What is carbon dioxide (CO2)?

Carbon dioxide (or CO₂) is a colourless, odourless gas consisting of one part carbon and two parts oxygen. CO₂ is a natural component of our planet's atmosphere and is one of the most common greenhouse gases. It is released through human activities such as burning fossil fuels and deforestation, but also by natural processes.

Because humanity releases more carbon dioxide –primarily through burning fossil fuels like coal and oil– into the atmosphere than current biological processes can remove, the amount and concentration of carbon dioxide in the atmosphere and ocean increases yearly.

There are other greenhouse gases beyond carbon dioxide, such as methane (CH₄), nitrous oxide (N₂O), or fluorinated gases (F-gases).