The following is a summary of the July 8 Hans von Storch talk and panel discussion, by Erika Engelhaupt, Nat Logar, and Marilyn Averill.
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Hans von Storch presented an analysis of climate reconstruction and climate science politicization titled “Hockeysticks and the sustainability of climate science” at the National Center for Atmospheric Research on Friday, July 8. Dr. von Storch discussed both scientific and political implications of the well-known “hockey stick”, the name given to a reconstruction of Northern Hemisphere temperature over the past 1,000 years by Dr. Michael Mann and colleagues R.S. Bradley and M.K. Hughes , which displays a long period of relatively stable temperature over most of the past millennium (forming the handle of the hockey stick) followed by an abrupt rise in temperature over the past century (the business end of the hockey stick). The hockey stick was made famous in Mann et al’s 1998 paper in Nature and was featured prominently in the IPCC Summary for Policymakers (TAR, 2001). Since then, the hockey stick has sparked significant controversy among climate scientists and policy makers as an important piece of the case for unprecedented 20th century warming. Dr. von Storch presented a critique of the Mann “hockey stick” curve, and then used his comparative modeling findings to ask more subjective questions about the nature of the scientific enterprise in general and of climate science in particular. A panel of respondents provided comments following his talk.

First, von Storch discussed his work with Eduardo Zorita and others, published in 2004 in Science, on a millennial-scale climate simulation that tested the methods used in constructing Mann’s model. The authors asked whether the hockey stick model is reliable in reconstructing low-frequency variability. In essence, the magnitude of this variability helps determine how dramatic that rise in the past century looks relative to the 900 years before it. Dr. von Storch emphasized that his work represents a critique of Mann’s methods, not of his results. A millennial run with von Storch’s model generates temperature variations considerably larger than Mann’s reconstruction, but similar to some other models (giving a fatter stick, though still showing increased temperatures in the 20th century). For full details, see the paper here (for those with access to Science). Critics have complained that von Storch’s curve may be no more accurate than the hockey stick, but von Storch was quick to point out that his message is not that his curve is the truth and Mann’s is not, but instead says that his curve “could be the truth” and that Mann’s methodology did not stand up to verification. Thus, von Storch says, “Do not believe advanced complex methods when they are advanced as magic bullets.”

The second part of von Storch’s lecture concerned politicization in the field of climate science, with the goal of organizing the science in a more sustainable manner. von Storch began by contrasting the traditional, truth-based perception of science with a climate science that has higher stakes, is more closely intertwined with practical considerations, and that has increased incentives for people to pursue motives other than truth. He then presented evidence of the political nature of climate issues, and of the way this has affected both the science and what is said about the science. Dr. von Storch presented examples in the form of a statement by renewable energy advocates that “Global warming is a more insidious and longer-term danger than Hitlerism”, along with concerns that the House of Lords have about the IPCC’s objectivity, and the letters sent by U.S. Representative Barton to MBH, the IPCC, and the NSF. For more of von Storch’s commentary on the Barton letters, see the Prometheus entry , “Hans von Storch on Barton”. von Storch was attempting to draw attention to “ongoing slight exaggeration [which] results in the formation of significant misinformation in the public realm.” He warns climate scientists that this overselling of scientific results is unsustainable in that it damages the social institution of science, as members of the public perceive that climate scientists have an agenda, whether true or not.

The hockey stick, according to von Storch, has become a symbol so central to the climate change debate that it cannot be challenged without undermining other aspects of climate science. He argued that the climate debate is constrained by a concern for “evil” skeptics, hopes for a successful Kyoto process, the putative infallibility of the IPCC, the idea that any theoretical failure threatens the authority of climate science in general, and the fact that many reject any statement supporting the climate change skeptics. Such constraints undermine climate science in particular, but also damage the social institution of science by eroding trust. Dr. von Storch called for more counseling from the social sciences, a decrease in the power of alarmists, and the engagement of climate skeptics in constructive dialogue.

The talk was followed by a panel discussion with von Storch, several NCAR climate scientists and modelers, and Roger Pielke, Jr. from the Center for Science and Technology Policy. The audience prompted a lively discussion of climate science and its role in policy. In opening statements, Warren Washington (NCAR) expressed faith in the iterative nature of science by contending that science is always helped by controversy, as scientists sort out the truth by finding and fixing flaws in the data. Washington said that if Mann et al. produced a flawed paper, they should admit it and science will move forward. Caspar Ammann (NCAR) discussed his own climate reconstruction work; Ammann has found similar results to von Storch, but with a smaller difference from MBH. Roger Pielke, Jr. spoke about the role of the hockey stick as a condensational symbol, one which evokes emotions and represents more than is held in its data (more here. Doug Nychka (NCAR) pointed out that it is human nature to want a single estimate of something, and we therefore tend to pay attention to the mean and ignore the variability around it. For example, Nychka said that the “hockey stick” refers to a single line, but the grey fuzz around it is the important part, which the IPCC tends to ignore. Others in the audience said that in the case of the hockey stick, the scientific process is working correctly, with continual refinement of models and new ideas. As one audience member noted, even Dr. Mann has moved on to refined techniques that don’t underestimate low-frequency variability as much as his 1998 model did. Dr. von Storch summarized by stating that the inner workings of science are functioning well, but that climate scientists need to think about how to interact with the public and policy in a way that benefits all.