Which is, wittily, Yamal backwards. The shape of this is now becoming clearer; I think it is safe to post.
I first ran across this in The Torygraph, which is worthless, but appears to be based on climateaudit.org/?p=7168. RC ripped into this but its a bit snarky (unlike me, obviously) and perhaps doesn’t make the main points all that clearly. And then we have Briffa’s statement.
So those main points are:
1. MBH ’98 doesn’t use the Yamal series in question. This isn’t too surprising, since it was first used in Briffa (2000). RC points this out. The Torygraph, above, failed to notice that, as did rather a lot of other people. Lots of other reconstructions don’t use it either. That leaves the “ah, but this proves that all the tree ring and all the climate folk are a bunch of fraudsters” nonsense but I think that is of no interest; if you think otherwise, usenet is over there.
2. Even those reconstructions that did use Yamal are, presumably, using it as only one series out of many. You could replace it with a flat line and (again, presumably) not change the overall reconstruction much. I notice that McI disagrees on this point, asserting that If the non-robustness observed here prove out… this will have an important impact on many multiproxy studies that have relied on this study. But he provides no evidence for that assertion that I can see.
3. [This one I'm less sure of, so don't quote me] So we’re down now to the (scientifically perhaps interesting, but in the great scheme of things fairly minor) issue of what the Yamal series ought to look like. McI (once he has got past the insinuations) says, if you add in a whole pile of other trees, then it goes flat. But this is a problem, because we know that the temperature there has increased recently – there are meteorological observations – so a series that goes flat isn’t reporting reality (again, if you’re one of the “but all GW is from UHI” then off you go). As I understand it (and I could be wrong) part of the process of generating a tree-based proxy series is to select only series that actually provide useful proxies over a training period (or similarly, to weight the contributions to the resulting composite by correlation over the training period), which would be the instrumental record (though only up to 1960, because after then there is the embarassing “divergence problem“). If your tree doesn’t do that, it gets thrown out or de-weighted. Which would presumably explain why all McI’s extra trees were thrown out – they aren’t recording temperature in a useful manner. [Also, Deep Climate has an email from H+S saying Briffa got it right; somewhere else I saw more detail on this... (updated) Ah, I was remembering BCL, who links to DC].
The moral of all this is that Peer Review is a good idea, and that getting your science from non-reviewed sources (even ones as august as this humble blog) is a bad idea. That isn’t to say that Blog Science is automatically bad – blog authors should be able to find reviewers too – but it enables bad habits. McI should have put his stuff into something like Climate of the Past where the open review process would have been very interesting to watch. Instead, we have a vast storm in a tea cup and when this all blows over (as it looks rather likely to, if it hasn’t already) a lot of time will have been wasted and mud thrown but no useful information generated.
Other stuff you want to read Cruel Mistress strokes the bunny who in turn hands you on to CIP to do my part 3, but I don’t think he really does. Incidentally, I don’t think see any reason why McI should make his own series.
[Update: point 3 remains the interesting bit. Bradley and Jones (Climate since 1500, chapter 1) say: There are 3 important steps in dendroclimatic reconstruction: (1) Standardization... (2) Calibration... (3) Verifictication. On (2), they say "Once a master chronology of standardized indices of some tree growth parameter... the net step is to relate this to variations in climatic data... The equation is developed over a period known as the calibration period..." -W]
[Late update: http://www.cru.uea.ac.uk/cru/people/briffa/yamal2009/]