cc: Tim Osborn <t.osbornatXYZxyz.ac.uk>, Keith Briffa <k.briffaatXYZxyz.ac.uk>
date: Sun, 22 Jun 2003 21:01:40 -0400
from: "Michael E. Mann" <mannatXYZxyzginia.edu>
subject: Re: Yang et al
to: "Raymond S. Bradley" <rbradleyatXYZxyz.umass.edu>, firstname.lastname@example.org, email@example.com, wigleyatXYZxyzr.ucar.edu
I'm in Volcano national park on my Honeymoon, so comment will be brief, by necessity...
In our GRL article, Phil and I weighted the records we used with respect to their decadal
correlations with the instrumental gridpoint surface temperature data for the same region
(numbers in parentheses in attached figure 1 from the paper), so if a series is truly crap
in an objectively determined sense, it got very low weight. The China series has a
reasonable (r=0.22), but not great correlation--and it gets a moderate low weight.
In my opinion, this is a better approach then simply deeming a record crap a priori (and
then getting criticized for not considering it). We considered all available records with
appropriate resolution that are putative temperature estimates, and weighted them
We also did careful cross-validation on the resulting reconstruction using independent
instrumental data, etc.---so I hardly think we are subject to criticism in how we used the
available data, relative to other analyses that have been done...
As for the Eos piece, I think a similar point holds--not showing it at all would seem a
conspicuous omission. We could add the local correlation values to each of the panels of
Figure 2, and comment briefly--this could be done at the proof stage.
I'll leave this to Phil (or Keith or Tim, who are helping out since Phil is also on
vacation) to take care of, as I have promised not to get involved with this sort of stuff
until my honeymoon is over. Phil and I can discuss this, if need be, when we meet in
Sapporo in a couple weeks,
At 06:37 PM 6/22/2003 -0400, Raymond S. Bradley wrote:
You commented that the Chinese series of Yang et al (GRL 2002) looked weird. Well,
that's because it's crap--no further comment on what stuff gets into GRL!
You appear to have used their so-called "complete" China record. You really should
consider what went into this --2 ice core delta 18O records of dubious relationship to
temperature (one is cited as correlating with NW China temperatures at r=0.2-0.4), 3
tree ring series, one of which is a delta C-13 record of questionable climatic
significance (to be generous). The other series include two records from a Taiwan
lake--a carbon/nitrogen isotope and a total organic carbon series (interpreted as
high="warm, wet") and an oxygen isotope series from cellulose in peat!!! (& don't ask
about the C-14 based chronology, interpolated to decadal averages!)
I loved this sentence:
"Although a quantitative relationship between the proxy records of the Jinchuan peat,
the Japan tree-ring series and the Taiwanese sediment records with modern climate data
are not given in the original works, the qualitative connectivity with temperature as
the dominant controlling factor has undoubtedly been verified"
Oh, undoubtedly!! And these are 4 of the 9 series going into the "complete China"
Finally, they use another record based on "phenology" and (somehow) this provides a
winter temperature series....
You just shouldn't grab anything that's in print and just use it 'cos it's there---that
just perpetuates rubbish. This series needs to be removed from Figure 2 in the EOS
forum piece--and if you included it in your GRL paper, I suggest that you reconsider it.
Raymond S. Bradley
Director, Climate System Research Center*
Department of Geosciences
Morrill Science Center
611 North Pleasant Street
AMHERST, MA 01003-9297
*Climate System Research Center: 413-545-0659
Paleoclimatology Book Web Site: http://www.geo.umass.edu/climate/paleo/html
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
e-mail: mannatXYZxyzginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137
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