answer all questions orderly with explanation a. Describe why O 2 is not a greenhouse gas, but H 2 O and CO 2 are. b. The temperature - water vapor - greenhouse effect is an important feedback loop in the earth system. Draw and describe this feedback loop. c. For smaller temperature changes, do you think the temperature-water vapor-greenhouse effect feedback loop or the temperature-ice-albedo feedback would be more important and why? What about for larger temperature changes?.