ASPHALT JUNGLES

Watching Budi tumbling and climbing, at play with ball and shadow and iPad alike, I marvel at the road the human race has traveled. Open your imagination to how we began—as semiupright apes who spent some of their time in trees; next as ragtag bands of nomadic hunter-gatherers; then as purposeful custodians of favorite grains, chosen with mind-bending slowness, over thousands of years; and in time as intrepid farmers and clearers of forests with fixed roofs over our heads and a more reliable food supply; afterward as builders of villages and towns dwarfed by furrowed, well-tilled farmlands; then as makers, fed by such inventions as the steam engine (a lavish power source unlike horses, oxen, or water power, and not subject to health or weather, not limited by location); later as industry’s operators, drudges and tycoons who moved closer to the factories that arose in honeycombed cities beside endless fields of staple crops (like corn, wheat, and rice) and giant herds of key species (mainly cows, sheep, or pigs); and finally as builders of big buzzing metropolises, ringed by suburbs on whose fringes lay shrinking farms and forests; and then, as if magnetized by a fierce urge to coalesce, fleeing en masse into those mountainous hope-scented cities. There, like splattered balls of mercury whose droplets have begun flowing back together, we’re finally merging into a handful of colossal, metal-clad spheres of civilization.

Among the many shocks and wonders of the Anthropocene, this is bound to rank high: the largest mass migration the planet has ever seen. In only the past hundred years, we’ve become an urban species. Today, more than half of humanity, 3.5 billion people, cluster in cities, and scientists predict that by 2050 our cities will enthrall 70 percent of the world’s citizens. The trend is undeniable as the moon, unstoppable as an avalanche.

Between 2005 and 2013, China’s urban population skyrocketed from 13 percent to 40 percent, with most people moving from very rural locales to huddled megacities whose streets jingle with chance and temptation. At that pace, by 2030, over half of China’s citizens will live in cities, and instead of farming food locally they’ll import much of it from other nations, paying with the fruits of industry, invention, and manufacturing. That’s already the case in the U.K., where by 1950 a checkerboard of cities embraced 79 percent of the population. By 2030, when the U.K.’s city-dwellers reach 92 percent, it will be a truly urban nation, joining a zodiac of others. Ninety percent of Argentinians already dwell in cities, 88 percent of Germans, 78 percent of the French, 80 percent of South Koreans. For a rural nation, one needs to journey to Bhutan, Uganda, or Papua New Guinea, where nearly everyone lives in the countryside, with a scant 10 percent committed to metropolitan life—so far.

Our city-chase has reached such a frenzy that the idea of migration doesn’t begin to capture its rush or rarity. This isn’t surprising in an economically lopsided world where, too often, newcomers end up in crowded shantytowns, favelas, and slums, because cities concentrate the very poverty from which they offer an escape. But that won’t slow the influx as long as hope wears Nikes and is steeped in fumes.

Oz-like cities shimmer as beacons of prosperity, with enhanced education, better medicine, more jobs for women, and wide streaks of upward mobility. Even environmentally, cities can eclipse sparsely settled country life. When roads, power lines, and sewers lie closer together, they require fewer resources. Apartments are insulated by the civil geometry of the buildings, making them easier to heat, cool, and light. Crowded neighbors can share public transportation, and most destinations tend to be close, within walking or biking distance; people rarely need cars. As a result, city-dwellers actually create a much smaller carbon footprint than rural-dwellers do. Cities like New York boast the lowest amount of energy use per household and per person, and so, paradoxically, although the city as a whole uses more energy, each person uses less. It seems counterintuitive, but city life can be a more eco-friendly way for humans to live. Cities in developing countries also use less energy—but that’s because the number of poor tends to be higher there and they consume less, including less food and fresh water.

Still, despite clustering services and leaving smaller individual footprints, the record number of people fleeing the countryside for city life is worrisome to climatologists, because cities are environmental game-changers. Big cities are hotspots, on average ten degrees warmer than their surroundings, and they emit most of the planet’s pollution, as cars prowl their streets and food caravans travel long distances to stock their groceries. On some summer days, the air hangs thickly visible, like the combined exhalations of millions of souls. Steam rising from vents underground makes you wonder if there isn’t one giant sweat gland lodged beneath the city.

One of the paradoxes of our age is that we’re urban primates who are still adapted to the wilderness, which we long for and need, at the same time that we’re destroying, building over, and farming all that’s wild. Since the crowd-rush to these asphalt jungles is accelerating, we need ingenious ways of harmonizing city life with human and planetary well-being. Our challenge will be finding a way to have both, while also preserving the planet.

Some of the best ideas I’ve encountered do just that, transforming our cities from grimy energy guzzlers into dynamic ecosystems.

City parks are essential, but in addition, picture shade-loving wildflowers in gated alleyways, fresh vegetables growing on roofs and piers, lushly planted walls, vertical farms in skyscrapers, rooftop beehives brewing honey, and nature trails threading through rusty old infrastructure. Greening a city with vegetation is a proven way to cool it down, filter the air, suck out carbon dioxide, ladle in more oxygen, and offer pockets of calm amid the bustle and din.

Hoping to achieve that intermingling, a new branch of environmentalism known as “Reconciliation Ecology” has emerged, which strives to preserve biodiversity on our doorstep in cities and other human-dominated habitats. The term “reconciliation ecology” was coined by Michael Rosenzweig in his book Win-Win Ecology, and it has a lovely ring to it. It suggests fence-mending and coexisting in harmony, not a wallop of blame. It’s based on figures showing that we haven’t enough unsettled land left on Earth to protect all of life’s biodiversity, but we can make room for plenty more in our cities and yards.

Along country roads near my house, where cornfields and houses predominate, you’ll see nest boxes for bluebirds, provided by thoughtful bird-lovers because natural tree cavities have grown scarce. When replacing wooden fence posts with steel ones led to the rapid disappearance of shrikes (medium-sized birds with hooked beaks like birds of prey), locals restored the wooden fence posts (on which shrikes like to perch), and the shrikes returned. These may be small acts of reconciliation, but if you create enough of them it can change the big picture. And not just in the countryside. Some of the most improbable-sounding efforts are blurring the line between civilized and wild. “Wastewater Treatment Plant” may not sound like a natural or particularly scenic destination. But some symbiotically minded towns have been designing a new breed of wildlife preserve, one that gives recycling a lively twist. Instead of dumping treated water, they return it to nature as the essence of an ecosystem that offers food and habitat to animals. As the water is further purified by vegetation, migrating and native birds find a home, entangled communities of plants and insects take up residence, and a hodgepodge of wild animals bustle in.

City-dwellers then needn’t travel far for an interlude to refresh their habit-dulled senses. Strolling, gawking, sitting, camera-clicking, humans become one more changing feature in the perpetual tableau, another flock of familiar creatures to whom the scores of nesting birds pay little mind.

A favorite such preserve of mine is the Wakodahatchee Wetlands in suburban Delray Beach, Florida. On a boardwalk raised ten feet above any hazard, one can watch an alligator gliding among the bulrushes, fish defending their mud nests from marauding turtles, dabbling ducks and teals, wading birds stalking their prey. The shallow water and raised trail make many dramas visible from above, including whiskered otters catching whiskered sail-finned catfish. Pig frogs grunt like their namesakes. If you’re lucky, you might see a patch of water fizzing like frying diamonds in the sun—where a male gator is bellowing in a bass too low for human ears. Or you might spot a giant prehistoric apparition standing like a sentinel in the water, as an endangered wood stork displays its distinctive gnarled-wood bald head and long curved beak.

The wooden walkway loops for nearly a mile through fifty acres of swamps, marshes, ponds, reeds, and bogs. Wherever water and land meet, life seems to thrive. Flapping around an archipelago of brushy and treed islands, ibis run a regular feeding patrol to nests full of squawking chicks.

Despite the usual urban hubbub, 140 species of birds broadcast on every channel at Wakodahatchee, from a pitying of collared doves to a pandemonium of monk parakeets. Red-nosed moorhens create a steady background score of trumpeting, clucking, and loud monkey-cackling. Courting roseate spoonbills play the castanets of their bills. Red-winged blackbirds spout the only buzzwords.

Though surrounded by restaurants, offices, condos, malls, and highways, Wakodahatchee’s wetlands attract a bounty of life, including wild plants one rarely sees in cities. What at first seems a flush of algae, or a pointillist canvas of sunstruck water, is brilliant chartreuse duckweed. This simple aquatic plant floats everywhere on the slower-moving waters of our planet, offering food to birds, shade to frogs and fish, and a warm blanket to alligators and small fry. One day it may also provide a cheap source of high protein for humans (it’s already eaten as a vegetable in some parts of Asia) or a cheap producer of biofuel that will power cars while filtering carbon dioxide from the air.

There’s no stigma attached to reconciliation projects being lucrative. Israel’s Red Sea Star Restaurant, for example, 230 feet off the shore of Eilat, is a combination bistro and observatory, seating people in its colorful, marine-inspired dining room sixteen feet down from the surface on the sandy sea floor. Plexiglas windows offer diners, sitting on squid-shaped chairs under dimmed, anemone-shaped lights, a view of a wealth of sea creatures in the coral gardens by day or night. Equally curious fish also get to ogle the diners. It happens to be an architectural showpiece, but it’s also an ecological triumph that has restored a coral reef that was lost through human pollution and overuse. Architects began by choosing a barren stretch of sea floor, laying down an iron meshwork, and transplanting coral colonies onto the trellis, where they cling like slow-motion trapeze artists and continue to attract marine life.

In an acrylic tube submerged in the Indian Ocean, at Hilton Hotels’ Ithaa Restaurant, in the Maldives, diners are also surrounded by fish and coral as they eat. Although the Maldives, a nation of islands only five feet above sea level, emits but a tiny fraction of the world’s pollution, its president, Mohamed Nasheed, has set the most ambitious climate goals of any country on Earth, promising to go carbon neutral within ten years, while building sustainable hotels and restaurants and even a floating golf course. “Our oil-fired power stations will be replaced with solar, wind, and biomass plants,” Nasheed explains. “Our waste will be turned into clean electricity through pyrolysis technology, and a new generation of boats will slash marine transport pollution. By 2020, the use of fossil fuels will be virtually eliminated in the Maldivian archipelago.” Greening the economy is good for the Maldives, which has begun attracting a flock of eco-tourists and investors, and it’s also a model for changes radical enough to help fix the climate.

In some cities, coexisting with nature means salvaging rusty old infrastructure, reclaiming abandoned blocks and trashyards, and forging junked metal into inviting habitats for plants, animals, and humans. In every U.S. state, and many other countries from Iceland to Estonia, Australia, and Peru, out-of-work railroad tracks have morphed into peaceful “rail trails” ideal for biking, hiking, and cross-country skiing. Most often they slip through towns or skirt farmlands, drawing both humans and wildlife to leafy byways. I’ve biked or cross-country skied on some beauties in Ohio, California, Arizona, and New York. Memorably, biking on a rail trail outside Gambier, Ohio, at dawn, I was chased by a flock of farm geese. I knew their charge was merely bravado, so I pedaled slowly and let them nip at my pant legs, which seemed to give them a sense of territorial satisfaction, and they soon returned to the barnyard. I enjoyed their brief honking companionship, and learned something about geese I didn’t know: what clamorous watchdogs they make.

A different stripe of oasis growing in popularity is the High Line on Manhattan’s West Side, a surprising sprawl of undulating benches, nests, perches, and lookouts, giving New York City yet another bridge—this one between the urban and the rural. An old elevated freight spur, little more than a rusty eyesore on the Hudson, it’s metamorphosed into a tapestry of self-seeding wildflowers and domestic blooms. It isn’t the first raised park (there’s the Promenade Plantée in Paris, and remember the Hanging Gardens of Babylon?), but the High Line is the loveliest city rail trail I know.

Picturesque, with many scenic views, it’s also richly detailed and alive, allowing you to feel elevated in spirit, floating in a garden in space where butterflies, birds, humans, and other organisms mingle. In a practical sense, it’s a lofty shortcut, a sky alley that avoids all the intersections. A million people have already strolled its landscaped corridors, and it’s inspired other cities hoping for similar sky parks. Chicago, Mexico City, Rotterdam, Santiago, and Jerusalem are among those following suit with their derelict trestles, each an urban renewal project featuring regional plants and its own special character or sense of humor. In Wuppertal, Germany, the rails-to-trails corridor includes a brightly colored LEGO-style bridge. Like the wastewater wetlands, such projects are widening our notion of recycling and yielding an urban lifestyle that’s interwoven with nature.

As one salve in our medicine cabinet of good ideas, these vest-pocket urban parks and wildlife corridors have deep roots around the world, from nest boxes for storks in Romania, Switzerland, Poland, Germany, Spain, and other havens along their well-flapped migration routes to species-rich Central Park in the heart of New York City, London’s eight city parks (in several of which deer roam), the temperate rainforest of Vancouver’s Stanley Park, Moscow’s Losiny Ostrov (“Moose Island”) National Park, Sanjay Gandhi National Park in Mumbai, sod roofs and greenways from Germany to the Faroe Islands, St. Luke’s Hospital rooftop garden in Tokyo, mandatory rooftop gardens in Copenhagen (and proposed in Toronto). A surprising jumble of native species thrives in and around heavily planted Rio de Janeiro, Istanbul, Cape Town, Stockholm, and Chicago, which have become biodiversity hotspots. Then there’s Singapore’s big, blooming, downtown Gardens by the Bay, enriching city life with more than 240,000 rare plants, flowers, and trees in domes that rise sixteen stories over the city. Including a cloud forest and aerial walkways, the gardens collect rainwater, generate solar electricity, and bathe the air. Opening on June 29, 2012, they drew 70,000 nature-hungry visitors during the first two days.

Although these new city oases won’t work for all species, or for all communities, the trend for rewilding our cities is growing. It’s positive, it enlightens, it’s widespread, and it helps. We need to retrofit and reimagine cities as planet-friendly citadels. They’re our hives and reefs. Sea mussels aren’t the only animals living in individual shells that are glued together.