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Where does this come from? We're currently in a 100+ year long population explosion that is wreaking havoc on the planet. Even if models predict the population

Where does this come from? We're currently in a 100+ year long population explosion that is wreaking havoc on the planet. Even if models predict the population growth will slow down and may turn to a decline after peaking 50 years from now, it feels quite rash to over-extrapolate and panic now about a potential eventual decline from the 15 billion peak to a genetic population bottleneck (1000-ish). The population would have to halve ~25 times which would take ~1000 years if it declined at a similar speed as it's been growing now.

somewhereoutth 3y ago
Exponential growth works just as well in reverse - the point is that our current social structures seem incompatible with even replacement levels of child birth. And that is before we consider the effects of the second order transition (i.e. going from a growing population to a shrinking population). That in itself wrecks things like pension provision.
- fulafel 3y ago
  Yes, exponential (has been doubling every ~40 years for a long time, and a scenario of halving at the same rate) is what I was talking about above.
- ninkendo 3y ago
  > the point is that our current social structures seem incompatible with even replacement levels of child birth. This means our current social structures need to change. We can’t have exponential growth forever. It’s literally not possible on a planet with finite resources. > And that is before we consider the effects of the second order transition (i.e. going from a growing population to a shrinking population). That in itself wrecks things like pension provision. Pension provisioning will suck yes. But it’s not an “existential threat to our civilization, if not our species. As much as climate change.” You are drastically overstating the drawbacks to population decline, as evidenced by your immediate moving of the goalposts when probed.
  - somewhereoutth 3y ago
    Um I meant the transition effects are also a problem, not that they are a bigger problem - my wording was a bit slack there. Yes probably we could overcome those issues, but with no clear reason for birth rates to increase as population falls (and quite a few reasons for the reverse - e.g. greater proportion of elderly requiring care that would otherwise be given to infants), our population and civilization would simply evaporate.
- stephc_int13 3y ago
  Our current social structure was built on wrong assumptions, this is what need to be fixed. This is probably not as difficult as it seems. We talk a lot about the proportion of active / inactive, but we often forget that most population under 20 is inactive and also supported by the active population.
ren_engineer 3y ago
"fortune is of sluggish growth, ruin is rapid" https://en.wikipedia.org/wiki/Seneca_effect https://en.wikipedia.org/wiki/Seneca_effect Look at how easily supply chains collapsed due to lockdowns, complex systems are hard to sustain and the focus on efficiency above all else has resulted in reduced redundancy. With less people around it will be hard to even maintain things, let alone improve them
iteratethis 3y ago
It's not just the raw numbers, it's the ratio between old and young that is absolutely essential which you're not including. Say we're below replacement rate and the first "halving" has occurred. The replacement rate now no longer is 2.1 (as it currently is), it would be perhaps 3-4. Which won't happen, so then it becomes 5. Which won't happen so then it becomes 6. And so on. Once the serious decline sets in, it cannot be stopped.
- deleted 3y ago
  [deleted]

somewhereoutth 3y ago

Exponential growth works just as well in reverse - the point is that our current social structures seem incompatible with even replacement levels of child birth. And that is before we consider the effects of the second order transition (i.e. going from a growing population to a shrinking population). That in itself wrecks things like pension provision.

fulafel 3y ago
Yes, exponential (has been doubling every ~40 years for a long time, and a scenario of halving at the same rate) is what I was talking about above.
ninkendo 3y ago
> the point is that our current social structures seem incompatible with even replacement levels of child birth. This means our current social structures need to change. We can’t have exponential growth forever. It’s literally not possible on a planet with finite resources. > And that is before we consider the effects of the second order transition (i.e. going from a growing population to a shrinking population). That in itself wrecks things like pension provision. Pension provisioning will suck yes. But it’s not an “existential threat to our civilization, if not our species. As much as climate change.” You are drastically overstating the drawbacks to population decline, as evidenced by your immediate moving of the goalposts when probed.
- somewhereoutth 3y ago
  Um I meant the transition effects are also a problem, not that they are a bigger problem - my wording was a bit slack there. Yes probably we could overcome those issues, but with no clear reason for birth rates to increase as population falls (and quite a few reasons for the reverse - e.g. greater proportion of elderly requiring care that would otherwise be given to infants), our population and civilization would simply evaporate.
stephc_int13 3y ago
Our current social structure was built on wrong assumptions, this is what need to be fixed. This is probably not as difficult as it seems. We talk a lot about the proportion of active / inactive, but we often forget that most population under 20 is inactive and also supported by the active population.

ren_engineer 3y ago

"fortune is of sluggish growth, ruin is rapid" https://en.wikipedia.org/wiki/Seneca_effect https://en.wikipedia.org/wiki/Seneca_effect Look at how easily supply chains collapsed due to lockdowns, complex systems are hard to sustain and the focus on efficiency above all else has resulted in reduced redundancy. With less people around it will be hard to even maintain things, let alone improve them

iteratethis 3y ago

It's not just the raw numbers, it's the ratio between old and young that is absolutely essential which you're not including. Say we're below replacement rate and the first "halving" has occurred. The replacement rate now no longer is 2.1 (as it currently is), it would be perhaps 3-4. Which won't happen, so then it becomes 5. Which won't happen so then it becomes 6. And so on. Once the serious decline sets in, it cannot be stopped.

deleted 3y ago
[deleted]