Predictions from Climate Models -- Some Expert Criticisms

by Liberty and Power

Dr Roger Pielke Sr has made some important comments recently on some significant points in climate studies.

First, his short & pithy explanation of why short-term weather forecasting is so much easier, while long-term climate prediction is so fraught:

A Short Summary Of Why Skillful Climate Prediction Is Much More Difficult Than Skillful Weather Prediction (23rd May 2007)

The IPCC make the following scientific claim in one of its reports [WG1], published 2007:

‘Projecting changes in climate due to changes in greenhouse gases 50 years from now is a very different and much more easily solved problem than forecasting weather patterns just weeks from now. To put it another way, long-term variations brought about by changes in the composition of the atmosphere are much more predictable than individual weather events.’ [from page 105]

Having quoted this [again, see below], Dr Pielke states:

“This weblog provides a short summary of why such a claim is absurd.”

Dr Pielke then says (as I understand it): Short-term weather modelling is based on real-world data that remain constant for short periods only. Long-term climate modelling involves more variables, more complex processes, & is less capable of correction from real-world data.

His final para:

“The claim by the IPCC that an imposed climate forcing (such as added atmospheric concentrations of CO2) can work through the parameterizations involved in the atmospheric, land, ocean and continental ice sheet components of the climate model to create skillful global and regional forecasts decades from nowis a remarkable statement. That the IPCC states that this is a ‘much more easily solved problem than forecasting weather patterns just weeks from now’ is clearly a ridiculous scientific claim. As compared with a weather model, [in] a multi-decadal climate model prediction there are more state variables, more parameterizations, and a lack of constraint from real-world observed values of the state variables” [emphasis added].
--------------
2. Dr Roger Pielke Sr has some valuable comments on the approach adopted by many ‘climate science’ papers. Outcomes of models are not established facts:

More Presentation Of Climate Predictions as Scientific Fact (21st May 2007)

“…paper…clearly is an example of the publication of a prediction, which has yet to be tested in its accuracy, as a scientific contribution” [emphasis added].
------
3. Dr Pielke is also critical of some of the material in the IPCC’s scientific reports for 2007:
WG1 IPCC Chapter 1 - More Scientifically Erroneous Statements (18th May 2007)

He first quotes from the IPCC, who say:

‘Projecting changes in climate due to changes in greenhouse gases 50 years from now is a very different and much more easily solved problem than forecasting weather patterns just weeks from now. To put it another way, long-term variations brought about by changes in the composition of the atmosphere are much more predictable than individual weather events.’ [from page 105]

Dr Pielke’s comments:-

“This is a remarkable claim, and forms the basis of the entire IPCC concept. The hypotheses that need to be tested to support their claim (and which should have been presented in Chapter 1 of the IPCC Report) are discussed on the Climate Science weblogs: [….]” Dr Pielke goes on:-

“[This] is such an absurd, scientifically unsupported claim, that the media and any scientists who swallow this conclusion are either blind to the scientific understanding of the climate system, or have other motives to promote the IPCC viewpoint. The absurdity of the IPCC claim should be obvious to anyone with common sense” [emphasis added].
---------
4. Now, Dr Pielke’s comments on trends in temperature:-

Does The 2007 IPCC Statement For Policymakers Accurately Present The Observations Of Recent Global Temperature Trends?
(10th May 2007)

Again, he first quotes from the IPCC report, which says:

‘Eleven of the last twelve years (1995 -2006) rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850)’ [based on ‘The average of near surface air temperature over land, and sea surface temperature.’].
and
‘Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures…’

Dr Pielke’s own comments:-

“This claim, which is repeated throughout the media reports on the IPCC report…is disingenuous. Other analyses of global heat system changes do not support the claim of continued warming of the climate system. [….]

1. Since about 2002 there has been NO statistically significant global average warming in the lower and middle troposphere,
and
2. Since about 1995 there has been NO statistically significant cooling in the stratosphere. […]”

In short, says Dr Pielke, the actual data from recent years do not match the models’ predictions:

“However, the neglect to include the recent lack of tropospheric warming and stratospheric cooling (both of which are predicted to continue quasi-linearly for the coming decades by the multi-decadal global climate models, except for major volcanic eruptions) results in a seriously biased report by the IPCC.” [emphasis added].
---------
The above are observations from a senior climate scientist on the scientific materials contained in the IPCC reports. As such, they are worth pondering by interested lay inquirers. I would even say these observations should be borne in mind when reading claims about the causes of predicted future changes in climate.

comments powered by Disqus

More Comments:

Sudha Shenoy - 5/29/2007

1. On his (highly professional) blog, Dr Pielke has had extensive discussions on how well climate models have predicted. The discussions _always_ (always) include citations to the relevant professional studies.

2. References to successful retrodictions would be very helpful. This is because: Geologists, who have found considerable changes in the climate, are of the opinion that the influences that determine these climate changes, are _not_ known.

Whit Blauvelt - 5/26/2007

The thing about climate models the good doctor is apparently ignoring is that they are routinely tested by doing retrospective predictions - by going back to a previous time, putting only the data available then into the model, and seeing how well its results correlate with what the climate actually did between that previous time and the present. It's a plain fact that the current state-of-the-art climate models handle that with more precision than the current state-of-the-art in day-to-day weather predicting models, in similar retrospective testing. Handwaving about the relative number of variables (which is a bit silly since there are in principle infinite variables involved in both cases) does nothing to explain away the quantified superiority of current climate models vis a vis weather models.

Sudha Shenoy - 5/26/2007

Sir John Maddox is not directly involved in climate studies. Study of the environment is distinct. Dr Pielke Sr _is_ directly involved in climate studies. He directly studies some of the many real-world influences on local/regional climate. So too the other scientists who are outside the climate consensus which is the basis for the IPCC. Hence my quotes from him.

Tim Sydney - 5/26/2007

Agreed, ...and some have. In particular Edwin Dolan. His views are summarised in the PDF here.

I don't agree with Sudha's use of the IPCC label. It is not all a matter of "to IPCC, or not to IPCC".

There are plenty of scientific supporters of the AGW hypothesis who disagree to varying degrees with the IPCC. It would be a mistake to assume all scientific or technical criticism of the IPCC amounts to an endorsement of the "business as usual". Some IPCC critics think it is too weak and others think it is too strong.

An example of a pro-AGW but anti-IPCC (too strong) position is John Maddox. At least that was his position circa 1997. (See here, page 5 for discussion of AGW).

Although I am not an economist, my guess is that AGW will ultimately end up being described in economics textbooks as a diseconomy of scale from atmospheric CO2 dumping as higher ratios are reached, combined with a commons mismanagement weakness in developing policy responses.

To date proposals for 'privatisation' of the atmospheric or oceanic commons has generally been a non-starter. One gets the impression that to date not even avid free marketeers take it seriously.

My guess is that it may require new technical and legal developments. Probably the development of a new body of atmospheric law, akin to common law or admiralty law. And the development of new technologies to allow more specific determination of pollution sources. Satellite and chemical surveillance technology is improving so this may be a new entrepreneurial opportunity. This may assist by lowering the transaction and information costs of bringing suit against specific polluters. Still this requires that the background legal structure needs to be one that reinforces rather than restricts private property. I don't imagine that Kyoto etc will do anything other than get a few politicians re-elected.

My guess is that AGW will have to become a more serious ecological and economic problem, and for a generation of statist attempts at a solution to be tried and fail before any serious free market effort is applied. Not a very optimistic scenario I'm afraid. At least AGW skeptics don't need to worry about this sort of stuff.

Sudha Shenoy - 5/26/2007

There is nothing to stop people who accept the IPCC's view, from putting forward free-market solutions. Unanimity is not required amongst free-marketeers.

Tim Sydney - 5/26/2007

I'm all for disputing the science, especially scientists disputing other scientists' science. For those of us who are not scientists some caution make sense. For every Galileo there are a hundred crackpots.

Maddox, who is certainly in a better position to evaluate different scientific viewpoints than I, says the burden of proof is on the AGW skeptics. He is saying that their science is not as good as that of the so called 'consensus'.

(It should be noted that the so called skeptics lack any 'consensus' among themselves too.)

Classical liberals would be well advised to take Maddox at his word and apply their principles to creatively resolving the issue rather than running their own pre-Galileo style belief driven agenda.

If classical liberals believe the whole AGW hypothesis is an example of corporate / state / environmentalist corruption of scientific process, go out and prove it. So far the critique is virtually all assertion no evidence. Maddox can hardly be considered a green alarmist.

The AGW hypothesis of itself will impoverish no one. It's the kind of policies that are implemented to deal with it that may or may not impoverish people. Classical liberals have a lot to offer to the policy debate, classical liberals as such have about nothing to add to the debate as to whether AGW is a real phenomenon or not. It's not our expertise. Let's say just as a thought experiment AGW is real. If we do nothing about it, it will possibly impoverish people too. And classical liberals presumably know that not all wealth is measured in dollars and cents. So there are other forms of impoverishment too besides a low per capita GDP.

I'm not saying that the AGW hypothesis might not be wrong. Frankly I hope it is wrong. I also hope that the biotic theory of the origin of petroleum is wrong too. Classical liberals need to consider where they and we will all be if the AGW hypothesis is right. The current "over-investment" by the classical liberal community in the AGW skeptic position will most probably turn around and bite us on the bum. And we will have no one to blame but ourselves.

Keith Halderman - 5/25/2007

You use the words "disputing the science" as if they were a bad thing. The whole history of human progress is based on disputing the science. When Galileo asserted that the earth revolved around the sun he was disputing the science. The burden of proof is on those who want to impoverish people in the name of global warming and despite the "consensus" they have not met that burden. They have not eliminated the other and to my mind much more logical causes.

Sudha Shenoy - 5/25/2007

1. I quote directly from Dr Pielke Sr's own website ('Main conclusions'):

"...IPCC [& others] have _overstated_ the role of....anthropogenic increase of CO2 relative to....the diversity of human climate forcing on global warming and....climate variability and change." [emphasis added].

I now paraphrase other of his conclusions: a. Human activities affect climate in many different ways. b. The IPCC do _not_ state properly that climate models _cannot_ forecast the full range of future climate possibilities.

It is always best to go direct, wherever possible, rather than look at secondary reports.

2. Informed decisions are better than uninformed ones. Even lay people can listen more intelligently if they have some idea of the _issues_ under debate. The majority, as we are told repeatedly (ever since 1990), are indeed the majority. They do have the numbers. That is why it is all the more necessary to pay attention to the _arguments_, observations etc of the minority. That is all the latter have; they cannot (by definition) have the numbers.

Tim Sydney - 5/25/2007

So does Professor Pielke dispute the CO2 - Anthropic Global Warming link?

Well not according to Wikipedia anyhow. Here is a quote:

"..the evidence of a human fingerprint on the global and regional climate is incontrovertible as clearly illustrated in the National Research Council report and in our research papers.."

If long range climate prediction were more difficult than weather prediction, there is no inherent reason why would this be an argument against policies aimed at mitigating or preventing AGW. If we don't know, we don't know.

Frankly if precise statistical modelling of the consequences of adding more CO2 to the atmospheric system was unknown, and if we know from historical experience that our past CO2 levels were safe, that is hardly reason to keep pumping CO2 into the atmosphere willy nilly.

In the absence of reliable climate modelling, then we would be forced to rely on whatever knowledge we do have. There is plenty of laboratory and other testing that reasonably predicts that, increased CO2, all else being equal, adds to average temperatures.

As economists know better than anyone, of course, ceteris paribus, "all else being equal" is the start of a tangle of woes. We know ceteris paribus that higher minimum wages create more unemployment. Yet we still advocate repeal of minimum wage laws. We don't say ceteris paribus, so lets keep them on. Repeal is what we recommend. And so we should.

There is still a lot to learn, but until we do have reliable long range climate modelling, then surely the appropriate policy course is one of climatic caution, not business-as-usual.

Whether or not the AGW hypothesis is true or not is a debate that is largely outside the purview of classical liberals and free marketeers per se. We don't weigh in as free marketeers on whether heart disease is caused by an unknown virus or stress. Nor should we.

The normal processes of scientific debate are the best system we have for resolving those issues. Classical liberals should not be in the business of "picking winners" in this debate.

Some highly qualified classical liberals like Robert Higgs, an economist and historian, for whom I have the highest respect, have highlighted some weaknesses in the peer review system.

Fair enough. Still none of these criticisms as yet amount to anykind of systematic quantified analysis, just commentary. Until critical evidence is supplied we have no particular reason to believe that normal science is systematically and critically malfunctioning.

Nor should classical liberals succumb to the Panglossian temptation to cherry pick from the diversity of scientific opinions to reinforce what they imagine is the softest policy option. If anything we need to be putting our heads around the hard cases more often.

At risk of sounding like a broken record, the free market community has for historically understandable reasons (namely past environmentalist alarmism and a healthy skepticism of the anti-AGW public policies so far proposed), but of themselves non-logical reasons, over-invested in the "climate skeptic" camp.

There is prima facie no reason from liberal economic theory why this should be so. Adam Smith would surely have recognised the planet's climate system as an unmanaged commons and presumably thus subject to the kinds of economic disorders unmanaged commons are prone to.

AGW is the atmospheric equivalent of over-grazing.

Over in the scientific community, most mainstream scientific opinion has moved on from the climate skeptic position. Sir John Maddox was the editor of "Nature" for decades. This journal has been the market selected standout. Maddox as editor was a specialist in evaluating scientific views from diverse disciplines. Maddox is no ecological alarmist, in fact he was author of "The Doomsday Syndrome", still one of the best rebuttals of environmentalist alarmism ever penned. Yet Maddox tells us the climate debate has now moved on to the point where it's the skeptics who have to prove their case, not the AGW supporters.

There is the hypothesis that public choice factors may be distorting the objectivity of the scientific community on AGW. Still despite the claim being oft repeated there remains remarkably little empirical analysis or study of this hypothesis. Surely if this is important someone should go out and pull in the evidence. Until then it remains something of a gripe, a "just so" story.

Until and if the skeptics manage to overthrow the AGW hypothesis, and they aren't there yet, (despite some scientifically interesting hypotheses like the cosmic ray / climate idea that has become popular of late) it would be prudent if free marketeers concentrated their energies on devising effective and reliable policy responses to AGW. We can all agree that the policies proposed by various governments to date are woeful. Hopefully classical liberals can formulate policies that enhance individual freedom. That approach would seem to me to be more productive and useful, than disputing the science.

Gus diZerega - 5/24/2007

http://environment.newscientist.com/channel/earth/climate-change/dn11654

http://environment.newscientist.com/channel/earth/climate-change/dn11649