Carbon dioxide is an infrared active molecule that absorbs the long infrared radiation emitted by the Earth’s surface. It was the summer of 1856, and Eunice Foote was trying to determine the factors affecting heat from the sun’s rays. Her experiments led her to the conclusion that a confined environment rich in carbon dioxide heats up much faster in sunlight than in ordinary air.
It also cools much more slowly when removed from direct sunlight. In her paper, which she was not even allowed to present because she was a woman, she wrote: “The atmosphere of this gas would have given our Earth a high temperature, and supposing that at some period of its history the air was mixed with a larger proportion than it is now…” This observation didn’t get much attention at the time, but now it looks at us every day with renewed vigor. That’s because we’re obviously living in the not-so-pleasant future that Eunice envisioned. You probably know that carbon dioxide is the greenhouse gas responsible for global warming (although technically “we” are responsible for it). But what allows it to be considered a greenhouse gas while the other major components of the air are not? Let’s find out how the gas that makes your soda makes the glaciers melt!