Climate Change: The Facts by Alan Moran

Author:Alan Moran [Moran, Alan]
Language: eng
Format: epub
Publisher: Stockade Books
Published: 0101-01-01T00:00:00+00:00

Are the alarming forecasts the product of scientific forecasting methods?

The IPCC forecasts are derived from the judgments of the scientists that the IPCC engages. Computer modellers write code to represent the scientists’ judgments that, in turn, provides long-term forecasts of global mean temperatures. Is this use of expert judgment a valid approach to climate forecasting?

For nearly a century, researchers have been studying how best to make accurate and useful forecasts. Knowledge on forecasting has accumulated by testing multiple reasonable hypotheses about which method will provide the best forecasts in given conditions. This scientific approach contrasts with the folklore that experts in a domain will be able to make good forecasts about complex uncertain situations using their unaided judgement, or using unvalidated forecasting methods.8

Scientific forecasting knowledge has been summarised in the form of principles by 40 leading forecasting researchers and 123 expert reviewers. The principles summarise the evidence on forecasting from 545 studies that in turn drew on many prior studies. Some of the forecasting principles, such as ‘provide full disclosure’ and ‘avoid biased data sources,’ are common to all scientific fields. The principles are readily available in the Principles of Forecasting handbook.9

We used that knowledge to assess whether the procedures described in the ‘Climate Models and their Evaluation’ chapter of 2007 IPCC Assessment report amounted to scientific forecasting.10 To do so, we first examined that IPCC chapter’s references to determine whether the authors had relied on validated forecasting procedures. We found no references to validation. We then sent emails to all of the authors of that section for whom we were able to obtain email addresses,11 asking for references for credible forecasts of global average temperatures and the methods used to derive them. The few useful responses we received referred us to the ‘Climate Models and Their Evaluation’ chapter or to works that were cited in it.

We then audited the IPCC forecasting procedures using the Forecasting Audit Software available on ForPrin.com. Our audit found that the IPCC followed only seventeen of the 89 relevant principles that we were able to code using the information provided in the 74-page IPCC chapter. Thus, the IPCC forecasting procedures violated 81 per cent of relevant forecasting principles.12

It is hard to think of an occupation for which it would be acceptable for practitioners to violate evidence-based procedures to this extent. Consider what would happen if an engineer or medical practitioner, for example, failed to properly follow even a single evidence-based procedure.

We analysed the IPCC’s forecasting procedures to assess whether they followed the Golden Rule of Forecasting. The Golden Rule of Forecasting requires that forecasters be conservative. This means that they should use procedures that are consistent with knowledge about the situation and about forecasting methods. The Golden Rule is the antithesis of the common anti-scientific attitude that ‘this situation is different,’ which leads forecasters to ignore cumulative knowledge.

The Golden Rule is a unifying theory of how best to forecast. The theory has been tested for consistency with the evidence in a review of the literature from all areas of forecasting that found 150 studies relevant to the Golden Rule.

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