Paul H made the following statement in the context of the Swindle discussion:
If a practising scientist selected a 1987 data set over more recent versions, failed to cite it correctly, altered the appearance of the data without a clear explanation and didn’t include the data from the last 20 years then I think we’d all be asking serious questions about their professionalism.
One would think that that would be the case in most scientific fields, but in paleoclimate when the Team is involved, the option is to make the scientist a lead author in IPCC AR4. I’ve shown the truncation of the Briffa MXD reconstruction in IPCC TAR previously. I’m in the process of doing an updated post showing this even more vividly. In the process of doing so, I wanted to show the exact effect of the truncation by reproducing the IPCC TAR spaghetti graph with the untruncated Briffa MXD reconstruction.
This is not all that easy to do, since the archived version of the MXD reconstruction in Briffa et al is truncated in 1960 as well. However, there’s just enough information available that I was able to able to emulate the Briffa et al MXD calculation for use in this diagram. This post gives some working notes on that emulation. Continue reading
I’ve found an unlikely ally in my questioning of the smoothing of MBH99 in the original publication and in IPCC TAR: Keith Briffa.
Not that Briffa has posted a comment endorsing my observation. However, the smoothed version of MBH99 in Briffa et al 2001 (near contemporary with TAR) is virtually identical to what I got.
A CA reader has sent me a digitization of the MBH99 smooth and I’ve attempted to reverse-engineer the weights in the filter to yield the reported smooth. Even with reverse-engineering I’m unable to replicate the Swindlesque S-curve in the Mannian 20th century smooth (by “Swindlesque” here, I mean a curve showing a noticeable mid-century decline).
As I re-examined the IPCC TAR spaghetti , I noted that there was considerable evidence in Figure 2-21 that the Maestro himself is in the house and we should therefore be prepared for the unexpected.
There is an interesting replication problem in the TAR spaghetti graph where I’d welcome ideas. Here’s the TAR spaghetti graph (their Figure 2-21). On the right is a blow-up of the right side, which I’ve shown before. In the blow-up, you’ll notice that the Briffa MXD series and two other dark-colored series come into the blade of the hockey stick, but only two series come out. Hey, it’s the Team and you have to watch the pea under the thimble. The Briffa MXD series in this graphic ends about 1960, In the citation (Briffa 2000), it continues on to 1994 with a very large divergence. But more on this on another occasion. I want to focus on a smaller problem right now.
The smoothing in these series was said to have been done using a 40-year Hamming filter with 25-years end-point padding. Briffa would have used a gaussian filter. The use of a Hamming filter indicates to me that the Maestro is in da house.
[Update Aug 29, 2014/ Jean S: Steve’s surmise was correct. The CG1 letter 0938108842.txt reveals that the figure below was plotted by Ian Macadam based on data prepared by Mann. Additionally, notice a small detail that went unnoticed at the time: although the full (black) and the latitude restricted (blue) versions of MBH9X are very similar, the full version has the Swindlesque S-curve (as termed in the next post) in the 20th century where as the latitude restricted version resembles more like an upside-down U. The reason is that the trick was not used for the latitude restricted version, and that curve is essentially showing how the end of the MBH99 smooth would look like without the trick.]
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Figure 2-21 from IPCC TAR. Comparison of warm-season (Jones et al., 1998) and annual mean (Mann et al., 1998, 1999) multi-proxy-based and warm season tree-ring-based (Briffa, 2000) millennial Northern Hemisphere temperature reconstructions. The recent instrumental annual mean Northern Hemisphere temperature record to 1999 is shown for comparison. .. All series were smoothed with a 40-year Hamming-weights lowpass filter, with boundary constraints imposed by padding the series with its mean values during the first and last 25 years.
Below is a plot of the Jones 1998 and MBH99 series downloaded from WDCP MBH99 Jones98 using a 40-year Hamming filter (See script below) and 25-year end-period padding. I’ve used the native Jones 1998 centering as archived and re-leveled the MBH99 version by subtracting the difference between the MBH instrumental means between 1902-1980 (The native version ) and 1961-1990 (the IPCC version), a re-leveling of 0.165 deg C.
This results in a variety of small and medium-sized discrepancies:
1. the smooths of the Jones 1998 versions don’t match as the emulation is a little smoother than the IPCC version. For example, , if you look at the 19th century portion of the Jones series, there’s a little up-bump in the IPCC version in the 19th century that is smoothed in the emulation using Hamming 40-year smooth.
2. the smooths of the MBH99 versions don’t match, but in this case there’s an opposite discrepancy, as the emulation is a little smoothed than the IPCC version. In the 13th century, in my emulation, there are 3 bumps using a 40-year Hamming filter, while in the IPCC version, there are two bumps.
3. the MBH re-leveling using the instrumental mean differences doesn’t work. The late 11th century high is further from the zero line in the emulation than in the IPCC version.
4. But the most interesting difference is in the modern portion of the MBH series. In my emulation, the far right hand portion levels off with even a slight decline, while in the IPCC version, it has a high in the 1930s, a Swindle-esque decline in the 1960s and ends on an increase. Using the difference of means to re-level, the 0 mark isn’t reached by MBH. So their re-leveling amount was not equal to the difference in the instrumental means. If it’s not the difference of instrumental means, then what was it?
These replication difficulties are more good evidence that the Maestro is in da house.
Figure 2. 40-year Hamming filter applied to archived versions of MBH99 and Jones 98.
Through some experimentation, I can get a fairly close replication of the IPCC version of Jones 1998 by using a truncated 50-year truncated gauss filter, as shown below. The other mysteries remains. Ideas welcomed. Maybe Bob Ward can explain the provenance of this figure. The good part is going to be re-visiting the Briffa series.
Jones 1998 smoothed with 50-year truncated gauss filter; MBH99 with 40-year Hamming filter as before, re-leveled by 0.16 deg C).
UPDATE: The IPCC smooth is visually identical to the smooth in MBH99, which is shown below (the smooth is a little hard to read but it’s there and it visually matches the IPCC version). It’s described in MBH99 as a 40-year smooth with no further particulars.
Figure from MBH99.
Theres another version of this smooth on the NOAA website in connection with Mann et al 2000, shown below here. IT shows the smooth fairly clearly.
From NOAA website in connections with Mann et al 2000.
Here’s a straightforward implementation of a 40-year Hamming filter on the MBH data in the same format as the NOAA version (1400-1980 here which is a little easier to read,) Aside from the 20th century being a type of plateau to gentle decline – lacking the mid-century decline observable in the smoothed version, the replicated smooth does not reach the same values as shown in the MBH smooth. For example, their smooth ends at a value of 0.2, while the emulation levels off at 0.1, Here I’ve plotted actual MBH reconstruction values without swamping them with an instrumental overlay as in the MBH graphic. It’s very difficult to see how the reconstructed values can by themselves – regardless of filter – close at a value of 0.2 deg C. I experimented with a shorter filter to see if the characteristic shape of the MBH smooth could be replicated – nope, Also the level of the 20th century doesn’t reach the MBH smooth levels.
There was an exchange between Mann and Soon et al over end-point padding. Three of the most standard boundary methods for showing a smooth are: no padding; padding with mean over (Say) half the bandwidth; reflection. Mann has used a Mannian method in which he reflects vertically about the last value. In the graphic below, I’ve shown the Mannian method as well and it makes negligible difference in this case. You can barely see the tweak at the end. So end-period methodology has nothing to do with it.
Emulation of MBH smooth using 40-year Hamming filter (red); 20-year Hamming filter (blue)
As an experiment, I tried grafting the post-1980 instrumental record onto the reconstruction and see what that did to the smooth (through end-value influence.) (On an earlier occasion last year, we observed that MBH98 Figure 7 included a graft of the instrumental record onto the reconstruction, By doing this, I was able to get the closing value up to the level of the MBH smooth, but the shape of the 20th century record still didn’t match.
Experiment with graft of MBH99 1981-1998 instrumental values
So I tried one more variation: I grafted the instrumental record for 1902-1998 onto the reconstruction up to 1901. This further improved the replication of the MBH smooth version, but the exact topology of the MBH smooth version remains elusive.
Splicing instrumental record for 1902-1998 to reconstruction up to 1901.
As to whether Mann grafted the instrumental record onto the reconstruction in the calculation of the MBH smooth version illustrated in IPCC TAR, Mann himself commented on the more general issue of grafting instrumental records onto reconstructions as follows:
No researchers in this field have ever, to our knowledge, “grafted the thermometer record onto” any reconstruction. It is somewhat disappointing to find this specious claim (which we usually find originating from industry-funded climate disinformation websites) appearing in this forum.
I’ve been trying since 2003 to get detailed sample information from Lonnie Thompson on his tropical ice cores, some drilled 20 years ago. I reported on my most recent effort on Apr 19, 2007 under PNAS policies here.
Thompson has once more obfuscated a journal by falsely telling them that everything already is archived (without providing links), which the journal has duly retailed to me. I think that the journal editor should have been able to tell that Thompson was unresponsive, but I’ve written back one more time, providing a trail by which the journal can validate for itself that Thompson’s answer was false and unresponsive.
I was planning a new post on the truncation of the inconvenient 20th century downturn in the Briffa 2001 graphic in the IPCC graphic, that I observed some time ago here. Since data truncation is in the news, I was going to update the graphic in this post to better show just how cynical the IPCC truncation was (and will still do so.)
In the course of doing so, I thought that I’d check Briffa’s correlation claims and, surprisingly or unsurprisingly, found that my calculations were consistently lower than his. Also that the correlations over the full period of overlap were lower than the reported correlations over 1880-1960.
If you want one more inhomogeneity in station records, it seems that temperature measurements have been whitewashed – literally. The Stevenson screens used to be painted with whitewash which is a calcium carbonate with very specific infrared absorption properties. I gather that whitewash isn’t used much any more and so screens are routinely painted with modern white paint, which has very different infrared absorption properties. See here. Maybe Phil Jones should be collecting tree rings instead.
CA reader Geoff Sherrington, an Australian scientist, sends the following email exchange with Phil Jones in early 2006 (original post here). Geoff observes:
there is a reluctance to answer direct questions with direct answers and a lot of red herrings thrown in. Readers can deduce what they like from the exchange, where Phil says he no longer has the data used in early papers. Contrast this with the statement next from Australia’s Bureau of Meteorology (Blair Trewin, April 2006 email to me):
The first complaint by RMS (and others) against Swindle seems to be about their handling of the Hockey Stick. A new complaint from someone at the University of Bristol includes a spaghetti graph, including MBH, saying that it shows that the newer reconstructions use “superior methods”, “supersede” the earlier results and that the old IPCC 1990 version was “wrong”. They assert:
Seemingly, TGGWS uses the old versions of the reconstructions because, in the context of the program, they support the notion that the current warming trend is small by comparison to the medieval warm period. Their failure to cite this more advanced and recent work is puzzling, misleading and wrong.
I think that most of the Swindle battles are a waste of time because I don’t think that either side has played their cards very well.
In this case, I think there was a very powerful story line connecting the IPCC 1990 graphic to the Hockey Stick – one which Ross and I have used in presentations on several occasions. Had Swindle followed this exposition, I think that, on the one hand, it would have been a much better exposition and, on the other hand, it would not have been open to complaint about biased use of obsolete versions.
On the other hand, the complainants are opening up the entire Hockey Stick issue, which is a lousy issue for them. Imagine trying to defend Mannian methodology as an improvement on anything.
Think about the following storyline (or any subset of it) as an alternative to the present situation.
Continue reading
Climate Audit 
Nature Blog Withdraws Invitation
Yesterday I mentioned that we had been invited to make a post at the Nature blog. The invitation was withdrawn today. On May 10, we received the following invitation:
We immediately accepted the invitation. On May 11, von Storch and Zorita posted more personal criticism, to which I did not respond, because of the apparent opportunity to post our view of the matter in more temperate terms. On May 14, I mentioned this invitation on the blog yesterday. One day later on May 15, I received the following message:
The curious viewpoint of von Storch and Zorita in this blog entry has hardly been “hashed out” at length elsewhere. There have been only two posts to the von Storch thread during the past week, which have hardly “dominated” discussion at their blog. Since the issue has not “dominated” discussion at the blog, it is hard not to wonder whether someone higher up in the Nature organization specifically intervened to ask the blog editor to withdraw our invitation and to further wonder whether Nature received any communications urging that this invitation be withdrawn.