Humans produce on the order of 3.10^13 kg of CO2 [1] Atmosphere weighs 5.1 . 10^18 [2] so the CO2 we produce is 1/100000 (or 0.001%) of the total weight. Atmos

Humans produce on the order of 3.10^13 kg of CO2 [1] Atmosphere weighs 5.1 . 10^18 [2] so the CO2 we produce is 1/100000 (or 0.001%) of the total weight. Atmosphere contains 0.046% CO2 by weight [3]. So, next year, it's going to be 0.047%. In other words, each year we increase the concentration of CO2 by 2%. This isn't only cow farts. [1] http://www.epa.gov/climatechange/ghgemissions/global.html http://www.epa.gov/climatechange/ghgemissions/global.html [2] http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.htm.. http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.htm.... [3] http://www.engineeringtoolbox.com/air-composition-d_212.html http://www.engineeringtoolbox.com/air-composition-d_212.html