Geoscience Reference
In-Depth Information
of the forecasts. To that end, we examine whether or not the IPCC's forecasts of dangerous
manmade global warming are the product of scientific methods.
We then investigate whether alternative hypotheses of climate change provide more
accurate forecasts than the dangerous manmade global warming hypothesis. Specifically,
we test forecasts from the hypothesis of global cooling and from the hypothesis of climate
persistence.Wethenmakeforecastsofglobalaveragetemperaturesfortheremainingyears
of the twenty-first century and beyond using an evidence-based forecasting method.
Finally, we ask whether the IPCC forecast of dangerous manmade global warming is a
new phenomenon. To answer this question, we use the method of structured analogies to
seek out and analyse similar situations.
Are the alarming forecasts the product of scientific forecasting methods?
TheIPCCforecastsarederivedfromthejudgmentsofthescientiststhattheIPCCengages.
Computermodellerswritecodetorepresentthescientists'judgmentsthat,inturn,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
usefulforecasts.Knowledgeonforecastinghasaccumulatedbytestingmultiplereasonable
hypotheses about which method will provide the best forecasts in given conditions. This
scientificapproachcontrastswiththefolklorethatexpertsinadomainwillbeabletomake
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
theforecastingprinciples,suchas'providefulldisclosure'and'avoidbiaseddatasources,'
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
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
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.
