How Do Clouds Impact Climate Change?

One of the first things you learn in Meteorology 101 is the principle that when temperature increases, potential moisture increases (because the volume of the air expands). Twenty years ago, before either "Global Warming" or "Climate Change" were widespread buzz words, my college meteorology professor dismissed the idea of Global Warming because of clouds. He said "If global temperatures increase, that means more humidity right? Therefore more clouds... and the earth is cooled."

At the time, no one else was really talking about the topic, and definitive answers from official sources didn't come until today. Finally, this issue has been addressed by the U.S. Government. How will clouds impact Climate Change? The short answer is "we don't know, but we're working on it". The National Science Foundation (NSF) calls their presentation on the subject, released today, "Clouds: The Climate Change Wild Card."

They point out that there are two kinds of clouds - those that would shade the earth from incoming sunlight, and those which would trap energy like the Greenhouse Effect. Scientists aren't sure which type of cloud would be increased or decreased by a warming Earth so they can't say yet if the warming might be reversed, or made worse. But they say they have accounted for this in the IPCC predictions which indicate a range of +1.8 to +4.0 C change in global temperatures between 1900 and 2100.

My professor's thesis is confirmed in their article, before they propose an alternative:

Although the article doesn't answer the question, it's good to admit when you don't know the answer in science, because it eggs you on to try harder. They are working on improving the Climate Models used to estimate future temperature, but are concerned because the ones now have a global resolution of "about the size of Delaware" and you can fit a lot of clouds into the First State.