> 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

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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.