Spencer on the "Petition Project"

An acquaintance directed me to this (originally WSJ commentary) piece by Dr. Roy Spencer as refutation of my consistently held characterization of the scientific consensus on anthropogenic (human caused) climate change as "overwhelming." The Spencer piece has a lot of problems. One that undermines his very integrity is his citation of the "Petition Project," which he describes thusly:

Of the various petitions on global warming circulated for signatures by scientists, the one by the Petition Project, a group of physicists and physical chemists based in La Jolla, Calif., has by far the most signatures—more than 31,000 (more than 9,000 with a Ph.D.). It was most recently published in 2009, and most signers were added or reaffirmed since 2007. The petition states that “there is no convincing scientific evidence that human release of . . . carbon dioxide, methane, or other greenhouse gases is causing or will, in the foreseeable future, cause catastrophic heating of the Earth’s atmosphere and disruption of the Earth’s climate.”

This petition is a deeply troubled and conflicted operation that verges on outright fraud. It's an example of what you might call "push polling on steroids."

Obviously the petition doesn't and can't try to gauge scientific consensus or lack thereof. Unlike surveys that ask questions of verified respondents, the petition promotes a point of view. It comes with a cover letter from a famous climate change denier. It claims over 31,000 signatories, but has no way to verify who they are. Pranksters have submitted fake signatures with made up names. Most of the "more than 9,000" Ph.D.s that Spencer mentions are engineers, not scientists. From the project's own statistics, a minute fraction of signatories are climatologists or closely related specialists. A document included with the petition was deceptively designed to look like a reprint from the National Academy of Sciences, even though it wasn't. The NAS felt the need to publicly distance itself from the project, and to reaffirm its own assessment of scientific opinion.

Bottom line: If you're honestly trying to gauge scientific opinion, you don't include materials making the case against anthropogenic climate change. Respondents, particularly scientists, ought not need to be told by you what they should believe.

Here's a Wikipedia article on the project.

Spencer on Bray and von Storch

An acquaintance directed me to this (originally WSJ commentary) piece by Dr. Roy Spencer as refutation of my consistently held characterization of the scientific consensus on anthropogenic (human caused) climate change as "overwhelming." The Spencer piece has a lot of problems. For example, he tries to debunk the scientific consensus by highlighting scientific disagreement over things like computer models and cloud formation:

Rigorous international surveys conducted by German scientists Dennis Bray and Hans von Storch—most recently published in Environmental Science & Policy in 2010—have found that most climate scientists disagree with the consensus on key issues such as the reliability of climate data and computer models. They do not believe that climate processes such as cloud formation and precipitation are sufficiently understood to predict future climate change.

This is an odd argument. The "consensus" has nothing to do with the reliability of models. It is all about two questions: Is the earth warming? Is that warming mostly caused by humans? Scientists reach conclusions about those questions in a variety of ways.

Many climate scientists don't see much need for models. James Hansen says that understanding how the climate has operated in the past tells us what we can expect in the future. I'd guess most scientists would say that models, alleged warts and all, can be useful for specific purposes, but the case for climate change doesn't depend upon how "good" those models are judged to be.

The Bray and von Storch survey does ask the two questions, ignored by Spencer, against which consensus is gauged, and is briefly mentioned in a Wikipedia article entitled "Surveys of scientists on climate change." From the article:

In the section on climate change impacts, questions 20 and 21 were relevant to scientific opinion on climate change. Question 20, "How convinced are you that climate change, whether natural or anthropogenic, is occurring now?" Answers: 67.1% very much convinced (7), 26.7% to some large extent (5–6), 6.2% said to some small extent (2–4), none said not at all. Question 21, "How convinced are you that most of recent or near future climate change is, or will be, a result of anthropogenic causes?" Answers: 34.6% very much convinced (7), 48.9% being convinced to a large extent (5–6), 15.1% to a small extent (2–4), and 1.35% not convinced at all (1).

Let me rephrase that slightly. On the question of whether the earth is warming,  93.8% said they were convinced at least to "some large extent," 6.2% were convinced "to some small extent," and nobody said they were completely unconvinced.

On the question of whether the warming was caused by humans, 83.5% said they were convinced at least "to a large extent," 15.1% "to a small extent," and a mere 1.35% were not convinced at all.

A very strong result for consensus.

I personally think the Bray and von Storch survey has some problems, as do most efforts of its kind. It's darned hard to survey scientists about their beliefs. But Spencer cited it to make his case, even though we can see it surely works against him. And he completely ignored the part of the survey that bears directly on the consensus question he was ostensibly trying to address, and opted instead to delve inexplicably into scientific esoterica which is quite beside the point. This suggests either bad faith, a disturbing inability to reason, or perhaps just unfamiliarity with the survey.

With respect to the various survey attempts, the Wikipedia article says "they have generally concluded that the majority of scientists accept that human activity is contributing to global warming."