NEARLY 20 YEARS AGO, while driving in a taxi through a serene, rural region in Odisha, a state in southeastern India, I came upon rows of hills with huge gouges exposing their red-earth insides. On their jagged tops, a few trees still clung on, but for the most part, the hillsides facing me were devastated, devoid of life. The taxi driver told me they had been cut for mankada pathar, or red laterite, which was used to build homes in the nearby cities of Cuttack and Bhubaneswar. Back then, as a young, city-bred journalist, the sight spoke of a violence I hadn’t considered before. I’ve since seen many devastated landscapes, but those broken hills were the first that helped me understand viscerally what a city demands.

Our cities occupy less than 4 percent of Earth’s land surface, but they are resource-gobbling behemoths with ecological footprints that reach far beyond their boundaries. Herbert Girardet, cofounder of the World Future Council, refers to the modern city as the “petropolis,” a place that requires “massive injections of non-renewable fossil fuels” to keep it running and supplied with goods and services. The “metabolism” of such cities follows the linear input-output model of the Industrial Age, he says. Like a vortex, the city pulls in energy and resources from a depleting biosphere via global supply chains, and spits out refuse and waste that the biosphere cannot reuse. This system, says the German-British cultural ecologist and author of Creating Regenerative Cities, turns “inherently renewable systems like soils, forests, and rivers into non-renewable systems.” Today’s cities use up two-thirds of the world’s energy, account for more than 70 percent of global greenhouse gas emissions, have humongous water and waste footprints, are responsible for large-scale land conversion and degradation, loss of natural habitats, and land, water, and air pollution both locally and beyond — and they are growing.

Cities are also sites of wealth and culture, discovery and innovation. They have powered the advance of civilizations through the ages.

It is time we reimagine cities, and urgently. According to the United Nations’ Department of Economic and Social Affairs, over the next eight years (the same amount of time we have to limit global warming to 1.5 degrees Celsius), the world is projected to add 10 more megacities — those with 10 million or more inhabitants — bringing the total to 43. Future projections also show that in less than 30 years, three out of four major cities will have a completely different climate from that for which their infrastructure was designed. In other words, while humanity is trending towards an urban future, the current fossil-fueled model of the city itself is trending towards collapse. Urban decline, accelerated by heat waves, droughts, and flooding, will be messy, and likely lead to local and regional conflicts over resources. And, as always, the heaviest costs will be borne by their most vulnerable residents: the old, the poor, the powerless.

“When it comes to the really big picture of climate change and biodiversity loss, cities are certainly right at the heart of the problem,” Girardet, who’s studied cities for decades, told me over the phone from his home in Wales. Yet, he added, viewing cities simply as resource sinks ignores the conundrum they represent. That’s because cities are also places that bring a diversity of people together and aid the fomenting of ideas. They are sites of wealth and culture, discovery and innovation. They have powered the advance of civilizations through the ages. Handan, one of China’s oldest cities, gave us the compass 6,500 years ago. The world’s first plays were performed in Athens. Johannes Gutenberg invented the printing press in the German city of Mainz. Marie Curie discovered radiation treatments for cancer in Paris. And the cities of Silicon Valley, California, ushered in the digital age. The worldwide growth of cities, Giradet says, thus poses both an immense challenge to sustainability and an unprecedented opportunity to rethink our relationship with the natural systems that sustain us.

FOR CITIES TO THRIVE, we need to rapidly transform the petropolis into an “ecopolis,” Girardet posits, shifting a city’s metabolic cycle to a “resource-efficient and regenerative circular system.” Such cities would incorporate the ecological principle that all things are connected, that there is no “waste” in nature. An ideal city would have a reciprocal relationship with living systems within and beyond its reaches, returning materials in forms that would allow those systems to reabsorb and regenerate as well. It would rely on locally or regionally sourced food and energy and be a natural refuge for plants and animals.

Such ideas, epitomized in permaculture, have been part of the counterculture and environmental movement for decades, and these basic tenets have been practiced by Indigenous societies throughout time. But the need for a modern, city-scale ecopolis has grown more apparent as ecological collapse looms over humanity.

Given that, surprisingly few models of such cities exist. Perhaps the best developed is the experimental town of Pushchino, about 120 kilometers south of Moscow, Russia. The idea of the long-term project, begun in 1978, “was to create a special ‘ideal’ town with clean and green environments that encouraged Soviet scientists to work creatively and productively,” Maria Ignatieva, a professor of landscape architecture at University of Western Australia, wrote in a 2000 research paper. The fall of the Soviet Union in the 1990s ended the experiment, and little is known of what was learned. But Pushchino, which is now a science and biotech hub, still has an active conservation program, named Ecopolis.

Of course no one model, or city, will produce a formula that works for all, given different cities are at different stages of development, and each has its own unique challenges. The idea is to put ecological thinking at the center of urban design.

In Europe, North America, and Oceania, where, according to the latest UN projections, the majority of the population already resides in urban areas, growth is tightly limited — but finances are more available. Here, the key challenges are related to implementing ecologically sound infill development: building more energy-efficient homes or urban farms on underutilized lands; installing solar power and water-harvesting systems; improving waste recycling and affordable public transit; growing more tree cover; and strengthening links regional food, energy and other supply systems.

“Most of us live in cities, so they “are really the place to act.”

Much of this is already happening. The entire city of Sydney, Australia, for instance, which is home to around 250,000 people, is now entirely powered by renewable energy sourced locally from wind and solar farms in New South Wales. San Francisco diverts about 80 percent of its waste away from landfills. Sweden is generating biofuel from sewage waste and powering vehicles around the city. And Copenhagen is set to become the first carbon-neutral city by 2025.

In developing countries, meanwhile, where most of the urban growth is projected to take place, the transition from rural to urban life presents a different challenge. In these cities, where more than 70 percent of residents lack one or more basic service, such as clean water, sanitation, or electricity — people will have to make difficult decisions. This could mean choosing “between meeting the immediate and growing demand for services, and making longer-term decisions that shape the built environment,” points out a report by the World Resources Institute (WRI).

At the same time, the report notes, these cities offer “the opportunity to develop new approaches to providing services that are more affordable, reach more people, and are less environmentally damaging than traditional solutions developed in the Global North.” For instance, cities in India, one of the most water-stressed countries in world, are reviving ancient rainwater harvesting systems like the jalharas (stepwells) of Rajasthan and eri (tank) system of Tamil Nadu, which not only store water, but also recharge aquifers and serve as flood-control systems. At the same time, the country could invest in renewable energy and forego the expansion its fossil fuel infrastructure.

Most of us live in cities, so they “are really the place to act,” says Alison Sant, cofounder of the Studio for Urban Projects, an interdisciplinary design collaborative based in San Francisco. The effects of climate change, from wildfires, to extreme heat, to severe storms and flooding, all “impact the huge populations that live in our urban spaces,” she told me. She argues that “we need to act in cities both for humanitarian reasons” and because “the concentration of resources and people and solutions” are already in one place.

The UN urbanization report estimates that “some of the fastest-growing urban agglomerations are cities with fewer than 1 million inhabitants, many of them located in Asia and Africa,” and that, currently, “close to half of the world’s urban dwellers reside in much smaller settlements with fewer than 500,000 inhabitants.” The good news is that these smaller, developing cities have the most potential for being remodeled into regenerative urban systems, Girardet says. As efforts in cities like Copenhagen, Adelaide, Paris, and other relatively smaller cities demonstrate, smaller urban centers tend to be more nimble and relatively easier to retrofit, he says, compared to megacities like Shanghai and Tokyo, which have populations in the tens of millions. “When it comes to really large megacities, it is ever so hard to make them sustainable, or indeed regenerative in meaningful way,” he says. “Having said that, there’s certainly a lot of work going on, even within large cities, to reduce their environmental impacts.” A number of Chinese cities are using electric vehicles to reduce pollution, he notes, and Shanghai, a city of 26 million, has an urban farming initiative.

WHILE THERE IS NO SINGLE path to regenerative cities, researchers have identified common features of successful urban transformation. These include, according to WRI, “a strong coalition of urban change agents with a shared vision, who successfully address a seminal problem and unleash a cycle of positive change; the availability of financial resources to implement ambitious reforms; and a long-term political commitment.” Equity is also a key feature.

Sant — whose new book, From the Ground Up: Local Efforts to Create Resilient Cities, examines how US cities are mitigating and adapting to climate change while creating greater equity and livability — can attest to this. And she adds one more feature: The most effective solutions come from local communities themselves. “A lot of the folks I interviewed while writing this book said to me, ‘Look, we have solutions,’” Sant says. “From bike lanes and bioswales to urban forests and oyster reefs, they have laid the foundations for effective projects in their neighborhoods. They need support to realize them and scale their successes.”

“How we come together in times of emergency is really critical to how we can be resilient in the future.”

At the moment, urban resiliency initiatives are largely driven by private initiatives or state, regional, and city governments. “At the national levels, we often see that good sentiments are expressed, but there’s no real action,” Girardet says. “When we look at real sustainability, or what I would call the regenerative urban development, we need sort of an 80 to 90 percent shift [in systems in order to avoid ecological breakdown] rather than the 10 to 20 percent we are seeing now.”

Sant is more upbeat. She holds out “profound hope” that our cities can scale up at the pace of change. “What’s really key in that is that we can’t scale things from the top down,” she says. “We have to scale them from the bottom up.” Pre-existing federal laws and programs in the US, such as the Clean Water Act and the Federal Emergency Management Agency’s disaster preparedness grants, provide some support to climate resiliency in cities, she points out. And the recently passed Inflation Reduction Act, which allocates $369 billion over 10 years to climate change mitigation and adaptation initiatives, too, offers hope. But more than anything else, it is we the people she’s betting on.

“I started with the idea that solid infrastructure, like green streets and oyster reefs along our shores, all of these things, were really important to providing solutions,” Sant says. “But along the way, I actually felt like it was the social networks that were ultimately providing solutions. How we come together in times of emergency is really critical to how we can be resilient in the future.”

Sant cites the sociologist Eric Kleinberg’s research on the extreme heatwave in Chicago in 1999 that killed more than 600 people to make her point. Kleinberg examined two adjacent low-income neighborhoods on the city’s West Side and found that North Lawndale, a Black community that had suffered residential and business flight ahead of the heatwave, had a death rate 10 times higher than Little Village, an immigrant Mexican neighborhood with a booming street life, its sidewalks choc-a-block with vendors and stores. The social networks of Little Village, more vibrant than those of North Lawndale, helped many at-risk people survive.

There’s a lesson there, Sant says. “As we create cities that are more generous and more porous and more lush, we’re actually creating more livable places. And those livable places are the places where our interactions with one another will help to make us resilient as well.”