Assuming the world’s growth rate trickles off and we stagnate at a specific world population indefinitely, what would that optimal population level be?
There has to be an upper limit because of resources.
The enjoyable upper limit is likely less than that because we would like some excess - of consumables and personal space.
There is an obvious lower limit, but we would clearly want enough people to keep a good infrastructure going.
We would also want the population large enough where there is still a great variety in cultures, ideas, art, and professions.
We are at ~7 billion right now, and I don’t think we are uncomfortable (at least here in the U.S) so maybe, aside from some redistribution, I think I’d love it right where it is.
In fact, yeah, could we all just start 2-person families with the occasional 3-person? Thanks!
Well, if you make the assumption that we will only ever use resources from the Earth (i.e. we won’t ever bother getting resources from the rest of the solar system), and if you want everyone to have a western lifestyle(?), AND if you want to sustain that lifestyle, and you don’t want things like nuclear power, and you posit that there will (or won’t) be continued technological change or…
…yeah, it gets complicated very quickly. The main stumbling block I see is energy to having a large population. Pretty much, every other resource can be expanded or managed if you have sufficient energy, including water (potable water that is), which is the only other large resource that’s relatively scarce. So, in a discussion about optimal world population you need to consider energy at the primary curtailing force, as well as what level of lifestyle you’d want (or if you don’t want any particular one at all but let folks figure it out on their own, then how long the current population limits are sustainable given the limitations of the current energy resources…so, a few hundred years at most). The only other consideration would be environmental impact for things like global climate change.
Given that most of this hasn’t been defined for the discussion, I’m going to give a WAG of a few billion people, assuming the neo-Luddite faction holding back nuclear power is gotten out of the way and we are able to get a handle on the shifting climate. With abundant energy I think those levels are sustainable, assuming no great technological breakthroughs and just using the tech we have today. Make different assumptions though and you are going to get vastly different results on what is or isn’t optimal or sustainable…or whether sustainability is even one of the things you’d be going for.
I agree with the idea that energy is probably the simplest limiting factor to work with. As such, an estimate for this would be to take the renewable energy produced and divide it by the energy used per capita in the US. Using this wikipedia pageas a source, let’s add up Hydro, Nuclear, and Other Renewable energy production (8283, 3208, 15284 TWh respectively) which gives us 26875 TWh. Using 87216 kWh per capita in US, and that gives us roughly 308 Million.
Of course, that assumes that all non-renewable resources are exhausted and that we never improve the efficiency of those renewable resources or tap into new ones. That all said, if we could start getting more Nuclear or Hyrdo plants built in place of Coal and other non-renewable energy sources, we could probably get a lot more energy. In fact, if we’re going to take a huge hit in population anyway and energy is going to be scarce, I could easily see populations centering around places that can take advantage of hydro, tidal, and geothermal energy.
I’d also presume that in the time between now and when our non-renewable resources start to run out, we’ll have more and more incentive to pursue research into finding new renewable resources and making the ones we have more efficient. I think once that technology becomes more advanced and more competitive with non-renewable, we’ll probably find we have a much higher ability to produce renewable energy than we’re actually taking advantage of. Also, I’d expect that the American lifestyle could probably be made more energy efficient, better use of energy efficient lighting, heating, and appliances, better use of mass transit, etc.
So, taking all of that into account, I’d probably put the real sustainable population in the foreseeable future once fossil fuels run out somewhere around 2-3 Billion.
The Earth is already greatly overpopulated today. There is no doubt about that. If you dispute that, pay attention to the news and science about fossil fuels, global warming, pollution and the mass extinction of thousands of species just for starters. All of those are tied directly to an overpopulated world and no amount of anticipated technology can make the population even at today’s level sustainable and yet it is still growing.
Everything I have read on the subject agrees with some of the others. The long-term, sustainable human population is less than 1/3rd of what we have now and would ideally be about 2 - 3 billion people who also have the advantages of fuel efficient technology but also a lower rate of raw materials consumption than we have now at least in the 1st world.
3 Billion. That’s about where we were before the Green Revolution, and a lot of that is built on fossil fuels which aren’t going to last. I figure if we have a decent amount of nuclear energy plus the rest of modern technology, we could support those 3 billion at a comfortable lifestyle rather than the wretched subsistence level most were at in the 1950s.
But throw fusion, or Dyson spheres, or some other pie-in-the-sky “free” energy system into the works, and who knows what will happen?
It basically depends on our long term energy capabilities, and what you consider an “optimal” number of starving third world dirt farmers.
We can do a lot more with energy efficiency than we currently do, even if we discount any future technological improvements.
Lots of houses around the world leak like sieves. Improve insulation, plug cracks, change appliances, and so on and you can save tremendous amounts of energy.
More efficiency doesn’t just mean that your washing machine takes less water and electricity and soap. It can mean replacing whole categories of activity. Email instead of mail. Work from home instead of commute 60 miles. Recycle instead of use virgin materials–there’s plenty of aluminum oxide in the Earth’s crust, the problem is the energy it takes to make metallic aluminum. And on and on.
The reason we aren’t doing these things today is that they aren’t cost effective–energy is so cheap that we waste a lot. Increased energy prices in a world where we have to rely on an annual renewable energy budget plus nuclear mean that we’re going to decide to save a lot more energy.
The OP question is impossible to answer because it matters much more what those people are doing than how many there are.
Absolute world population decline is likely to happen, and likely to hurt the environment because it will be associated with economic decline, which means less money available for environmentalist projects.
Despite much lower population than the reductions proposed so far in this thread, ancient peoples still created environmentalist disasters:
Switzerland often comes up number one on list of the most environmentally successful nations despite having more than five times the population density of the US:
A world population of 500 million to 1 billion should provide plenty of genetic diversity, cultural variation, and buffer against disaster to perpetuate the species while being low enough to reduce our ecological footprint to something both sustainable and quite comfortable.
What does that have to do with anything? Extinction can be caused by multiple things. I am referring most directly to habitat destruction that is the result of a population that continues to climb well past the sustainable numbers although there are other, more indirect effects that are causing the same thing.
I am not some radical environmentalist in the usual sense. In fact I think most of them have it wrong and are basically just pissing into the wind with half-assed measures that can buy some time but not enough of it.
The fact remains that the only reason the human population can be as high as it is today is because we are burning through non-renewable resources of all types in order to sustain it and it isn’t sustainable in the long term.
We have already made tremendous progress in destroying things that can never be recovered in the last 100 years alone - a blink of an eye. I don’t think the whole system will crash tomorrow and probably not in my lifetime but the earth does not have enough resources whether we are talking about fossil fuels, water, biodiversity or even raw minerals to support the population now for the next 200 - 300 years let alone the anticipated increase.
The Earth itself won’t care. You can’t hurt it in any meaningful way but we can make life a hell of Earth for upcoming generations. Unfortunately, I don’t think this is a solvable problem but the consequences also aren’t optional or something we can argue away.
There isn’t a way to force population levels down to where they need to be other than through a series of catastrophes. They will come in due time whether it is through mass starvation, a pandemic or nuclear war over dwindling resources once humanity gets to that point.
There is no hope that technology can solve all the problems necessary to make the anticipated population levels sustainable. It is quite to the contrary. Technology is directed at extracting resources ever more efficiently and extending human life expectancies. That just compounds the problem.
I would say I can understand and probably agree with the conservative estimates. However, isn’t the world population supposed to eventually level up and then decline as time moves on? In developed countries this is already the case, correct?
I can’t see a way around the population increase. I think “well, I’d like to have 3 kids” and you know what? I will. I’ll have 2 and adopt 1. I’d consider having 1 and adopting 1 instead, but only if others would agree to the same measures. Since I can’t coerce them to do the same, I’d be screwing myself.
And then suggesting another country should slow down to your country’s pace…good luck!
It would also get into that ugly question of who gets to decide…
Perhaps we could draw up a global treaty that each nation would enforce each couple only having 1 child for say…100 years? Punishment for violating the treaty would, of course, be terribly complicated to draw up and enforce.
My heart weeps at the idea of the world having to fall apart before it gets any better. I think of all the wildlife that will be used for every fucking drop we can greedily get out of it and my stomach turns.
… damn you, I was coming in to post that.
Anyway it MOIDALIZE, me, and the babes. All the rest of y’all can fuck off now, planet’s closed. And leave a tip !
That depends very much on how large you want the ‘anticipated population’ to be. There is no real shortage of resources on our planet, although helium will run out in due course since it rises to the top of the atmosphere and escapes; since helium is the second most common element in the universe, we could import some more if we really needed it.
Everything else can be recycled, or mined from greater depths. We’ve barely scratched the surface of this planet, so don’t tell me we are running out of anything yet. This can all be achieved if we have enough energy to play with - and there is plenty of that. 174 petawatts, according to this wiki page.
We could have a very ‘enjoyable’ time with a population of fifty billion people or more on our planet- but if we did we’d have to kiss the rest of the biosphere goodbye. Every square kilometre (including the seas and oceans) would be dedicated to power collection or food production - no room for whales, or ten million species of insects.
Your claim is that people harm the environment because of sheer numbers. I gave counter-examples where small human population density harmed the environment while higher population density occurs in combination with good environmental stewardship. This seems to have everything to do with it.
Saying over and over that habitat destruction has to do with absolute numbers, and then throwing in hypotheticals about some future population numbers likely never to be reached (because of declining birth rates and future medical advances in birth control) is not evidence.
Talk about wanting to control women’s bodies! This is far more extreme than outlawing abortion, since a woman could still have considerable control over her fertility using birth control.
Suppose a female married couple both get inseminated at the same time. How we decide who gets a forced abortion, or , if that’s not your enforcement method, sent to prison?
Just because a house can be demolished by things that are not fire, does not mean there is no such thing as a fire so hot it must destroy a house it is in.
Human beings are straight-up pulling resources out of the biosphere in destructive ways; harvesting organic products at greater than replacement rate (such as ivory, or cod) and displacing other lifeforms to build our farms and housing.
Whether optimal or not, current data seems to suggest we will end up with a reasonably static population of around 11 billion in total.
TED favourite Hans Rosling did a great new show on the BBC lately regarding world population - I’m not sure if it’s available on line anywhere, but if you can find it, well worth a watch.
Ivory? African countries like Tanzania, with the biggest poaching problems, have relatively low population density. One thing that’s bad for poaching, as a business, is crowds of people. Could crowds of people, despite being good for poaching enforcement, be bad for elephants in other ways? Sure, that’s possible. But large pachyderms completely died out in North America at quite low human population densities. It’s not how many people there are, but whether they preserve elephant habitats and enforce laws against poaching.
As for cod, a couple hundred million people with no effective fishing regulations could empty the oceans of fish pretty effectively, because, in that scenario, 95 percent of environmentalists working to save ocean habitats never got born.
When environmentalists urge people to have fewer children, who do you think is listening? Conservatives parents who oppose environmentalism? Obviously not. The only people are can reasonably be influenced are those who are environmentally-friendly. Because the views of children correlate with those of their parents, this sort of thread is an attempt to hand over power to the forces which you as an environmentalist should oppose.