The insanity of exhorting humankind to quit advancing and prospering on the basis of computer models of the climate

Mike Jonas at Watts Up With That makes this abundantly clear.  

The fourth IPCC report [para 9.1.3] says : “Results from forward calculations are used for formal detection and attribution analyses. In such studies, a climate model is used to calculate response patterns (‘fingerprints’) for individual forcings or sets of forcings, which are then combined linearly to provide the best fit to the observations.”

To a mathematician that is a massive warning bell. You simply cannot do that. [To be more precise, because obviously they did actually do it, you cannot do that and retain any credibility]. Let me explain :

The process was basically as follows

(1) All known (ie. well-understood) factors were built into the climate models, and estimates were included for the unknowns (The IPCC calls them parametrizations – in UK English : parameterisations).

(2) Model results were then compared with actual observations and were found to produce only about a third of the observed warming in the 20th century.

(3) Parameters controlling the unknowns in the models were then fiddled with (as in the above IPCC report quote) until they got a match.

(4) So necessarily, about two-thirds of the models’ predicted future warming comes from factors that are not understood.

Now you can see why I said “You simply cannot do that”: When you get a discrepancy between a model and reality, you obviously can’t change the model’s known factors – they are what they are known to be. If you want to fiddle the model to match reality then you have to fiddle the unknowns. If your model started off a long way from reality then inevitably the end result is that a large part of your model’s findings come from unknowns, ie, from factors that are not understood. To put it simply, you are guessing, and therefore your model is unreliable.

He then enumerates the factors that comprise the global climate, briefly describing each one, and then offers this chart showing how well each is understood and the extent to which they affect predictive models.

Factor	Understood?	Contribution to models’ predicted future warming
ENSO	No	0%
Ocean Oscillations	No	0%
Ocean Currents	No	0%
Volcanoes	No	0%
Wind	No	0%
Water Cycle	Partly	(built into Water Vapour, below)
The Sun	No	0%
Galactic Cosmic Rays (and aerosols)	No	0%
Milankovich cycles	No	0%
Carbon Dioxide	Yes	37%
Water Vapour	Partly	22% but suspect
Clouds	No	41%, all highly suspect
Other (in case I have missed anything)		0%

And the Pope and the Most Equal Comrade and Naomi Klein would have our entire species drastically change its way of living and halt its upward trajectory based on this?