What is Carbon Dioxide (CO2)?

Carbon dioxide (CO₂) is one of the most prevalent greenhouse gases in the Earth's atmosphere. Prior to the industrial revolution, the concentration of CO₂ was stable for millions of years, at about 280 parts per million. In the past century it has risen to over 380 parts per million, a 35 per cent increase. Industrialization in the developed world and deforestation in developing regions are cited as the main causes.

CO₂ is produced when organic compounds such as fossil fuels are burned in the presence of oxygen. The process is called a combustion reaction and it takes place in everything from car engines and furnaces to plants and the human body, producing CO₂, other gases and energy. While the CO₂ is returned to the atmosphere, we use the energy to run our vehicles, heat our homes, manufacture our products and, in the case of plants and humans, grow.

Humans-through their personal and industrial activities-emit close to eight billion tonnes of CO₂ every year, which accounts for more than 75 per cent of total greenhouse gas emissions. Forests, on the other hand, absorb CO₂ and release pure oxygen, and the carbon is incorporated first into the trees, leaves and soil, and then stored indefinitely in the wood products made from the trees.