I'm as density-friendly as it comes, but I think that we'd be much better off at maximum 20,000/sq km or so.
(That's not a magic number - that's about the density of the city of Paris, ignoring inner ring and outer ring. That's average across Paris, mind you, not some absolute maximum.)
Oakland is 3,000ish per sq km, for reference. Now, I'd prefer that we don't have to live in the 400 sq ft/40 sq meters kind of options that are older Parisian apartments, and I think that proper sound insulation is ground stakes (which current 5 over 1s in America don't do a great job with) but I think we can make the argument of more density without pushing for the extreme argument here.
I do agree that decentralizing the jobs is a really good thing. But while people want to cram into the same area, the government should not fight them.
So it's not necessarily dense that's the most environmentally friendly.
Imagine if no zoning code could prevent a developer from creating up to 3 story, multi-unit buildings on standard quarter acre lots. Just that alone would more than double the density in the United States overtime and still give most people PLENTY of space before we even have to start making sacrifices
That's why I think upzoning to medium density 15-minute cities is the best of both worlds.
Not to mention that living in a dense urban environment has a worse quality of life for a lot of people - that's why people don't want to do it. They like the space.
as one commenter suggested, the problem is that job locations are too concentrated. we have already proven that remote work is effective, so there is no need for that any more, and super high density is not necessary.
the environmental issue with low density is mostly cars, which can be solved with good public transport, which btw will also be needed in super high density areas because people will also want to go out of the city some times. i also believe that environmental friendly construction affects the possible density a city can have. concrete is not exactly environmental friendly material. (for high density steel without concrete would be better, it's more lightweight too, so allows for higher buildings)
in short, there are a lot of factors that go into environmental friendly living. what are the factors that favor high density?
good point.
i live in an area where climate control is not needed at all, so that changes the equation considerably here.
First, only some jobs can be done efficiently in a remote way. We should not be in a rush to generalize this to every job.
Second, public transit can be more energy and cost-efficient when in a denser context. In addition to public transit, there's also cargo transport for things like food, which given dense areas can be handled by more carbon efficient methods like water and rail instead of trucks. We haven't even touched on the efficiencies for water, sewer, and electrical infrastructure.
Third, dense construction can be done with timber. We've now reached a point technologically where a 100m building can be constructed primarily out of wood (search "plyscraper"). Wood is a very ecologically friendly material, as using it means capturing carbon.
Fourth and finally, building up instead of sprawling out means less deforestation, less draining wetlands, and less paving over prairies.
In short there are a lot of factors that go into environmentally friendly living, and most of them favor higher density.
i am skeptical about that. at least with the existing huge high density cities like those in china. less density (well, actually small islands of high density, in relation to your point four) would allow space for local food production. and truck vs train is not a factor of distance. if anything longer distances are more efficient by train and water whereas the last mile likely will remain with trucks (which could be electric though)
i agree with the other points, and i wasn't aware that wood construction went that far already.
capturing carbon
coincidentally i was just listening to a german audiodrama about capturing carbon.
Suburban houses require more resources and energy to build, maintain, heat/cool. Transport is just a small part of it.