The best ones I've seen so far involve massive engineering projects in orbit to let us control the amount of sunlight hitting the earth.
Those are technologically feasible, theoretically workable, and at least somewhat reversible.
However, they don't really take human nature into account. Megasatellites for solar gain control would be an intensely scarce, valuable resource, and a de facto superweapon - "agree to our terms or you'll never have good crop growing sunlight again."
Nobody would be willing to cede or share control of such a system to someone else. Wars would break out quickly, and no deployed system would go undestroyed for long.
The other plans I've seen seem problematic to me either morally ("first world gets to keep its tech but you guys who are bootstrapping with carbon can go DIAF"), technologically ("We think there will turn out to be some way to capture carbon super-efficiently that we haven't found yet"), or reversibility ("whoops, we put too much dust in the atmosphere - guess we're starving three billion people for the next year or four, folks").
I'm not saying there is no possible solution - just that I haven't seen a realistic one myself.
That's what I was referring to when I referenced hurting third-world economies badly.
My understanding is that a lot of developing regions are using their carbon stores to improve quality of life and lifespan for their inhabitants - bad as coal may be for your lungs, it's not as bad as having no reliable energy for things like sewers.
Hence my comment saying "...if you're bootstrapping with carbon you can go DIAF."
Those are technologically feasible, theoretically workable, and at least somewhat reversible.
However, they don't really take human nature into account. Megasatellites for solar gain control would be an intensely scarce, valuable resource, and a de facto superweapon - "agree to our terms or you'll never have good crop growing sunlight again."
Nobody would be willing to cede or share control of such a system to someone else. Wars would break out quickly, and no deployed system would go undestroyed for long.
The other plans I've seen seem problematic to me either morally ("first world gets to keep its tech but you guys who are bootstrapping with carbon can go DIAF"), technologically ("We think there will turn out to be some way to capture carbon super-efficiently that we haven't found yet"), or reversibility ("whoops, we put too much dust in the atmosphere - guess we're starving three billion people for the next year or four, folks").
I'm not saying there is no possible solution - just that I haven't seen a realistic one myself.