I mean, step 1 would be forcing the suburbs to pay the actual cost for their own power lines, plumbing and sewage, roads, phone lines, etc. Since as it stands, most of that cost is subsidised by the highly productive inner city, and that infrastructure is far cheaper per-person in dense neighbourhoods than it is in suburban tumours (sure, live out there if you want, but accept that you will either be paying a fortune for the infrastructure upkeep that supports you, or accept lower-class, cheaper infrastructure. I have a great aunt and uncle who live out in the countryside, and they have a dirt road, a septic tank and a rainwater tank, only their electricity and phone lines are comparable to what you get in cities, because it literally does not make economic sense to run paved roads or plumbing out to where they live).
Once people have realised that single-family housing with paved roads, sewage, plumbing and reliable electricity is well outside the economic reach of the vast majority of people, UPZONE. Demolish suburbs to replace them with far denser urban neighbourhoods, ones made up of townhouses, apartment blocks and mixed residential/commercial buildings. Change the zoning laws so that anyone can start a commercial business out of the front yard. Designate parks and other community areas in between your blocks of apartments and townhouses so that nobody is ever more than 15 minutes’ walk away from one. And for those who still want to live out in suburban sprawl, make the transition to being more self-sufficient easier.
Then, you have a city dense enough that you can start running vast amounts of public transport through it. Not just busses, but trains and trams as well. A train is more or less the ideal form of fast transportation along a known, unchanging transport corridor, with far more energy efficiency than anything that runs on tarmac, the ability to hit highway speeds inside city limits, and the ability to be extended almost infinitely. They can also be run from overhead power lines, no need for batteries or internal combustion engines. Oh, and the same lines you run urban rail along can also be used for freight trains, so they can replace both car journeys and freight truck journeys.
When you have dense cities with well-designed and extensive public transport, you can get almost anywhere with just one transfer, your bus/train/tram comes often enough that you’re never at the stop for more than 10 minutes, and even a trip from one edge of the city to the other will rarely be more than an hour. Plus, you don’t have to pay attention to the road, nor pay for fuel and maintenance.
Source: I live in a city where you can sharply draw a divide between the pre-car and post-car zones, and the pre-car zones are mostly like how I describe, while the post-car zones are suburban sprawl shitholes that might have a train station if they’re lucky
“Sure, the planet is unfit for human habitation now, but at least we got to have lawns in front of our houses and meat every day until the world ended”
Stopping climate change requires drastic action, rethinking how we live every aspect of our lives, and the wastefulness of suburbs means they must go, just like the internal combustion engine and the animal agriculture industry. How will you justify to future generations that you left them with a ruined world, all because you and those like you were too selfish to give up your current style of living?
Additionally, they are provably a blight on cities. They cost far more to maintain than they produce, since they lack any serious commercial activity, so no taxes, and the spread-out nature of them means that any infrastructure is far more expensive per person. You wouldn’t even need to actively demolish them, just cut off all maintenance, and watch them rot. Plus, they keep literally bankrupting cities, so often there is no choice, the money is no longer there to maintain them.