I showed a little while ago the impact of the Polar Urals update on the Briffa 2000 reconstruction – using it instead of the Yamal substitution resulted in an MWP index higher than the 20th century.
Today I’ve done the same calculation for Jones et al 1998, this time substituting the Polar Urals update using additional 1998 information (from Esper et al 2002) for the earlier Briffa version. I’d more or less surmised this, but the beauty of using the Esper version is that I don’t have to argue or justify my RCS calculation, since Esper’s already done it.
With the Polar Urals update, the 20th century Jones et al 1998 index is no longer higher in the 20th century than the MWP. This is from merely replacing one series with an update used in a later multiproxy study.
Top – Archived version; bottom – with updated Polar Urals version using my emulation of Jones et al 1998 methods.
The medieval portion of D’Arrigo et al uses almost the same roster as Briffa 2000 (all but one series.) Although they had no access to the Yamal data, as discussed before, they substituted the Yamal series for the Polar Urals update (which they calculated.) So it will almost certainly follow the same pattern as Briffa 2000 where the Polar Urals update has a similar effect relative to the Yamal substitution.
Esper et al (obviously) used the Polar Urals update and still claimed higher modern levels (although he had the warmest MWP). How did this happen? Just speculating for now, but Esper used TWO foxtail series. At this point, I have no idea how Esper got to his final answer. I’m going to average the sites (I’m trying to decide what to do about the missing Mongolia data – this is the sort of stuff that stalls analysis).
What do you want to bet that he needs both foxtail series to drag down MWP values? I’m going to check that soon. You can see why it was such a fight getting data from Esper. He’s probably more aware than anyone that he’s had to use two foxtail series to offset the Polar Urals update and probably knew long before me where I’m going to get to once I get into his data.
So you can see where I’m going with this. I’m going to test the impact of the Polar Urals Update and the bristlecones on all the "other " studies. There are many problems, but this will be a nice unifying theme that one can reduce to a journal soundbite. For the Team, the problem with the lack of "independence" of the various studies is that the entire corpus becomes vulnerable to a problem in one of the common series.
Leaving Moberg aside (which stands or falls on different issues), if IPCC were hypothetically assigning likelihood to whether the modern or MWP periods are warmer based on this sort of data, essentially they are taking an opinion on whether the Polar Urals Update or the Yamal Substitution is a more accurate thermometers – an issue on which there has been precisely ZERO discussion in the specialist literature.
The Yamal Substitution was accomplished sub rosa by Briffa, without any exposition of the issues. I don’t see how IPCC can take any view on relative MWP-modern warmth without an informed view on the Yamal substitution.