How nature can help cities survive

This story was originally published by Undark and appears here as part of the Climate Desk collaboration.

Cities are at war with the natural world. To build them, forests are razed, streams get buried underground, wetlands are filled in, and wildlife gets exiled to the suburbs and beyond. Worst of all, Ben Wilson reports in Urban Jungle: The History and Future of Nature in the City, the residents of cities are outsized consumers of the Earth’s resources, responsible for three-quarters of global carbon emissions, and requiring ever vaster tracts of agricultural land to be cleared to satisfy their appetites for meat and out-of-season fruits and vegetables.

In the pre-urban past, our relationship with nature was far more intimate and reciprocal, the author reminds readers: For millennia, people consumed plants and animals, but also fertilized agricultural fields with their bodily wastes. We took only what we needed, reused and recycled rare resources, and managed wild areas for the benefit of both nature and ourselves.

Urbanization changed all that. Modern cities, Wilson tells us in this sweeping history, are unsustainable and rapidly metastasizing across the planet. “Every day, an area of land the size of Manhattan gets urbanized,” he writes. In 2010, around half of all humans lived in cities; by mid-century, that number will have soared to between about 65 and 75 per cent.

Given this explosive growth, one might expect another apocalyptic environment book foretelling the end of nature and naming cities as the culprit. What Wilson, a British historian and the author of five books, offers instead is more nuanced, and even guardedly optimistic. Urban areas are “ecosystems deserving of our protection and nurture,’’ he writes. “Cities should be the conservation sites of the 21st century.”

The author is hopeful because many cities are rethinking the urban enterprise in light of climate change. Faced with the prospect of coastal flooding, deadly heat waves, regional droughts, and wildfires raging at urban edges, planners are looking to nature itself for ways to cushion the blows and keep cities livable. Skyscrapers in Singapore are being draped in high-tech gardens; abandoned factories in Newark are becoming hydroponic farms; old industrial sites in Berlin are being transformed into inner-city nature parks; and engineers in Copenhagen are replacing hard street surfaces with green spaces to better manage stormwater.

Urban areas, we learn, only gradually became divorced from the natural world. In the distant past, city dwellers kept small farms and garden plots. They produced much of their own food, and they met most of their modest energy needs from the forests and rivers that existed at the edge of town.

As metropolises swelled, however, their citizens longed for the solace of the pastoral environments that their ancestors once enjoyed. Ancient rulers built sylvan enclaves like the terrace gardens of Babylon and the pleasure gardens of the emperor Nero in Rome — distant forerunners of the modern city park. Urban garden parks of the 18th and 19th centuries, Wilson writes, were efforts to prettify and impose an artificial order on the chaos of raw nature, which city planners hoped would then translate to “improved behaviour” among the lower classes.

More recently, many city parks have evolved from places for recreation to dynamic ecosystems for the preservation of nature. Our esthetic judgments have also changed. “In an era of human-made environmental degradation,” Wilson observes, “we see beauty in wildness and spontaneity that would have been inconceivable to our recent forebears.”

At the same time, he acknowledges that degradation: “For a long time, we have been used to the idea that hard engineering can solve our problems. The lesson of climate change is that our urban way of life is tied up with nature.”

At the core of Wilson’s book is his contention, supported by ecologists, that inviting nature back into our urban areas can help to clean polluted air and water, cool cities during ever-hotter summers, and provide natural barriers to flooding and rising sea levels.

Cities are also increasingly preserving wild spaces along their edges. Critical in an era of climate change are the efforts to restore salt marshes (along New York City’s coastline) and mangrove forests (in Singapore and Mumbai), which function as buffers against sea-level rise and destructive storm surges that threaten coastal cities. Beijing is engaged in a huge “green necklace” reforestation program on its borders to protect against desiccating Siberian winds and sandstorms. Madrid is planning a 47-mile forest belt.

Wilson’s style is highly readable and journalistic as he moves adroitly between the past, present, and future. And while he focuses on the good news, he does not ignore the bad. Jakarta is sinking into its own depleted aquifer, for example, while Mumbai is destroying the mangrove forests that buffer it against the sea. Meanwhile, the greening of wealthy cities has not been matched in the overcrowded slums of the developing world. “Many megacities — particularly those lacking stable government — are becoming hazardous places,” he writes, lacking trees, becoming unbearably hot in summer, and increasingly vulnerable to flooding.

But Wilson delights in puncturing the image of urban biological deserts. Consider Los Angeles — once a virtual moonscape devoid of trees. The creativity of homeowner gardens, combined with water from the Owens River and the Colorado River, has made it, in Wilson’s words, “an urban biome created by generations of residents” containing seven times more species than the sparse desert on its fringes. There are also plans to transform the Los Angeles River — currently a trickle of “sludge entombed in its concrete coffin” — into a parkland with native trees and grasses.

Meanwhile, cities like New York are creating novel microhabitats: backyards, empty lots, bridges, and even highway meridians, each with assemblages of species that contribute to a surprising urban biodiversity, the author tells us, which is often far more varied than the wild surrounding lands. And larger wild creatures are returning as well: otters to Singapore, wild boar to Berlin, koalas to Brisbane, lion tamarins to Brazilian cities, and coyotes and peregrine falcons throughout North America.

Wilson also cites multiple scientific studies showing how urban environments are forcing rapid evolutionary change: Citified foxes are developing shorter, wider snouts that are better at sniffing out rotting street food, city birds of many species are becoming bolder and more exploratory, and the brains of small mammals are becoming larger to cope with the greater cognitive demands that cities make.

At times, Wilson’s optimistic assertion that “metropolises could well be where we conserve a significant chunk of biodiversity,” begins to feel a bit too rosy. He acknowledges as much toward the end: “It is not enough to plant thousands of trees, establish roof gardens, clean up rivers and wild green spaces; all of this is futile if it merely conceals a ruthless assault on nature elsewhere.”

But he leaves us with another hopeful example — that of Amsterdam, which aspires to perform “at least as well as a healthy local ecosystem.” The Dutch capital recently announced plans to become virtually car-free, and to halve its consumption of consumables by 2030 through a campaign of reuse, repair, and recycling, as well as produce its own power with renewable solar and wind energy.

“Cities can be agents of change when it comes to achieving more sustainable lifestyles,” Wilson concludes. “They are where innovation has happened throughout history. We have a sliver of reason to be optimistic.”