Right now, mostly because we've burned so much fossil fuel, the atmospheric concentration of CO2 is 390 ppm—that's way too high, and it's why ice is melting, drought is spreading, forests are dying. To bring that number down, the first task is to stop putting more carbon into the atmosphere. That means a very fast transition to sun and wind and other renewable forms of power. If we can stop pouring more carbon into the atmosphere, then forests and oceans will slowly suck some of it out of the air and return us to safe levels.
Is 350 politically possible?
It means switching off fossil fuel much more quickly than governments and corporations have been planning. But we can change that--if we mobilize the world to swift and bold climate action, and shift the world to a clean energy future.