Publication: USA Today

UCLA Expert: Suzanne Paulson: Professor, Atmospheric and Oceanic Sciences; Director, Center for Clean Air; Member, Institute of the Environment and Sustainability

Synopsis:  A false claim is circulating the internet that the weight of a carbon dioxide molecule means it can't rise or cause warming.

UCLA News: It’s true that carbon dioxide has a higher molecular weight than oxygen and nitrogen; however, it still rises into the atmosphere, Paulson said. Gasses — including carbon dioxide — are constantly moving around and mixing in the lower levels of the atmosphere regardless of their weight. If gasses were in stratified layers and carbon dioxide sunk below oxygen, humans would not be able to breathe. Paulson, along with some of her students, calculated that if carbon dioxide did not rise into the atmosphere, the Earth would be covered in an 11-foot-thick layer of carbon dioxide. "Carbon dioxide at moderate concentrations makes you sleepy, but if it were pure carbon dioxide — or even majority carbon dioxide — we would have all been asphyxiated due to lack of oxygen." Instead, carbon dioxide intermingles with other molecules. It also absorbs infrared radiation and re-radiates it back to Earth, causing a warming effect. That's why carbon dioxide is one of the main contributors to the greenhouse gas effect and global warming. 

Read more at USA Today.