London had a problem. In 2016, more than 2 million of the city’s residents—roughly a quarter of its population—lived in areas with illegal levels of air pollution; areas that also contained nearly 500 of the city’s schools. That same air pollution was prematurely killing as many as 36,000 people a year. Much of it was coming from transport: a quarter of the city’s carbon emissions were from moving people and goods, with three-quarters of that emitted by road traffic.

But in the years since, carbon emissions have fallen. There’s also been a 94 percent reduction in the number of people living in areas with illegal levels of nitrogen dioxide, a pollutant that causes lung damage. The reason? London has spent years and millions of pounds reducing the number of motorists in the city.

It’s far from alone. From Oslo to Hamburg and Ljubljana to Helsinki, cities across Europe have started working to reduce their road traffic in an effort to curb air pollution and climate change.

But while it’s certainly having an impact (Ljubljana, one of the earliest places to transition away from cars, has seen sizable reductions in carbon emissions and air pollution), going car-free is a lot harder than it seems. Not only has it led to politicians and urban planners facing death threats and being doxxed, it has forced them to rethink the entire basis of city life.

London’s car-reduction policies come in a variety of forms. There are charges for dirtier vehicles and for driving into the city center. Road layouts in residential areas have been redesigned, with one-way systems and bollards, barriers, and planters used to reduce through-traffic (creating what are known as “low-traffic neighborhoods”—or LTNs). And schemes to get more people cycling and using public transport have been introduced. The city has avoided the kind of outright car bans seen elsewhere in Europe, such as in Copenhagen, but nevertheless things have changed.

“The level of traffic reduction is transformative, and it’s throughout the whole day,” says Claire Holland, leader of the council in Lambeth, a borough in south London. Lambeth now sees 25,000 fewer daily car journeys than before its LTN scheme was put in place in 2020, even after adjusting for the impact of the pandemic. Meanwhile, there was a 40 percent increase in cycling and similar rises in walking and scooting over that same period.

What seems to work best is a carrot-and-stick approach—creating positive reasons to take a bus or to cycle rather than just making driving harder. “In crowded urban areas, you can’t just make buses better if those buses are still always stuck in car traffic,” says Rachel Aldred, professor of transport at the University of Westminster and director of its Active Travel Academy. “The academic evidence suggests that a mixture of positive and negative characteristics is more effective than either on their own.”

For countries looking to cut emissions, cars are an obvious target. They make up a big proportion of a country’s carbon footprint, accounting for one-fifth of all emissions across the European Union. Of course, urban driving doesn’t make up the majority of a country’s car use, but the kind of short journeys taken when driving in the city are some of the most obviously wasteful, making cities an ideal place to start if you’re looking to get people out from behind the wheel. That, and the fact that many city residents are already car-less (just 40 percent of people in Lambeth own cars, for example) and that cities tend to have better public transport alternatives than elsewhere.

Plus, traffic-reduction programmes also have impacts beyond reducing air pollution and carbon emissions. In cities like Oslo and Helsinki, thanks to car-reduction policies, entire years have passed without a single road traffic death. It’s even been suggested that needing less parking could free up space to help ease the chronic housing shortage felt in so many cities.

But as effective as policies to end or reduce urban car use have been, they’ve almost universally faced huge opposition. When Oslo proposed in 2017 that its city center should be car-free, the backlash saw the idea branded as a “Berlin Wall against motorists.” The plan ended up being downgraded into a less ambitious scheme consisting of smaller changes, like removing car parking and building cycle lanes to try to lower the number of vehicles.

In London, the introduction of LTNs has also led to a massive backlash. In the east London borough of Hackney, one councilor and his family were sent death threats due to their support for the programme. Bollards were regularly graffitied, while pro-LTN activists were accused of “social cleansing.” It was suggested that low-traffic areas would drive up house prices and leave the only affordable accommodation on unprotected roads. “It became very intimidating,” says Holland. “I had my address tweeted out twice, with sort of veiled threats from people who didn’t even live in the borough saying that we knew they knew where I lived.”

Part of that response is a testament to how much our cities, and by extension, our lives are designed around cars. In the US, between 50 and 60 percent of the downtowns of many cities are dedicated to parking alone. While in the UK that figure tends to be smaller, designing streets to be accessible to a never-ending stream of traffic has been the central concern of most urban planning since the Second World War. It’s what led to the huge sprawl of identikit suburban housing on the outskirts of cities like London, each sporting its own driveway and ample road access.

“If you propose this idea to the average American, the response is: if you take my car away from me, I will die,” says J. H. Crawford, the author of the book Carfree Cities and a leading figure in the movement to end urban car use. “If you do that overnight, without making any other provisions, that’s actually approximately correct.” Having the right alternatives to cars is therefore vital to reducing city traffic.

And any attempts to reduce urban car use tend to do better when designed from the bottom up. Barcelona’s “superblocks” programme, which takes sets of nine blocks within its grid system and limits cars to the roads around the outside of the set (as well as reducing speed limits and removing on-street parking) was shaped by having resident input on every stage of the process, from design to implementation. Early indicators suggest the policy has been wildly popular with residents, has seen nitrogen dioxide air pollution fall by 25 percent in some areas, and will prevent an estimated 667 premature deaths each year, saving an estimated 1.7 billion euros.

When it comes to design, there’s also the question of access. Whether it’s emergency services needing to get in or small businesses awaiting deliveries, there’s an important amount of “last mile” traffic—transport that gets people or things to the actual end point of their journey—that is vital to sustaining an urban area. If you want to reduce traffic, you have to work around that and think of alternative solutions—such as allowing emergency vehicles access to pedestrianized areas, or even using automatic number plate recognition to exempt emergency vehicles from the camera checks that are used to police through-traffic in LTNs (which is what Lambeth is doing, Holland says).

But even then, it’s often just hard to convince people an entirely different city layout is possible. Getting people to accept that how they live alongside cars can be changed—say, with an LTN—takes time. But government surveys of the UK’s recently implemented LTNs have indicated that support from residents for such schemes increases over time. “If you start seeing more and more of those kinds of things, things become thinkable,” explains Aldred. If you start unpicking the idea that car use can’t be changed, “it starts to become possible to do more and more things without cars for people.”

The other issue is that, to put it simply, cars are never just cars. They’re interwoven into our culture and consumption as symbols of affluence, independence, and success, and the aspiration to achieve those things in future. “A man who, beyond the age of 26, finds himself on a bus can count himself a failure,” the British prime minister Margaret Thatcher reportedly once said. “That’s how we got in this mess in the first place, though,” says Crawford. “Everybody saw that the rich people were driving cars, and they wanted to too.”

That divide goes some way to explaining why the opposition to car-reduction schemes is often so extreme and can devolve into a “culture war”—which is what Holland has found in her experience with LTNs. But that struggle also outlines an important fact about car-free urban areas—that once cities make the decision to reduce or remove cars, they rarely go back. No one I spoke to for this piece could name a recent sizable pedestrianization or traffic-reduction scheme that had been reversed once it had been given time to have an effect.

Many of the cities that pioneered reducing car use—like Copenhagen in the 1970s—are rated today as some of the best places to live in the world. Even with London’s experimental and often unpopular LTN scheme, 100 of the 130 low-traffic areas created have been kept in place, Aldred says.

“Generally speaking, if a sensible program is adopted to really reduce or eliminate car usage in a central urban area, it seems to stick,” says Crawford. “If you go back a year or two later, people will just say: well, this is the best thing we ever did.”

Reaching net zero emissions by 2050 will require innovative solutions at a global scale. In this series, in partnership with the Rolex Perpetual Planet initiative, WIRED highlights individuals and communities working to solve some of our most pressing environmental challenges. It’s produced in partnership with Rolex but all content is editorially independent. Find out more.