The Lancet: World population projections by 2100

The Gates foundation has a interest in keeping estimates of the population down low.

It's important to help promote global community now, today when it matters.

And given how rich countries progress, extrapolation to poor countries make sense.

But it's not how it will go down, look at attempts 80 year ago what they thought 2020 would be

Not a great example, but it's well under -

https://www.ssa.gov/oact/NOTES/pdf_studies/study033.pdf

There are massive changes coming, and they won't be in the negative direction.

Longevity will mean increased fertility.

UBI means things other than money will matter, like it or not when jobs start decreasing.

> Longevity will mean increased fertility.

I don't see how. We already live long enough to have a dozen kids per family. It's just that our society is structured such that raising kids is an expensive nightmare.

"The global population was projected to peak in 2064 at 9·73 billion (8·84–10·9) people and decline to 8·79 billion (6·83–11·8) in 2100."

Baseline of 9.73 billion.

"China was forecasted to become the largest economy by 2035 but in the reference scenario, the USA was forecasted to once again become the largest economy in 2098"

That sounds like they they forecast war?

Also

"meeting the Sustainable Development Goals targets for education and contraceptive met need would result in a global population of 6·29 billion (4·82–8·73) in 2100"

Is the 2.4 billion people missing people a form of genocide or just good heath?

"Funding Bill & Melinda Gates Foundation."

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 birthrates. They might increase in population, but it happens due to immigration. However, will this pattern hold?

As I understand it, before the industrial revolution, the population was what's described as Malthusian. As a country became richer it tended to have a population increase, which meant that an estimate of GDP per capita remained relatively similar. Over thousands of years you'd see maybe a doubling or quadrupling of it. Ie the median person in the year 500 AD lived rather similarly to the median person in the year 1500 AD.

When the industrial revolution rolled around, things changed. The estimate of GDP per capita increased faster than the population. People became richer and their lives became significantly better. This came with a substantial population increase, because people started living longer. The fruits of progress spread to poorer areas. The increase in food availability and medicine made many population counts skyrocket.

At some point during this it turned out that the richest areas started seeing a significant decrease in birthrates though. Why? I'm unsure. Perhaps people wanted better lives for their children and they couldn't afford to have as many children? Perhaps it wasn't necessary to have as many children anymore (social security)? Regardless what the reason is, birthrates have declined in developed countries. This allows us to plot a peak for the human population and decline afterwards. We don't need to worry about overpopulation anymore.

Will this pattern hold though? What if it turns out that when a society hits a GDP per capita of $500k of today's money that the birthrates start increasing again? 3% growth of GDP per capita plotted over 80 years would put US GDP per capita at $668k. What's the chance that there is no societal break point in the future that reverses the birthrate decline? Quite a few countries seem to be actively working on trying to find something like that.

It’s not just about money, the enjoyment/benefits of having a child decreases dramatically with each child you have. Having more than 1/2 children is really tough on, particularly on the mother, both physically and mentally. If you have the choice most people will not opt for more than 2 or 3.