About that water vapor

One commonly misstated misconception by global warming skeptics is that "water vapor is the most important greenhouse gas, and scientists ignore it". Or something to that mistaken effect. So how's a skeptic to explain:

Water Vapor Confirmed as Major Player in Climate Change

From this summary article: "Andrew Dessler and colleagues from Texas A and M University in College Station confirmed that the heat-amplifying effect of water vapor is potent enough to double the climate warming caused by increased levels of carbon dioxide in the atmosphere.

With new observations, the scientists confirmed experimentally what existing climate models had anticipated theoretically. The research team used novel data from the Atmospheric Infrared Sounder (AIRS) on NASA's Aqua satellite to measure precisely the humidity throughout the lowest 10 miles of the atmosphere."

And further down:

"AIRS is the first instrument to distinguish differences in the amount of water vapor at all altitudes within the troposphere. Using data from AIRS, the team observed how atmospheric water vapor reacted to shifts in surface temperatures between 2003 and 2008. By determining how humidity changed with surface temperature, the team could compute the average global strength of the water vapor feedback.

"This new data set shows that as surface temperature increases, so does atmospheric humidity," Dessler said. "Dumping greenhouse gases into the atmosphere makes the atmosphere more humid. And since water vapor is itself a greenhouse gas, the increase in humidity amplifies the warming from carbon dioxide."

OK, so skeptics, you can drop this particular claim. Water vapor amplifies greenhouse gas-induced warming. For sure. No doubt about it. Most important greenhouse gas, indeed.

Some supplemental linkages:

How not to discuss the water vapor feedback


Anthropogenic greenhouse forcing and strong water
vapor feedback is rapidly warming Europe


The Dust Settles on Water Vapor Feedback