Complex Models and The Impact of CO2

Here is a challenge laid down by Steve McIntyre
http://www.climateaudit.org/?p=3361#comment-282602
"I think that it is important for people in the field to write out a careful “engineering quality” exposition of how doubled CO2 leads to 3 deg C in which all the key parameterizations and feedbacks are written down and described."

Modelling is on the horns of a dilemma. A simple model can't predict the detailed fluctuations.

A complex model may start to predict the *phenomena* of these detailed fluctuations (ie. You get El Nino) but may fail to predict numerically what fluctuations will take place when. As soon as you try to predict the complex details, the additional assumptions introduced will have their own uncertainty and that may well destroy the predictive power in itself.

Climate prediction is therefore astoundingly difficult *in theory*.

What the *practice* is like is a different matter; it's hard to know.

My impression of climate models is good but based on poor evidence(I haven't personally worked on climate models). Its done in the UK by the Hadley Centre, part of the Met Office who are well funded and have to make testable predictions every day. I have also been impressed by those I have seen presenting from the UK (e.g. Peter Cox).

Some have argued that all personal scientific understanding is a sort of model. See discussion of the Lucidity Principle by Michael McIntyre (Prof of Atmospheric Science at Cambridge) http://www.atm.damtp.cam.ac.uk/people/mem/

In general I think it is necessary to build up a hierarchy of models which are themselves scientific understanding, from the very simplest Stefan-Boltzmann Radiative Balance. The books I have/has (I've given some of them away) and recommend are:
  • 'A Climate Modeling Primer', which has a CD attached
  • 'Elementary Climate Physics' by Taylor
  • 'Global Warming: a complete briefing' by Sir John Houghton.
This in part is a solution to Steve McIntyre's request. He should read the books and outline a hierarchy of models himself.

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