You need to look at the fact that our rate of population growth is negative. Sperm counts are averaging around 40 mill which is enough to require medical assistance. The human race is, in fact past peak growth and declining.

So our second derivative is negative. It is fundamentally unsustainable for anything else to be the case forever, right? That would imply linear or greater growth in perpetuity on a finite planet where we and our livestock already comprise 96% of all mammal biomass.

The drop in sperm count is of course concerning, though if we can't get our act together on birth control and family planning then it's probably one of the least tragic ways for our population to get knocked down to a more sustainable level. Humans generally fail at prisoner's dilemma ("if we have fewer babies, other nations will overtake us!"), so it seems necessary that some outside force eventually mitigate our continual failure there--and again, when compared to mass wars or starvation, lower fertility rates is actually a pretty peaceful course-correction.

We largely have gotten our act together on family planning, which is why birth rates are below replacement everywhere but sub-Saharan Africa, and dripping there too. Only reason population is still increasing is a combination of lag (it takes the smaller year groups now growing up in India and China to become adults before those countries will tip into population decline (excluding immigration), and waiting for the decline in Africa to hit replacement as well.

UN projections indicate somewhere around the end of the century for a net reduction in people, but long before that we'll see developed countries starting to compete agressively for immigrants, combined with campaigns to push fertility up to try for a soft landing.

"at some point growing population is unsustainable"

This is a logical fallacy that has been bounced around, in catastrophic terms, for centuries. (see Thomas Malthus [1], "The Population Bomb" by Ehrlich [2], etc.) Ehrlich went as far to say that in the 1970s, HUNDREDS of millions of people would starve. Did that happen? No. These ideas about some theoretical limit on food or resources of the Earth are alarmist and do not benefit the public discourse.

Sure, maybe the Earth has a limit to how much population it can support, but it could easily be 100 billion. Who knows? Do you know that the entire population of the Earth can fit in an area the size of the state of Texas, in single family homes? [3]

In contrast to the disproven "unsustainable growing population" idea, depopulation and the aging of the population will have severe consequences within the next few decades, and already has had negative consequences in places like Japan [4], Italy [5], and many others.

We definitely need to deploy policies to increase the number of births to address these issues.

[1] https://www.britannica.com/biography/Thomas-Malthus [2] https://en.wikipedia.org/wiki/The_Population_Bomb [3] https://theblogmocracy.com/can-you-fit-the-entire-world-popu... [4] https://www.bloomberg.com/graphics/2019-japan-economy-aging-... [5] https://www.bloomberg.com/news/articles/2020-02-12/italy-is-...

The fact that the malthusian catastrophe has not yet occured does not discredit it. In fact this can be explained by agricultural yield gains that were substantial in the first half of the 20th century, thanks to using hybridized cultivars and industrial fertilizers and pesticides. Where will the gains be in the future when we approach another resource limit? We will have to continue to use genetic modification to improve our crop yields, and these days marketing executives have poisoned that word in the minds of many who now seek out gmo free foods specifically. This is also to say nothing about the state of the environment, how we take out elemental resources from the land that took a very long time to deposit in this place, bring them to a distant market and never replace them, diminishing the fertility of the area. Or how we do the opposite to our aquatic environments through eutrophication.

The idea that technology will always bail us out seems foolish to rely upon in the grand scheme, eventually the disequilibriums we create in these environments we exploit will be too extreme to successfully manage and maintain a system as complex as a local ecology. These disequilibriums are already extreme in many places and policy makers rarely seem to care unless some stakeholder is set to see a profit.

>The idea that technology will always bail us out seems foolish to rely upon in the grand scheme, eventually the disequilibriums we create in these environments we exploit will be too extreme to successfully manage and maintain a system as complex as a local ecology. These disequilibriums are already extreme in many places and policy makers rarely seem to care unless some stakeholder is set to see a profit.

Your assumption that technology may not be capable of helping us enormously down the road is much more of an assumption than the pro-technology argument. Because unlike the anti-growth malthusian argument, the reality so far for centuries has been that technology did indeed make life easier and better for people despite an ever growing population.

There's actual, consistent precedent contradicting all malthusian predictions across several centuries of human development, with entirely artificial political disasters mostly being responsible for any failures. On the other hand, we've not yet seen any concrete examples of human development failing in the face of hard natural limits to growth. Wherever it has failed has been because of mismanagement in some form or another, not lack of possible solutions.

Thank you, I could not have stated it better myself. When there are many real-life examples that contradict an idea, and only theories and logic that stem from certain questionable assumptions to support that idea, then at very least it is a very poor idea on which to base public policy

It did indeed make life better but thats because we never considered the externalities, then we would realized we erred too hard on the side of environmental exploitation. What takes millions of years of give and take to produce is squandered in a fortnight.

In biology, balanced relationships, mutually symbiotic relationships take orders of magnitude longer to evolve than parasitic relationships. We do not have a balanced relationship with this planet, we have a parasitic one. We are speaking the same things when you say that whenever we have failed was because of mismanagement, in other words being to parasitic to our hosts. To not mismanage something would be to understand all the latent variables affecting the system before we act. We never do that, we act, then only react after the system is so obviously affected by our actions.

I don't know if 1000 square feet per person is the exact same as people living in single family homes as it wouldn't include roads, farms, retail or any of the other spaces you would need, it's just 268,581 square miles divided between 7 billion people.

Population growth has overall largely been a function of increased energy availability, from the industrial revolution onward through the consumption of fossil fuels which are inherently unsustainable.[1]

Also, assuming the number is for example 100 billion, it seems like you still have the same issue of infinite population growth being inherently unsustainable but just on a different timescale.

[1] https://www.resilience.org/stories/2009-04-20/peak-people-in...