Each of us can look towards the sky and see the sprawling space and resources available. We have companies today organized under the premise to go out and mine asteroids, explore other planetary bodies and much more. Yet, some continue talking as if the Earth were more valuable than the only thing (humans) that can ascribe it value. Gaia worship and similar propaganda should be exposed for the anti-human agenda it is. I sincerely despise this line of thinking.
Whether we like it or not, humanity is the steward of this Earth. Being good stewards of our resources SHOULD NOT first appeal to last-ditch efforts like controlling the population. We all have imaginations; along with the ability to create solutions to problems. Stop perpetuating the idea that future generations are evil, bad, doomed or unwanted; they are very welcome and wanted. Now, and always. Our parents did not put our generation to slaughter for selfish reasons, so we have no justification for it either.
Instead of proposing anti-humanist goals of little thought or substance, set your mind to work and stop being intellectually lazy. We already have hints from various nations who have tried to control populations, with evidence of detrimental and unintended side-effects. I am by no means saying there are simple fixes. But immediately jumping to population control is pure lazy thinking.
Except there isn't a sprawling amount of resources for an exponentially growing population. Let's say we reach the resource limit of Earth and start reaching for the stars to find new places to live. If we can colonize one Earth-like planet around every single star of the 400 billion stars in the Milky Way, we would run out of places to live after 2685 years if the human population kept growing at a rate of 1 % per year. That isn't even enough time to reach all places in the Milky Way even if we could travel at the speed of light. Actually you could barely cross 2 % of the diameter of the Milky Way in that time. Exponential growth is unsustainable. Period.
There is a growing group of people who believe the world is over populated. I want to push back against that mentality a little bit, because we should not resign ourselves to hopeless thinking. There are plenty of things we can do to improve our situation before resorting to dramatic actions. I want to avoid "there is no other solution" like thinking. Once we stop looking for other solutions, it will become a self-fulfilling prophecy. That is what I mean by lazy and morally hazardous.
It is not lazy to try to control population growth, it is the only viable longterm solution because technology can not solve this problem. The goal must be to stop population growth or, for practical matters, increase the doubling time at least to the order of millennia. That is why I gave the example with colonizing the Milky Way, to make clear how bad the problem is and how infeasible technological solutions are.
less desirable options: uncontrolled global civilisation collapse with rapid decline in living standards and population, nuclear war, etc
more desirable options: intentionally adjusting lifestyle / affluence in western countries, non-coercive methods of population control (e.g. better healthcare, increased access to family planning, increased opportunities for women to participate in education / economic activity, etc), less focus on short-term appropriation of wealth
One could ponder whether it would make sense to use population control in addition to improved technology and development to make the ride across the world population peak smoother, to make the peak lower and happen earlier. There would almost certainly be at least some benefits to this, but given how long political debates about that would probably take, never mind implementing and enforcing the decisions, there might actually not be enough time to do this and get some noticeable impact out of it.
As long as it looks like the world population will peak around the end of the century, go for technology to make it as pleasant as possible, but if the outlook indicates that the world population does not peak or at least stabilize in the foreseeable future, then population control is really the only way or it will become pretty unpleasant as you indicated in your first scenario.
Is there a recognized exhaustable availability of resource X? Then we simply don't allow that resource to be used as a means of capitalist value extraction from a planet. The resources belong to the commons, and we must shift away from allowing profits to guide the use of raw materials.
I look at, say, the last century of the automobile, and cannot avoid wondering just how different our lives would be if we'd bypassed the idea of placing a couple tons of metals and plastics in everyone's driveways. What else might we have used those materials for, if we mandated that using them had to be done in a way that benefited a large number of people with the same material cost. This really goes for nearly every consumer product made available to the markets.
I don't think we'll be able to come up with viable long-term strategies for handling population growth, and providing a high quality of life to all members of that population, until we move beyond status-driven consumerism and the capitalist economies that create and depend on them.
I'm obviously missing something in the figures you're using to calculate here, but how exactly would we consume all the galaxy's resources in < 3,000 years? We've been doing our thing on Earth for more than 3,000 years, and there are still resources available.
I'm not disputing that we consume far too many resources in a very irresponsible fashion. That just seems to me to be a very much higher rate of resource consumption than we've seen historically. Surely, if we were to develop the ability to colonize other planets, we wouldn't reproduce the same wasteful resource consumption patterns and history, because we'd have greater technology and, more importantly, improved philosophical outlooks on how we use those resources. Are you thinking we'd move 100% of the human population to each new planet and just set up the same wasteful shop we have till we exhausted the planet? I'd expect moving a smaller portion of the population to each new place, and setting up a far less wasteful colonization effort, that itself would continue to improve (hopefully).
With a population growth rate of 1 % per year the population doubles every 70 years. 2685 years are about 39 doubling periods which means that the population will increase by a factor of 549,755,813,888 over this time and if we needed on Earth at the beginning we then need that many Earth-like planets or the entire Milky Way under my assumptions of 400 billion stars and one inhabitable Earth-like planet per star. This assumes no further or at least only negligible technology advances over those 2685 years, i.e. we do on the new planets what we did on Earth when the carrying capacity of Earth was reached, but which we assumed was the best thing possible at that point in time.
Exponential growth is really that bad and 1 % per year is a pretty high growth rate. We could never have sustained such a growth rate for extended periods. We only surpassed 1 % per year in the early 20th century, before that it was a lot lower. My entire point was to demonstrate that exponential growth with 1 % per year is so huge that it would grow beyond any realistic resource limits in pretty short time. Decreasing the growth rate by a factor of 10 to 0.1 % per year will only increase the doubling time by about a factor of 10 and we would still reach the carrying capacity of the Milky Way in relatively short 26,728 years. Stabilizing the population at some point is really the only option, exponential growth can not possibly work besides with growth rates that are essentially zero.
Which population is that? Certainly not humans.
And, because you mentioned the end of the century, there is still »The Limits to Growth« and it predictions. I am actually not sure on which side I am here. I can't really imagine a collapse of society as we know it in the second half of the century but I am also aware of the sudden and unexpected behavior of complex systems and how hard it is to counteract a system with a lot of inertia. But if the predications come true, population control may become an issue sooner than we like.
The moment you describe it as "slaughter," you've completely lost me. A gradual reduction by having children at below replacement rate isn't "slaughter" and doesn't in any way imply that future generations are somehow bad or unwanted.
If population reduction really is such a bad idea, you should be able to come up with much better arguments against it.
Similarly, it is not helpful to decree that any discussion of population is tabu.
Other societies have very different standards of what is morally normal and acceptable when it comes to population growth.
E.g. Jared Diamond's book Collapse discusses the island of Tikopia  -- the people living on this isolated island (~1200 people on 5km^2 of land) managed to live sustainably for hundreds of years with a stable population:
> Most readers of this book will have practiced one or more of those methods [of population regulation], such as contraception or abortion, and our decisions to do so may have been implicitly influenced by considerations of human population pressure or family resources.
> On Tikopia, however, people are explicit in saying that their motive for contraception and other regulatory behaviours is to prevent the island from becoming overpopulated, and to prevent the family from having more children than the family's land could support.
Traditional methods of regulating population included: contraception, abortion, infanticide, celibacy of younger sons and "surplus" marriageable women, suicide, "virtual suicide" (setting out on dangerous sea voyages with essentially no hope of survival), and one instance of warfare between clans (after a decrease of fish and shellfish population led to starvation and conflict over the remaining land and coastline).
> Most of these seven methods for keeping Tikopia's population constant have disappeared or declined under European influence during the 20th century. The British colonial government of the Solomons forbade sea voyaging and warfare, while Christian missions preached against abortion, infanticide, and suicide. As a result, Tikopia's population grew from its 1929 level of 1,278 people to 1,758 people by 1952, when two destructive cyclones within the span of 13 months destroyed half of Tikopia's crops and caused widespread famine.
Some might argue it did help China. I'm curious what examples you are thinking of (citation) besides obvious genocide and murdering.
> I am by no means saying there are simple fixes. But immediately jumping to population control is pure lazy thinking.
There is nothing wrong with a nation having sensible mild restrictions or tax relief for taking up less resources. We tax tobacco, liquor and gasoline. Hell red meat should probably be taxed as well (one could argue liquor is not as bad for you as cow and for sure cow is worse on the environment). It doesn't have to be draconian for a mild behavior changes.
As with dietary weight loss real changes can be made with out being that innovative or being that extreme. Some might even say the lazy (your word) thing is reaching for the latest panacea instead of being disciplined and/or consistent.
BTW in nature many animals deal with population control with given limited resources (some nasty and some just not producing as much offspring). Probably a genetic trait to avoid extinction.
Half the earth is both outrageously huge and within the realms of possibility. If we debate the merits of it, then we're more likely to entertain more modest proposals.
In addition to agriculture & food production, transportation (road+rail), strip/open pit mines, and you have just take a look at
The global impact of farming on the environment is revealed in new maps, which show that 40 percent of the Earth's land is now given over to agriculture.
From our mostly meat diet to our inefficient mostly individual transportation systems to our consumerist society that produces tones of useless garbage all of these with very high carbon footprint, pollution and big environment impact.
And all of this just to satisfy some old human habits that are no longer possible at this scale without irreversible damage to the ecosystem.