Hansen has just released what is said to be the source code for their temperature analysis. The release was announced in a shall-we-say ungracious email to his email distribution list and a link is now present at the NASA webpage.
Hansen says resentfully that they would have liked a “week or two” to make a “simplified version” of the program and that it is this version that “people interested in science” will want, as opposed to the version that actually generated their results.
Reto Ruedy has organized into a single document, as well as practical on a short time scale, the programs that produce our global temperature analysis from publicly available data streams of temperature measurements. These are a combination of subroutines written over the past few decades by Sergej Lebedeff, Jay Glascoe, and Reto. Because the programs include a variety of
languages and computer unique functions, Reto would have preferred to have a week or two to combine these into a simpler more transparent structure, but because of a recent flood of demands for the programs, they are being made available as is. People interested in science may want to wait a week or two for a simplified version.
In recent posts, I’ve observed that long rural stations in South America and Africa do not show the pronounced ROW trend (Where’s Waldo?) that is distinct from the U.S. temperature history as well as the total lack of long records from Antarctica covering the 1930s. Without mentioning climateaudit.org or myself by name, Hansen addresses the “lack of quality data from South America and Africa, a legitimate concern”, concluding this lack does not “matter” to the results.
Another favorite target of those who would raise doubt about the reality of global warming is the lack of quality data from South America and Africa, a legitimate concern. You will note in our maps of temperature change some blotches in South America and Africa, which are probably due to bad data. Our procedure does not throw out data because it looks unrealistic, as that would be subjective. But what is the global significance of these regions of exceptionally poor data? As shown by Figure 1, omission of South America and Africa has only a tiny effect on the global temperature change. Indeed, the difference that omitting these areas makes is to increase the global temperature change by (an entirely insignificant) 0.01C.
So United States shows no material change since the 1930s, but this doesn’t matter, South America doesn’t matter, Africa doesn’t matter and Antarctica has no records relevant to the 1930s. Europe and northern Asia would seem to be plausible candidates for locating Waldo. (BTW we are also told that the Medieval Warm Period was a regional phenomenon confined to Europe and northern Asia – go figure.]
On two separate occasions, Hansen, who two weeks ago contrasted royalty with “court jesters” saying that one does not “joust with jesters”, raised the possibility that the outside community is “wondering” why (using the royal “we”) he (a) “bothers to put up with this hassle and the nasty e-mails that it brings” or (b) “subject ourselves to the shenanigans”.
Actually, it wasn’t something that I, for one, was wondering about it all. In my opinion, questions about how he did his calculations are entirely appropriate and he had an obligation to answer the questions – an obligation that would have continued even if had flounced off at the mere indignity of having to answer a mildly probing question. Look, ordinary people get asked questions all the time and most of them don’t have the luxury of “not bothering with the hassle” or “not subjecting themselves to the shenanigans”. They just answer the questions the best they can and don’t complain. So should Hansen.
Hansen provides some interesting historical context to his studies, observing that his analysis was the first analysis to include Southern Hemisphere results, which supposedly showed that, contrary to the situation in the Northern Hemisphere, there wasn’t cooling from the 1940s to the 1970s:
The basic GISS temperature analysis scheme was defined in the late 1970s by Jim Hansen when a method of estimating global temperature change was needed for comparison with one-dimensional global climate models. Prior temperature analyses, most notably those of Murray Mitchell, covered only 20-90N latitudes. Our rationale was that the number of Southern Hemisphere stations was sufficient for a meaningful estimate of global temperature change, because temperature anomalies and trends are highly correlated over substantial geographical distances. Our first published results (Hansen et al., Climate impact of increasing atmospheric carbon dioxide, Science 213, 957, 1981) showed that, contrary to impressions from northern latitudes, global cooling after 1940 was small, and there was net global warming of about 0.4C between the 1880s and 1970s.
Earlier in the short essay, Hansen said that “omission of South America and Africa has only a tiny effect on the global temperature change”. However, they would surely have an impact on land temperatures in the Southern Hemisphere? And, as the above paragraph shows, the calculation of SH land temperatures and their integration into global temperatures seems to have been a central theme in Hansen’s own opus. If Hansen says that South America and Africa don’t matter to “global” and thus presumably to Southern Hemisphere temperature change, then it makes one wonder all the more: what does matter?
Personally, as I’ve said on many occasions, I have little doubt that the late 20th century was warmer than the 19th century. At present, I’m intrigued by the question as to how we know that it’s warmer now than in the 1930s. It seems plausible to me that it is. But how do we know that it is? And why should any scientist think that answering such a question is a “hassle”?
In my first post on the matter, I suggested that Hansen’s most appropriate response was to make his code available promptly and cordially. Since a somewhat embarrassing error had already been identified, I thought that it would be difficult for NASA to completely stonewall the matter regardless of Hansen’s own wishes in the matter. (I hadn’t started an FOI but was going to do so.)
Had Hansen done so, if he wished, he could then have included an expression of confidence that the rest of the code did not include material defects. Now he’s had to disclose the code anyway and has done so in a rather graceless way.