cheaper than tunneling or even strip-mining: just pulverize the entire top third of a mountain, sluice out the coal with a few million gallons of water, push what’s left over the side, and blast again.

Not even the Amazon laid bare rivals the shock of this planar void. In every direction, it’s simply gone. Grids of white dots—the next round of dynamite charges—provide the only remaining texture on naked plateaus that were once vertical, verdant heights. Demand for coal has been so ferocious—100 tons extracted every two seconds—that often there hasn’t even been time to log here: oaks, hickories, magnolias, and black cherry hardwoods have been bulldozed into the hollows, to be buried by a former Allegheny mountain of rubble—“the overburden.”

In West Virginia alone, 1,000 miles of streams flowing through those hollows have been buried as well. Water finds a way, of course, but as it pushes through tailings for the next several thousand years, it will emerge with more than the normal concentration of heavy metals. Yet even given projected world energy demand, industry geologists—and industry opponents—believe that deposits in the United States, China, and Australia contain about 600 years’ worth of coal. By mining this way, they can get at much more of it, much faster.

Mountaintop removal, West Virginia. PHOTO BY V. STOCKMAN, OVEC/SOUTHWINGS.

If energy-drunk humans were gone tomorrow, all that coal would remain in the ground until the end of time

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