What is CO2?
Carbon dioxide (CO₂) plays a central role in our lives. But what exactly is it?
It is non-flammable (used in fire extinguishers) and soluble in water (used to make sparkling water), where it forms an acid.
As a gas, CO₂ is colourless and odourless, so you cannot see or smell it.
CO₂ is a molecule made up of two elements: one carbon atom (C) and two oxygen atoms (O₂).
CO₂ is the most emitted greenhouse gas as a result of human activity.
Human intervention in the natural carbon cycle increases the CO₂ content in the atmosphere and intensifies the greenhouse effect.
CO₂ is a small but important natural component of our air.
CO₂ is part of Earth’s carbon cycle: carbon is constantly exchanged between living organisms, the atmosphere, land and water, and one of the chemical compounds formed in the process is CO₂.
Once in the atmosphere, CO₂ does not break down on its own. It is naturally broken down through processes such as photosynthesis, in which plants absorb CO₂ from the air.
CO₂ is one of the atmospheric greenhouse gases that surround Earth like a thermal blanket and thus infl uence the planet’s temperature.
CO₂ is mainly produced during combustion processes (e.g., respiration, decomposition of organisms, burning of organic material such as coal, oil, gas or wood) where ‘C’ combines with ‘O₂’ (C+O₂=CO₂). This produces energy that is used for life, growth and heat production.
Elevated levels of CO₂ in the air we breathe, e.g., in rooms, can be dangerous (3-5% leads to faster breathing, from 5% to unconsciousness, 8% to death).