1. Space Mirrors
By launching trillions of space shades in between the sun and the earth, the amount of sunlight the planet would reach would be lessened.
Proposed back in 2006 by Dr. Roger Angel, the only problem with this project is its scope and cost. The trillion mirrors required would take up both a lot of time and money
Then there’s also the fact that we have yet to perfect any form of technology that would allow us to go to-and-fro space without much casualties.