9 january 2010

A Rebuttal to a Cool Climate Paper

By ANDREW C. REVKIN, Dot Earth, New York Times blog, January 9, 2010

Richard Lindzen, the meteorology professor at the Massachusetts Institute of Technology best known for his longstanding rejection of research pointing to dangerous climate disruption from human-generated greenhouse gases, has been bluntly challenged over a popular paper in Geophysical Research Letters last year that he co-wrote with post-doctoral researcher Yong-Sang Choi. The paper, assessing tropical sea surface temperatures in relation to flows of energy into and out of the atmosphere, asserted that the climate system was far less sensitive to human actions than the predominant view had it.

In a followup paper accepted for publication in the same journal that examines the same question using the same sea-temperature data sets, four scientists say the Lindzen-Choi conclusions are “seriously in error.” When one flaw is fixed, they say, the analysis produces a much warmer estimate of future climate. But the result gets hotter still, they add, if an objective method is used to select the sea data in place of the choices made by the M.I.T. team.

Three of the authors of the new paper, John Fasullo, Kevin Trenberth and Chris O’Dell, have posted a guest commentary on elaborating on the issues raised by their analysis. There’s more background here, as well as a separate analysis by Gavin Schmidt on

In a telephone interview today, Dr. Trenberth told me that the flaws in the Lindzen-Choi paper “have all the appearance of the authors having contrived to get the answer they got.”

Earlier today I also sent the new paper to Dr. Lindzen. Here’s his reply (alluding to one of the authors, Takmeng Wong of the NASA Langley Research Center):

"Thanks for passing on the paper. I had not seen it. However, Wong had communicated much of the material independently, and some of it is certainly valid. However, we have addressed the criticisms and have shown that the results remain — especially the profound disconnect between models and observations. We are currently preparing a new version, and it should be ready shortly.

"I asked Dr. Trenberth to run the numbers on how much the difference in analysis amounts to in terms of warming from a doubling of the carbon dioxide concentration that long prevailed before the industrial revolution. He said that, if done correctly, the Lindzen-Choi analysis would have produced a 1.5 degree Fahrenheit warming instead of the 0.9 degree warming the paper initially contained. But rectifying an additional flaw — the paper’s selection of sea temperatures in a way that did not appear to be objective — produces a warming of 4.1 degrees, a level at the heart of what most climate simulations and other studies project. That did not include issues related to the original paper restricting its analysis to the tropics, he added."

Dr. Lindzen and Dr. Choi will now have their chance to come back with a fresh take on their approach to checking the sensitivity of the climate system to human influences.

In his analysis, Dr. Schmidt, who studies climate for NASA, noted that the Lindzen-Choi paper was a valuable effort to attack a persistent question — how warm will a certain buildup of carbon dioxide and other heat-trapping gases make the world?

But he criticized the many commentators who quickly inferred that it was a definitive refutation of decades of work pointing to a growing human contribution to climate change:

Even if it now turns out that the analysis was not robust, it was not that the analysis was not worth trying, and the work being done to re-examine these questions is a useful contributions to the literature –- even if the conclusion is that this approach to the analysis is flawed.

More generally, this episode underlines the danger in reading too much into single papers. For papers that appear to go against the mainstream (in either direction), the likelihood is that the conclusions will not stand up for long, but sometimes it takes a while for this to be clear. Research at the cutting edge – where you are pushing the limits of the data or the theory – is like that. If the answers were obvious, we wouldn’t need to do research.

This is a very similar thought to my notion of journalistic “whiplash” a while back. It’s probably more useful to assess the trajectory of understanding on a particular issue related to climate and pay less attention to the paper-by-paper tussles along the journey. The Intergovernmental Panel on Climate Change, for all its flaws, is thought by many people to provide this sort of climate compass.

For those out there seeing any talk of a human warming influence as a hoax, it’s also useful to note that this intellectual tussle over climate sensitivity is over how much human-produced greenhouse gases will warm the world, not if they can do so.

While science, in retrospect, is sometimes perceived as an orderly climb toward understanding, the trajectory is determined through a sustained battle over the quality of evidence and analysis. The ball is in the Lindzen court. Now the question is, will this latest clarification be communicated by the blogosphere as fast and far as the assertions of a cooler track for warming did in 2009?

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