Carbon dioxide (CO2)

CO2 totalt, Koldioxid


Carbon dioxide (CO2)

CAS no


Molecular formula


Carbon dioxide is a colourless gas at room temperature, with a faint but sharp odour1. Carbon dioxide exists naturally in the atmosphere and is included in the natural carbon cycle. In order to compare the effect of different greenhouse gases, emissions are converted into carbon dioxide equivalents2.


Pure carbon dioxide gas has several application areas, for example for freezing or cooling of food products. Carbon dioxide is also used in fire extinguishers, where it extinguishes the fire by cooling and displacing the air. Another use is for carbonation of e.g. soda pop. Carbon dioxide is also used within medicine at keyhole surgery and it may be added to oxygen gas in order to stimulate breathing for patients3. Carbon dioxide is used as shielding gas during welding, often together with other gases.

Industrial carbon dioxide is produced by purifying the carbon dioxide emissions from combustion, fermentation and production of ammonia4.

Sources and transportation pathways

Carbon dioxide exists naturally in the atmosphere and is essential for the photosynthesis. However, emissions from anthropogenic sources contribute to the rising carbon dioxide levels in the atmosphere, affecting the natural carbon cycle. The global concentration is about 400 ppm (2015) and continues to increase every year5. The most important anthropogenic emission sources of carbon dioxide are combustion of fossil fuels, cement production and other industrial processes. Land use change (mainly deforestation) also contribute to emissions of carbon dioxide6,7. In Sweden the largest emissions sources of carbon dioxide are larger point sources within the energy sector, production and processing of paper and wood and iron and steel production. Transportation is another important source.

Effects on environment and health

Carbon dioxide is a greenhouse gas that contributes to the increased greenhouse gas effect8. The increased greenhouse gas effect results in an increase of the average temperature on earth, which for example leads to climate change and rising of the sea level9,10. Carbon dioxide also contributes to acidification of land and water. Acidification harms plants and animals, both on land and in water10. When the ground turns acidic, vital nutrients are leached from the soil, which eventually may result in reduced forest growth. Furthermore, metals are released in the ground that can harm decomposing organisms in the ground as well as birds and mammals higher up in the food chain, including humans12.

Exposure to high concentrations of carbon dioxide may cause oxygen deficiency13.

International agreements and regulations

Carbon dioxide is regulated by the UN Framework Convention on Climate Change (UNFCCC), as well as by the EU MMR regulation (525/2013/EU) and the EU ETS (2003/87/EU). The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on carbon dioxide emissions is made available.