Many of the world’s major cities, from Singapore to New York to Paris, once contained marshlands, swamps, grasslands, and forests.

But as the populations of these cities grew, the original ecosystems were drained, ripped up, covered, and ultimately destroyed. Today, asphalt and concrete obscure nearly all evidence of their rich ecological history, except for the sloping and winding hills and valleys that sometimes evoke the memory of waterways and complex environments. 

When the Industrial Revolution began more than 250 years ago, cities became engines of the global economy, fueling technological breakthroughs, fostering social growth, and becoming hubs for cultural excellence.

Over time, a pattern developed: as cities attracted more people, they used more fossil fuels to support infrastructure and people’s needs. Their environmental footprint invariably grew in the form of more air, water, and soil pollution, along with exponential resource consumption, all of which contributed to the broader climate and biodiversity crisis.

But cities can break out of this pattern, minimizing and containing their environmental impact. The technology and resources are available for this shift to happen immediately — and the fate of the planet hangs in the balance.

Countries have until the end of this decade to halve global emissions in order to keep temperatures from rising more than 1.5 degrees Celsius above pre-industrial levels. And cities are central to this plan. 

That’s due to the fact that the world’s cities account for an estimated 75% of greenhouse gas emissions. Because the majority of people live in cities, they command most of the planet’s natural resources. In the years ahead, cities can either continue down the business-as-usual path of old technologies and infrastructure or become trailblazing sites of future-building, returning to their environmental roots to save the planet. 

The latest Intergovernmental Panel of Climate Change (IPCC) reports discuss the tremendous potential of cities and argue that the technology, resources, and financial capacity is already available to usher in this revolution. The only thing standing in the way of this green future is political will.

Here are eight ways cities are becoming environmental stewards to heal the planet. 

1. Greener Transportation

Image: Flickr/ Florian Lehmuth

The most immediate impact of fossil fuels in cities is air pollution. As vehicles big and small burn through gasoline, the local atmosphere fills with contaminants that are a leading cause of premature deaths worldwide

For many cities, the costs of this air pollution have become too steep. Now, they're taking steps to expand public transport, phase out single-passenger cars, and mandate the adoption of electric vehicles, all in an effort to limit fossil fuel and mitigate the climate crisis in the process. 

Singapore is striving to have 80% of its residents live within a five- to 10-minute walk of a subway station. Oslo has been replacing parking lots with bike lanes and parks while also banning cars from its city center to prevent air pollution. In the Parisian suburb of Creteil, plans are underway for an aerial tramway that will transport commuters to and from their destinations without polluting the air.  

Barcelona’s “superblocks,” vast spaces with no cars, have become models for sustainable development and allow pedestrians to reclaim the streets. 

2. Greener Buildings

Image: Felix Fuchs via Unsplash

While cars make it harder to breathe, buildings are quietly consuming the largest share of fossil fuels in urban spaces and contributing the most to the climate crisis. 

In many major cities, buildings account for around three-quarters of energy-related fossil fuel use to generate heat and electricity for people, along with the emissions associated with construction.

Around 61% of major cities around the world are implementing ambitious plans to overhaul existing building infrastructure, according to a report by the US Green Building Council (USGBC), C40 Cities Climate Leadership Group (C40), and the World Green Building Council.

The report notes that Beijing requires all new buildings to have the highest energy efficiency rating under the China Green Building Label, while building owners in Amsterdam, Mexico City, and New York receive subsidies for installing green roofs. Around 73% of the cities studied have policies in place for green schools, and 67% have policies for green buildings.  

There are many ways to make buildings more energy efficient — well-sealed windows and doors, smart temperature and air circulation systems, smart lighting systems, and building materials that better insulate and shield buildings from the elements. Many cities are beginning to introduce buildings made from wood that act as carbon sinks. 

Over the next 40 years, the world will add urban space equivalent to the size of New York City each month, according to Architecture 2030

Ensuring that all of this construction follows stringent environmental standards will be essential, and many cities are showing that it’s possible. 

3. Investing in Renewable Energy

Image: Nicholas Doherty/Unsplash

Hundreds of cities worldwide have pledged to get 100% of their energy from renewable sources in the years ahead.

As of 2018, more than 40 cities had already secured 100% of their energy from renewables, and another 100 have passed the 70% mark. While prices for renewable energy continue to plunge, making it more accessible than ever, overall generation lags demand. In other words, there aren't enough solar panels, windmills, and other renewable sources available yet. 

Some cities are accelerating the market transition by directly funding new renewable energy projects. New York, for instance, is turning an old port into a manufacturing and transport site for offshore wind production. 

4. Reforestation 

Image: Pexels

Forests and cities, once foes, are becoming close friends in many regions. That’s because forests provide countless benefits to cities, and their ongoing disappearance would have devastating consequences.

The campaign Cities 4 Forests, spearheaded by the World Resources Institute, is helping to turn cities everywhere into forest protectors by identifying forests for protection, providing technical conservation expertise, and including everyday people to create public support. 

The campaign has three areas of focus: “inner forests (such as city trees and urban parks), nearby forests (such as green corridors and watersheds), and faraway forests (such as tropical and boreal forests).”

“If we want trees to survive and thrive and continue to function as effective places to store carbon, and as effective places for people to live and work, and appreciate for their economic, emotional, and cultural value, then you have to make sure that the trees that are being planted are going to thrive and can keep up with the changes that are already happening to them,” Alejandra Borunda, a former climate scientist who writes about climate change for National Geographic, told Global Citizen.

“The most important thing is to protect the old growth and the old, undisturbed forests that still exist around the world,” she said. “That’s the incredible stuff that I really hope we can figure out a way to preserve and protect, in a way that works for the communities that live there.”

Already 73 cities have signed up for Cities 4 Forests. Addis Ababa in Ethiopia is planting eucalyptus trees to provide families with additional sources of income and to reprieve from worsening climate impacts. Cali in Colombia is going all in on its reputation as “the city of birds” by conserving all facets of surrounding local ecology to ensure the steady flow of eco-tourism, while Salvador in Brazil is restoring forest reserves within the city itself. In both Antalya, Turkey, and Amman, Jordan, reforestation efforts are helping to safeguard dwindling water supplies.

5. Parks and Wildlife Corridors

Image: Pexels

People have an innate affinity for grass, plants, trees — wildlife, in general. It makes sense from a biological perspective. Wildlife provides us with food, filtered water and oxygen, and shelter. Simply looking at a tree is a natural stress-reliever, almost as if our bodies recognize its benevolence.

During any warm day, people in cities flock to parks to be around nature. From an urban planner’s perspective, parks have historically been classified as places for leisure. But parks have myriad other environmental benefits for cities of which government officials are beginning to take stock. 

By expanding parks and planting more trees, cities are helping to draw down carbon dioxide from the atmosphere, provide refuge for wildlife across the animal kingdom, and mitigate climate impacts.  

For example, as global temperatures rise, cities are becoming much hotter than surrounding areas because of the “urban heat island effect.” The abundance of concrete, asphalt, and other manufactured materials absorb heat from the sun and radiate it outward, significantly increasing local temperatures during hot spells. By planting trees and expanding parks, cities are shielding residents from the impact of heat waves. 

Parks can also mitigate flooding during extreme rain events by absorbing excess water and reducing pressure on city drainage systems. After Houston, Texas, was devastated by floods during Hurricane Harvey in 2017, the city turned to “super trees” to counteract its climate vulnerabilities.

6. Urban Agriculture 

Image: Blaine O'Neill/Flickr

Around 80% of the world’s food gets shipped to cities, often traveling very far distances in refrigerated containers, resulting in massive amounts of greenhouse gas emissions. To make matters worse, a lot of this food gets wasted, generating even more emissions. 

Many cities are working to minimize their food-related impact by growing food within their borders and sourcing more food from local farms and producers.  

Vertical farms, community gardens, and rooftop agriculture together can produce 180 million tons of food per year, providing people with easy and low-carbon access to nutritious produce.

In Paris, city planners are working to cover 100 hectares of rooftops, walls, and other spaces with vegetation. Singapore’s “Community in Bloom” initiative has fostered more than 1,500 community gardens, while the Good Food strategy in Brussels aims to provide 30% of the city’s vegetables and fruits through urban farming by 2035. 

7. Coastal Regeneration

Image: Daniel Hartwig via Flickr

Historically, people established cities on coastlines because it facilitated trade, allowing boats to come and go easily. But the proximity to the ocean is a threat in the age of climate change, as sea levels rise and extreme storms worsen, with catastrophic floods becoming a common occurrence.

Many cities are working to reverse development trends of the past that degraded coastlines to better protect communities from storm surges, rising sea levels, and flooding. 

China’s “sponge city” initiative aims to create green spaces and other infrastructure that can absorb and reuse a majority of rainwater to minimize flood damage. 

A group of 40 cities are banding together to protect and restore coastal mangrove ecosystems. The thick roots of mangroves help to buffer coastlines from storm surges, while the trees themselves can absorb 10 times more carbon dioxide than other types of forest. Mangroves also support fisheries and other forms of wildlife that provide livelihoods for urban communities. 

Surabaya, Indonesia, launched the One Soul One Tree campaign to combat poverty by creating sustainable communities centered on mangrove protection. 

In New York, environmentalists have hatched the “Billion Oyster Project” to clean local waterways, protect coastlines from flooding, and restore degraded ecosystems.

8. Zero Waste and Circular Economies 

Image: OCG Saving The Ocean, Unsplash

Current levels of resource extraction are depleting the planet’s ability to regenerate itself. In fact, humanity would need 1.6 Earths to sustain its consumption patterns. If everyone lived like the average US citizen, humanity would need four Earths worth of resources.

In the future, sustainability will be synonymous with circular economies and zero waste, as countries seek to reuse all resources, end waste, and minimize their overall environmental footprint. 

Many cities have found ways to reduce their environmental impacts. Hundreds of cities have enacted plastic bag restrictions, while others have invested in improved recycling facilities and transforming landfills into nature reserves

Singapore fuels homes with energy generated from waste. Alappuzha, India, turns household waste into home cooking fuel. Penang, Malaysia, is turning food waste into fertilizer for rice farms

The Shift FoCo challenge in Fort Collins, Colorado, aims to significantly reduce the city’s per capita emissions by facilitating household energy reductions. Glasgow has enshrined circular economy principles across its entire government operations. 

The most sustainable city, however, may be Tübingen, Germany, where most residents are vegan and get local produce, bike lanes are the norm, solar panel rooftops are required, and single-used packaging is taxed.

Global Citizen Explains

Defend the Planet

8 Ways Cities Are Healing the Planet

By Joe McCarthy