Why CO2 matters

The Good
The sun provides the energy and heat that enables life on earth. Some is absorbed, and a great deal is released in the form of infrared rays. Some of these rays are trapped by gases such as CO2, keeping the earth temperate and livable. This is the friendly aspect of the greenhouse effect.

The Bad
However. The steady accumulation of heat trapping gases – so called greenhouse gases – means that less and less heat can escape, and the planet thus heats up. In fact, as heat is a form of energy, the more we heat the planet, the more turbulent it becomes – much like a pot of water over a flame.

Of all greenhouse gases, CO2 is the most abundant in the atmosphere. There are also other, potentially more powerful heat-maintaining gases such as methane - generated, for example, in landfills - and nitrous oxide, stemming from fuel combustion, amongst other causes.

Scientists have developed a convention in which all greenhouse gas emissions are described in CO2 equivalents. Thus the CO2 footprint refers to the impact on climate of a variety of gases.

Bringing it down to earth
When trees grow, they take CO2 and water, and using the sun’s energy, turn it into wood (carbon) and oxygen, which is released into the atmosphere. So, growing trees effectively transform carbon dioxide into two useful products. While mature forests begin to decay, and release the carbon, growing forests take in considerably more than they give off – thus helping manage the climate and balancing the concentration of CO2.

Greenhouse gas on Wikipedia