Trillion person Earth

[mindstalk]

Some calculations I did on rasfw. Comments?

Comments

[pompe.livejournal.com]

Yes. The impact of human Manhattan-style habitation on 1/3 of Earth is going to have big effects on biomass, unless you place habitation in less than abundant areas, which in turn will mean you need more energy.

Furthermore, it isn't just a case of transforming solar energy to food unless you use some sort of replicator tech. There's going to be energy losses, nutrient requirement etc. 1/3 of the Earth's land sounds nice, but in reality that's four times what we do now. Then you have to factor in transports between agro-zones and urban-zones. For one trillion people, that's a lot of transport.

[mindstalk.livejournal.com]

I don't magically turn solar energy to food; I had plants doing that, at 1% efficiency. Transport I figure should be covered by the 10 kilowatts per person figure taken from American usage (though I had to fudge that a bit; 300 billion people might be more like it.) Nothing changes there, except scale.

[purpletigron.livejournal.com]

With current agricultural technology, and diet patterns, the Earth can support up to 9 billion people with land-grown food. Of course, sea grown food is currently significant. But the collapse of fisheries makes that unreliable.

[wizwom.livejournal.com]

I think it's been shown that aquaculture is a viable commercial endeavor. I'd imagine most of the shallow seas given over to farmed seaweed, using dredge from under fish-farms as fertilizer.

[purpletigron.livejournal.com]

Industrial-scale aquaculture potentially hits the wall with ecological viability.

http://www.panda.org/about_wwf/what_we_do/marine/problems/aquaculture/

[wizwom.livejournal.com]

Well, as I said, sea farming - not domesticated fish farms, but seaweed, plant farming - in shallow seas.

The fish farms, in order to be economically viable ought to be of scecies which are reasonable deep-water species - tuna, salmon, macarel. They should include a "waste catch" under the fish pen, and not be placed in shallom areas (since shallow areas are good for planing seaweed, of course).

I realize this is not the current situation, but it's not a hard situation to envision.

[pompe.livejournal.com]

Sure you can have plants which manage a 1% photosynthesis-to-carbon-fixation rate. Normal temperate crops have about 0.6%. But humans will not be 100% effective in eating that biomass. The average large mammal has a 3% efficiency in utilizing food - herbivores are worse because they need to spend energy to digest their energy-sparse fare.