Carbon dioxide

Also: CO2, carbon dioxide

CO2

Carbon dioxide is a greenhouse gas produced by fossil fuel combustion. Many natural processes also release and absorb CO₂.

According to the AGGI, CO₂ contributes 66% of the human-caused greenhouse effect and is the only greenhouse gas whose contribution is rising rapidly. This graph plots CO₂ against global temperature change.

CO₂ is long-lived; a large study found that natural sinks remove about 60% of it after 100 years (graph). As the ocean absorbs CO₂ from the atmosphere, ocean pH drops, which is called ocean acidification. CO₂ is the reference gas that other greenhouse gases are measured against, so its Global Warming Potential is 1.