In today’s post, I’ll connect an important conclusion in the draft AR5 report to an email exchange that is given extensive treatment in Climategate 2.0.
The Climategate 2.0 “editor” has greatly increased exposure of the campaign against Soon and Baliunas 2003, as a result of which the article was declared to be “discredited”. Efforts were even made by many prominent climate scientists (even Pachauri was copied on emails) to punish both the journal (Climate Research) and the editor (Chris de Freitas) for the temerity of publishing an article that was unacceptable to Mann, Jones and their posse.
Although the extended Team managed to persuade the wider community that Soon and Baliunas had conflated temperature and precipitation proxies, the actual text (when re-read) shows that that Soon and Baliunas had clearly distinguished between “extreme” precipitation events (an important issue in themselves) and temperature events. In their abstract, they stated:
Across the world, many records reveal that the 20th century is probably not the warmest nor a uniquely extreme climatic period of the last millennium.
“Extreme” in their usage is defined in terms of precipitation and can include either wet extremes or dry extremes (just as IPCC expresses concern about droughts and floods.) The distinction between “warmest” and “most extreme” is observed through the article, e.g.:
Fig. 3 shows that most of the proxy records do not suggest the 20th century to be the warmest or the most extreme in their local representations
However, the proxies show that the 20th century is not unusually warm or extreme.
The proxies analysed by Soon and Baliunas (including precipitation proxies) include many proxies that were not included in the then canonical multiproxy reconstructions (or for that matter in the AR4 reconstructions), including (for example): Stine’s tree stumps in California and Patagonia, Haug’s Cariaco sediments, Hodell’s Yucatan lake proxies, African lake proxies from Verschuren, Stott’s Warm Pool ocean sediments, South American geomorphological evidence (Cioccale and others), as well as more familiar proxies from the Northern Hemisphere extratropics that made up the MBH and other networks. (Ironically some of the Soon and Baliunas proxies are used in Mann et al 2008.)
Other specialists e.g. Briffa, Cook clearly understood that, despite Mann’s claims to have achieved a hemispheric (and even global) temperature reconstruction, Mann’s network did not actually contain qualifying information from the NH tropics – nor did the other AR4 reconstructions. Indeed, the MBH network for example did not contain any NH tropical proxies prior to AD1600. And the few NH tropical proxies in later periods included precipitation proxies, even including instrumental precipitation from two gridcells in India. As long-time CA readers are aware, Mann’s locations for his precipitation data are transposed. “The rain in Maine falls mainly in the Seine.” The provenance of the actual precipitation data for the gridcell containing Mumbai is unknown; the closest match that I could find was Philadelphia. But that’s another story.) The tropical values in Mann et al were extrapolated from extratropical proxies (more precisely, bristlecones).
An email from Briffa to Cook clearly demonstrates their recognition of the absence of tropical proxies in the IPCC networks:
June 17, 2002 (5055). I am sick to death of Mann stating his reconstruction represents the tropical area just because it contains a few (poorly temperature representative) tropical series. He is just as capable of regressing these data again any other “target” series , such as the increasing trend of self-opinionated verbage he has produced over the last few years , and … (better say no more) Keith
Wigley clearly recognized that Soon and Baliunas had raised valid issues in connection with precipitation proxies, but, instead of acknowledging valid points, conspired with the others to deny them any credit whatever. Wigley’s conduct here seems to me particular despicable. As a senior scientist, he should have been setting a good example to the younger scientists. In connection with the drafting of Mann et al (EOS), he wrote to the others:
June 5, 2003 (email 0682). By chance SB03 may have got some of these precip [sic] things right, but we don’t want to give them any way to claim credit.
In fact, the proxies listed above – ones that were used in Soon and Baliunas but not in the canonical AR4 multiproxy studies – went on to become widely used in recent studies of “medieval hydroclimate” e.g. Peterson and Haug 2006; Newton et al 2006 and a series of studies cited in IPCC AR5 Zero Draft: Graham et al 2007; Seager et al 2007; Herweijer et al 2007; Seager et al 2008; Graham et al 2010.
Like Soon and Baliunas, each of these later studies provides a narrative discussion of the proxies (rather than the sort of statistical “assimilation” demanded by Mann et al 2003). This literature describes a coherent change from the Medieval period to the Little Ice Age. Peterson and Haug 2006 and Newton et al 2006, for example, attribute the coherence to latitudinal migrations of the ITCZ, hypothesizing that it (and other patterns) was further north in the Medieval period and further south in the Little Ice Age, explaining antiphase changes in precipitation whereby northerly tropical sites became drier in the Little Ice Age (Cariaco, Yucatan etc 15N or so) while more southerly tropical sites became wetter in the Little Ice Age (Lake Titicaca, Lake Malawi, Quelccaya etc. all at 10S or so). The preferred explanation in the IPCC AR5 “Zero” draft is a combination of “modes” – El Ninos and NAO and AMO – that I find less attractive than the less favored ITCZ migration, but the proxy history is not disputed among the parties: the Seager et al and Graham et al articles rely on substantially the same proxy evidence as the Peterson and Haug/Newton et al articles.
The IPCC AR5 Zero Draft summarize the present evidence on precipitation extremes over the past millennium as follows:
Overall, multiple studies suggest that current drought and flood regimes are not unusual within the context of last 1000 years [(e.g., Cook et al., 2010; Seager et al., 2008; Graham et al., 2010)].
I expect that this finding is not one that will be heavily promoted by WWF or Greenpeace. It would have been nice if they had also cited Soon and Baliunas, who, as Wigley had recognized, had drawn a similar conclusion about precipitation from similar evidence.
I’m not suggesting that Soon and Baliunas 2003 was above criticism. However, the reaction of the climate community was out of proportion to its faults. (In contrast, when methodological defects in Mann et al 1998 were identified, defenders argued that the defects didn’t “matter” because you could “get” a similar answer in a different way or that it was a brave “first” attempt. No such indulgence was extended to Soon and Baliunas.)
In future posts, I intend to examine the proxies which led the IPCC to the conclusion that current flood and drought regimes were “not unusual” in a 1000-year context and a re-examination of the 2003 attack on Soon and Baliunas.