More here at ICECAP
Roger Pielke Sr also has a post about this on his climate science weblog, where Steve McIntyre has posted this comment:
“I have made my 3rd request for access to GISS source code to try to decode what they do. They have refused prior requests. Lack of access to source code makes this sort of exercise far more time consuming than it ought to be.
Yesterday they completely overwrote their US data set, changing virtually every number prior to 2000, explaining this only with a cursory comment on their webpage. In addition, they have changed their UHI adjustments so that in many cases the changed UHI adjustments offset the error in their “raw” data.
Even before these change, I was unable to track their pre-2000 data to any archive. It was sort of like USHCN adjusted data in the 1990s but diverged in earlier periods. I’ve requested a copy of the original data set or information on its provenance.
I would welcome letters to GISS urging them to fully disclose their source code.
BTW the CRU situation is much worse as they have refused to even identify the stations that they use. In fairness to GISS, they provided enough information that you could leverage on it, but CRU has resolutely refused such information. ”