I have just noticed an article by Jeff Id at “WattsUpWithThat” that says the BEST project analysing global temperature records – does this – “They detect steps in the data, chop the series at the steps and reassemble them.”
Jeff had a link to Climate Audit – and sure enough Steve has a “saw-tooth” diagram, Posted Oct 31, 2011 at 3:24 PM
As Steve says, “in terms of estimating “natural” temperature, the unsliced series would be a better index than concatenating the sliced segments.” Dead right.
As far as I can tell, this diagram expresses exactly what the two GISS diagrams did in 2001 – see from Hansen, J.E., R. Ruedy, Mki. Sato, M. Imhoff, W. Lawrence, D. Easterling, T. Peterson, and T. Karl 2001. A closer look at United States and global surface temperature change. J. Geophys. Res. 106, 23947-23963, doi:10.1029/2001JD000354. and a pdf can be downloaded.
I have a page here explaining the thing –
Also a blog post.