Are American cities ready to build enough housing and infrastructure to handle a collective influx of over 120,000,000 Americans currently living in suburbs and rural areas? HA! I wouldn't and actually couldn't (financially) move to a major city as it stands barring a pretty sumptuous raise or downsizing from my 2 BR apartment to a studio. Rents are ridiculous, taxes are higher, air is much more polluted, traffic is horrible, public transit is hit or miss and often unreliable. If all of that improved I might reconsider, and I'll land my flying pig on my urban apartment balcony when that happens. For all the mayors' talk about meeting the Paris accords, or as "enlightened" as many cities think they are (looking at you SanFran), many of those cities will need their own bastille day where the city zoning laws are literally torn up burned in the streets before being "pro-city" is even reasonable for anyone lower than upper-middle-class.
Complete revolution would be ideal for meaningful change but is highly unlikely. As it stands we have to adapt existing systems to be clean, or at least cleaner. That means LED light bulbs, more solar (rooftop or grid) and wind/hydro/geothermal where possible, and electric vehicles. Which is where we're heading right now. Given the current rate of expansion, I imagine suburban emissions from housing/transportation will drop drastically over the next 50 years. Meanwhile those yards are carbon sinks.
The problem with American cities is NIMBYism: existing property owners are the ones with control of the zoning and the approval for new construction. So SanFran can't replace its too-small housing with lots of high-density high-rises because the people who own the other land there don't want it.
The fix for this is to move control of zoning and construction permits to the state level.
Complete revolution would be ideal for meaningful change but is highly unlikely. As it stands we have to adapt existing systems to be clean, or at least cleaner. That means LED light bulbs, more solar (rooftop or grid) and wind/hydro/geothermal where possible, and electric vehicles. Which is where we're heading right now. Given the current rate of expansion, I imagine suburban emissions from housing/transportation will drop drastically over the next 50 years. Meanwhile those yards are carbon sinks.