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Comment by thinkling | Hacker News Reader

People have proposed approaches to increasing the earth's albedo (and thus reflecting more sunlight) without launching material into the atmosphere.

Best known is probably the idea of painting roads and rooftops white.

Another interesting approach: setting up very light-weight (thin plastic?) mirrors in large quantities in farmer's fields. Farmers have incentive to do this in areas that are getting hotter and where crops may already grow better with some partial shade than in full sun. Spacing mirrors on posts in fields can provide this.

This is being proposed by Ye Tao, an MIT Chemistry PhD who has pivoted to this project. Discussed on Dave Robert's Volts podcast [0].

[0] https://www.volts.wtf/p/volts-podcast-dr-ye-tao-on-a-grand#d...

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Painting roofs white seems like a good idea, and I remember seeing a study once saying it could have decently significant effect.

But it does have one disadvantage: if you don't like the effects, you have to paint all those roofs again. With stratospheric aerosols, if you don't like the results you just stop doing it, and they'll fall out of the atmosphere in a year or two.

If the lifetime of a roof is ~20-30 years, in that time we won't have 'solved' climate change, so exceedingly unlikely that you'll need to repaint it for climate reasons at least.

What I mean is bad localized effects in important areas.

Painting roofs sounds completely benign, but if it's as effective as other geoengineering methods, then there's little reason to think it doesn't have the risks of other methods.

(Personally I think those risks are probably worth taking, given climate tipping points.)

White roads sounds like a recipe for glare-induced accidents, especially in sunny locations.

Cement roads?

If only we had some sort of glare reducing technology that can be strapped to our faces.

I think this came up at a recent panel discussion https://www.climateresolve.org/reflecting-sunlight/

tl;dr: Not an issue. We're not talking about painting roads bright white, it's more like a change from dark asphalt to light gray asphalt (similar to cement sidewalks).

>We're not talking about painting roads bright white, it's more like a change from dark asphalt to light gray asphalt (similar to cement sidewalks).

In this case, perhaps people should stop proposing "painting roads white" and secretly meaning "light gray" and thinking everyone can read their minds, and instead they should propose "painting roads light gray".

We could also use large white rafts in unused parts of the ocean.

Is this something that's been studied seriously? A quick google attempt doesn't find anything.

I like the idea of launching mirrors into space as well. Preferably we stop adding things to the atmosphere we can't breathe but that seems to be a hard ask for us...

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