From: "Michael E. Mann" ,,,Subject: RE: IPCC revisions Date: Wed, 22 Sep 1999 12:35:24 -0400Alleged CRU Emails - Searchable
Walked into this hornet's nest this morning! Keith and Phil have both raised some very good points. And I should point out that Chris, through no fault of his own, but probably through ME not conveying my thoughts very clearly to the others, definitely overstates any singular confidence I have in my own (Mann et al) series.
...I had been using the entire 20th century, but in the case of Keith's, we need to align the first half of the 20th century w/ the corresponding mean values of the other series, due to the late 20th century decline.
So if Chris and Tom (?) are ok with this, I would be happy to add Keith's series. That having been said, it does raise a conundrum: We demonstrate (through comparining an exatropical averaging of our nothern hemisphere patterns with Phil's more extratropical series) that the major discrepancies between Phil's and our series can be explained in terms of spatial sampling/latitudinal emphasis (seasonality seems to be secondary here, but probably explains much of the residual differences). But that explanation certainly can't rectify why Keith's series, which has similar seasonality *and* latitudinal emphasis to Phil's series, differs in large part in exactly the opposite direction that Phil's does from ours. This is the problem we all picked up on (everyone in the room at IPCC was in agreement that this was a problem and a potential distraction/detraction from the reasonably concensus viewpoint we'd like to show w/ the Jones et al and Mann et al series.
So, if we show Keith's series in this plot, we have to comment that "something else" is responsible for the discrepancies in this case. Perhaps Keith can help us out a bit by explaining the processing that went into the series and the potential factors that might lead to it being "warmer" than the Jones et al and Mann et al series?? We would need to put in a few words in this regard. Otherwise, the skeptics have an field day casting doubt on our ability to understand the factors that influence these estimates and, thus, can undermine faith in the paleoestimates. I don't think that doubt is scientifically justified, and I'd hate to be the one to have to give it fodder!
[J Shukla] Is "model democracy" a valid scientific method? The "I" in the IPCC desires that all models submitted by all governments be considered equally probable.Alleged CRU Emails - Searchable
From: Phil Jones To: Tom Wigley , Ben Santer Subject: Re: help please Date: Tue Oct 6 13:35:34 2009
GISS is inferior - not just because it doesn't use back data. They also impose some
urbanization adjustment which is based on population/night lights which I don't think is
I think you can say that GISS is inferior to CRUTEM3. In Ch 3 of AR4 I put the station number counts in.
GISS and NCDC have more, but almost all of this is more data in the US. Their non-use of a
base period (GISS using something very odd and NCDC first differences) means they can use
very short series that we can't (as they don't have base periods) but with short series it
is impossible to assess for homogeneity.