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An Echo Chamber of Climate Change Denial

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There was a startling demonstration last week of how quickly messages of climate change denial can spread from the United States to the United Kingdom.

The initial trigger was the publication of a paper by Roy Spencer and Danny Braswell of the University of Alabama in Huntsville in the journal 'Remote Sensing', called 'On the Misdiagnosis of Surface Temperature Feedbacks from Variations in Earth's Radiant Energy Balance'.

The paper explores an apparent discrepancy between NASA satellite measurements of the amount of radiation escaping the atmosphere and the results of computer models of climate. The authors conclude that the mismatch is due to inaccurate estimates of the "feedbacks" in the climate system which largely control how much global temperature changes in response to the "forcing" exerted by the rise in greenhouse gas concentrations in the atmosphere.

However, mainstream climate scientists have poured scorn on the paper because of its assumptions about how clouds affect temperature. In an e-mail to me, Professor Andrew Dessler of Texas A&M University, the author of a key paper on the influence of clouds on climate which appeared in the journal 'Science' last year, explained the main problem with the approach adopted by Spencer and Braswell.

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 vapour, on the other hand, is a feedback because the amount of water vapour is set by the surface temperature of the planet. As the planet warms, you get more water vapour in the atmosphere, and since water vapour 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. Spencer's 2010 JGR paper as well as the new Lindzen and Choi 2011 paper both make this argument.

Overall, the argument made in all of these papers to support the conjecture that clouds are forcing the climate (rather than a feedback) is extremely weak. What they do is show some data, then they show a very simple model with some free parameters that they tweak until they fit the data. They then conclude that their model is right. However, if the underlying model is wrong, then the agreement between the model and data proves nothing.

I am working on a paper that will show that, if you look carefully at the magnitudes of the individual terms of their model, the model is obviously wrong. In fact, if Spencer were right, then clouds would be a major cause of El Niño cycles - which we know is not correct. Talk to any ENSO [El Niño Southern Oscillation] expert and tell them that clouds cause ENSO and they'll laugh at you.

Finally, the best way to put Roy's paper into context it is to recognise how Roy views his job: "I would wager that my job has helped save our economy from the economic ravages of out-of-control environmental extremism. I view my job a little like a legislator, supported by the taxpayer, to protect the interests of the taxpayer and to minimize the role of government." (he wrote that on his blog). 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.

Over at the realclimate.org blog, Kevin Trenberth and John Fasullo were even more scathing, complaining that "the basic material in the paper has very basic shortcomings", and suggesting that it would never have been published if it had been subject to a more rigorous review.

Despite these damning critiques, the paper has received a great deal of publicity from self-proclaimed 'sceptics' and some parts of the media, most of whom have exaggerated its significance.

The University of Alabama in Huntsville issued a press release on 26 July which was largely an accurate reflection of the paper, except for the headline "Climate models get energy balance wrong, make too hot forecasts of global warming".

The contents of the release were turned into hyperbole on a blog posted on 27 July on the website hosted by Forbes magazine, claiming "New NASA Data Blow Gaping Hole In Global Warming Alarmism". This was written by James Taylor, a senior fellow at free-market-fundamentalist group The Heartland Institute, which organised a festival of climate change denial in Washington DC last month.

Taylor's contribution was picked up a day later by the 'sceptic' website 'Watts Up With That', and within 24 hours Fox News had covered the paper on its website under the headline: "Does NASA Data Show Global Warming Lost in Space?".

On 29 July, the story also crossed the Atlantic, and by the early hours of the following day the 'Daily Mail' had published its online report with the headline "Climate change far less serious than 'alarmists' predict says NASA scientist". And by the afternoon of 30 July, this story was being disseminated to the supporters of Nigel Lawson's 'sceptic' lobby group, the Global Warming Policy Foundation.

This is a clear demonstration of how the rapid communication of information between self-proclaimed 'sceptics' through the blogosphere and mainstream media can act like an echo chamber which amplifies and distorts with each repetition.

Bob Ward is policy and communications director at the Grantham Research Institute on Climate Change and the Environment at London School of Economics and Political Science.