This important dataset was left out of climate analysis because if you want the Medieval Warm Period to disappear, and you want a hockey stick at the end showing “unprcedented” warming…then you can;t possibly have data like this included.
Climate Audit explains:
[T]he Law Dome series was discussed by IPCC authors in the preparation of AR4. Their Southern Hemisphere graphic showed two proxies: Cook’s Tasmanian and Oroko Swamp NZ tree ring chronologies. As noted a few days ago, these two proxies are the only two proxies in the medieval portion of the Gergis et al network. So despite its claims to novelty, there is nothing new in its medieval portion.
A Climategate email shows that Phil Jones asked about the omission of the Law Dome series from the IPCC illustration in the AR4 First Draft. I asked the same question about the AR4 Second Draft. They realized that the Law Dome graphic had an elevated medieval period and thus, including it in the graphic would – to borrow a phrase from the preparation of AR3 – would “dilute the message” and perhaps provide “fodder to skeptics”. CRU’s Tim Osborn, expert in such matters, proposed that they discuss Law Dome in the running text (thus providing themselves deniability), but not illustrate Law Dome in the graphic (since a picture was worth a thousand words.) CLA Overpeck endorsed Osborn’s sly ‘solution”, sneering at the supposed lack of expertise at even raising the “ambiguity” in the first place:
Hi Tim, Ricardo and friends – your suggestion to leave the figure unchanged makes sense to me. Of course, we need to discuss the Law Dome ambiguity clearly and BRIEFLY in the text, and also in the response to “expert” review comments (sometimes, it is hard to use that term “expert”…). Ricardo, Tim and Keith – can you take care of this please. Nice resolution, thanks.
In making this proposal, Osborn observed (CG2 3092. 2006-07-18)
(2) Goosse et al. showed Deuterium excess [for Law Dome] as an indicator of Southern Ocean SST (rather than local temperature). Goosse et al. also showed a composite of 4 Antarctic ice core records (3 deuterium, 1 O18). Neither of these comes up to the 20th century making plotting on the same scale as observed temperature rather tricky!