Saturday, January 7, 2012

A Judith Curry Nonsense Sampler

I enjoy Climate Etc.,  which in my imagination always carries the subtitle "The decline and fall of a once-respected climate scientist."

For those interested in an introduction, Curry has helpfully provided a brief summary of her major intellectual faceplants, in a post titled, in a notable example of unconscious self-referential irony, "The real holes in climate science." She starts out with one of her very favorite delusions:
People cry ‘fraud’ and ‘misconduct’ when they perceive that scientists are trying to hide uncertainties.
Dr. Curry loves to attribute the science denial emanating from the hard right wing to what in her opinion are the shortcomings in climate scientists' characterization of uncertainty. In Dr. Curry's worldview, Rush Limbaugh was innocently and trustingly perusing his copy of the Journal of Climate when he determined that Michael Mann's use of an invalid principal component method resulted in an understatement of the noisiness of his temperature proxies. This resulted in his denouncing climate science as a hoax to his 15 million listeners on a daily basis.

The ostensible purpose of the post is to highlight the eponymous article, which has just won a journalism prize. The author writes, sensibly, of the problems with our modelling of precipitation:
A 2007 study, published too late to be included into the last IPCC report, found that precipitation changes in the twentieth century bore the clear imprint of human influence, including drying in the Northern Hemisphere tropics and subtropics. But the actual changes were larger than estimated from models — a finding that concerns researchers.
“If the models do systematically underestimate precipitation changes that would be bad news”
This gives Professor Curry the opportunity to elucidate the single most bizarre lacuna in her understanding, which is that, despite writing voluminously on uncertainty and risk, she completely fails to grasp that more uncertainty does not imply less risk:
 The poor performance of the climate models somehow gives rise to greater alarm about the future.  Go figure.
Her position on this is as clear as it is indefensible: the less we understand the radical changes we have set in motion in the earth's climate, the less we need to worry about them. If the science cannot reduce the uncertainty to an unspecified, but very low level (as determined by Curry herself, based on subjective criteria she has never specified), we are asked to ignore the science completely.

The ultimate defense

The truth, which even a bright ten-year-old could grasp, is that there are different kinds of uncertainties, and different degrees of uncertainty, and the effects on risk vary, sometimes implying more risk, sometimes less (but in no case do the reduce the risk to zero.) For someone who claims to be interested in uncertainty and how it impacts our decisions, the character of the uncertainty does not seem to interest Curry at all.

Above we have a particularly egregious example of this. Scientists have accurately projected changes in precipitation, but they are happening faster than the models predict. In the world according to Judith Curry, this is supposed to be reassuring, because:

1. The climate models didn't get it exactly right.
2. Climate models are unreliable.
3. Therefore, the risks climate science is telling us about (based on a heap of evidence, including the models) aren't anything to worry about.

You can see how a first year undergrad who had just learned about the problem might fall into this fallacy, but for a PhD who claims uncertainty as a research interest, it's insane. Curry would have us believe that if somebody comes to your house and tells you your kid was hit by a truck going 60mph, and you rush to the scene only to be told by the highway patrol that your kid was struck by a truck going 80mph, that you ought to relax and go home, since clearly the first person didn't know what they were talking about.

A particular target for Curry's ill-informed pronouncements on uncertainty is the assessment by the IPCC that most of the observed warming is caused by human activities (with high -- >90% -- confidence):
The uncertainties in the paleoclimate record and the aerosol forcing discussed in Schiermeier’s article are alone sufficient to question the high confidence in the IPCC’s attribution statement.
She can, of course, question whatever she wants to, but neither she now anyone else has seriously challenged the reasoning or the evidence of the IPCC's finding. A higher or lower aerosol forcing implies a higher or lower transient climate sensitivity, but doesn't at all affect the reality that the world is warming or the observation that an enhanced greenhouse effect is the primary cause. As for the "uncertainties in the paleoclimate record," they are likely a large part of the reason the assessment says "most" of the warming is human caused, rather than reflecting the central estimate -- that all of it and perhaps and little more than all of it is cause by human activities, with a slightly negative natural forcing.

Even if we presuppose huge uncertainty in the paleoclimate record, between that and a serious challenge to the attribution statement is a whole chain of mutually dependent unsupported premises, a veritable daisy chain of wishful thinking:

1. That the uncertain record involves radical upward and downward spikes in temperature.
2. That these are not only not clearly demonstrated in the record, but were not noted at the time -- despite the fact that a similar warming in the past might be expected to produce dramatic changes in the ice sheets, the glaciers, growing seasons and animal habitats, as we see screaming at us throughout the world today.
3. That besides it being merely possible (based on the imaginary spikes of warming in the radically uncertain record) for natural variation to produce the present warming, that it is producing the current warming, despite the fact that:
3a. No one can detect this mystery forcing or forcings, and;
3b. We observe at that time an increase in the greenhouse gas forcing that would be expected, based on two centuries of settled science, to produce a dramatic warming, as we observe is happening.

I expect scientific illiterates like Christopher Monckton or Willis to pull stunts like this, taking two cents of uncertainty in an active area of research and proceeding via a long string of biased reasoning to terminate in a nonsensical assertion. But it is a source of continuing bafflement to mean that a working scientists should think this way.

Professor Curry is not only emulating the pseudoscientists' reasoning, but even their excuses for their irrelevance:
The article raises the important issue of the holes in climate science, but only seeks perspectives from establishment scientists.
"Establishment scientists," saints preserve us. By all means, let's weigh scientific expertise according to the ideas of balance and equity popularized by the Washington press corps (it's worked so well for Washington.) Don't accept the dominance of "establishment scientists," and while you're at it, tell the airline you want to take your next flight without any stuffy establishment pilots on board. Don't leave your health in the hands of establishment doctors and nurses -- next time you're sick, consult a Galileo-like dissenter from the germ theory of disease. Let me know how your surgery goes.

If you are writing about science, talk to scientists. If they disagree, reflect that disagreement. If they broadly agree, that is not a problem requiring you to expand your search to less and less credible voices until a dissenter is found.

1 comment: