Even better would have been to give the mass instead of the volume, because the volume depends on the temperature and pressure. Assuming STP, I get 2.16 billio

Even better would have been to give the mass instead of the volume, because the volume depends on the temperature and pressure. Assuming STP, I get 2.16 billion kg, which I guess most people would call 2.16 million tonnes, though I'm rather inclined to write it as 2.16 Tg :-) That's .01% of worldwide annual emissions from burning fossil fuels. (Someone should check my arithmetic -- it's been a long time since I last applied the ideal gas law.)