Back in February, the Subcommittee on Energy and Environment of the U.S. House of Representatives Committee on Energy and Commerce held a hearing emitted “The Climate Crisis: National Security, Economic, and Public Health Threats.” World Climate Report’s Pat Michaels testified that we should be careful when assessing future threats from climate change because our understanding of what climate change the future may bring is grossly uncertain. Dr. Michaels backed up his contention by a demonstration that climate models are having a tough time getting the present and recent past right—which casts a pall on their future forecasts.

Also testifying at that hearing was General Gordon Sullivan (Ret.), President and Chief Operating Officer, Association of the United States Army who discussed potential national security threats from global warming—primarily from “unrest” in other parts of the world as food and water supplies grow scarce in some regions.

In the current issue of Nature magazine is an essay which seeks to counter this “myth.”

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We are just back from the 2009 International Conference on Climate Change sponsored by the Heartland Institute, aka “the global warming skeptics” conference. There were about twice as many attendees at this year’s conference (the second annual) than at last year’s inaugural meeting—an indication, at the very least, that the skeptical view of global warming is not fading away.

In fact, the behavior of the earth’s climate in recent years (a slowdown in the rate of global warming and sea level rise) has emboldened climate skeptics and is helping to win over public opinion that much of what they hear about global warming and its ill effects are exaggerations of the most likely outcome. Andy Revkin of the New York Times writes about a just-released Gallup poll that shows that a growing number of Americans think that the “seriousness of global warming” is being “exaggerated” in the news. The Gallup’s findings are similar to other recent poll results that also show that global warming is not high on American’s list of concerns.

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A week or two ago, Andrew Dessler and Steven Sherwood published a “Perspectives” (largely opinion) piece in Science magazine that argued that the water vapor feedback was unassailably strong and positive. This means that the warming from the increase in greenhouse gas concentrations leads to more water vapor in the atmosphere which leads to even more warming (water vapor is a strong greenhouse gas itself). This positive feedback results in roughly twice as much warming as would occur from anthropogenic greenhouse gas increases alone.

Dessler and Sherwood concluded:

There remain many uncertainties in our simulations of the climate, but evidence for the water vapor feedback—and the large future climate warming it implies—is now strong.

This conclusion has drawn a lot of attention within the community of researchers investigating the behavior of water vapor and the role of water feedback in climate change—and most of it has been highly critical.

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