In January, when Steven E. Koonin welcomed participants to the Climate Change Statement Review Workshop that he was chairing for the American Physical Society, he made a point of acknowledging “experts who credibly take significant issue with several aspects of the consensus picture.” Participating, and fitting that description, were climate scientists Judith Curry, Richard Lindzen, and John Christy. Now Koonin has published a high-visibility commentary in the Wall Street Journal under the headline “Climate science is not settled.” In the paper version, the editors italicized the word not.

The WSJ identifies Koonin as

* President Obama’s former Energy Department undersecretary for science,

* director of the Center for Urban Science and Progress at New York University,

* a past professor of theoretical physics and provost at Caltech, and

* a past chief scientist for BP, “where his work focused on renewable and low-carbon energy technologies.”

It can be added that Koonin has a long past in investigating and pronouncing on physics questions of special public importance. A quarter century ago, the New York Times article “Physicists debunk claim of a new kind of fusion” included this: “Dr. Steven E. Koonin of Caltech called the Utah report a result of ‘the incompetence and delusion of Pons and Fleischmann.’ The audience of scientists sat in stunned silence for a moment before bursting into applause.”

Koonin’s 2000-word WSJ commentary dominates the front page of the Saturday Review section, with a jump to an interior page. The editors signposted it in several ways. The subhead says, “Climate change is real and affected by human activity, writes a former top science official of the Obama administration. But we are very far from having the knowledge needed to make good policy.” A call-out line in boldface on the front page says, “Our best climate models still fail to explain the actual climate data.” Another, after the jump to p. C2, says, “The discussion should not be about ‘denying’ or ‘believing’ the science.” A photo caption on the jump page says, in part, “Today’s best estimate of climate sensitivity is no more certain than it was 30 years ago.” A caption on the front page says, “While Arctic ice has been shrinking, Antarctic sea ice is at a record high.” (Although that photo plainly shows only the extraction of an ice-core sample, the caption adds, “Above, scientists measure the sea level in Antarctica.”)

Here are excerpts from Koonin’s commentary:

* The idea that “Climate science is settled” runs through today’s popular and policy discussions. Unfortunately, that claim is misguided.

* The crucial scientific question for policy isn’t whether the climate is changing. That is a settled matter: The climate has always changed and always will. . . . Nor is the crucial question whether humans are influencing the climate. That is no hoax: There is little doubt in the scientific community that continually growing amounts of greenhouse gases in the atmosphere, due largely to carbon-dioxide emissions from the conventional use of fossil fuels, are influencing the climate. There is also little doubt that the carbon dioxide will persist in the atmosphere for several centuries. The impact today of human activity appears to be comparable to the intrinsic, natural variability of the climate system itself. Rather, the crucial, unsettled scientific question for policy is, “How will the climate change over the next century under both natural and human influences?”

* Even though human influences could have serious consequences for the climate, they are physically small in relation to the climate system as a whole. . . . Since the climate system is highly variable on its own, that smallness sets a very high bar for confidently projecting the consequences of human influences.

* The oceans, which change over decades and centuries, hold most of the climate’s heat and strongly influence the atmosphere. Unfortunately, precise, comprehensive observations of the oceans are available only for the past few decades; the reliable record is still far too short to adequately understand how the oceans will change and how that will affect climate.

* We often hear that there is a “scientific consensus” about climate change. But as far as the computer models go, there isn’t a useful consensus at the level of detail relevant to assessing human influences.

* Work to resolve . . . shortcomings in climate models should be among the top priorities for climate research. Yet a public official reading only the IPCC’s “Summary for Policy Makers” would gain little sense of the extent or implications of these deficiencies.

* While the past two decades have seen progress in climate science, the field is not yet mature enough to usefully answer the difficult and important questions being asked of it.

* We can and should take steps to make climate projections more useful over time. . . . The science is urgent, since we could be caught flat-footed if our understanding does not improve more rapidly than the climate itself changes.

* Policy makers and the public may wish for the comfort of certainty in their climate science. But I fear that rigidly promulgating the idea that climate science is “settled” (or is a “hoax”) demeans and chills the scientific enterprise, retarding its progress in these important matters. Uncertainty is a prime mover and motivator of science and must be faced head-on.

* Individuals and countries can legitimately disagree about these matters, so the discussion should not be about “believing” or “denying” the science. Despite the statements of numerous scientific societies, the scientific community cannot claim any special expertise in addressing issues related to humanity’s deepest goals and values. The political and diplomatic spheres are best suited to debating and resolving such questions, and misrepresenting the current state of climate science does nothing to advance that effort.

---

Steven T. Corneliussen, a media analyst for the American Institute of Physics, monitors three national newspapers, the weeklies Nature and Science, and occasionally other publications. He has published op-eds in the Washington Post and other newspapers, has written for NASA's history program, and is a science writer at a particle-accelerator laboratory.