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The science of global warming

Greg Studen  |  09/19/08 @ 4:46pm

Recently I received two papers that each directly contradict the International Panel on Climate Change (IPCC) conclusions and recommendations on climate change.

(The IPCC's latest report Climate Change 2007-The Physical Science Basis was issued on February 2, 2007. See the IPCC Summary Report for Policymakers (pdf) for a concise review of the results with helpful charts and graphs).

Climate Change 2007 is a summary of what I will call "mainstream science" on climate change. A few statements from the Summary Report will underline the tenor of the IPCC's conclusions:

Warming of the climate system is unequivocal.

Natural systems are being affected by regional climate changes, particularly temperature increases.

There is very high confidence that the net effect of human activities since 1750 has been one of warming. [italics in original]

Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG concentrations. [GHG="green house gas"]

The two contradictory reports challenge the IPCC conclusions in almost every respect. They do agree that there has been "modest" global warming since about 1800 but argue that it is caused by changes in solar irradiation, and not CO2 emissions or any other human activity. Far from considering warming as a problem, they argue that it will be modest and beneficial. These reports have taken on the mission of opposing the IPCC and the mainstream science consensus on global warming.

One of the papers, published by The Heartland Institute, is entitled Nature, Not Human Activity, Rules the Climate. Heartland is a libertarian/conservative public policy think tank that promotes free-market environmental and energy policies. Its report, printed in April 2008, was published for the "Nongovernmental International Panel Change."

Heartland got together with a number of other libertarian-leaning organizations in New York on March 4, 2008, and held a conference that was organized around the idea of supporting the thesis that recent climate change stems from natural causes, is likely to be fairly benign, and that governmental approaches to combatting it are excessively costly and counterproductive. The 40-page report is available at the Heartland website.

The other report was written by principals at the Oregon Institute of Science and Medicine (OISM), and published in the Journal of American Physicians and Surgeons Vol. 12, pp. 79-90 (2007). The OISM was founded by Art Robinson in 1980. Robinson is listed on OISM website as one of eight faculty of the institute. His children Noah and Zachary are listed at two of the eight faculty. Robinson is an independent scientific researcher of libertarian persuasion who works from his home in southern Oregon.

The OISM has organized a "Petition Project" to gather scientific support for the position that there is no credible evidence of human-caused global warming. This 12-page report can be accessed at the Petition Project website. Here is the abstract of the report, taken from the website:

A review of the research literature concerning the environmental consequences of increased levels of atmospheric carbon dioxide leads to the conclusion that increases during the 20th and early 21st centuries have produced no deleterious effects upon Earth's weather and climate. Increased carbon dioxide has, however, markedly increased plant growth. Predictions of harmful climatic effects due to future increases in hydrocarbon use and minor greenhouse gases like CO2 do not conform to current experimental knowledge. The environmental effects of rapid expansion of the nuclear and hydrocarbon energy industries are discussed.

These two papers are perhaps the two best-known examples of what has come to be known as "climate denial." They represent a vigorous undercurrent of dissent from the mainstream science consensus on global warming. In spite of much support for the IPCC position, this dissent has not gone away, and is not likely to abate any time soon. Papers like these have fed much of the political opposition to strong government controls on greenhouse gases in Congress, and have had a definite political impact. Recent polling has shown that support for the thesis of global warming has declined among Republicans in general, see here, and here. One can speculate that this may be because of distrust of elite science--support for the global warming thesis goes down as education levels among Republicans goes up--as well as receptivity to the free-market and anti-regulatory principles that are promoted by the papers' authors and others of similar persuasion.

What is the average citizen to make of this controversy? How should we evaluate this kind of criticism of a majority scientific position? Here I will suggest two possible approaches. One I will call an analysis of the papers that is "internal" to the science involved. By this I mean that the papers can be evaluated according to the norms that scientists commonly use when they publish results and thereby subject themselves to criticism. Broadly speaking, these norms all into two categories: first, logical coherence with the body of existing accepted scientific knowledge, and second, consistency with the available evidence that bears on the subject.

In the ideal of science as conducted in accordance with its internal norms, there is a process of model building, hypothesis formation, data gathering, and experimentation, all done by groups of scientists who publish their results and then subject their conclusions to mutual criticism. In this view, what the "science" is on any particular topic is just the consensus (if there is one--it took time for the "science" of global warming to develop) of active, qualified scientists who are working on the topic and sharing and criticizing results in a progressive manner. The process is progressive if it continues to produce results that are consistent with both the logic of existing models and the evidence. Who is qualified to make these judgments is determined by the scientists themselves in a process of mutual acceptance over time of work on a research program that is considered progressive . I refer to the results of this process as "mainstream science."

The second approach is to evaluate the papers from a perspective that is "external" to the science itself. In this case we look at who are the people involved, what are their prior beliefs, their motivations, their interests, economic or otherwise. This external approach stems from the work of Thomas Kuhn ,who in his 1962 book The Structure of Scientific Revolutions laid the ground work for the field of "sociology of science." On this view the conclusions of scientists are determined more by historical and social factors-these may include what they are taught and by whom, their worldview, what is popular at the time, their desire for power and prestige, the need to belong to a group of like-thinking people, and their economic interests-as they are by internal logical/rational methods, practices, and norms.

First let's take a look at the "external" factors influencing these two important global warming papers. The people who are the principal authors of the papers are not involved in the mainstream of climate science. While they rely on the results of many working scientists, and make scientific arguments (which we will consider later as part of the "internalist" critique), they are not accepted by the mainstream group of qualified scientists working on global warming. They are also ideologically committed to libertarian and free market ideas. Fred Singer, principal of the Heartland paper, has a history of contrarian views on science and public policy, including criticism of the US EPA for attempting to regulate second-hand tobacco smoke. Singer is not part of any university faculty, and is 88 years old. While his age is not a disqualification in itself, it does suggest the degree to which he is not part of the active working network of climate scientists.

Arthur Robinson and his co-authors of the OISM report are also outside the mainstream of science. Although by many accounts a brilliant man, Robinson works with his family members, whom he has home schooled, in Cave Junction, Oregon. Robinson markets a home schooling kit for "parents concerned about socialism in the public schools." see here. Some of the OISM faculty are associated with the Association of American Physicians and Surgeons (AAPS), which is an anti-regulatory, conservative to libertarian-leaning group of doctors. see here. The AAPS publishes the Journal of American Physicians and Surgeons. Why medical journal would publish an article on global warming denial is not clear, except as part of a general anti-regulatory agenda. The OISM paper also contains a section on "Environment and Energy," which has nothing to do with global warming as such, but supports unlimited development of both fossil fuel and nuclear energy as the only way to a secure and prosperous human future .

By now this may start to look like an ad-hominem "hatchet job" on the authors of these papers, and may lead skeptical readers to wonder what the authors' personal histories has to do with the validity of their views. The problem is that scientists are people who come to their work with backgrounds and world views that may significantly color their work. In complex scientific disciplines like climate modeling, no one person can possibly put together the entire picture of the facts. It takes a collegial approach, in which scientists propose theories, gather data, publish, and then criticize, and sometimes argue and fight with each other over the results and implications. Though they may disagree, they are working together and are criticizing each other's work according to the "internal" norms of science. Mainstream climate scientists work by and large as full-time researchers at universities and government agencies. They are the scientists from whom the body was chosen by the IPCC to confer and study the state of climate modeling and studies, and to develop a consensus report. Heartland and OISM are not part of this collegial group, and so their results have not been subjected to the same degree of discussion, analysis and criticism. Their papers were not reviewed by the mainstream group of scientists prior to publication. They have political and economic agendas that are transparent. For this reason, we should be very cautious about accepting what they say as "good science."

To be fair, the external, sociological critique of science works both ways. Here is what Heartland says of the IPCC on page vi of their report:

"Why have the IPCC reports been marred by controversy and so frequently contradicted by subsequent research? Certainly its agenda to find evidence of a human role in climate change is a major reason; its organization as a government entity beholden to political agendas is another major reason; and the large professional and financial rewards that go to scientists and bureaucrats who are willing to bend scientific facts to match those agendas is yet a third major reason."

Without a touch of irony, the report goes on to say on page vii: "We regret that many advocates in the debate have chosen to give up debating the science and now focus almost exclusively on questioning the motives of "skeptics" and on ad hominem attacks."

I would say that it is entirely fair to look also at the credentials and motives of the IPCC scientists, and at the process used to produce the consensus report. These are described on the ippcc website. In addition, I would recommend visiting Real Climate, which is published by a groups of mainstream working climate scients. Real climate is a strong supporter of the global warming mainstream consensus, and of the IPCC process and report. Go to the link to "Contributor bios" on the right. I'm sure that you will agree that these are highly skilled specialists who have dedicated their lives to the ideals of climate science (including the realization that they are not always right), and they are not in it for the money. Nor would I suggest that OISM or Heartland have purely financial motives; rather, they are dedicated contrarians who clearly resent the power and influence of institutionalized mainstream science. We need to take a look at their criticisms, but also need to understand where they fit in the process of developing a scientifically accurate picture of the world.

Surely there are dangers in any complex scientific research program of a kind of "group think" that unfairly excludes new or challenging ideas. There is always a tension between the external and internal factors that influence the consensus opinion. The collegial scientific process has a self-correcting tendency because of the pressure that is constantly exerted by the internalist forces of coherent argument and interpretation of evidence, against any externalist motives that tend to create a comfortable consensus.. There is no guarantee that this will always come out "right," but at any given time the best we can hope for is that a robust interchange of ideas and criticisms will lead to a more accurate picture of the world. The IPCC process and the aftermath of continuing research and vigorous debate are doing a reasonable job of maximizing the influence of these self-correcting forces. The result is that the majority of active, full-time climate scientists strongly believe that anthropogenic global warming is real.

When we turn our attention to an internal critique of the Heartland and OISM papers, the average citizen has a real problem. Even those who have some scientific background, and may in fact be expert in some scientific discipline, would have a hard time evaluating the reports unless they are full-time climate scientists. On their face the graphs, charts, and arguments of the two papers are logical and reasonable. The only way to see if they hold up to criticism is to turn to the work of full-time climate scientists, and see what they have to say about the same issues.

Fortunately, the two papers are well known to climate scientists,and have been subjected to detailed scientific scrutiny. The OISM paper has been analyzed by Michael MacCracken, Chief Scientist for Climate Change Programs at the Climate Institute. He has a B.S. from Princeton, Ph.D. from the University of California Davis/Livermore, and is President of the International Association of Meteorology and Atmospheric Sciences. www.iamas.org. The MacCracken paper can be viewed here. MacCracken vigorously defends the IPCC process and criticizes the OISM paper for not being subject to the same level of peer-reviewed scrutiny as the IPCC work. His twenty three pages of closely argued criticism cannot be reproduced here, but it is worth summarizing the following essential points:

1. Robinson in the OISM paper relies extensive on correlations and assumes causation when it is not demonstrated. Many of the raw facts that are presented are true, but the arguments and conclusions are not valid.

2. The crux of the OISM and Heartland argument is that changes in solar radiation can account for the global warming observed since 1800. MacCracken argues that changes in solar flux are nowhere near enough to account for the warming observed, but well-tested scientific theories show that changes in concentration of CO2 and related greenhouse gases are sufficient. .

3. OISM data frequently refers to limited localities, e.g. the Sargasso Sea, which cannot be reliably extrapolated to worldwide conditions.

4. OISM denies that the role of CO2 and other greenhouse gases are sufficient to force radiative heating of the Earth and to trigger positive feedbacks that amplify the heating process. This is clearly opposed to the settled mainstream science on the subject that goes back 100 years.

5. Only complex models that have been tested, such as used by the IPCC, can account for observed effects. OISM relies on simple correlations that have no explanatory power.

6. Uncertainties in climate models mean that prediction of certainties is not possible, but consensus scientific judgment of an informed community of experts (what science is) says that there is a high probability of severe consequences.

The Heartland arguments are similar. Real Climate has gathered a wealth of additional information at its "RC Wiki," that provides a thorough review of arguments covered by both the OISM and Heartland papers. Anyone with the time and interest can spend several hours sifting through the debate.

In the end, where does this discussion leave us? Let's suppose we're the "average citizen," with enough science background to understand the issues, but limited ability to sift through and evaluate the complex arguments and conflicting data. I suggest that the following conclusions are reasonable:

1. As process, a complex science like climate studies has to rely on the cooperative effort of full-time working scientists who specialize in the field. The have to communicate through publication of theories and results, and subsequent criticism. Membership in this group is by necessity determined by an ongoing process of sharing and criticizing research and results. The results of the process are not guaranteed to be correct, but they are subject to constant improvement. At any given time, any social decision based upon the "facts" about climate change must rely on this process.

2. The IPCC was and is a fair effort to create a scientific decision making process that is based upon the ideals of science. Its working groups relied on the cooperation of over 1000 scientists who work in the various climate change disciplines. To the extent that the process has been subject to political influence, its conclusions may underestimate the possible future effects of climate change, in an effort to appease the politics of economic growth.

3. The IPCC results have be criticized by Heartland, OISM, and others. These criticisms are fair, and in turn have been subjected to rebuttal.

4. As a person who cannot independently evaluate the complex scientific arguments and data, you have to decide who to trust. Try to look honestly at your own background. Then look at the backgrounds of the respective scientists who present their views. Which are most likely to be free of bias?

5. Looking at the arguments, there are two fundamental questions: 1. Can changes in solar radiation can account for perceived climate effects, on the time scale observed? The scientific consensus says no. 2. Is there a convincing argument, coherent with science as a whole, that CO2, together with associated greenhouse gases, can force the radiative heating of the Earth and lead to amplified warming through positive feedback? The scientific consensus says yes.

6. Looking at the evidence-data on CO2 levels, historical temperature records, glaciers and polar ice melting, oceans acidifying, sea levels rising, corals bleaching., ecosystems changing as warm-climate species move farther north-the research supports the conclusion that the Earth is warming, consistent with the greenhouse gas theory.

7. Looking at the most plausible theories and the evidence, the conclusions of the IPCC represent the best science that we have on the subject. From a social decision making point of view, we must view these conclusions as the facts about global warming.

There will always be skeptics who deny the validity of accepted scientific models. This is a normal part of the scientific process. Criticism and debate make science more successful. However, as political and social decision makers, which is what we are every day when we decide what to buy, how to live, and who to vote for, we cannot afford to ignore the consensus of mainstream science. Global warming is real, and we have to act quickly to avoid consequences that may soon be disastrous for life as we know it.

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