If the first assumption doesn't hold, restricting ourselves will not matter. > Short of dimming the sun, I don’t see how you can keep “all this carbon in atmos

If the first assumption doesn't hold, restricting ourselves will not matter. > Short of dimming the sun, I don’t see how you can keep “all this carbon in atmosphere” and still only get 2°C. This one assumes the carbon is main or even major substance that keeps heat on Earth. You do realize that we have much more water in the atmosphere, and water keeps heat much better than carbon? It's not as simple as "more carbon, higher temperatures".