>Third, and most importantly, you've just decreased the amount of energy coming to earth. You've not solved the problem, you've changed it. There's a lot of EM

>Third, and most importantly, you've just decreased the amount of energy coming to earth. You've not solved the problem, you've changed it. There's a lot of EM that neither chlorophyll nor existing PV can use. Hopefully a sunshade would be chosen that selectively works on those less-useful bands. I hope that someone is looking into aerogels for this purpose; they can cover a lot of area per unit mass and have tunable optical properties.