Even if it weren't fuck nuts suggesting it, this is surely a bad idea. We need direct sunlight to hit the earth. The problem is the dissipation of the heat generated by that light due to greenhouse gas saturation. Blocking the sunlight in the first place WILL cool the Earth, but with the cost of decreased capacity for plant and algae life to carry out photosynthesis and, thus, remove carbon dioxide from the air and produce oxygen at a minimum. Seems like that would contribute to the greenhouse gas problem, rather than address it, with the additional consequence of reduced yield for crops. I'm sure there would be other consequences too. They have the potential of being MASSIVE!