GATES: "The CO2 stays in the atmosphere for thousands of years, and that’s what forces the temperatures to go up. And so it’s really the sum of all those emissions starting in the industrial age that’s causing this temperature forcing with all of its ill effects. You know, there’s no magic date that it’s all great until then and it’s, you know, terrible once you cross the threshold. It’s pretty linear as far as we know. 2050 happens to be the soonest realistic date for the world to change all of these sources of emissions which are actually quite broader than most people are aware of because you’ve got things like steel and cement, not just cars and electricity."