Here are some excerpts from the IPCC's guidance papers concerning the Third Assessment Report. While you should be careful about taking things like this out of their original context, I hope that this will show that I'm not completely crazy when I say that the Earth Simulator models and their results are flawed.Â
"Attempts to achieve more consistency in assessing and reporting on uncertainties have not received much attention. Some researchers have expressed concern that it is difficult to even know how to assign a distribution of probabilities for outcomes or processes that are laced with different types of uncertainties."
"The term "uncertainty" can range in implication from a lack of absolute sureness to such vagueness as to preclude anything more than informed guesses or speculation. Sometimes uncertainty results from a lack of information, and on other occasions it is caused by disagreement about what is known or even knowable. Some categories of uncertainty are amenable to quantification, while other kinds cannot be sensibly expressed in terms of probabilities."
"It is certainly true that "science" itself strives for objective empirical information to test theory and models. But at the same time "science for policy" must be recognized as a different enterprise than "science" itself..."
"Problems with data
1. Missing components or errors in the data
2. "Noise" in the data associated with biased or incomplete observations
3. Random sampling error and biases (non-representativeness) in a sample
Problems with models
4. Known processes but unknown functional relationships or errors in the structure of the model
5. Known structure but unknown or erroneous values of some important parameters
6. Known historical data and model structure, but reasons to believe parameters or model structure will change over time
7. Uncertainty regarding the predictability (e.g., chaotic or stochastic behavior) of the system or effect
8. Uncertainties introduced by approximation techniques used to solve a set of equations that characterize the model.
Other sources of uncertainty
9. Ambiguously defined concepts and terminology
10. Inappropriate spatial/temporal units
11. Inappropriateness of/lack of confidence in underlying assumptions
12. Uncertainty due to projections of human behavior"
"Thus, poorly managed projected ranges in impact assessment may inadvertently propagate uncertainty. The process whereby uncertainty accumulates throughout the process of climate change prediction and impact assessment has been variously described as a "cascade of uncertainty" or the "uncertainty explosion". When an assessment progresses from the biogeochemical cycle to radiative forcing and climate sensitivity calculations through to economic and social outcomes, including valuations of climate damages, considerable uncertainty can be accumulated."
"Thus many estimates or outcomes will be affected not only by uncertainties in their immediate substantive domain, but also by uncertainties in the scenarios or parameters generated in other areas of research."
"Strictly speaking, a surprise is an unanticipated outcome. However, in the IPCC Second Assessment Report (SAR), "surprises" were defined as rapid, non-linear responses of the climatic system to anthropogenic forcing... Strictly speaking, it would be better to define these as imaginable abrupt events."
"Overconfidence is a cognitive illusion that has been reported to bias experts' judgments. A considerable amount of evidence has been amassed for the view that people suffer from an overconfidence bias. The common finding is that respondents are correct less often than their confidence assessments imply."
Guidance Papers for the Third Assessment Report of the IPCC
The full document may be found here: http://www.ipcc.ch/pub/xcutting.pdf.
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