0

... we all go horse and buggy. Whale fat oil and candles.

We can do this. Make Earth Great Again

Technically possible but practically (and politically) impossible so what's the point of the speculation?

Just my humble, non physicist opinion, but we would need more energy than the energy previously hold in all that burnt fossil fuel, released over the decades to power civilization.

There are big power sources around. Light isotopes for nuclear fusion. Heavy elements for nuclear fission. The earth heat from the underground. And of course the biggest of them all, the Sun (my favorite idea being space based solar power collection).

We could also choose a very stable way to fix all this excess carbon in the world, like diamonds or silicon carbide. we could just dump "solid-state-global-warming" into the ocean floor and forget about it

But I believe we will struggle through global warming instead of reversing it. Because there is too much inertia, no political and economical will. No real global coordination to build so much infrastructure and so much technology. We will continue to deal with the problem by not dealing with it

I'd say it is more likely than every country phasing out fossil fuels, at this rate.

Actually zero.... if all humans die today, the climate will reverse itself within 10,000 years.

But with humanity 'thriving' we will need to reverse climate change with technology, within a capitalist system, as an ongoing process (as long as there are humans). AI, quantum computing and nuclear fusion breakthroughs are soon to be upon us, optimistically we will reach the point where we are able scale them commercially to where the marginal cost of intelligence and energy is close to zero. Economically this means that there will be infinite resources able to be diverted towards engineering a better environment and uplifting humanity.

Sorry i digress and ramble, there is no number here to answer your question based on current technology and economics.

Might be zero:

https://www.science.org/content/article/draw-down-carbon-and-cool-planet-ocean-fertilization-gets-another-look

> we would need more energy than the energy previously hold in all that burnt fossil fuel

That would be necessary if we had to split all the CO2 into carbon and oxygen. But we don't have to do that; we can inject the CO2 into deep basalt formations, where it will turn into rock.

So we just have the energy cost of concentrating the CO2 from the air and pumping it underground, which is a lot less.

Without fossil fuels and modern chemical fertilizers, the carrying capacity of the earth is probably a couple billion people lower than the current population.

So it's not going to be "we all."

Interesting, a more simple and practical solution

Earth will live and be strong

Humans thin out ... then become a heathy species again.

We can do this!

Which half of humanity do you want to be on the correct side of the "thinning out"?

Best of all worlds: move humanity off-world. Space, Luna, mars, etc.

Turn the Earth into a nature preserve folks occasionally visit...

Interesting site with data on average US energy usage

https://css.umich.edu/sites/default/files/2022-09/U.S.%20Energy%20System_CSS03-11.pdf

Not my choice or yours.

I said All.

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