Verified answer

CO2 has the ability to be "transparent" to incoming UV radiation from the sun (from above), but absorbs IR as it it is re-emitted (UV transforms to IR by the physical Earth surface)toward space.

The other thing about CO2 is that it can re-transmit IR after being absorbed initially thereby acting as a type of "mirror" itself. The argument that "warmers" present is that this re-emitted IR warms the Earths near surface atmosphere (lower Troposphere).

The problems with this "greenhouse" model are many:

the two gases contributing maximum critically to the organic greenhouse warming of the earth are water vapor and carbon dioxide. Methane, nitrous oxide, ozone and sulfur hexafluoride additionally are greenhouse gases yet make a smaller contribution to the greenhouse result through fact their concentrations are so low. different greenhouse chemical compounds, which includes chlorofluorocarbons, perfluorocarbons, and hydrofluorocarbons, are man made and have basically recognized in the ambience through fact the business Revolution

"Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared." is what wikipedia says. Basically it traps heat within the atmosphere.

http://en.wikipedia.org/wiki/Greenhouse_gas