Ever since I was a child, I have lived in cities. The largest of which was Seoul— a megacity home to 25 million people, and some smaller cities like London, Ontario with a population of 400 thousand. Now I live in Toronto, a city with over 6 million people that seems to be getting bigger and bigger every year. Not only Toronto, but seemingly every major city in the world is undergoing a population boom; it is expected by 2050 more than two-thirds of the entire world’s population will reside in cities—a far cry from a hundred years ago when only a third of the world lived in cities. Cities are undoubtedly beneficial not only for job prospects and spurring innovation; they also fulfil the human desire to socialize, form communities, and connect. Cities are the future, there is no doubt about it, which is why we need to build better and make them more sustainable and human-oriented.
Given that cities house much of the world’s population, it should be no surprise that it is also one of the largest sources of carbon emissions. It is estimated that cities are responsible for 60-80% of the world’s carbon emissions, generating half of the world’s trash, and consuming 75% of the world’s resources. While commendable progress has been made in recent years following the 2015 Paris Climate Agreement through initiatives like the Carbon Neutral Cities Alliance (CNCA), Sustainable Cities Initiative (SCI), and, UNSDG #11, significantly more effort is needed to ensure that cities can mitigate their environmental impact along with creating a liveable and equitable place to live.
Keeping it Simple
As mentioned, with a global migration into cities, many countries are rushing to improve existing, and in some cases develop new cities from the ground up. While building cities from the ground up provides a unique opportunity to include all the bells and whistles of what makes a great city and learn from other city’s shortcomings, some countries are opting to build cities that resemble more of a vanity project. You might have heard of Saudi Arabia’s Neom City (or known as “The Line”), an urban development project that is estimated to cost US$1.5 Trillion, plans to build a linear city spanning 170km and house 1.5 million residents. The project from the start was met with a lot of criticism for being unrealistic, and impractical, and in recent months, severe human rights violations have been reported in relation to the project. Neom represents everything you should not do when trying to develop a sustainable and liveable city; you do not (and should not) rely on unproven technologies and concepts in the hopes that it would be a magic solution that would solve all the issues facing cities today. If you are interested in reading more about Neom (and all of its woes), I will link some materials here, here, and, here.
There are much simpler and cheaper solutions out there that are proven to make cities more sustainable and liveable—and I would like to take this opportunity to introduce some of them to you below.
Zoning
If you have ever been to any major North American city, you soon realize the cities are massive and it forces a lot of people to drive. North American cities often fall victim to urban sprawl—a symptom where cities grow outwards putting people further and further away from the city centre. The phenomena can be characterized by three distinct factors: low-density openness, single-land use, and car-centric design. Urban sprawl is not only costly for cities to develop and maintain, it is generally very energy-intensive and contributes significantly to CO2 emissions and pollution. While many factors result in urban sprawl, one method to mitigate it from going out of control is zoning. Zoning laws dictate what can and cannot be built on a specific plot of land and can be seen as one of the most important tools that dictate how cities are developed. Despite its overwhelming importance, many zoning laws are out of date and have not been updated in decades. A study conducted by UC Berkeley researchers concluded that emissions from suburbs negate all the climate benefits produced by cities and suburbs are contributing up to 50% of all household CO2 emissions.
Source: City of Toronto
The map above shows Toronto’s zoning map. As you can see, much of the city is covered in “neighbourhoods” which are mostly areas designated for single-family homes. Mixed-use areas are concentrated only in the downtown core, along a handful of major roads, and are rarely found within neighbourhoods. Given the city’s design and its inadequate transit system (which we will get to later), it forces a lot of people to drive to their destination as there simply is no better alternative. In 2024, Toronto was awarded the title of North America’s most congested city, and third in the world for 10km travel time—which on average takes 29 minutes to travel—, only behind London, England and Dublin, Ireland.
Multiple studies have demonstrated that higher-density land usage results in significantly less energy usage and carbon emissions. Some studies have concluded that those living in denser urban areas have up to 50% lower carbon footprints compared to the national average while those living in low-density areas produce twice the average. For cities to become truly sustainable, low-density and exclusive zoning laws need to be revised to become more inclusive and allow for multi-purpose land use. More efficient land development policies can naturally discourage private vehicle use and provide people with more options to travel and commute, creating more inclusive communities. This development also allows more room for the city to develop facilities, such as parks and recreational zones, and other facilities that can help cities become more climate resilient along with being a net positive for citizens.
An extreme example that we could take some inspiration from is Tokyo. Other than the fact that it houses more than 30 million people, one of the city’s most unique features is their lack of zoning laws. North American cities have zoning laws that divide each area that need to be used in a specific way; in contrast, Tokyo takes a dramatically different approach where their zoning law simply tells people what they cannot build and everything else is free game. This rather liberal zoning law allows the city to grow more naturally and does not create the same problems found in many North American cities, and can foster a more sustainable way of living in such a large city. The topic is really interesting and I would highly recommend reading more about it here and here.
Public Transit
Another factor that other cities outside of North America seemed to have understood is that having a well-functioning and connected transit system will do wonders for your city. Not only does having a functioning transit system reduce the reliance on individual vehicle use, but it also allows cities to better utilize land that would have otherwise been allocated for roads. Public transit continues to be one of the best and most cost-effective solutions to reduce carbon emissions from urban centres. It is estimated that every vehicle on the road produces a pound of CO2 per mile driven, and each car on average emits 4.6 tons of CO2 annually; for every fully loaded bus on the road, it takes 75 cars off the road, that's 345 tons of CO2 emissions saved by one bus. Subways reduce emissions even further; a study conducted by the World Bank concluded that cities with subway systems had 50% lower CO2 emissions compared to cities that did not.
Given that vehicles are one of the largest sources of urban carbon emissions, a functional transit system across thousands of cities could reduce carbon emissions immensely. If a person were to switch from taking their car to using public transit on their 32km commute, they could reduce their emissions by 20 pounds a day or more than 2.1 tons of CO2 annually.
While it is clear that a functional transit system has immense potential to dramatically reduce carbon emissions, for public transit to be fully utilized, cities also need to be designed in a way that promotes better usage. Going back to zoning, North American cities are designed largely (from a transit perspective) as a hub and spoke model, meaning that there is a central point in the city (usually the downtown core) where all the subway lines meet. This is good for getting people into the city; however, when someone wants to travel from their home to their friend's house across town, it makes the journey rather inconvenient and oftentimes forces the individual to drive. However, if cities were designed in a way that does not rely on a central downtown core, it would force transit systems to adapt and adopt more of a point-to-point model where the transit system can take you as closely to your final destination as possible.
Comparing Chicago’s transit system and Barcelona’s transit system, it becomes clear that Chicago’s subway is designed to only shuttle people to work and back whereas Barcelona’s transit system offers much more flexibility and connections that allow for better utilization of the system and reduces reliance on cars. The results speak for themselves; despite Barcelona having a million fewer people than Chicago, Barcelona’s transit system (including both trains and buses) carried over a billion people in 2023, compared to Chicago's 279 million riders in the same year. While the results carry more nuance, they show that people will use public transit if they are designed well.
Policies
The final tool that could help build more sustainable cities is rather an obvious one; implementing sustainable policies. As mentioned previously through various alliances and initiatives, major cities around the world are adopting a wide range of sustainable urban policies. There is a vast array of different policies that can tackle sustainability issues, ranging from addressing heat islands to policies aimed at structurally changing the city. For example, heat islands are most commonly found in urban centres where they experience higher temperatures than their surrounding areas, which can be 1-7 degrees higher than areas outside of heat islands. Studies show that heat islands significantly drive up energy demands and can increase energy costs by up to 40% for every degree increase in temperatures. Cities have implemented policies to reduce the effects of heat islands by turning to agriculture and vegetation; cities across Europe have adopted policies to cover as many urban areas with trees which has reduced temperatures as much as 12 degrees in central Europe and up to 4 degrees in southern Europe. Other solutions include green tramways and cool roofs, which have been proven to reduce temperatures significantly; green tramways have also shown that it can play a role in reducing noise pollution along with improving air quality in urban centres. While these policies not only help reduce temperatures throughout the city, they also benefit citizens directly as they reduce energy consumption and pollution throughout the city.
Structural policy changes can help dramatically alter the way we use cities and have proven that they can also make cities more sustainable without significant cost implications. One policy that is being adopted throughout many large cities is implementing low-emission zones, areas where vehicle use is restricted or banned altogether. This policy is found mostly in Europe where over 320 low-emission zones operate, but other cities such as Rio de Janeiro and Seoul have begun to adopt similar policies. The city of London has seen their pollution levels and carbon emissions dramatically decrease; within the first 10 months, carbon emissions were down 6% while other pollutants such as nitrogen oxides decreased by 35%. London’s Ultra Low Emission Zones (ULEZs) now expand throughout the entire city and have resulted in carbon emissions dropping by 26% compared to what they would have been without these zones. These zones can also be repurposed into pedestrian-only areas which provide the city with an opportunity to reclaim roads and repurpose them into parks or public spaces as they have done in Seoul with the Cheonggyecheon project, and the Rose Kennedy Greenway project in Boston, which have contributed significantly in reducing vehicle usage within the city along with revitalizing a once car-centric downtown core.
Implementing climate-positive policies, paired with a functioning transit system and improved zoning can fundamentally change the way we live and make cities much more sustainable. Cities do not need to spend billions (or trillions) of dollars on glitzy sci-fi projects that have no evidence that they will live up to their expectations. Oftentimes, the boring and more proven methods will almost always outperform “silver bullet” solutions. For the mentioned tools to be effective, they need to work in harmony and complement each other to maximize their potential. Cities are the way of the future. We need to change the way we live and use our cities to meet future demands and ensure that cities are places where people want to live, not because they have to.
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