>Your description of the algorithm I implemented is correct. I only did it for the Mauna Loa CO2 data, not temperature, since you seemed to be focused on the green curve. There are some missing values. It could be done with the data sets RealClimate used too. I ran their script and it produced the relevant output without errors, so I’m not sure what’s going on with the one missing data set.

OK so diff12 is the annual difference of the annual average.
If I take the annual average for the co2 curve I will get an "average curve", i.e. a curve, around which the actual co2 curves oscillates.
If I take the annual differences of this curve of averages then similarily as for the annual difference of the values themselves
-by looking at the curve- I also expect a rather constant, slightly wiggly line.

Of course one could amplify the wiggles of this line (like by multiplying with a factor), but similarily as in the argumentation above
- but I don't see why these wiggles should be in necessarily in (lag)-correlation with the temperature values. So it would be important to get the temperature values.
It is strange that the program runs without the temperature data set. There is an if statement in the code, which seems to refer to another location, however the link there doesnt seem to refer to a dataset either: http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3gl.txt
Some hadcrut3 data seems to be here now: http://www.metoffice.gov.uk/hadobs/hadcrut3/data/download.html It's not clear to me though if this is the same data as used in Humlum et al or in the realclimate post.