Who Knew? Climate Scientists Have Been Underestimating Climate Change. It's Time to Fix That.

If the recent deluge of climate change reports is getting on your nerves - there's no nice way to put this, it's worse than you've been told.

Scientific American takes a look at this long-recognized problem and what we can must do to fix it.

Consistent underestimation is a form of bias—in the literal meaning of a systematic tendency to lean in one direction or another—which raises the question: what is causing this bias in scientific analyses of the climate system? 

The question is significant for two reasons. First, climate skeptics and deniers have often accused scientists of exaggerating the threat of climate change, but the evidence shows that not only have they not exaggerated, they have underestimated. This is important for the interpretation of the scientific evidence, for the defense of the integrity of climate science, and for public comprehension of the urgency of the climate issue. Second, objectivity is an essential ideal in scientific work, so if we have evidence that findings are biased in any direction—towards alarmism or complacency—this should concern us. We should seek to identify the sources of that bias and correct them if we can.

The article, written by prominent scientists Naomi Oreskes, Michael Oppenheimer and Dale Jamieson, previews their new book, 'Discerning Experts.'

In our new book we explored the workings of scientific assessments for policy, with particular attention to their internal dynamics, as we attempted to illuminate how the scientists working in assessments make the judgments they do. Among other things, we wanted to know how scientists respond to the pressures—sometimes subtle, sometimes overt—that arise when they know that their conclusions will be disseminated beyond the research community—in short, when they know that the world is watching. The view that scientific evidence should guide public policy presumes that the evidence is of high quality, and that scientists’ interpretations of it are broadly correct. But, until now, those assumptions have rarely been closely examined. 

We found little reason to doubt the results of scientific assessments, overall. We found no evidence of fraud, malfeasance or deliberate deception or manipulation. Nor did we find any reason to doubt that scientific assessments accurately reflect the views of their expert communities. But we did find that scientists tend to underestimate the severity of threats and the rapidity with which they might unfold.

A defensive herd mentality or 'safeguarding the messenger.'

Among the factors that appear to contribute to underestimation is the perceived need for consensus, or what we label univocality: the felt need to speak in a single voice. Many scientists worry that if disagreement is publicly aired, government officials will conflate differences of opinion with ignorance and use this as justification for inaction. Others worry that even if policy makers want to act, they will find it difficult to do so if scientists fail to send an unambiguous message. Therefore, they will actively seek to find their common ground and focus on areas of agreement; in some cases, they will only put forward conclusions on which they can all agree. 

The push toward agreement may also be driven by a mental model that sees facts as matters about which all reasonable people should be able to agree versus differences of opinion or judgment that are potentially irresolvable. If the conclusions of an assessment report are not univocal, then (it may be thought that) they will be viewed as opinions rather than facts and dismissed not only by hostile critics but even by friendly forces. 

Playing it safe.

A second reason for underestimation involves an asymmetry in how scientists think about error and its effects on their reputations. Many scientists worry that if they over-estimate a threat, they will lose credibility, whereas if they under-estimate it, it will have little (if any) reputational impact. In climate science, this anxiety is reinforced by the drumbeat of climate denial, in which scientists are accused of being “alarmists” who “exaggerate the threat.” In this context, scientists may go the extra mile to disprove the stereotype by down-playing known risks and denying critics the opportunity to label them as alarmists. 

Many scientists consider underestimates to be “conservative,” because they are conservative with respect to the question of when to sound an alarm or how loudly to sound it. The logic of this can be questioned, because underestimation is not conservative when viewed in terms of giving people adequate time to prepare. (Consider for example, an underestimate of an imminent hurricane, tornado, or earthquake.) In the AR4 WAIS debate, scientists underestimated the threat of rapid ice sheet disintegration because many of the scientists who participated were more comfortable with an estimate that they viewed as "conservative" than with one that was not. 

The combination of these three factors—the push for univocality, the belief that conservatism is socially and politically protective, and the reluctance to make estimates at all when the available data are contradictory—can lead to “least common denominator'' results—minimalist conclusions that are weak or incomplete.

The authors contend that science needs to get past 'univocality' and consensus to present more raw opinion to our political caste, the decision makers. To me that sounds like embracing futility.

How many of these craven political grifters, from our country or any other, would hesitate to exploit uncertainty? How many of them even act on the watered-down consensus?  Our prime minister? Hell no. Despite the recent warnings of the urgent need to slash GHG emissions by half by 2030, the Dauphin is still using Harper's emissions cuts targets and failing to meet even those. Every damned Conservative and Liberal politician in this country is a petro-pimp. That's what they need from the scientific community - more wiggle room.

Honesty is good, always. There's nothing wrong with the science types admitting they've been putting a lot of water in our wine. But to suggest that honesty has any currency with our decision makers is the height of naivete.