The Human Age: The World Shaped by Us Read online

  When we talk about the Age of the Dinosaur or the Age of the Trilobite, we expect to find fossils. But that’s not true in the Age of Humans. It’s not necessarily our bones that future geologists will ponder, but an altogether different kind of evidence. Not our bones but our residue will signal the beginning of the Anthropocene, a point delineated by a “golden spike”—a marker scientists pound into the rock strata to denote an internationally agreed-upon start of a geological time period. Most spikes are in Europe’s heavily studied ribbons of exposed rock, with seven golden spikes in the United States, and dozens more throughout the world.

  Let’s suppose once more that we are astronauts, this time visiting Earth millions of years after humans have left to pioneer other worlds, allowing Earth to lie fallow for a spell and restore its bounty. Few signs of us remain—on the lush, overgrown surface, that is. Exposed rock and ice cores outline our story, and a future geologist—we’ll call her Olivine—is looking for “time-rock,” layers that show magnetic, chemical, climatic, or paleontological signs of the new age that we created.

  From the warmth of her sky-tent tethered above what once was Patagonia, she travels the world and digs, measures, and tests, unearthing clues like shards of pottery. In sedimentary rock near the coasts, she pores over the fossil remains of cities: low-lying mazes once called Miami or Calcutta. She detects radioactive pulses from nuclear waste dumps. She finds a layer of woodland pollen suddenly replaced by agricultural pollen, and another ribbon where agriculture gave way to cities. Seams of concrete and metal abound. Scouting the oceans, she detects how, in our age, we plowed up the seabeds by bottom-trawling with large heavy nets dragged across the ocean floor, scooping up any marine life in their paths. Olivine is briefly envious. They were the first generation of humans, she thinks, with the instruments and satellites to be able to measure how geology was changing during their own lifetime. What an exciting era that must have been.

  Everywhere she travels, she stumbles upon a mass of fossils of species far from their native habitats, and clumped together, on a scale unique in all of Earth’s geological history. Long before we began shuffling life forms, species invaded new lands when continents collided in slow motion. But during our geologic moment, we’ve rushed the process, and quickly surpassed plate tectonics as a rearranger of species.

  Olivine smiles as she identifies rose and Scotch broom pollen in a rock sample not far from her tent, in Patagonia, once a wild and windswept frontier where armadillos roamed and the beach pebbles were jasper. Roses in Patagonia, she thinks. Those old Anthrops were rose addicts. And Scotch broom—didn’t they realize it would spread for miles? Probably transplanted by settlers. She knows the Scotch broom flailed long pokers of yellow flowers and, with weedlike momentum, colonized hundreds of acres and retuned the chemistry of the soil.

  Special prizes are bits of human bones, whose DNA shows how our species began continent-jumping like hopping spiders, with some lineages predominating but most mixing, homogenizing, traveling far from their native shores, in a worldwide flux binding us all together.

  She and her colleagues have argued some about the exact start of the Anthropocene—Agriculture? Industry? Nuclear bombs?—but they all agree that our world dramatically changed around the year 1800. That’s when the Industrial Revolution, powered by a massive use of fossil fuels, led to rising carbon dioxide levels. We tend to forget that the steam engine was first invented to pump water out of coal mines, and only later adapted to move boats, cars, and trains. It’s also when land clearing speeded up, and ecosystems were converted from mostly wild to mostly human-centered. Agriculture and mining became mechanized giants, spilling more fertilizer into the rivers and oceans, and more pollution into the air. The new textile mills and factory system drew laborers from the country into rapidly booming modern cities. That’s when we first began adapting the planet to us on a large scale—changing the climate, changing the oceans, changing the evolution of plants and animals.

  In the process, we’ve left our signature everywhere. Our impact is already measurable in the geologic record. The rocks hum with radioactive elements from atom bomb tests of the 1960s. The fossil pollen Olivine studies in the strata will reflect how, during our epoch, the wild brew of species that once thrived for centuries on the prairies and in the forests suddenly gave way to unbroken fields of single crops—corn, wheat, soy—and vast clans of cows, pigs, and chickens.

  Because plastics take so long to degrade, they, too, will show up in the fossil record. Not as flattened lawn chairs and PVC pipes, but as veins of tiny plastic tears, which is as far as plastic denatures. Quasi-crystals (crystals with orderly but nonrepeating patterns), transparent aluminum, and other newly invented forms of matter will appear in the matrix as well.

  That alone is astonishing. We’re adding new elements to the sum of creation. The wide world of nature, with all its chemicals and potions, plants and animals, rocks, crystals, and metals, is not enough for us.

  We’re also minting brand-new states of matter, metals no earthly eyes have ever seen—photonic clusters that can slice like light sabers, ultracold quantum gas known as polar molecules, fleecy electric, synthetic radioactive elements from einsteinium through copernicium to ununoctium, among many other artificial sprinklings. Monuments needn’t be large, or even visible to the naked eye, to declare our godlike powers. It’s one thing to rearrange bits and bobs of nature to create, say, an antibiotic or an atom bomb. But it’s quite another to cook up exotic blazons of matter, adding them like new spices to the cosmic stew. I’m amused to think of a future geologist like Olivine puzzling over weird taffylike wads, trying to figure out what chem lab sport might have spawned them.

  All of these elements will ultimately show up as indisputable signs of our presence. We’re leaving tracks in the strata never seen before in Earth’s five billion years. What did you add to the fossil record today? The plastic from a six-pack or a water bottle? A midden of candy wrappers, plastic bags, and orange juice cans? Did you drive your car? If so, you’ve changed the weather by a whisker, and that, too, will ultimately add to the patterns in the rock, a legacy of our meddling from deep sea to outer space.

  MONKEYING

  WITH THE WEATHER

  How extraordinary that we’ve modified the whole big baggy atmosphere, where the carbon dioxide, now climbing to historic levels, is a third higher than even two hundred years ago. The synthetic fertilizers that plump up our crops churn out more nitrogen than all of the plants and microbes do naturally. Analyzing sedimentary core samples from Arctic lakes, future geologists like Olivine will see how we’ve addled the chemistry of the oceans and the air.

  We’re but one hotshot species on a planet squiggling with life, and yet we’ve grown powerful enough to befuddle the world’s weather and sour all the oceans. That’s the speed and scale of our influence. On land, humans figure as a geologic agent comparable to the relentless power of erosion or volcanic eruption, and in the oceans, our impact is on par with an asteroid’s. The reef death we’ve caused will be visible in the fossil record. As a point of comparison, the last time reef death happened was sixty-five million years ago, when a real asteroid wiped out the dinosaurs and many other life forms.

  Once you’ve glimpsed reef death, you don’t forget its lunar landscape. I’ve always loved scuba diving and the cell-tickling feel of being underwater. Offshore in Jamaica, I once swam through a button collector’s variety of vividly colored fish and was so spellbound that one hand automatically touched my chest and my eyes teared. My guide’s eyes questioned me through the fishbowl of his face mask. There was no way to mime that I wasn’t hurt or frightened, but jubilant, merely glad to the brink of tears. How do you scuba-sign wonder?

  Are you in trouble? he signaled.

  No, no, I answered emphatically. I’m okay . . . My heart is stirred—I put an open palm over my heart, then made a stirring motion in the water—and my eyes . . . I made a rain-falling movement beside one eye with my fingers.
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  Surface? he motioned, his knitted brow adding a question mark.

  No! I signaled stiffly. I’m okay. Wait. Wait. I thought for a moment, then made the sign French chefs use in commercials, the gestural esperanto for This dish is perfection, making a purse of my fingers and exploding open the purse just after it touched my mouth. Then I swept a hand wide.

  Even with the regulator stuffed in his mouth and his eyes distorted behind the faceplate, he made an exaggerated smile, yawning around the mouthpiece so that I could see he was smiling. He nodded his head in a magnified Yes!, then made an Okay sign with one hand and led me deeper, using his compass and surfacing once to check his direction by sighting the boat.

  After a ten-minute swim, we suddenly came to a maze of underwater canyons thick with enormous sponges and coral fans, around which schools of circus-colored fish zigzagged. Plump purple sea pens with feathery quills stood in sand inkwells. Tiny tube worms—shaped like Christmas trees, feather dusters, maypole streamers, and parasols—jutted out of the coral heads. Sea relationships are sometimes like those in a Russian novel; a worm enters the larder of a fine, respectable coral to steal its food, and just stays there, unevicted. I moved my palm over a red-and-white-striped parasol, and in a flash it folded up its umbrella and dragged it back inside the coral. A game divers love to play with tube worms. Hocus-pocus and the tube worm vanishes.

  On a coral butte just in front of us, a dark gorgonian jutted out between the canyon walls, its medusoid hair straggling in the current. I laughed. That gorgonian’s hair’s like my own, I thought. And then I remembered: We’re mainly saltwater, we carry the ocean inside us. That was the simple, stupefying truth—as a woman, I was a minute ocean, in the dark tropic of whose womb eggs lay coded as roe, floating in the sea that wet-nursed us all. I pulled my mask up and washed my face with saltwater, fitted it back on, and exhaled through my nose to clear it. From then on, I was hooked, and often returned to the sea to reexperience the visible links of that invisible chain.

  I was lucky. When I returned to that same spot twenty years later, I found the bare bones of a deserted reef, a moonscape.

  There’s no need to travel to the Caribbean to spot climate change’s handiwork—I see it in my New York backyard. Perhaps you do, too, if you take the time to look closely. The looking closely part is essential. For most people, everything may still seem normal, because the seasons come and go in a familiar way, even if one blows in stormier or exits drier than usual. For many of us, the changes are too subtle to notice as we go about our lives.

  But clues abound, and not just in my own backyard. Global warming is fiddling with garden thermostats to such an extent that the National Arbor Day Foundation has redrawn the U.S. Hardiness Zone Map—which tells gardeners what and when to plant. For thirty years (as long as the maps have been drawn), Ithaca lay in frostbitten, forget-about-lavender-hued-roses zone 5. Now most of New York State is in the warmer planting zone (6) that used to lie farther south. The “what” and “when” to plant have changed, but not in a predictable way.

  A row of ornamental cabbages (always annuals) has begun overwintering and sending up tall stalks of bushy yellow flowers for the first time. No one told the pansies, high summer blossoms, to call it quits in early winter. They keep blooming through snow showers, frost crackles, and quick melts . . . always with a pensive face. What became of all my Japanese beetles, those polychrome hedonists who used to mate in flesh piles, while eating, atop the roses? I haven’t seen any for three years. But the number of Lyme ticks and other insects has soared. When I first moved to upstate New York decades ago, no Lyme ticks trickled through the grass; the cold climate was too hostile. They usually begin their blood-sucking on the white-footed mouse. Last summer’s prolonged sizzle reduced the acorn crop, a mouse staple, and with fewer mice to hitch rides on and use as all-purpose canteen-nursery-gadabout-vectors for disease, the pesky parasite ticks began hopping aboard more humans. At least that’s how it seemed; people venturing across a meadow inevitably returned with a Lyme tick in tow.

  Imagine if you arrived home from work one day to discover that your pet spaniel had morphed into a wolf. You know that dogs evolved from wolves that we domesticated and hybridized . . . you just didn’t expect to find one gnawing on the sofa leg. Something similar happened in my garden. A favorite yellow Canadian rose bush, well adapted to the cold climate, has been blooming faithfully and true for years. Like many other garden roses, it’s a hybrid produced by grafting domestic and wild strains together. However, last summer, the rose suddenly revealed its lurking Id. To my amazement, from its feral heart it launched flutelike canes of heavily-flowering, tiny white roses. The wild rose ribs sprang from the same trunk as the well-bred yellow tea rose ribs. It was like having Siamese twins, one of which was Neanderthal, the other Homo sapiens.

  Heaven knows what it will do this summer. Wild roses are hardier, better adapted to unstable temperatures. Will climate change favor one or the other? Will all of the domesticated roses run wild? A garden is always full of surprises. Last summer, for the first time in the decades I’ve lived here, my yard was a deafening amphibian rave, where hundreds of croaking frogs (especially the drum-eared bullfrogs, whose croak should really belong to a snoring bull, and the smaller banjo-plucking green frogs), bleatingly love-sick, drowned out human conversation. This year all I expect is the unexpected.

  Canadian scientists warn of fewer backyard ice-skating rinks and frozen ponds in the future, and in some regions none at all, because of winter’s waning bite. This inspired geographers at Wilfrid Laurier University in Waterloo, Ontario, to found a website to track the effect of a warm climate on Canada’s tradition of thousands of icy flat playgrounds.

  “We want outdoor rink lovers across North America and anywhere else in the world to tell us about their rinks,” they urge on RinkWatch.org. “We want you to pin the location of your rink on our map, and then each winter record every day that it’s skateable. We will gather up all the information from all the backyard rinks and use it to track the changes in our climate.”

  Many of Canada’s legendary ice hockey players learned to skate on such tiny rinks, and Canadians hold them dear. An invisible thorn in the ozone layer can be denied, but when backyard hockey season is delayed, people notice.

  Not everyone is warming up. Jim River, Alaska, a grizzly bear’s backyard and a grizzled hiker’s paradise, set a record low of -80°F. Residents there said the air hurt wickedly to breathe; they could feel it grate on every cell inside the nose. Exposed skin and eyes burned. Spit froze before it struck the ground. Frostnip took its toll. After a short spell outside, as people stepped back indoors, eyeglasses fogged up and froze to the face.

  From Colorado to British Columbia, due to twenty years of unusually warm weather, spruce and pine bark beetles have chewed through four million acres of trees. This is fabulous for the bark beetles, but bad news for all the drought-weakened trees. Wildfires gust across their dry remains, sending flares through vast swaths of vegetation, as in the historic wildfires that blackened over 170,000 acres of caramel-mesa-ed New Mexico, and the record-breaking wildfires in mountain-blessed Colorado.

  These massive conflagrations are bad not just for timber harvesters and tree lovers but for anyone who thrives on oxygen-rich air, since forests are the lungs of the planet, inhaling carbon dioxide and exhaling oxygen. We inhale their flammable waste to stoke the fires in our cells. They inhale ours. Bears, humans, and trees are as seamlessly connected as in and out breaths. And all this ash lies down quiet as snowfall, slowly settling to leave its trace, our trace, as the fire-debris weaves into the geological record. A fine line perhaps, but indelible as the cinders of Vesuvius.

  Frostbite and torched forests may be the extremes, but 2012 and 2013 were legendary scorchers throughout the United States. Across the heartland, around the church suppers, cicada songs, and quiet nights of teenagers sitting on the paint-peeling white bandstands in the middle of town, frying heat doomed crops and br
oke 29,300 high-temperature records. Fall drought withered crops in 80 percent of the country’s farmlands. Broad-brimmed-hatted, slow-drawling Texans saw the driest year since record-keeping began in 1895, drier even than the rawhide soil of the Dust Bowl. So dry that, as farms resorted to irrigation, public water supplies plummeted. The Lone Star State alone had $5 billion in damages. Not just from crop losses, either. The earth became so parched that it cracked all over like a callused heel, in the process wrenching apart water mains (forty in Fort Worth alone) and buckling the pavement on bridges and roads.

  Worldwide, the past year ushered in record-breaking snowfalls, droughts, rains, floods, heat, hurricanes, wildfires, tornadoes, even plagues of locusts. The whole bag of tricks, biblical in their proportions, including weather pranks we usually expect, but not all and everywhere and wound up to such an extreme. Taken as a whole, as one weatherworks out of balance, it understandably starches the mind, widens the eyes, and fills parents with worry about their children’s future. Every six years or so, the United Nations Panel on Climate Change issues a report. In September 2013, the panel of 209 lead authors and 600 contributing authors, from 39 nations, poring over 9,200 scientific publications, came to these landmark conclusions: global warming is “unequivocal,” sea levels are rising, ice packs are melting, and if we continue at this pace we “will cause further warming and changes in all components of the climate.” However, they added, we can slow the process down if we begin at once.

  How the story plays out will be a tale told by the silent, everlasting rocks, in colorfully hued bandwidths. They’ll recall a time when Earth was swarmed over by intelligent apes who whipped the weather into something they hadn’t quite intended.

  Yes, our tinkering has given Earth a low-grade fever, which we need to quickly calm before it climbs. But global warming won’t be tragic everywhere and for every species. That would only be true if Earth’s creatures, landforms, geology, waters, and climate were spread evenly around the planet, and they’re not. Earth is a patchwork of many different habitats, and climate change will visit them in uncanny ways: cool hot zones, heat cool zones, flood dry zones, dry temperate zones. Thanks to climate change, Europe’s growing season has been lengthening, with warm-season crops thriving farther north, to the delight of farmers (although in central and southern Europe, crops have suffered because of the extreme heat and drought). In Greenland, local farmers, seeing fertile soil for the first time, began avidly planting. Milder winters require less heating, which saves on energy, and travel and homesteading in the north is much easier in a warmer world. Not that long ago in the grand scheme of things, we had a famously balmy spell. During the Medieval Warm Period, from 950 to 1250, the Vikings found the lack of sea ice so good for travel that they established a colony in present-day Newfoundland.