[eru]

What do you mean by 'so many people'?

The carrying capacity of earth is likely hundreds of billions of humans, if we were to set our mind to it.

Just to concentrate on food alone: we are barely harvesting anything from the oceans. Even on land, using greenhouses everywhere would give us vastly more agricultural yield.

We are not using greenhouses everywhere right now, because that's a huge capital investment; and given current food prices, it's generally not worth it. But if push came to shove, we could totally do it. (Just like we _could_ totally get rid of fossil fuels, if we really had to and run everything on wind and solar. It's just not economically viable to do that right now.)

There's lots more techniques you can do to produce more calories. For example fusion power could help a lot to power lots of artificial lighting in vertical farms, and to purify sea water. (And even without fusion power, we could generate lots and lots of power from fission with current technology. It's just unpopular.)

> Maybe we also accept that some limits can't be surpassed, at least not at an acceptable cost.

I guess you would say that the suggestions I made above fall under the second clause of unacceptable costs?

Do you mean economic costs or some kind of ethical or moral or metaphysical costs?

I can see how some people might be queasy about putting fission reactors everywhere. But I don't really see anything against Dutch-style greenhouses apart from economic costs?

[giantg2]

"The carrying capacity of earth is likely hundreds of billions of humans, if we were to set our mind to it."

I've never seen anything that states that. Link? UN and others estimate 8-12 billion. And none of those estimates are accounting for sustainable population. You say 100s of billions, but with what quality of life? With scare resources comes conflict.

"we are barely harvesting anything from the oceans."

Most major fish stocks are down more than 90%. Farm raised means feed and and antibiotics. Sure we can increase stuff like seaweed consumption, but that's not very significant.

"Even on land, using greenhouses everywhere would give us vastly more agricultural yield."

What are those greenhouses going to be made out of? Petroleum based plastics, glass (CO2 for melting), or cellulose/corn plastic (that requires chemicals that aren't environmentally friendly)? Where are we getting the nutrients? We already use a massive amount of petroleum based nitrogen.

"But if push came to shove, we could totally do it."

No, if push came to shove then people would start literally shoving in the form of a war.

"(Just like we _could_ totally get rid of fossil fuels, if we really had to and run everything on wind and solar. It's just not economically viable to do that right now.)"

That's another unsubstantiated claim. Even the EU says they cannot convert fast enough to get off of Russian gas. Let's see a link that says wind and solar are completely feasible to meet current power demands, including the energy storage required.

"I can see how some people might be queasy about putting fission reactors everywhere."

So are you changing from just the wind and solar mentioned earlier to include nuclear?

[eru]

> Most major fish stocks are down more than 90%. Farm raised means feed and and antibiotics. Sure we can increase stuff like seaweed consumption, but that's not very significant.

I agree that hunter-gatherer tactics are beyond their limits.

What makes you think seaweed consumption has to stay insignificant? See also https://news.ycombinator.com/item?id=30648873 for slightly more.

> What are those greenhouses going to be made out of? Petroleum based plastics, glass (CO2 for melting), or cellulose/corn plastic (that requires chemicals that aren't environmentally friendly)? Where are we getting the nutrients? We already use a massive amount of petroleum based nitrogen.

I had mostly glass in mind. But whatever works, works. You can make your glass with any energy source, doesn't have to be CO2 producing.

You can take nitrogen out of the air. Also, the atoms that fertilizers are made of don't get destroyed.. so you can recycle them indefinitely (with some effort). We are also sitting on a huge ball of matter.

You can also use substantially less fertilizers and insecticides in a controlled greenhouse environment, perhaps with drip feeding.

I hope we both agree that those approaches take energy to pull off? So the question is whether humanity can get enough sustainable energy.

> Even the EU says they cannot convert fast enough to get off of Russian gas.

We seems to be talking about different time scales here? Getting off Russian gas is something they'd want to do in the next few months or years at most. I'm talking about decades at the least.

(And, the EU could totally get off Russian gas next month. It would 'just' make energy a lot more expensive at least in the short run, and likely put the EU into a severe recession for a while. That's a more painful than the shame of buying from Russia, so they keep buying from Russia.)

> No, if push came to shove then people would start literally shoving in the form of a war.

I don't think so. But for the sake of argument: a few wars here or there don't have much of an influence on carrying capacity. Unless, of course, the wars are bad enough to kill off a substantial fraction of humanity directly or even just destroy the economy badly enough to kill off indirectly.

(That's something we can argue about, if you want to. But we don't need to argue about a few minor wars.)

> So are you changing from just the wind and solar mentioned earlier to include nuclear?

Sorry for mixing examples. I used fission reactors as an example of non-monetary costs that someone might object to.

I suspect we _could_ run everything on wind and solar (especially if you also add solar in orbit via power satellites), if we really had to. But adding nuclear fission (or fusion) to the mix would allow us a higher standard of living.

> I've never seen anything that states that. Link? UN and others estimate 8-12 billion. And none of those estimates are accounting for sustainable population. You say 100s of billions, but with what quality of life? With scare resources comes conflict.

It's more than reasonable to ask for more background information. Sorry, it's a bit hard to Google for this stuff quickly.

So here are just two links that touch on the topics mentioned:

http://www-formal.stanford.edu/jmc/progress/

https://www.youtube.com/watch?v=8lJJ_QqIVnc

---

Also just to clarify: I am arguing that physically and technically we could support vastly more people on earth. I share your fear that people might blow each other up anyway.

[giantg2]

I see the Stanford link talks about 15 billion, not hundreds of billions. It still does not mention the sustainability at that level.

[midhhhthrow]

There’s no way in the world voters will ever allow you to produce that much housing. There’s already a vast over population on this planet relative to number of shelters

[eru]

I'm not sure about the latter. But I agree that political considerations are important, and I deliberately ignored them and only talked about technical feasibility.

[StanislavPetrov]

>Just to concentrate on food alone: we are barely harvesting anything from the oceans.

Just to cite one of of your statements, the oceans have been decimated with countless species extinct and many more on their way there due to overfishing and habitat destruction. The oceans are also filled with industrial chemicals, plastics and have numerous massive "dead zones" due to nitrogen run off from the huge factory farms we run to sustain our massively overpopulated planet.

The suggestion that the earth isn't overpopulated, let alone the idea that the earth could support "hundreds of billions of people" is beyond absurd. We are losing biodiversity among animals, insects, fish and every other form of non human life due directly to massive overpopulation. Saying this ignores the decimation of our ecosystem and the food web that has left our planet teetering on the brink.

[eru]

You are right that we are past what hunter-gatherer approaches can yield from the ocean. And that we are doing a bad job at protecting the habitat of wild-life.

However, there's vast patches out in the open ocean where almost nothing grows. Mostly because the areas with sunlight (at the top) are not where the minerals are that plants need to grow (mostly the sea floor). See eg https://en.wikipedia.org/wiki/Iron_fertilization for an overview.

If you mind putting fertilizer directly into the open ocean, someone more clever than me can probably work out a scheme for enclosing some water in a giant floating bag, and growing your stuff in there. (Or something much better than this.)

[WalterBright]

> the oceans have been decimated with countless species extinct and many more on their way there due to overfishing

The Tragedy of the Commons. Note that cows and chickens are not endangered species, despite our vast consumption of them.

[MattGaiser]

> The carrying capacity of earth is likely hundreds of billions of humans, if we were to set our mind to it.

At an absolute poverty level in a Warhammer like hive city perhaps.

[eru]

According to Google, the land surface area of earth is about 510 million km^2.

Divided by a trillion people, that gives you 510 m^2 per person.

For comparison, Singapore has 128 m^2 per person.