Re: [asa] Level of certainty in science

From: Don Winterstein <>
Date: Thu Feb 08 2007 - 02:39:16 EST

On the face of it one of the more disturbing things about trust in climate scientists' predictions is their record or lack thereof on forecasts. We know how to do hindcasts, and after fiddling endlessly with them they can look impressive. But forecasts--if accurate--are where the payoff will be. How good are climate scientists at forecasting anything? To my knowledge they have no record.

If so, by taking the forecast capabilities of their models seriously we'd be sticking our necks out for people who have essentially no record of either success or failure. That would make me nervous if I were betting a lot on their being correct.


  ----- Original Message -----
  From: PvM<>
  To: Don Winterstein<>
  Cc: asa<>
  Sent: Tuesday, February 06, 2007 8:48 PM
  Subject: Re: [asa] Level of certainty in science

  You are correct that skepticism about models is good. However, models
  do not exist in a vacuum but rather take existing data from the past
  and use hindcasts as well as forecasts to validate the performance. In
  addition, climate models are based on laws of physics and while they
  may miss relevant processes, climate models are well founded in
  Sure, all these models may be wrong and the earth may end up cooling
  and the scientists may look foolish, on the other hand the earth may
  actually follow the predictions and who would look foolish then?
  Science is never certain and global warming is no exception but there
  are good or even strong reasons to believe that these predictions are
  quite valid.

  <quote>For example, the Program for Climate Model Diagnosis and
  Intercomparison at Lawrence Livermore National Laboratory has been
  conducting model comparison and validation tests since 1989 (including
  the climate models used by the IPCC), and published a publicly
  available report of its research in the summer of 2004. [see<> ]</quote>

  IPCC is also involved in validation of models and I believe that most
  scientists understand that models are supplementary to other
  scientific data and cannot stand alone.<>

  AR4 draft also shows the hard work done here:<>
      * Executive Summary
      * Advances in Modeling
      * Evaluation of Contemporary Climate as Simulated by Coupled Global Models
      * Evaluation of Large Scale Climate Variability as Simulated by
  Coupled Global Models
      * Evaluation of the Key Relevant Processes as Simulated by Coupled
  Global Models
      * Model Simulations of Extremes
      * Climate Sensitivity
      * Evaluation of Model Simulations of Thresholds and Abrupt Events
      * Representing the Global System With Simpler Models

  <quote>There is considerable confidence that climate models provide
  plausible quantitative estimates of future climate change,
  particularly at continental scales and above. Confidence in these
  estimates is higher for some climate variables (e.g. temperature)
  than for others (e.g. precipitation). This confidence comes from the
  foundation of the models in accepted physical principles and from
  their ability to reproduce observed features of recent climate (see
  Chapters 8, 9) and past climate changes (see Chapter 6). In this
  summary we highlight areas of progress since the TAR:

  On 2/6/07, Don Winterstein <<>> wrote:
> Pim Van Meurs wrote: "What is so scary about science being correct once
> again? If one
> believes this to be scary, imagine how scary it could be when
> Christians, as Augustine pointed out, are observed spouting scientific
> nonsense?"
> Who's got more to lose here? The climate data may be fairly firm, but the
> models, from which scientists make predictions, are likely much less
> trustworthy. They're Earth science models, after all. If Earth starts
> cooling within a few decades--as it's been known to do, climate scientists
> and other scientists by association will lose credibility for a long time to
> come.

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Received on Thu Feb 8 02:38:12 2007

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