What is carbon dioxide?
Carbon dioxide, CO2, is a colorless gas made of one carbon atom and two oxygen atoms. It is breathed out by animals, used by plants for photosynthesis and is the main greenhouse gas driving climate change.
Carbon dioxide is a natural part of Earth's atmosphere and carbon cycle. Animals and people release it when they breathe out, and plants absorb it to make food through photosynthesis. Oceans also absorb large amounts. Volcanoes, wildfires and decaying matter release it too.
Burning fossil fuels such as coal, oil and gas releases carbon that was stored underground for millions of years. Since the Industrial Revolution, CO2 levels in the atmosphere have risen from about 280 parts per million to more than 420 parts per million, trapping more heat and warming the planet.
Everyday uses
Carbon dioxide puts the fizz in soda and sparkling water. Frozen solid, it becomes dry ice, used to keep things cold and create fog effects. It is used in some fire extinguishers because it smothers flames. Greenhouses sometimes add CO2 to help plants grow faster.
Did You Know?
As oceans absorb extra carbon dioxide, they become more acidic, which can harm corals and shellfish.