So how does this create a greenhouse effect?  The greenhouse effect occurs because the atmosphere is relatively transparent to the wavelengths of solar radiation, while it absorbs infrared radiation.  So a large chunk of the sun’s radiation makes it to the earth’s surface.  At the same time, the atmosphere containing greenhouse gases absorbs the radiation emitted by the earth’s surface, and re-emits it back to the surface, increasing the total energy the surface receives.  This forces the earth’s surface to become warmer than it would be otherwise.