There is recorded evidence from solar eclipses that the moon's shadow has a detectable weather effect.
If we placed a disk in space we could project a cold spot onto the planet and control it's position using the position of the spacecraft. In simple terms warm air moves towards cold, so that could be used to pull weather systems out of their normal track.
- What is the smallest disk that would create a 300km shadow
- Where would be the best place to put it between the earth and sun
- What size of effect would you have?
- Could you move a monsoon from flooded Asia to drought Australia
- How big would the shadow need to be to have an appreciable effect?
- If it was always "on" (i.e. you could turn it "off" by rotating it on edge), would the cooling effect be significant?
It's not going to stop global warming but it might buy some time and help redistribute the water more evenly.