Via Noel Sheppard, the guys who exposed the big data bug in the NASA temperature calculations last week have now responded to the global warming believers who naturally downplayed the error and dismissed it as irrelevant to GW trends. No commentary here from me; just follow the drill from the last post and read Steve McIntyre’s and Warren Meyer’s posts slowly and carefully. The bullet points version of McIntyre to guide you as you go:

1. NASA and James Hansen have allegedly shown an astonishing amount of bad faith in protecting their bogus numbers. Last week’s posts noted how secretive Hansen has been in hoarding the algorithm he uses to make temperature adjustments, but most of McIntyre’s wrath this time is reserved for NASA, which pointedly declined to mention prominently that it had revised its own data lest it attract any unwelcome public attention.

2. While the revisions to U.S. data didn’t have an affect on global averages, they did obviously have a “significant” effect on U.S. averages while pointing up potential errors in data collection worldwide. Specifically, according to McIntyre, not only are certain U.S. temperature measurement stations that are thought to be unreliable being “adjusted” by algorithm, even stations not thought to be unreliable may be undergoing adjustment. Quote:

The USHCN station history adjustments appear particularly troublesome to me, not just [at the Grand Canyon] but at other sites (e.g. Orland CA). They end up making material changes to sites identified as “good” sites and my impression is that the USHCN adjustment procedures may be adjusting some of the very “best” sites (in terms of appearance and reported history) to better fit histories from sites that are clearly non-compliant with WMO standards (e.g. Marysville, Tucson). There are some real and interesting statistical issues with the USHCN station history adjustment procedure and it is ridiculous that the source code for these adjustments (and the subsequent GISS adjustments – see bottom panel) is not available/

3. The flip side of the last point: how many global measurement stations are unreliable and are not undergoing adjustment? Quote again:

[M]any of the stations in China, Indonesia, Brazil and elsewhere are in urban areas (such as Shanghai or Beijing). In some of the major indexes (CRU,NOAA), there appears to be no attempt whatever to adjust for urbanization. GISS does report an effort to adjust for urbanization in some cases, but their ability to do so depends on the existence of nearby rural stations, which are not always available. Thus, ithere is a real concern that the need for urban adjustment is most severe in the very areas where adjustments are either not made or not accurately made.

Meyer makes a similar point about what systemic problems in U.S. data collection and adjustment portend for global measurements. As he put it last week, “This is not the end but the beginning of the total reexamination that needs to occur of the USHCN and GISS data bases.” Which explains his first recommendation now.

Now go read McIntyre, making sure to stay with him through the devastating conclusion.