[margalabargala]

I did the math on this once out of curiosity. If we launch lots of bits of thin, reflective mylar film to the L2 Lagrange point with the sun, it will reflect incoming light and lower the Earth's insolation. About $200 billion worth of Falcon Heavy launches, all carrying mylar film to L2, would be sufficient to lower insolation by 1/20th of a percent, which would indeed halt global warming.

Obviously this would have tons of other consequences for the planet, and doesn't account for solar wind pushing the mylar out of position, etc.