Honestly, I don't see it happening unless we get orbital elevators off the ground (Hah!) - otherwise there's just no safe and efficient way of getting the energy back down to Earth. You may just have to settle for reflecting the sun's energy away, and little else for the short term.
Also, you'll have to be careful about how much you shade at once and where. Even though only a tiny fraction of the energy that the sun gives off hits the Earth, it's still a fuck-off huge amount. You can only too easily turn Death Valley into a huge open-air reefer where you can just leave whole sides of beef out and they'll keep for a week or so. And that will do horrible things to weather patterns here.
Also, you'll have to be careful about how much you shade at once and where. Even though only a tiny fraction of the energy that the sun gives off hits the Earth, it's still a fuck-off huge amount. You can only too easily turn Death Valley into a huge open-air reefer where you can just leave whole sides of beef out and they'll keep for a week or so. And that will do horrible things to weather patterns here.