> We're above the carrying capacity of Earth for humans, and though we've done a lot of tricks to expand capacity, we're currently putting a large swath of the biosphere in danger.

Given the vast differences in climate impact between different populations and consumption habits, this doesn't seem to be the case.

Perhaps a better way of phrasing it would be "We're above the carrying capacity of Earth for Rich Americans".

The issue is that the U.S. isn't overpopulated. India, China are tho.

Worth remembering that the average person in the US emits far more than the average person in India or China.

I don't think most people have a problem with having a smaller population in general, they have a problem with the shift in the age distribution. Having less people is fine, having few young people who have to care for a general aging population is not.

What is the carrying capacity of earth for Humans? I recall in the 70s there was hype about the “Population Bomb” but those fears were never borne out.

As well, what makes you think we will reach an equilibrium for good neighborhoods? Some housing will be abandoned, causing blight; blight causes good neighborhoods to become less desirable, and they spiral down from there.

Detroit is a great example of what happens when neighborhoods lose people.

It's really hard to say what the carrying capacity is, because unlike other species, humans keep modifying their environment. Without clothing, the answer is probably a few million. Without agriculture, the number is south of half a billion. With mechanized agriculture, large-scale land use changes, and artificial fertilizer, we can probably still double our current population. But at the cost of stressing the rest of the environment. I'd guess the "safe" level is somewhere in the low billions, i.e. 1-5 billion.

I was mainly talking about the SF case, where lower global population should make it more affordable rather than causing things to be abandoned. This is what is playing out in Tokyo, which is still growing while the countryside is abandoned. As for the small towns, it sucks, but dying small towns has been a thing for quite a while now as agriculture has become more mechanized. Detroit's kind of the odd man out being a depopulating metropolis, so I'd actually argue that it's a terrible example, at least for the next 100 years.

On a global scale, SF is tiny. Fewer than 1m people in a state of 44m, a country of 350m, and a world of 7,000m.

The impact of global population on SF is and will be negligible.

I'm not getting your point. The thing about global trends is that they are global, which means that they'll apply to all of the large cities. Some large cities might have other trends that might hide the signal, like falling into the ocean, but the point is the global mass migration.