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Response to ‘Assessing the Credibility of CFI’s Credibility Project’

Follow-up

Stuart D. Jordan

Volume 34.1, January / February 2010

This issue presents contributions by Gary Posner and Robert Sheaffer (letters section) critiquing the Credibility Project I helped produce. They suggest that the Senate Minority Report criticized by the Credibility Project is just as valid as The Intergovernmental Panel on Climate Change (IPCC) Physical Science Report-2007, and one of them notes, correctly, that the full subtitle of this IPCC report is “The Physical Science Basis.” I have several comments on their main points.

The Senate Minority Report was generated with encouragement from a United States senator notorious for making bogus statements to the effect that “global warming is the biggest hoax perpetrated on the American People.” That claim is patent nonsense. Global warming over the past three decades is an observationally based scientific fact. Even the current period, cool only relative to the twenty-five-year rise ending in 2005, was predicted by the best climate models, which also predict that within a decade—and possibly much sooner—we will experience another sharp global temperature rise. Vetting a questionable report was the motivation for our Credibility Project, and no such motivation existed for us to vet the IPCC-2007 science report.

It still doesn’t. We were careful in defining what a climate scientist is, and our definition was rather broad. Whether the same definition was used by the scientist quoted by Sheaffer is not clear, but it is not hard to find a few contrarians willing to define terms to suit their conclusions. As for the number of scientists actually doing climate science, properly defined, even if “only” 620 appear as actual authors of the sections in IPCC-2007 science report, this work is supported by well over 2,000 climate scientists whose work in the peer-reviewed literature is referenced in that document.

As for the science itself, recalling that peer-reviewed science is a self-correcting process, not only has the predictive power of global climate science been confirmed, but actual observations of melting icecaps in Greenland and deteriorating conditions in the Arctic paint an even more dire picture than was available in the IPCC-2007 science report, as noted in our Credibility Project. In contrast, no scientific results based on observations have emerged to challenge the large consensus of the climate science community. Those who invoke the solar cycle, to which there is no global temperature correlation even if one allows for phase shifts, or who cite possible increases in solar flux, of which observations show none over this warming epoch, are especially off the mark. Yet many contrarians continue to propose the Sun as the dominant driver of global warming, possibly for lack of other hypotheses.

What about the cautious nature of the stated conclusions in our Credibility Project? We leave it to the reader to decide if we are pursuing “an agenda.” Consider our penultimate sentence, in which we make it clear that we are restricting ourselves to what we know best—the science: “The authors of this Credibility Project are not qualified to assess the engineering and economic questions associated with proposed legislation addressing climate change.”

At this point, it may be best to move the debate into the halls of Congress, where there is a huge scientific community prepared to defend the legitimacy of climate science against the small number of scientific claims to the contrary. I have had a civil exchange with one of the above critics of our project and think both Sheaffer and Posner are sincere in their skepticism. I also commend the Skeptical Inquirer for presenting both sides of this issue while reminding the reader that this does not imply equal weight to all positions when science is involved. Following the above quote from our conclusion is our final, summary statement on the Credibility Project: “We are disturbed by any document that may misrepresent the state of the global scientific effort to address this problem.”

We stand by that statement.

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Stuart Jordan is a senior staff scientist (retired emeritus) at the NASA Goddard Space Flight Center. He has a PhD in physics and astrophysics and is science advisor for the Center for Inquiry’s Office of Public Policy in Washington, D.C., where he works on science-related policy issues, such as climate change.