Climate [Junk] Scienists Debunk Latest Bunk by Denier Roy Spencer | ThinkProgress

[Dessler] To understand this paper, you have to understand the difference, between a “forcing” and a “feedback.” Forcings are imposed changes to, the climate, while feedbacks are processes that respond to changes in, the climate and amplify or ameliorate them. So the addition of carbon, dioxide to the atmosphere by humans is a forcing—it is simply an, imposition on the climate. Water vapor, on the other hand, is a, feedback because the amount of water vapor is set by the surface, temperature of the planet. As the planet warms, you get more water, vapor in the atmosphere, and since water vapor is itself a greenhouse, gas, this leads to additional warming.

The canonical way to think about clouds is that they are a feedback—as, the climate warms, clouds will change in response and either amplify, (positive cloud feedback) or ameliorate (negative cloud feedback) the, initial change.

What this new paper is arguing is that clouds are forcing the climate, rather than the more traditional way of thinking of them as a, feedback. This is not, in fact, a new argument.
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Thus, his paper is not really intended for other scientists, since they do not take him seriously anymore (he’s been wrong too many times). Rather, he’s writing his papers for Fox News, the editorial board of the Wall St. Journal, Congressional staffers, and the blogs. These are his audience and the people for whom this research is actually useful — in stopping policies to reduce GHG emissions — which is what Roy wants.
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[Trenberth] In addition, I find the whole discussion to be out of touch with reality. The external radiative forcing of the climate system is mostly well known and comes from the changes in atmospheric composition (greenhouse gases) and the sun spot cycle etc. The part not so well known is the pollution (aerosol), but that is small. Nearly all of the variations in water vapor and clouds, except for those affected by aerosol, are a response to the weather and climate variations; they are NOT a forcing. This is a major error that continues in Spencer’s work.