[tremon]

You mean, it is not a problem because the planet can support that many? Or do you mean it is a problem, but it will solve itself? I don't think either is correct. The first is only true today because non-First World inhabitants are living on a much smaller ecological footprint than Europe and the US. However, that footprint is increasing rapidly. The second reading at least acknowledges there is a problem, but I think you are underestimating the correction required. I think the correction will not happen (at all, or fast enough) through natural means.

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.

[flgb]

The earth doesn't have a "carrying capacity" or a "maximum population". The earth has resources that are used more or less sustainably at different times and in different places. If we all still lived like hunter gatherers we would have run out of resources and become extinct thousands of years ago. Luckily we've had social, economic, and technological development.

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.

[Bill_Dimm]

About 20 years ago, when I was a grad student, I attended a colloquium where the speaker (a physicist, for better or worse) had computed the number of people that the planet could support if everyone consumed natural resources at the rate that Americans do. His number was 2 billion. I don't remember who the speaker was and I don't know what assumptions he made -- I don't know how much error there might be in his result or how improvements in technology might change it. If his number is even close to being right, "global populations will peak in my lifetime" isn't even close to being adequate unless you expect the bulk of the population to be satisfied with remaining poor while a small proportion of the population devours the planet.

[Idontagree]

Which is a calculation based on current technological standards, which is also not proof that we will not become more efficient and better able to manipulate our resources as needed.

[Panoramix]

Ah, the good old "future generations will solve it, so let's trash this place"

[throwaway_789]

Strawman. Strong environmental protections and positive population growth can coexist.

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.

[tremon]

"Ecologists define carrying capacity as the maximal population size of a given species that an area can support without reducing its ability to support the same species in the future" http://www.dieoff.org/page112.htm

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?

[hguant]

I think the post is saying that defining the carrying capacity of a technological species is an exercise in futility. Malthus was writing about this many years ago - humans have a habit of raising the bar.

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.)

[tremon]

I (think I) understood the GP post, I just have very little tolerance for idiotic and easily falsifiable statements. Therefore, I chose to respond to the first sentence only, and ignore the rest of the post.

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.

[ubercore]

I interpreted the opposition to using carrying capacity to mean that it's not helpful from the perspective of a technological species. If we had that many humans, the odds seem high that we would have a way to supplement resources available to use from outside Earth. Carrying capacity is really about an _ecosystem_ and the resources it can provide vs competition with other species. We effectively have no competition, and we can create our own ecosystems, so it's kind of a strawman to apply the wildlife biology concept to our understanding of how human populations will evolve in the future.

[tremon]

Ah, but that would have been an interesting discussion. We could have discussed the merits of carrying capacity with respect to a species that builds its own ecosystem, or whether it makes sense to consider the entire planet a single ecosystem. We could have a meaningful discussion about the various population estimates and what they're based on. Or we could have discussed whether it makes sense to consider ourselves in competition with future generations.

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).

[hellbanner]

Eventually we'll have to reach other planets.. and invent wormholes to move past the universe expanding preventing our light cones from reaching other materials.

[TeMPOraL]

Aren't we a cancer that consumes the worlds?

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.

[brlewis]

What are the "modest levels of first-world consumption" in the estimates you mention? And how recent are these estimates? There are many factors that likely will contribute to a smaller first-world footprint, e.g. http://fivethirtyeight.com/features/americans-will-burn-less...

[tremon]

http://agrpartners.com/wp-content/uploads/2013/09/AGR-Though...

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.

[brlewis]

Two of the estimates have years associated with them: 1994 and 1999. The survey itself was published in 2013 so didn't have the data available that fivethirtyeight cited. I think it's time for researchers to update their capacity estimates.

[xixi77]

Historically, all such "carrying capacity" estimates have been shown wrong. What makes you believe the 7.7 one is any better?

[tremon]

I don't. But I've always been a glass-half-empty kinda guy, so I tend to err on the side of caution (or, in this case, catastrophe).

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.

[ZenoArrow]

> "Even the most generous estimates I've seen place the Earth's carrying capacity at 7.7 billion people."

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?

[tremon]

Sadly, no. I never bookmark or save articles as I come across them. It's a pity, as I've been searching for one specific article which compared our energy use with the total solar energy absorption of the planet (iirc, we were using more than 50% of total input).

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.

[TeMPOraL]

Denying people their meat or SUVs is an equivalent problem to limiting the number of children they have. People won't give their "freedoms" voluntarily - you have to force them either by law or by economy (and letting the free market take care of it will likely be too little too late).

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".

[ZenoArrow]

Are you suggesting most people have the same level of attachment to SUVs as they have to their fellow human beings?

[TeMPOraL]

I'm suggesting people have a smiliar level of attachment to being allowed to buy a SUV as they have to being allowed to have a child in the future.

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.

[ZenoArrow]

Would people miss what they never had though? What if public transport was so good that people just didn't need to buy cars anymore? As in, so good that there wasn't any practical reason to own a car. Would a generation of people raised with a strong public transportation system still find enough of a reason to use a car (aside from as a form of recreation)?

[TeMPOraL]

I think they wouldn't. That's why I find most of those objections silly - they're just something people got used to. It's like every time Facebook improves their UX, there's this huge uproar about the fact they dared to change things, but it dies out within a month as people get used to the new look and are still happy.