why does carbon dioxide trap heat?

Question

what properties of carbon dioxide are responsible for heat trapping? why are other gases such as oxygen, nitrogen not green house gases?

Answer 1

Because it is transparent to visible radiation like sunlight but opaque to infrared radiation, which is "heat".

CO2 lets sunlight through but blocks the resulting heat from leaving. O2 and N2 are transparent to infrared also, so they don't block the heat.

Note that I am simplifying. The gases are not perfectly transparent or perfectly opaque. But the point is still true.

Answer 2

Everything retains heat, some things are better at retaining it than others. To explain why requires complicated (and boring) physical and chemical principles such as thermochemistry, endo and exothermicity, (latent) heat of vapourization and other strange stuff. I'll avoid all of that.

You'll know that some solids and liquids retain heat better than others and that some hot things cool down quicker than others. It's the same principle with gases such as carbon dioxide. A gas is, after all, a solid that has boiled; the most obvious example being water which boils and turns to steam.

Carbon dioxide isn't really all that good at retaining heat. There's a scale called the Global Warming Potential (GWP), on this scale CO2 has a GWP of 1 whereas methane has a GWP of 62 after 20 years. Hydroflourocarbon has a GWP of 10,000 even after 500 years, other gases have higer values still.

Oxygen and nitrogen do retain some heat but not much. The term 'greenhouse gases' is often (incorrectly) used to describe the gases that humans have added to the atmosphere and that contribute to global warming.

Greenhouse gases are all the gases (natural and human), that retain heat from the sun. Without them life on earth would be impossible. The moon has no greenhouse gases (it has no atmosphere) and although pretty much the same distance from the sun as we are, it experiences extremes of heat and cold on a daily basis (107°C by day and -153°C by night).

This site might help explain further...
http://www.vitalgraphics.net/climate2.cfm?pageID=6

Answer 3

It doesn't, this is arrant nonsense aimed at stopping 3rd world growth and taxing the poor for essentials.
If it did stop or trap heat/light/radiation how would it get down through the atmosphere to us in the first place and why wasn't the great global cooling scare of the 1970's true either?!

Answer 4

cause' its one of those deadly smokes that do a lot of crazy stuff

Answer 5

probably because it makes plants grow.