I really wish Newt was serious when he said that.
Because if he was, and I was American I would think very hard about voting for him.
But in all seriousness we are looking at the wrong planets.
Venus is where we want to go. We can terraform that puppy in 20 years. Use the science from that to combat any sort of climate change on earth. Also have a near earth planet in weight.
Venus terraforming would take at least 100 years, and that wouldn't solve all the problems. The atmosphere is way to dense, full of sulphides and the planet suffers from a runaway greenhouse effect. The best thing we can do is drop some genemanipulated algae in there, wait a 100 years while they clean up a bit of the atmosphere and then we still have to build our base floating in the air because the pressure on the surface would turn us into pancakes. Also, while there would be enough oxygen in the atmosphere to breathe, the sulphides make the air extremely poisonous and corosive. Doesn't sound like a good place to live to me.
As for using the science to combat global warming on earth, forget it, the best we can get are some Co2 eating, higly acidic resistant algae.
I'd like to think we could do it faster.
Giant solar sails to cool down the planet. Drop some anti suphides.
It will be surviveable in 20 years. Habitable in 50.
And then we got earth 2.0
Best plan out there. No bone loss or anything.
Problem is Venus atmosphere is 92 times as thick as earth, wathever you do, you can't get those away.
Solar sails are a way to propulse spacecraft, not cool planets, I think you want some sort of solar lense shield. Problem with that is that planets are really freacking big, in order to build a lens that would cool the earth by 1K for a respectable budget, you would need to be able to launch Saturn V's for 900$ a piece.
Anti sulphides exist, but Venus atmosphere is really thick, so you would need a mindboggling big amount of them to have any effect.