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.

Skeptics are rightly challenged to assess claims made by all parties when an issue of major public importance arises. This is especially true when any action taken may have unpredictable economic consequences for the entire country. Questions related to global warming, climate change, and national energy policy represent such an issue today.

Both proponents and opponents of action are now arming themselves for a major political fight. Proponents have collected a large body of scientific evidence predicting that maintaining the status quo will consign the world to climate disaster. Opponents are arguing that an economic collapse could result from expensive, dramatic action. Some opponents also argue that we need more research. In light of this, a continuing effort for objective assessment is needed.

This year, the current administration in Washington is preparing legislation that would, if fully implemented, mandate significant reductions in carbon dioxide emissions and also collect several hundred billion dollars in carbon taxes over a ten-year period. These taxes would be collected through a mechanism known as cap-and-trade by selling carbon credits—allowances to produce carbon dioxide—to industries that generate this known greenhouse gas. President Obama has endorsed this approach, which has been in place for several years in the European Union. Not surprisingly, there are opposing views on how well cap-and-trade has worked in Europe.

In response to this legislation, proponents and opponents have embarked on a major effort in Washington to pass, modify, or defeat it. Nearly every environmental organization, the majority of scientific organizations, and most Democrats support the legislation; most spokespersons for the energy industry, some scientists, and the more conservative Republicans tend either to oppose it or at least to seek major modifications. For example, The Intergovernmental Panel on Climate Change (IPCC) Physical Science Report-2007 summarizes the work of approximately 2,000 scientists worldwide and supports major initiatives to curb carbon emissions. Representing the opposition according to Environment Maryland, a citizen-based environmental advocacy organization, are approximately 2,000 lobbyists who have been engaged by American energy industries to identify flaws in the IPCC-2007 arguments and in the administration’s legislation.

Both sides have made significant efforts to establish scientific credibility with the public. Those favoring action rely heavily on the IPCC-2007 science report and note some alarming recent research that suggests the Greenland icecap may be melting at a faster rate than even IPCC-2007 reported. In contrast, a well-known opponent of human-induced global warming, Senator James Inhofe of Oklahoma, has sought to persuade people that the current scientific majority view is misguided. (Inhofe is the ranking Republican member of the Senate Committee on Environment and Public Works.) In consequence, his office has issued a Senate Minority report titled United States Senate Minority Report on Global Warming. It can be found at epw.senate.gov.

The minority report lists a number of individuals identified as scientists who allegedly dissent over man-made global-warming claims. As of January 2009, the number of such persons listed was 687. Noting that there were indeed some quite well-known scientists on the list, and in view of the importance of the issue, the Center for Inquiry/Office of Public Policy decided to vet the list carefully to establish how credible it is overall.

This research produced the following information on the 687 people listed in the Senate minority report. Categories included name, education, summary of publications in the refereed literature based on the better-known climate science and solar physics journals, current institutional affiliations, and professional identifications.

The proportion of them who have published articles on climate science proved to be slightly less than 10 percent. Rounding off, a total of 15 percent exhibited a significant publication record in subjects at least related to climate science. We found no evidence that 551 (~80 percent) had any peer-reviewed publications bearing on climate science. At least fifty-five had no science credentials at all, and many others identified as meteorologists proved to be weather reporters. Almost 4 percent expressed support for the general consensus supporting anthropogenic causes of global warming, the near-consensus expressed by the IPCC-2007 science report, and therefore should not have appeared on the list in the first place.

How should a skeptic deal with this information? All trained scientists admit that scientific truth is ultimately probabilistic, even when the probabilities appear to be approaching certainty. It is also true that the climate scientists I know grant that there are still a few “dark corners” in the realm of cloud theory that need to be explored in more detail using new data obtained on a smaller grid. Finally, it cannot be ruled out that some as-yet undiscovered natural process may be playing a larger than anticipated role in global warming. Opponents of human causation often propose the sun as the likely driver of contemporary global warming. While no one can say with certainty that the sun plays only a small role in climate change today, as a solar physicist I can say that the various solar mechanisms proposed to date have either been discredited by current research or have been presented in highly speculative arguments not now supported by observations.

Where does this leave us? As concerned citizens we need to recognize that we are dealing with a two-step decision process. The first step is getting the science right. There is no doubt that a large majority of the scientific research community thinks global-warming-driven climate change is due primarily to anthropogenic greenhouse gases. That there remains a much smaller number of research scientists who disagree and that no one can claim certainty about this complex problem is equally true. This makes it relatively easy for those who wish to delay or prevent action to claim to the public that there is a big controversy over the science, implying that action, and especially expensive action, would be unwise. However, the evidence suggests otherwise. That there is a big and growing scientific controversy over anthropogenic sources of global warming is almost certainly untrue.

The second step in the decision process is the political one, which necessarily brings in the economic issues. This brief piece cannot address those issues except to acknowledge their critical importance. Nevertheless, we can ask the skeptic who is not acquainted with the relevant science where he or she thinks the most credible scientific assessment lies—with the scientists whose published research is reported in the IPCC-2007 science report or with the much smaller group of scientists collected for the Senate minority report.

It is important that the public have a reasonable understanding of what science is and of what science can and cannot do in helping to settle issues that eventually reach the public square and thus take on a political dimension. Most people understand that science is a process for seeking the truth about how the natural order works. It is the process itself, not the results of applying it, that lies at the heart of science. Fewer people may realize that this process virtually guarantees the integrity of science in the long run even if individual scientists make mistakes, as all occasionally do, or if a (very) rare individual is actually dishonest and falsifies data. This guaranty results not from any intrinsic moral superiority of scientists themselves, but from the fact that research examined by scientific colleagues in the most prestigious medium, the refereed publications, is quickly subjected to ruthless examination for any errors. Those who detect an error often gain as much credit for their scrutiny as those whose work survives it. Scientists who deliberately avoid this scrutiny by publishing their work in less respected media are understandably and properly given less credence for their efforts. History has demonstrated convincingly that the latter work is much more likely to contain serious errors.

Science does not offer certainty. The results of modern science are typically presented in the language of statistics and probabilities. This is especially true of scientific studies of complex phenomena, of which climate science is an excellent example, even though these phenomena remain rooted in the basic laws of nature. Nevertheless, the existence of “uncertainty” has led some individuals less familiar with science to interpret any uncertainty as evidence for “a major scientific controversy” even when there is none. Thus the general public is vulnerable to the claim that a major scientific dispute over climate science is underway between two equally large and well-qualified groups of scientists, when this is simply not so. Often this false claim is made by those who wish to discourage action to address the problems associated with climate change. There are certainly a few scientists of integrity who remain skeptical of the current near consensus, but the interested reader might consider the language of some of the critics and investigate their sources.

The real issue at stake today is what to do in light of what science has uncovered. Here there is a real controversy. One group favors action in response to the alarming evidence that global warming is definitely occurring, most likely driven by anthropogenic greenhouse gases, while the other side opposes this view for reasons ranging from a few still-unresolved scientific questions to concerns of a more economic and political nature. Typically, the latter group is dominated by those fearing change of the industrial status quo, and they tend to be more vehement in advocating their position.

This leads into two final issues needing comment. The first acknowledges the importance of addressing the economic dislocations and economic opportunities that will result from actions to mitigate the effects of global warming. There is an understandable—not always unwise—human tendency to want to continue with the familiar. This produces a natural inclination to oppose change unless it becomes disastrous not to do so, which can lead to overlooking the many—in this case economic—opportunities associated with pursuing more climate-friendly and eco-friendly technologies. These include many technologies already available, with others undergoing current development that could be accelerated if proper economic incentives were provided. Interested readers can find examples, which I was unable to include in my articles due to space constraints, at www.cfidc.org/opp/jordan.html. The final question I wish to address is what the responsibilities of scientists are in a democracy that, de facto, provides much of the funding for their research. Many working scientists would prefer to have little to do with the political process, yet there is no denying that most scientists today receive much of their support from governments. Performing one’s research with integrity is obviously part of the answer, but is it the full answer? Some would say yes and defend this position by noting that distracting a competent researcher from his or her research is likely to reduce scientific productivity. As one who has both performed and managed research, I agree with this position under most circumstances. However, if major public policies depend on science for their proper formulation, as is true of climate science today, a strong case can be made that it becomes the duty of the scientist to inform the public and the political establishment of the best science available on the issue, especially when there are others exerting a major effort to suppress consideration of it. A historical example was the effort of the atomic scientists following World War II to inform the public of the unprecedented power and appalling destructiveness of nuclear weapons. A growing number of climate scientists, and others in related fields, are engaging in a similar educational effort today. I believe this effort serves the public well, and that it should continue.