Behind the curtain at the IPCC

Pay No Attention to the Bad Data

By STEVEN F. HAYWARD

Thought experiment: Imagine you are a national security reporter, covering the release of a massive, 2,000-page report on domestic intelligence gathering activities and future threat assessment from the National Security Agency. But instead of issuing the full report, the NSA issues a 30-page “Summary for Policymakers” (SPM) written by political appointees at the Justice Department, promising that the full 2,000-page report will be released a few days later. Would you print a front-page story based only on the 30-page summary, or would you demand to see the full report?

If you’d go with the politically massaged summary, then congratulations​—​you too can be an environmental reporter. Because that’s exactly what the U.N.’s Intergovernmental Panel on Climate Change (IPCC) did on Friday, September 27, in Stockholm, releasing only the SPM while withholding the full report. And the media played along, generating predictable headlines over the weekend about the increasing certainty of climate scientists that humans are warming the world.

To be fair, if they had waited until Monday’s release of the full Working Group I report on the current state of climate science, they’d have had to make sense of a jargon-filled report that Dutch scientist Arthur Petersen told the BBC “is virtually unreadable!” Churchill once quipped about a massive bureaucratic report that “by its very length, it defends itself against the risk of being read.” The IPCC appears to be following this example.

It is important to understand that the IPCC report is not an original scientific inquiry but a wide-ranging literature review and “synthesis.” The technical nature of climate science is such that only other scientists can possibly follow it, and even that is doubtful, as the specialized nature of so many aspects of climate science is beyond the grasp of scientists who work in widely scattered subfields. Whether the domain of climate science can be “synthesized” in this way is a debatable question.

A close reading of some of the key passages shows that it cannot bear the weight of the sensationalized parts of the SPM, at least as rendered in the media. One of the most misleading aspects of this story is the way in which the SPM conveys a “95 percent confidence” or certainty of its findings, as though this figure represented a rigorous or robust test familiar to first-year students of statistical correlation. The IPCC’s methodology behind these conclusions is thoroughly opaque. When you strip away the fog, the IPCC admits these conclusions are “qualitative,” and based essentially on a poll of the self-selecting participants in the IPCC review process itself. 

This is like polling the Romney campaign staff about how confident they are their candidate will win the election, and representing it as
the firm “consensus” of all political scientists. The IPCC’s main report finally admits that the methodology for their confidence calibrations is derived from social science, and that “confidence should not be interpreted probabilistically, and it is distinct from ‘statistical confidence.’ ” You won’t see this admission reflected in any of the breathless news reports about the IPCC’s high confidence of our future doom.

The late James Q. Wilson argued that social scientists should quit trying to predict the future because they can’t predict the past. The climate science community might heed this advice. While the domain of climate science is highly complex, the heart of the enterprise is the calibration of climate models to explain the modest warming we have observed, mostly from 1960-98, which in turn is supposed to enable us to predict the future. Much was made in the media in recent weeks of how some governments were pressuring the IPCC to offer an explanation of the current 15-year “pause” in warming that is confounding the models. (This raises a curious question: Why do we need a “Summary for Policymakers” if policymakers determine what’s emphasized in the summary? Clearly the SPM should be called by its true name: Summary for Headline Writers.) The “pause” is glossed over in the SPM, because the underlying chapters in the full report do their best to skip over this inconvenient fact.

This conundrum is what makes Chapter 9 of the full report (“Evaluation of Climate Models”) fascinating reading. Out of the dense prose a reader can make out increasing confidence that by twisting the computer knobs (called “parameterizing”) we can match up models to the observed temperature record and other empirical data on clouds, oceans, and a multitude of other variables. But there are admissions of serious limitations of the models. Many of the models still produce results that match up poorly with the observational data, and some aspects of the models can’t be validated at all. The IPCC can’t even agree on a method for singling out the most accurate models. Our understanding of clouds​—​one of the most important variables for understanding climate​—​remains very low: “There remain significant errors on the model simulation of clouds,” the chapter says. Among other problems, our grasp of what’s going on in the oceans is still severely limited, and our ability to simulate the dynamics of the Amazonian basin is very poor.

But more important is the carefully worded concession that all this computer knob-twisting to make the models match the temperature record may not work for the future​—​or the past. An early draft of Chapter 9 included this startling sentence: “The ability of a climate model to make future climate projections cannot be directly evaluated.” This has been dropped from the final draft; now the chapter includes an embarrassing excuse for the failure of the models to match up with the current temperature “pause”: “[T]hese projections were not intended to be predictions over the short time scales for which observations are available to date.” Translation: Pay no attention to our models behind the curtain; just trust our judgment that the end is nigh.

The 12 chapters of the report are full of anomalous findings and admissions of scientific weaknesses that are not reflected in the SPM. Not to worry: the report is not final. The fine print on the IPCC’s website says that “following copy-editing, layout, final checks for errors, and adjustments for changes for consistency with the Summary for Policy-makers, it will be published online in January.” (My emphasis.)

In other words, this supposedly authoritative product of international scientific consensus will be reverse-engineered to match up with the politically determined SPM. No wonder skepticism of the climate science community is on the rise.