Slide 12 in this series.
Black body radiation is an essential part of the radiation mechanisms. Not all bodies that radiate IR are perfect black bodies, but the theory is of value. In AGW theory one mechanism that is used to further gobal warming coming from the GHE and CO2 is the back radiation of energy to the earth's surface. In AGW theory this back radiation heats the earth's surface, meaning that a cooler body can warm a warmer one. This violates the 2nd Law of Thermodynamics clearly.
NEXT: The atmosphere composition is our next stop.
These links are the topics for this section.
Modelling Temp Natural Factors
Earth and the Science of Radiation
Milankovith Overlapping Cycles