Mining The Source Code

In the last post we saw that accusers are willing to quote mine the released CRU emails, selectively taking a choice phrase at face value and missing the preceding and proceeding context in the longer email.

Now we will see them doing similar with some of the released CRU source code. The released source code included source for some of CRU's surface temperature record and source code for some proxy work.  No climate model source code was released as far as I know, although that hasn't stopped many of the accusers rampantly assuming there has been - presumably either confusing or not knowing the difference between temperature records and climate models.

This post concerns the an accusation which is now spread far and wide all over the internet.

Here is one example:

http://esr.ibiblio.org/?p=1447

Here's the code and comments in question:

;
; Apply a VERY ARTIFICAL correction for decline!!
;
yrloc=[1400,findgen(19)*5.+1904]
valadj=[0.,0.,0.,0.,0.,-0.1,-0.25,-0.3,0.,- 0.1,0.3,0.8,1.2,1.7,2.5,2.6,2.6,$
2.6,2.6,2.6]*0.75 ; fudge factor
if n_elements(yrloc) ne n_elements(valadj) then message,’Oooops!’
;
yearlyadj=interpol(valadj,yrloc,timey)

The accusers point to the words "very artificial", "fudge factor" and to the nature of what is being done. 

yrloc is assigned a 20 element array, the first value starts at 1400, the second at 1904 and the rest increment by 5 until 1994. Ie 1400, 1904, 1909, 1914, ... 1994. They are obviously years.

valadj is another 20 element array, you can see the values it is assigned above in the line "fudge factor". The 'Oooops!' message is displayed if the number of elements in the yrloc and valadj arrays are different. They shouldn't ever be according to the code, this line was probably added in as a first pass safety check and not subsequently removed.

yearlyadj=interpol(valadj,yrloc,timey)

I have to guess a little here (I don't know IDL), but I think this is producing an array yearlyadj to hold an adjustment value for every year since 1400, derived by interpolating yrloc over valadj

Despite so many accusers citing this snippet of code, they amazingly fail to mention (or perhaps notice?) that directly following this snippet is:

;filter_cru,5.,/nan,tsin=yyy+yearlyadj,tslow=tslow
;oplot,timey,tslow,thick=5,color=20
;
filter_cru,5.,/nan,tsin=yyy,tslow=tslow
oplot,timey,tslow,thick=5,color=21

The top line contains yyy+yearlyadj. This is the only place where the previously created adjustment array is used, I presume (I don't know IDL, the language used here) that yyy contains each years temperature data and that this is adding the adjustments to the temperature data to produce the plot. But notice at the start of that line is a semi-colon. That line is commented out, inactivated. The lines that are used instead do not contain the use of yearlyadj and therefore do not apply the adjustment, they only plot yyy.

Of course it would be trivial to switch the comments around and activate the adjustment, but as the accusers are relying on a face-value interpretation of the source code they should fall by such silliness.

They haven't even shown their quoted adjustment was used, let alone what it's purpose is. A proper analysis of this would require knowing what the adjustment was based on (it clearly isn't arbitrary), why it was done (perhaps nothing more than an experiment), and not to forget - whether it was even used at all in published results.

It's not difficult for me to point out why the accusations of fraud are misplaced. All I have to do is point out that they have insufficient evidence. Come back with better, if you can. I am surprised they haven't picked up on the mispelt "artifical", surely that beggars belief - true scientists wouldn't spell words wrong! Quick to the blogs!

Isn't it surprising some of the same people who demand so much evidence when faced with the science behind manmade global warming are surprisingly relaxed at placing accusations of fraud with such a dearth of evidence?