A nice talk from Hans Rosling on this: https://www.youtube.com/watch?v=eA5BM7CE5-8
We are already at more than twice a sustainable population level. Even the most generous estimates I've seen place the Earth's carrying capacity at 7.7 billion people. But most estimates say that the Earth can support 2-3 billion people at modest levels of first-world consumption. The more our planet will be stripped of its resources now (whether through overfishing, destruction of forests, or climate change), the lower the sustainable planet population will become.
Put differently, we need to lose at least 5 billion people in the next decades without replacing them with a younger generation to be able to sustain the emancipation of emerging countries. It's not about population growth stabilizing, we need both massive negative population growth and halving of current energy use in developed countries. The only "natural" means through which I can see that happening is massive food shortages or horrific wars, and I think it's a pretty safe bet that the former will trigger the latter. It's also a pretty safe bet that our global society will disappear in that scenario, so I'd rather we have better solutions before that happens.
As soon as anyone frames sustainability challenges in terms of the earths "carrying capacity" they are revealing a bias that is unhelpful. Even if you accept the premise that the earth does have some 'maximum population' then so what? It's a useless proposition -- what are you going to do, force everyone to only have one child, that is unsustainable as China discovered.
Luckily, as the parent pointed out, overpopulation is not a problem. The rate of growth continues to decrease, and global populations will peak in my lifetime.
It gives me an idea for a sci-fi story, where a stable civilization of smart beings faces a threat of the sphere of all-consuming humans expanding at the speed of light.
In the interest of (scientific) discourse, it is generally unhelpful to redefine or ignore generic definitions. Are you asserting that the earth doesn't support any species, or that is perfectly possible to have googolplex people living on earth without reducing earth's ability to support googolplex people in the future?
In answer to your googolplex question - I think it's safer to bet on the technology developing to support such a population than against it. (Though I think we'll either be extinct or an interstellar species before then.)
My use of that population number was simply that: a refutation of the assertion that the earth has no population limit, as it will be hard to argue that our planet can support 10^9980 humans per square millimeter of land area. A genuine "argumentum ad absurdum", to counter the GP's completely nonsensical opening statement.
But instead of that, the initial reply:
- refused the basic premise that would have allowed that discussion, by indirectly positing that space on earth is infinite
- followed it up with a very questionable assertion that earth's resources are used "more or less sustainably" (which is already at odds with the previous assertion that resources are infinite, and ignores the many species we've already hunted to extinction)
- added a non-sequitur that we would have run out of resources as hunter-gatherers (again at odds with the initial statement)
- justified the plain refusal of the basic premise with an ad-hominem about bias
- continued on with the apathetic rationalization that nothing can be done anyway
- concluded by reiterating the initial statement without further substantiation
Now, you may argue that my refusal to engage in that discussion is my weakness and it would still have been possible to salvage something positive, however my time is finite and there's better, less taxing discussions to be had.
(/me out, accepting that meta-justification is considered offtopic and will be downmodded).
And, of course, we should be striving in our generation to solve these existential challenges, rather than squandering our time optimizing sales funnels and click-through-rates.
This has a survey of capacity estimates on page 10. I took the median of those, which more or less matched the sources I've encountered over the past year.
Can you show me these estimates? Do they take into account ways we could live with a smaller footprint (e.g. vegetarian/vegan diet) and/or advances in eco-friendly technology?
The whole argument sounds to me like "we don't have to force people to change their lifestyle to adjust for Earth's capacity - we can always force people to change their lifestyle".
Which is pretty visible in the West; every time the government tries to limit access to something, you get a stream of arguments that look exactly the same as those against one child policy that are posted here.
As for your question, I doubt that they would include an all-vegan world scenario, as it's considered unattainable, regardless of whether it would theoretically help. Technological advances are generally included, but with very conservative gain estimates.
Quite frankly, it doesn't matter to me whether the "real" capacity is 1 billion or 20 billion or 100 billion, as I don't believe we (as a species) have any chance of moderation in the face of opulence. As long as there's any surplus capacity left on this planet, we will find a way to use it. As fast and as wasteful as we can, until it all comes crashing down.
What do you expect is causing this? Isn't a large part of the reason for this due to changes in society rather than a synchronised biological trend? For example, couples choosing to have children later, if at all.
If the reasons are social rather than biological, then there's no reason why birth rates (I'm using the term birth rates as it's a more general term for what we're considering) can't increase in the future. The view that overpopulation is a non-problem seems to be based on wishful thinking and/or short-sighted analysis.
- enormous reduction in child mortality - increased female emancipation and economic opportunities - (direct and opportunity) costs of child-raising becomes relatively larger when societies get richer
I don't expect any of those trends to reverse itself
> If the reasons are social rather than biological, then there's no reason why birth rates can't increase in the future.
Sure, and there's no reason why the worldwide decrease cant' accelerate further either. The only question is, why do you think some scenario is more likely than the other?
> The view that overpopulation is a non-problem seems to be based on wishful thinking and/or short-sighted analysis.
To me the view that population increase is/will be some huge problem seems to be continuously redressing the Malthusian nonsense that's been wrong for over 2 centuries
I don't expect any of those trends to reverse itself"
Those aren't the only trends that matter. How about:
* Reduction in working hours/increased leisure time.
* Possibility for development of life extension technology (so long as this comes with an increased window of opportunity for raising kids).
* Changes to family structures (for example, an increase in popularity in tribe-like family structures, which reduces the burden on individual carers).
The point is if birth rate is only slowing down because of how our society currently is, then birth rate predictions are based on that society staying the same, and we have no guarantee of that being the case. Even if you think it's unlikely to change in the near future, humans will hopefully be living on Earth for thousands of years to come. If you were born 1000 years ago, do you believe you could predict how society would turn out in 2015?