(not a reply to seanmcdirmid) I couldn't reply directly to 'ayewo's post, so I reply here: I'm not sure where you are finding birthrates are climbing elsewhere. The forecast for most of the planet is birth decline over the next 50 and 100 years. Africa will mainly still contribute to population growth, but a lot of other areas/countries are headed for net decline in population, with the results hitting us in 50 and 100 years. It is not necessarily all bad, if we cope with it in relevant ways - a "solution" that was based on populations steadily forever climbing wouldn't be sustainable anyway, for many reasons.

Your opening sentence was well articulated.

But I’m not so sure about your second sentence. How does a situation where world wide population drops to 4 billion come about?

Even if US birth rates are declining, birth rates are climbing elsewhere so I’m struggling to see how in aggregate, the world population declines to half of what it is today.

> birth rates are climbing elsewhere

Where are birth rates climbing? Narnia?

Africa

Not enough to compensate for everywhere else plus even there most countries are tapering off.

[citation needed]

Every source I've looked at shows a drop in fertility.

Birth rate is a somewhat ambiguous term. Does it mean number of births? Or does it mean number of births per person?

You're talking about fertility rate, which is number of births per person. That's decreasing everywhere.

ayewo may have been talking about number of births. That is increasing in Africa, but even with Africa, is still decreasing in total worldwide:

https://ourworldindata.org/grapher/annual-number-of-births-b...

I'm pretty sure birth rate is universally seen as a second order thing rather than a first order thing.

What are you referring to by "birth rate"? Are you referring to the general society-wide system of babies being born? Or are you referring to a specific metric relating to how many babies are born?

From definitions I find online, first order vs second order refers to systems. So if you're applying those adjectives to a specific metric, I'm not sure that's correct.

I don't think we can say that people "universally" agree about what metric the term "birth rate" should refer to, because different people in this thread are using the term to refer to different metrics. However, I do think that generally the term "birth rate" refers to the number of babies born per year (or other unit of time), and the term "fertility rate" refers to the number of babies born per woman. Fertility rate is actually somewhat more complicated than that, because it takes into account the different fertility rates for women of different ages, and then sums those together, to simulate how many children a woman would have who passes through all the different ages.

https://en.wikipedia.org/wiki/Birth_rate

https://en.wikipedia.org/wiki/Total_fertility_rate

Not climbing coming down, but still high

not op but i think the climate catastrophe will curb population extensively. on the one hand by simply killing a lot of people directly (mostly war, famine and displacement), on the other hand by reducing birth rates (i.e. people not wanting to have children when there's not hope for the future).

Unemployment is low, labor force participation is high. We do not currently have an excess of labor, and a good deal of the reason that we had inflation was that there was no pool of waiting labor to soak up money injected into the economy during covid -- so instead that money bid up prices.

We have uber drivers complaining about too many people driving for uber in my area, so I don't think waymo would be welcome. We still have people who are unemployed or underemployed, for whatever reason, and automation pushes have huge resistance (e.g. dock workers in America don't want automation to hit ports like they have in China).

You are never not going to have some people who are unemployed. Don't mistake that for the idea that the economy is demand-constrained. It's clearly not right now, and automation of Uber workers would certainly make someone unhappy, but it would also very clearly lead to economic growth and vastly more people being better off than worse off.