Last year 232 people answered a questionnaire distributed by a committee set up to investigate the Intergovernmental Panel on Climate Change (IPCC). I’ve been examining the answers provided by a subset of these people – the IPCC authors, review editors, and overall project coordinators known as bureau members.

None of them were specifically asked for their opinions about climate models. Nonetheless, some used this questionnaire as an opportunity to express concern.

But first, a little background. Climate models are central to the notion that the world is in danger due to human-generated CO2. No climate models predicting potential bad things in the future, no cause for alarm. It’s pretty much that simple.

But what are climate models, exactly? Meteorologist Roy Spencer has spent 40 years studying climate. He’s one of those big bad climate skeptics you may have heard of – and the recipient of NASA’s Exceptional Scientific Achievement Medal for his work on temperature-monitoring satellites. Back in 2009 he wrote a great blog post titled How Do Climate Models Work? In his words:

Generally speaking, a climate model is a computer program mostly made up of mathematical equations.

Climate modellers attempt to simulate the real world in order to gain insight. But Spencer warns that these simulations have profound limitations:

even if a climate model handled 95% of the processes in the climate system perfectly, this does not mean the model will be 95% accurate in its predictions. All it takes is one important process to be wrong for the models to be seriously in error.

Now here’s another observation about climate models. It’s from Freeman Dyson – who happens to be one of the world’s most eminent physicists (in addition to being a climate skeptic):

I have studied the climate models and I know what they can do. The models solve the equations of fluid dynamics, and they do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields and farms and forests. They do not begin to describe the real world that we live in.

The real world is muddy and messy and full of things that we do not yet understand. It is much easier for a scientist to sit in an air-conditioned building and run computer models, than to put on winter clothes and measure what is really happening outside in the swamps and the clouds. That is why the climate model experts end up believing their own models.

So what did IPCC insiders spontaneously say about climate models? The first significant discussion appears on page 97 of a 678-page PDF (names were removed before these questionnaire answers were made public). There’s some technical jargon here, but the gist of this IPCC contributing author’s concern shines through nevertheless (all bolding added by me):

With regards to climate models, their deficiencies are airbrushed. We never see the actual temperatures simulated by the models, only their deviations, hiding fundamental problems of the model temperature simulations. There are no agreed upon metrics for evaluating climate models. (p. 97)

A few pages later, this person adds:

All climate models used in the IPCC assessment reports should undergo a formal validation and verification process, accompanied by clear documentation. Not just scientific publications, but actual manuals and documentation that are publicly accessible. The strengths, weaknesses and limitations of climate models and codes need to be stated explicitly and unequivocably. [sic] People are left with the impression that the 21st century simulations are actual climate predictions, and they are not. (p. 99)

That last theme is picked up nearly 100 pages later, when a coordinating lead author observes:

At the current time, [IPCC reports too often produce] flattened views of the world, where unreasonably high precision and confidence is accorded outcomes from numerical models which have known limitations, while use of information from other sources is not accorded equivalent status (where merited), and questions related to structural uncertainties in models are almost entirely ignored.” (p. 183)

In other words, even though the models have shortcomings, the IPCC appears to favour model results over information that comes from alternative sources.

Now for some further spontaneously-volunteered observations:

The current process of the IPCC has elevated global climate model outputs to a level of authority that the modelers themselves cannot be comfortable with. (p. 332)

The modelers have a particular feeling that their models are the TRUTH, and they do not properly recognize that the models are very limited in scope and in terms of processes included. The resolution is yet far too coarse, and the parameterizations used make the model results very uncertain, and the modelers and the IPCC report do not recognize this properly. (p. 374)

Many results described in [Working Group 2] are based on very limited studies, simulations with just one model, etc, that do not faithfully represent the range of uncertainty. This also makes the whole IPCC Report inconsistent: whereas the Report by [Working Group 1] includes results achieved with climate simulations performed by a whole suite of climate models, [Working Group 2] is much more limited and includes conclusions that are not valid when the full suite of IPCC climate models is considered (p. 383)

According to an insider, therefore, the IPCC places its trust in climate model results despite the fact that these models have never been systematically validated. This is a bit like boarding a cruise ship before anyone has confirmed that it’s seaworthy.

Four separate people express concern that the IPCC places too much faith in climate model simulations, given their well-known shortcomings. These individuals think the IPCC has not been upfront and honest about climate model weaknesses. In the words of one person, “deficiencies are air-brushed.” In the words of another, uncertainties are “almost entirely ignored.”

So how exactly did we arrive at our present situation? Governments around the world are now convinced CO2 emissions are dangerous and that drastic steps must be taken to curtail these emissions. And where did they get this idea? From computer models that even IPCC insiders say are uncertain, unreliable, and unvalidated.


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