2.4 children per woman is 8.9-fold growth after 300 years of 25 years between generations. 1.6 children per woman is a reduction to 6.9% of your initial population in the same way.
(Also, sustainability is a function of tech: the 1930s way of life was not long-term sustainable at any recorded population level).
> why would I worry if in centuries we are a billion less?
Indeed, this is my position too. Hyperbolic discounting of the future: we don't know what's coming, let the future sort itself out and worry about the next 5 years.
25 years, we might get AI good enough for robot workforce and we can all retire instantly with no need for more kids entering the workforce to replace the pensioners, might get anti-aging and an end to old-age pensions, might get both, might get neither.
(That said, the example I gave was a reduction to, not by, 6.9%; it would be a global population of 552 million).
'just' is doing a lot of heavy lifting. Lead is still in certain common fuels, some paints, and foods to this day.
That said, if you know how to turn any lab-only solution into an economically viable solution, please do — the world has plenty of room for improvement! :D
I think you can make a good argument that collective action helped end slavery, I don't think you can make a good argument that anything other than market forces is bringing us the transition to renewable energy.
Where's lead in that? I don't know. I don't even know if it's the same answer for each of your three uses of lead.
Ozone was easy to get an international agreement to fix, because it already had economic alternatives.
* and if you want to argue semantics over "are economic forces anything other than the de-facto collective action of the agents in the economy?", which I'm sure someone has energy for, but I'm not that someone, so I'll acknowledge it and move on.
2.4 actually has been sustainable for a couple of millennia by now, mostly because our technology (primarily the food production) was able to keep up with the exponential growth of population. How long this can last is a question, but even if it doesn't last -- going from 2.4 to 2.1 is not hard.
With 1.6 you don't even need to wait for millennia or even aforementioned 300 years to get into trouble. After two generations you get into the situation where working people have to share their income with too many elderly AND elderly don't only consume resources but also directly compete for them with the youth (the other class of people who consume without producing) which makes the fertility economics even worse. You can plug some holes with immigration and foreign trade but on the macro-level it's a death spiral. Very easy to get from 1.6 to 1.0, but extremely hard to return to 2.1.
Maybe I'm missing something but countries like Italy or Spain look to me like trains rushing into concrete wall. And it seems that people are mostly concerned about whether the train is running on a carbon-neutral fuel.
If it had been 2.4 children per woman* over that time frame, the current world population would have been 200e6 * (2.4/2)^(1000/25) = about 300 billion in 1000 AD, and 200e6 * (2.4/2)^(2024/25) = 514 trillion today.
> elderly don't only consume resources but also directly compete for them with the youth (the other class of people who consume without producing) which makes the fertility economics even worse.
Only if the elderly continue to consume pensions. If the economy collapses, pensioners protesting or voting for the other party in a democracy stops being an interesting threat, for the same reason they weren't much of a threat in 1889 when people were first taking ideas like "state pension" (in their modern usage and not e.g. medieval almshouses, and universal not e.g. what the Romans did for the military) seriously.
* I know I didn't mention "surviving to reproductive age" before, but that distinction is more of relevance to historical comparisons than future ones. I have no reason to think infant mortality will go up, after all.
Agreed
> Only if the elderly continue to consume pensions.
Well no, unless you literally starve them to death. State pensions or money in general is just a redistribution mechanism which doesn't change average available resources. What really matters on a higher level is the fact that a big part of population (elderly and youth) consumes but doesn't produce. Whatever they consume is either directly produced by the working part of the population or comes from the foreign exchange of the same said produce.
So if the state pensions system collapses it just means that instead of feeding your parents through taxes you now do it directly, which on average is almost the same (difference coming from elderly who don't have kids to feed them). Which still means you have less resources to spend on your kids.
The way this is currently playing out in the UK, is that pension ages are increasing.
At the extreme case, there's no more state pension: if you don't have a private pension, you're working until just before you die.
I was thinking more of heating (and, increasingly, cooling) rather than starvation: Food specifically isn't the main concern here, unlike in the 1800s, because of how few farmers we need to feed the entire population.
(And this whole thing may be inverted at short notice in a whole bunch of different ways; UBI is basically a pension age of zero, but I'm only expecting that when AI gets good enough, and IMO that's "at least five years after self driving cars, whenever that is".
I don't think you're approaching this conversation honestly.
This makes no sense. Sustainability means an ability to maintain the current trajectory. Yes, standards of living are not the same in different places but it has nothing to do with what "sustainability" means.
On a side note if you actually care about the bottom-line standard of living then you probably should wish for bigger population and bigger economy. The correlation between the two is very strong, many things we have now (like microchips) become unaffordable if you scale down production.
Well maybe, just maybe, try once looking at the historical data [1] to see how it works? Economy is not a zero-sum game where dividing resources among the smaller number of players gives you a win.
Yes, with the current technology stack lifting everyone to the current US level is impossible, that's precisely why it's so important to keep pushing. Earth continuously receives 44 quadrillion (4.4 x 10^16) watts of solar energy on average it's more than plenty to have decent standards of living for everyone if captured. The problem is, development of technology is extremely expensive, effectively impossible unless you spread the cost among a huge number of end-consumers.
If the population didn't grow like crazy in the past centuries we wouldn't have the technology we have today and the bottom-line standard of living would be way lower than what we have today. And so would be the US standard of living because US wouldn't be sitting on top of a 8-billion-people economic pyramid.
Very lucky for the world's poorest (and for all of us) that we didn't listen to cries of de-growers in the 18th century. In principle not much have changed since then. Amount of energy at our disposal is still laughable, so the road ahead is longer than what we did so far.
[1] https://en.wikipedia.org/wiki/Extreme_poverty#/media/File:Wo...
I struggle to understand why continuation of society in a particular way is important to someone hundreds or thousands of years after their death.
Claim 1: A “sustainable birth rate” is bounded by the efficiency of resource extraction and the repair rate of the environment for the damage the extraction does to it.
Claim 2: It would appear that technology has accelerated so far very closely at the same rate as global population growth.
Claim 3: Our efficiency of resource extraction has sky rocketed.
Claim 4: Our damage to the environment has exceeded its repair rate as this has increased.
Claim 5: A collapsed society would not immediately loose all of its population, and would likely be the most damaging to the environment in the shortest period of time. We won’t forget how to burn oil, but we won’t be using high efficiency well maintained engines when we do it.
With that. Seems like there are two options before humanity:
1. Burn it all down, reduce population growth rate (doesn’t matter if it’s controlled [Mao] or uncontrolled [The West Today]), eventually loose genetic entropy, and before that loose (or automate and replace) the labor force that allowed for the resource extraction.
The outcomes here are:
a) Society collapses (genetic entropy, climate change damage that has already been done, destabilization caused by population reduction measures, etc)
b) We automate labor and humans either are replaced entirely
c) or a small oligarchy of humans exist to rule that automation. That population must keep genetic entropy through gene editing (requires a lot of novel advancement which is harder with fewer people, unless we’re curating)
- or -
2. Address the reasons why people aren’t having kids in the west to maintain labor and genetic entropy, which mainly has to do with economic opportunity of young adults. And ensure that our resource extraction continues more efficient and that we either develop ways to limit damage or ways to accelerate the repair.
Outcomes are:
A) We fail to accelerate repair or reduce damage, and society collapses
B) We succeed and we’ve managed not to damage genetic entropy and don’t risk a conflict over population control.
The problem with option 1 is the implementation won’t be uniform, and population reduction globally cannot be achieved without some type of concerted effort. Consider for a moment how that is supposed to be implemented.
If things go wrong in that effort, that leads to conflict. It seems very likely that society collapses as well.
The other issue is considering the population number as the solution is it is a very short jump to the justification of genocide or some other form or population reduction. That also seems like it would accelerate conflict and therefore society collapse.
The problem with option 2 is there is only so much time before our damage exceeds allowable levels.