Wednesday, November 30, 2011

Oh, fudge: ClimateGate email--"Tuning may be a way to fudge the physics"

ClimateGate FOIA grepper! - Email 636

Solution 1: fudge the issue. Just accept that we are Fast-trackers and can therefore get away with anything.

[Hat tip: M. Hulme]

Email 5175-Tom Wigley - 2004

In any simple global formula, there should be at least two clearly identifiable sources of uncertainty. One is the sensitivity (d(melt)/dT) and the other is the total available ice. In the TAR, the latter never comes into it in their analysis (i.e., the 'derivation' of the GSIC formula) -- but my point is that it *does* come in by accident due to the quadratic fudge factor. The total volume range is 5-32cm, which is, at the very least, inconsistent with other material in the chapter (see below). 5cm is clearly utterly ridiculous.

Email 5054, Colin Harpham, UEA, 2007

I will press on with trying to work out why the temperature needs a 'fudge factor' along with the poorer modelling for winter.

Email 1461, Milind Kandlikar, 2004

With GCMs the issue is different. Tuning may be a way to fudge the physics. For example, understanding of clouds or aerosols is far from complete - so (ideally) researchers build the "best" model they can within the constraints of physical understanding and computational capacity. Then they tweak parameters to provide a good approximation to observations. It is this context that all the talk about "detuning" is confusing. How does one speak of "detuning" using the same physical models as before? A "detuned" model merely uses a different set of parameters that match observations - it not hard to find multiple combinations of parameters that give the similar model outputs (in complex models with many parameters/degrees of freedom) So how useful is a detuned model that uses old physics? Why is this being seen as some sort of a breakthrough?

Email 1047, Briffa, 2005

We had to remove the reference to "700 years in France" as I am not sure what this is , and it is not in the text anyway. The use of "likely" , "very likely" and my additional fudge word "unusual" are all carefully chosen where used.

Email 723, Elaine Barrow, UEA, 1997

Either the scale needs adjusting, or we need to fudge the figures...

Briffa_sep98 code

2.6,2.6,2.6]*0.75 ; fudge factor
if n_elements(yrloc) ne n_elements(valadj) then message,'Oooops!'


LuboŇ° Motl said...

Fascinating! A great keyword to search for: almost all the hits are priceless. ;-)

Ben M said...

Check this one out:

From email 1256735067

At 16:54 27/10/2009, Michael Mann wrote:

thanks Phil,
Perhaps we'll do a simple update to the Yamal post, e.g. linking Keith/s new
page--Gavin t?
As to the issues of robustness, particularly w.r.t. inclusion of the Yamal series, we
actually emphasized that (including the Osborn and Briffa '06 sensitivity test) in our
original post! As we all know, this isn't about truth at all, its about plausibly
deniable accusations,