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The Lancet: World population projections by 2100

thelancet.com

31–40 of 59 posts

Re: The Lancet: World population projections by 2100

#31

These studies are fascinating but I think they should stay away from such detailed predictions as 'in the reference scenario, the USA was forecasted to once again become the largest economy in 2098'. That's just way too far out to make any meaningful statements about a simple ordering of economies in relative size.

Is that really a prediction in the study? Or does their reference scenario use that (unknowable assumption) as a necessary input in calculating their population predictions?

Re: The Lancet: World population projections by 2100

#34
post #25
post #18

I find these predictions fascinating to think about. Did we get them right this time? I remember that we were taught about the idea of overpopulation in school. As I understand, it was believed in the 60s and 70s that the world population would keep massively increasing. People were worried about overpopulation. At this point we know that that's not true - it seems that essentially all rich countries see a decline in…

> we were taught about the idea of overpopulation in school That's a problem with school education. They give the wrong models. Exponential growth is impossible in nature because at some point it runs out of steam and fizzles out. Logistic curve or probit is a much better abstraction.

I think the assumption was that humans would continue growing exponentially until they reach the carrying capacity where they're all fighting for the same resources. Then the population stops increasing because there's not enough food/water/shelter to go around.

What actually happened is people in rich countries have plenty of food/water/shelter to continue reproducing... if they wanted to. The thing the models didn't account for is that people would choose to have fewer children based on standard of living.

To me it seems this had nothing to do with the standard limits of nature, but based on individuals' choices. Given those models' assumptions, I think they were valid. I would have made the same assumption based on past data as well.

Re: The Lancet: World population projections by 2100

#35

I refuse to believe that the only way for economic growth is population growth. Thats not sustainable. More investment in replacing the workforce with automation.

It's not. People used to believe we couldn't go to the moon. They just didn't see other models, or benefited from old models.

Even more than economic growth is growth in standard of living, quality of life, health, and other things that population growth is now causing to decline, however much it helped before. Plenty of human populations have lived peacefully, stably, and abundantly without economic growth. Plenty have grown to overshoot and collapse.

In Thailand, for example, Mechai Viravaidya helped lead a nation go from 7 children per woman to below replacement level. Think the opposite of the One Child policy -- instead of forced abortions and sterilizations, all voluntary, fun teaching kids about condoms and making them available everywhere. It increased stability, peace, and abundance. Here's his TED talk: https://www.ted.com/talks/mechai_viravaidya_how_mr_condom_ma... "Thailand's 'Mr. Condom,' Mechai Viravaidya, retells the country's bold plan to raise its standard of living, starting in the 1970s. First step: population control. And that means a lot of frank, funny -- and very effective -- talk about condoms."

Re: The Lancet: World population projections by 2100

#36

Isn’t the Lancet the publication who promoted that obviously bogus COVID study then retracted it without an apology? Why should we trust them again?

Yeah the Lancet has had some questionable publishing standards as of late, but the thing about science is that you should always hold everything loosely, run more experiments, try to disprove pást studies' findings, and take everything with a grain of salt until it's confirmed by several peer reviewed studies. So, we shouldn't trust the Lancet, and we don't need to, because everything in proper science should always be taken with a grain of salt.

Re: The Lancet: World population projections by 2100

#37
post #25

Earlier quoted context omitted.

> we were taught about the idea of overpopulation in school That's a problem with school education. They give the wrong models. Exponential growth is impossible in nature because at some point it runs out of steam and fizzles out. Logistic curve or probit is a much better abstraction.

I think the assumption was that humans would continue growing exponentially until they reach the carrying capacity where they're all fighting for the same resources. Then the population stops increasing because there's not enough food/water/shelter to go around. What actually happened is people in rich countries have plenty of food/water/shelter to continue reproducing... if they wanted to. The thing the models didn'…

That's not a new idea. Walter Greiling projected back in the 1950s that world population would reach a peak of about nine billion, in the 21st century, and then stop growing [0]

[0] https://en.wikipedia.org/wiki/Projections_of_population_grow...

Re: The Lancet: World population projections by 2100

#38
post #5

Earlier quoted context omitted.

China’s predicted population decrease is a logical consequence of its one child policy ( https://en.wikipedia.org/wiki/One-child_policy ) If you compare https://www.populationpyramid.net/china/1980/ with https://www.populationpyramid.net/china/2020/ , you see how drastic its effect on China’s population pyramid was. Drastically fewer kids means fewer parents 20-30 years later. (There also is a bit of an effect of ric…

Population Pyramid estimates the 2100 population of China to be 1.06B which is 45% higher than the 732M figure estimated by Lancet. 1B feels like a lot more realistic estimate than 750M.

The lancet error bars are 456 - 1499.

Re: The Lancet: World population projections by 2100

#39
post #25

Earlier quoted context omitted.

> we were taught about the idea of overpopulation in school That's a problem with school education. They give the wrong models. Exponential growth is impossible in nature because at some point it runs out of steam and fizzles out. Logistic curve or probit is a much better abstraction.

I think the assumption was that humans would continue growing exponentially until they reach the carrying capacity where they're all fighting for the same resources. Then the population stops increasing because there's not enough food/water/shelter to go around. What actually happened is people in rich countries have plenty of food/water/shelter to continue reproducing... if they wanted to. The thing the models didn'…

I recently heard about a survey where people on average said that they do want to have 2.something (lets say 2.4, but I don't remember the exact number) kids. I guess it is easier to prevent overshooting, but sometimes life circumstances prevent them from having as many as they wanted. That can be as simple reasons as not finding the right partner, etc. What you see less often though, is people that want to have 4 or 5 kids, which I think is stigmatized, but it could even out those that don't have kids.

Re: The Lancet: World population projections by 2100

#40
post #5

Earlier quoted context omitted.

China’s predicted population decrease is a logical consequence of its one child policy ( https://en.wikipedia.org/wiki/One-child_policy ) If you compare https://www.populationpyramid.net/china/1980/ with https://www.populationpyramid.net/china/2020/ , you see how drastic its effect on China’s population pyramid was. Drastically fewer kids means fewer parents 20-30 years later. (There also is a bit of an effect of ric…

Added to this, their economy has boomed due to not having to invest in future generations. At some point of course these chickens will come home to roost when the current population hump gets to an age where they retire, but for a good 20 years it can be a massive economic boon.

>Added to this, their economy has boomed due to not having to invest in future generations.

Can you clarify on what you mean by that please? Are you referring to pollution an environmental degradation?

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