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Comment by gremlinsinc | Hacker News Reader

What about mega structures...like super huge 'sun glasses' or shades that partially block sun rays from hitting earth so we can cool the planet that way? Maybe we just deal with 'near ice age' like weather for a couple years... we let the sun shine on farms only, block it for most other places forcing winter-like conditions year-round until the icecaps re-freeze...

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Space-based reflectors on the scale of 600,000 square miles could cost about $800B if we could get transport costs down to $50/kg, it'd cost about $400 Trillion at the current cost.

It is probably cheaper to confer cities with huge geodesic domes with high reflectivity and deal with excess heat.

Ecosystems may have some trouble with it.

With the amount of energy it takes to bring anything to orbit, I suspect a ground based solution that just recaptures CO2 or regrows trees is going to be much more cost effective.

And where would we find the resources to build something like that? Let alone move it to orbit.

We're passed the point of no return... because the ice has melted, permafrost is about to unleash a feedback loop that will warm us even more. I'm not sure if we could remove all c02 from the atmosphere today, if that would have a net effect. -- We need to find a way to recool and rebuild the ice deposits we've lost at the north/south pole and refreeze all the permafrost -- that's the only real long-term solution... -- As for resources for something like this...no effing idea, it'll cost in the trillions... maybe Bezo's could get it done, or Elon ... If we could get space mining going we could mine the resources needed in space, and build it on the moon to make it easier to launch... We could also make it modular so we don't need to build it all at once but could build it in portions...

Bottom line, we need a space elevator.

It's not clear if a space elevator on earth is physically possible.

On tiny scales, carbon bonds have sufficient strength/weight ratio so that the elevator might support it's own weight, but there's not that much margin left. As the macrostructure likely requires a multiple of weight, to account for the fact that a kilometers-long string can't be manufactured perfect to the single atom, and that damage can and will occur (e.g. any radiation), etc, etc - according to our current knowledge of physics it might as well be that a sufficiently strong macroscale material for an Earth-sized space elevator cannot exist. Moon or Mars is a different issue, though.

The melting arctic ice sheets cause an influx in cold freshwater in the north atlantic which works to slow the rate of thermohaline circulation, which is responsible for bringing warm sea water (energy) to the poles which accelerates melting. It's a big unknown what exactly will happen, but it's possible that the damages of climate change are less than projected if the thermohaline circulation slows sufficiently to bail out the world until it can start reducing carbon emissions cost effectively.

Or it could go the other way. No one is sure what happens if the major currents change. Northern Europe should probably get ready for a cold spell.

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