I had nothing to do with the Swindle presentation, and by and large the issues presented in Swindle are ones that I have not discussed here. I’m discussing these issues merely because it’s in the news.
A few days ago, I discussed the accusation by RMS and the 37 profs that Swindle had not used Hansen global data and that the 1940-mid 1960s decline in Swindle was greater than in Hansen data. As shown here, these claims were incorrect; given the demand by RMS and the 37 profs for due diligence, I expressed surprise that they would have made an allegation which could be shown to be invalid with minimal investigation.
A similar situation is discussed here in their claims about the course of sulphate emission, where the claim as articulated in the RMS letter is readily shown to be inconsistent with the discussion in the recent IPCC AR4 Second Draft, which was available at the time.
In their complaint about Swindle’s discussion of the mid-20th century temperature decline, RMS and the 37 profs objected that Swindle failed to discuss the theory that increased sulphate aerosol emissions over-rode the impact of CO2 in the period of decline, and that clean-up of sulphate emissions in the 1980s eliminated this offset.
The OFCOM code requires that there be no misrepresentation of “facts or views”. RMS said that the failure to mention the sulphate theory was a misrepresentation of the “scientific evidence”. There’s an interesting legal issue in the change of wording here – the regulation refers to “facts and views”, while the complaint refers to “scientific evidence”.
Is there a difference? Lawyers pay attention to such details and are governed both by the letter of the law and the letter of the complaint. While this sort of distinction is not relevant to scientific discussion, it may well prove relevant to any hearings that are ultimately held on this complaint.
In terms of scientific disclosure, as I’ve noted before, I firmly believe that scientists are obliged to disclose adverse results and, for example, would welcome initiative by RMS and the 37 profs to investigate the withholding of adverse verification r2 statistics, censored bristlecone results and things like that in a study that continues to be cited in the U.K. insurance industry, as John A recently observed in connection with Lloyds of London.
But let’s turn instead to the RMS letter. In a legal complaint about inaccuracies in Swindle, one would expect meticulous accuracy, but once again in their statements about sulphates, RMS and the 37 profs make claims in their complaint that are inaccurate according to the recent IPCC AR4 [Second Draft which was available at the time].
“It has been well-established in the scientific literature that the period of cooling that was most evident over North America and Europe between about 1940 and 1976 was largely due to increased concentrations of aerosols (particularly sulphates) released into the atmosphere by industrial processes, such as the combustion of coal. These aerosols lowered the amount of solar radiation reaching the Earth’s surface, for instance by scattering sunlight. The concentrations of these aerosols have been shown to be highest in the Northern Hemisphere, close to their industrial sources. A paper by David Stern, published in the journal Chemosphere’ in 2005, showed that sulphurous emissions around the world increased sharply between 1945 and about 1989, since when they have declined markedly. Sulphurous emissions peaked in North America and Europe during the 1970s.
However the IPCC Fourth Assessment Report Second Draft chapter 2, page 30, says:
However, over the same period SO2 emissions have been increasing significantly from Asia which is estimated to currently emit 17TgSyr-1 (Streets et al., 2003) and from developing countries (e.g., Boucher and Pham, 2002). The net result of these combined regional reductions and increases leads to uncertainty in whether the global SO2 has increased or decreased since the 1980s (Lefohn et al., 1999; Van Aardenne et al., 2001; Boucher and Pham, 2002),
Why would RMS allege so categorically that sulphate emissions “declined markedly” after 1989, when the contemporary AR4 draft says that no one can say whether there has been an increase or decrease. This is the sort of over-reaching that discredits their complaint.
Update- The IPCC AR4 Final Version changes this section in an interesting way. The mention of uncertainty as to whether sulphate emissions went up or down is removed. Be that as it may, obviously leading specialists in April 2006 said that they were uncertain. It would be interesting to know what evidence was brought to their attention between April 2006 and April 2007 to change their minds. Ian Castles in comments below points out inconsistencies between chapter 2 and later chapters.
However, over the same period SO2 emissions have been increasing significantly from Asia, which is estimated to currently emit 17 TgS yr—1 (Streets et al., 2003), and from developing countries in other regions (e.g., Lefohn et al., 1999; Van Aardenne et al., 2001; Boucher and Pham, 2002). The most recent study (Stern, 2005) suggests a decrease in global anthropogenic emissions from approximately 73 to 54 TgS yr—1 over the period 1980 to 2000, with NH emission falling from 64 to 43 TgS yr—1 and SH emissions increasing from 9 to 11 TgS yr—1. Smith et al. (2004) suggested a more modest decrease in global emissions, by some 10 TgS yr—1 over the same period. The regional shift in the emissions of SO2 from the USA, Europe, Russia, Northern Atlantic Ocean and parts of Africa to Southeast Asia and the Indian and Pacific Ocean areas will lead to subsequent shifts in the pattern of the RF (e.g., Boucher and Pham, 2002; Smith et al., 2004; Pham et al., 2005).
End Update May 7.
The reference to increased sulphate emissions in China poses another interesting question. We’ve spent some time looking at Chinese station data. During the period from 1954-1983 (the period of the Jones et al 1990 urban heat island effect study), there was negligible increase in Chinese temperatures. There was also negligible economic growth. In the 1990s, there has been explosive economic growth in Chinese, tremendous increases in aerosol and sulphate emissions – which presumably should cause local cooling – and a sharp increase in Chinese gridcell temperatures in HadCRU. While Phil Jones has thus far refused to disclose the station data used in HadCRU3 despite several FOI requests, my guess is that the stations with post-1990 information in HadCRU3 will prove to be predominantly from places like Beijing, Shanghai, Lanzhou etc. A recent article [cite…] has attributed the majority of the Chinese temperature increase to UHI.
I haven’t gone through the aerosol literature which has rapidly become vast. I’ve examined the statistics in two studies involving aerosols, both of which had major problems and both of which are widely cited in climate literature.
Previously I discussed Mann and Emanuel 2006, which purported to prove that aerosols caused the fact that the variance in SSTs in the eastern tropical Atlantic (the “main development region” for Atlantic hurricanes) was less than global variance. An alternative and much more plausible explanation is that variance in tropical oceans is less than variance in extratropical oceans (as seen for example in the ECHO-G GCM) all by itself. So aerosols were invoked here to explain a phenomenon that actually needed no such explanation. It does illustrate (one more time) that spurious results can result from regressions between co-trending series.
A second example is the discussion of MBH98 Figure 7, here here and here. This article purported to establish claims about the respective contributions of solar and CO2 forcing. In the earlier posts, we established that the article contained untrue statements – which to this date have not been corrected. However, for the purposes of the discussion of Swindle’s failure to discuss aerosols, let us merely observe that MBH98 likewise failed to include aerosols in their calculations. According to the RMS letter, the aerosol theory was “well-established” at the time that MBH98 was published. Did RMS or any of the 37 profs complain at the time about this failure? Why not? IPCC cited the results from MBH98 Figure 7, again without adversely commenting on its failure to include or discuss aerosols.
Now I haven’t studied the issues related to aerosols in any detail. I am not here venturing any opinion on the truth or falsity of the aerosol theory for the mid-century temperature, (which does however seem a little, shall we say, “convenient”). My main point here is that the RMS letter, publicly endorsed by the 37 profs, all supposedly experts in climate science, contains a statement about the course of sulphate emissions that is trivially seen to be inconsistent with the recent IPCC AR4 Second Draft view on the matter.
Update: I’ve collated Stern’s SO2 emission data in a tab-separaed ASCII file http://data.climateaudit.org/data/stern/so2.dat . Here is a plot of Chinese and Indian data to 2000 – this is not a cumulative graphic – each is separate. Chinese emissions in the early 2000s were said to be lower than 1988. I have no opinion on whether this makes sense or not, but it seems like it would be worth someone cross-checking.