How can Co2 exist, just floating around in the atmosphere? When the sun is shinning, photons impact the gas molecules and drive it down where if it encounters green foliage, you get photosynthesis. This is why 'smog' clears in the evening when the sun goes down, the sun literally holds the pollution back. Anything that manages to get up into the upper atmosphere would be released as our atmosphere is constantly in flux, opening/closing to space. The who thing can't exist w/out defying the laws of physics so it's just irritation to hear Elon talk about it.