Global warming is not a crisis, but it may be creating a crisis of intellectual integrity.

Last month, college campuses held a "National Teach-in on Global Warming Solutions." The thrust of the message was that there is a crisis because global temperatures are rising, endangering the world's future, and humans are to blame.

I agree that there may be a crisis, but I don't believe that it is a crisis of impending heat; it is, rather, a crisis of intellectual integrity.

First, let me point out something that most people may not realize. Since 1998, there has been no trend in world temperatures, neither up nor down, in spite of population growth, greater resource use, and lots of carbon dioxide production. True, 1998, was the warmest year on record, and we are still in a warm period, but world temperatures are no higher than when today's college seniors began middle school. The likelihood of the catastrophic effects that gave Al Gore a Nobel Peace Prize is weak.

The crisis that concerns me stems from the way that scientists are addressing the issue. Ever since 1988, when James Hansen, head of NASA's Goddard Institute for Space Studies, alerted a congressional committee to global warming, climate change has been a political issue.

Methods and standards that have stood the test of time since the Enlightenment have been shunted aside in order to promote a political objective. Climate experts are no longer expected to create hypotheses and test them but to assume that global warming threatens the planet and to use their expertise to justify this claim. Scientists who question aspects of the orthodoxy have been silenced or fired.

I have just read a lengthy compilation of many ways in which this compromise is occurring. The author is Richard Lindzen, a highly respected climate scientist at the Massachusetts Institute of Technology.

From the early days of the environmental crusade over global warming, Lindzen raised questions about how well scientists understand climate change. At first, he couldn't be ignored because he was so prominent in the field of climatology. As time went on, however, the science establishment managed to give Lindzen's work less attention.

Lindzen's commentary, available here, outlines the forces that have made science, in his words, "vulnerable to corruption."
We have the new paradigm where simulation and programs have replaced theory and observation.
- Richard Lindzen
Lindzen says that the science establishment gives priority to computer modeling of presumed climate forces and then tweaks the models, trying to make them conform to actual observations. Hand-in-hand with that tweaking is an effort to find and "correct" flaws in the empirical observations to make them conform to the simulations. Although science rightly seeks to make corrections, these are almost always in a single direction - toward conformity. That is outright data corruption.

Compounding this tendency is government funding, which furthers bureaucratic and political goals. Professional societies make lobbying their chief activity. The American Meteorological Society is represented by a former staffer for Al Gore. John Holdren, the new science advisor to the president, is a professor in Harvard's government department, not a scientific department; his major job was with the Woods Hole Research Center, an environmental advocacy group that is often (and perhaps deliberately) confused with a scientific research center, Woods Hole Oceanographic Institution. He's not a climate scientist.

Even the Inter-Governmental Panel for Climate Change (IPCC) is political. Its key document, "Summary for Policymakers," is written by a committee composed mostly of representatives of governments and advocacy groups. Few scientists have a role in crafting that paper, which is all that most policy-makers read.

Lindzen offers page after page of examples illustrating the distortion of scientific inquiry. For example, in 1999, Michael Mann and others revised the historical temperature record to eliminate the existence of a warm period during the Medieval era.

The Mann et al. paper, which relied mostly on tree-ring records, featured a "hockey-stick" graph showing flat temperatures for hundreds of years followed by a dramatic increase in recent years, conveying the message that recent warming is unprecedented. Subsequent papers have challenged the findings, but the "hockey-stick" appears in the most recent IPCC report.

Comment: The Medieval Warm Period has been confirmed as a global climatic event by hundreds of studies of physical evidence around the world.

See: CO2 Science
Was there a Medieval Warm Period? YES, according to data published by 675 individual scientists from 394 separate research institutions in 40 different countries ... and counting! This issue's Medieval Warm Period Record of the Week comes from Finland's Southern Boreal Forest, near Savonlinna, Finland. To access the entire Medieval Warm Period Project's database, click here.

In 2001, Lindzen and two colleagues published a paper in the Bulletin of the American Meteorological Society suggesting a strong cooling effect from clouds, which they called the "iris effect." Shortly after it was published, the journal published a paper challenging its existence. This would have been acceptable if, following the usual procedure, the editor had allowed Lindzen and his colleagues to rebut the criticism in the same issue of the publication. But they were not allowed to do so.

In 2007, Lindzen showed that independent data from satellites and weather balloons did not support the computer-model prediction that the greatest warming should occur in the upper troposphere (a layer of the Earth's atmosphere). Rather than explore possible reasons why the difference occurred, two papers quickly tried to undermine the findings. One revised the satellite data to bring them closer to the predictions; another paper simply rejected the temperature data, proffering highly uncertain temperature estimates based on wind data.

Lindzen also speaks of a professor who spoke out and lost his job and another who expressed "cautious" support for skepticism - and suffered ad hominem attacks as a result. And the views of scientists such as the prominent physicist William Nierenberg have been posthumously misrepresented.

Lindzen is not the only scientist to chronicle harassment of scientists who oppose current orthodoxy. In the preface to his new book written with Robert C. Balling, Jr., Climate of Extremes, Pat Michaels explains why he is resigning from the University of Virginia, where he serves as the state's climatologist. Virginia's governor, backed by the university's provost, told him that he could not identify himself as the state climatologist when talking about global warming.

Michaels also reports that Oregon's state climatologist resigned when he was told to stop saying things that undermined the state's greenhouse-gas policies. Delaware's state climatologist is not allowed to speak about global warming. And the assistant state climatologist in Washington state was fired for providing snowfall information to journalists and others.

Some of us might look to the presidents of universities - the supposed bastions of free scientific inquiry - to sound an alarm about this kind of treatment of scholars. But that would be expecting too much. Indeed, 614 university and college chancellors and presidents have signed a statement saying that global warming is "largely being caused by humans," and that they "recognize the need to reduce the global emission of greenhouse gases by 80 percent by mid-century at the latest" and to "reestablish the more stable climatic conditions that have made human progress over the last 10,000 years possible."

Having signed so strong a statement, will these presidents welcome - or even allow - scientists to objectively pursue knowledge about the climate? The evidence outlined by Lindzen and Michaels raises serious doubts.