Saturday, March 17, 2012


cc: Caspar Ammann <>,, Keith Briffa <>,,,,,, Scott Rutherford <>, Kevin Trenberth <>, Tom Wigley <>,
date: Thu, 09 Oct 2003 14:16:31 -0400
from: "Michael E. Mann" <>
subject: Re: draft
to: Tom Crowley <>

HI Tom,
My understanding of the papers from the borehole community ever since the 1997 GRL article
by Huang et al is that they no longer believe that the data has proper sensitivity to
variations prior to about AD 1500--in fact, I don't believe anyone in that community now
feels they can meaningfully go farther back that that. Huang contributed the section on
boreholes in chapter 2 for IPCC (2001), and wrote the very words to that effect...
Now, the possible influences on boreholes might lead to inferred trends in GST that are
different from those in SAT is a different one. A number of independent recently published
papers by (Beltrami et al; Stiglitz et al; Mann and Schmidt) and others have demonstrated
that there should be expectations for significant differences between past SAT (what we
care about) and GST variations (what boreholes in the best case scenario see) due to
snowcover influences, etc. We don't have time to discuss that in this very short piece, so
I tried, as briefly as possible, to cover our bases on this issue, in a way that doesn't
really stir up the pot w/ the borehole folks...
I'm interested in any further thoughts on the above,
At 12:38 PM 10/9/03 -0400, Tom Crowley wrote:

Hi, I don't understand why we cannot cite the borehole data for the MWP - that in a
sense is the only legitimate data set that shows a ~1 C cooling from the MWP to the LIA
- forget the deforestation problem for the moment, that is later in time -
if the borehole data for the MWP are legitimate then there is still a case for
concluding that the MWP was significantly warmer than the LIA

Thanks Phil,
a few brief responses and inquiries below...
At 04:17 PM 10/9/03 +0100, Phil Jones wrote:

Away Oct 11-16, so here are a few comments. A few times the tone could be a little
antagonistic. We don't want to inflame things any further. So remove the word laundry.

fair enough. You *should* have seen the first draft I wrote. This is quite toned down

1. With the boreholes do we want to get one of the borehole group to sign up, eg Henry
Would add a lot of weight to the last 500 year argument.

this has merit. unfortunately though I think it might open up a hornets nest of the
author list is not identical to the original list of authors on the Eos article. Other
thoughts on this...

2. On the UHI, there was a paper in a very recent issue of J. Climate by Tom Peterson,
for the USA that this is non-existent. Issue with UHI is one of large versus local
scale. One
station doesn't influence large-scale averages. All studies which look at the UHI
find very little effect (an order of magnitude smaller than the warming). Also the
in the 20th century is very similar between the NH and SH and between the land and

let me see if I can fit one or two sentences in on this and keep the article under the

Also, if we can't estimate temperature histories accurately, then SB can't say it
warmer in their MWP period. They believe the 20th century instrumental data when they
want to.

yes, one of a large number of amazing contradictions in their reasoning...

3. Keith is away till next week. I doubt we will have the space to do the 'tree issues'
Best just to say that there are an (equal) number of non tree-based proxy series??

I do think we need to address their spurious description of the putative biological
effects. Any way that you can get in touch w/ Keith for a response, perhaps just to
this one point? Also, Malcolm might want to comment on the current wording?

4. Ray, Malcolm and Henry Diaz have a Science Perspectives piece coming out in the next
couple of weeks on the MWP/E. This is also relevant.


5. Don't think we will get away with the last paragraph. Whether we want it is an issue
Shouldn't we be sticking to the science.

ok, I wasn't sure myself--yet it is a powerful rebuke, and reminds people that the
objection to the validity of their work goes beyond just our article--and that's
important. Does someone want to try to rephrase this paragraph, maybe reducing it to a
couple sentences?


At 21:37 08/10/2003 -0400, Michael E. Mann wrote:

Dear co-authors,
Attached is a draft response, incorporating suggestions Kevin, Tom W, and Michael. I've
aimed to be as brief as possible, but hard to go much lower than 750 words and still
address all the key issues. 750 words, by the way, is our allotted limit.
Looking forward to any comments. Feel free to send an edited version if you prefer, and
I'll try to assimilate all of the suggested edits and suggestions into a single revised
draft. If you can get comments to me within the next couple days, that would be very
helpful as we're working on a late October deadline for the final version.
Thanks for your continued help,
Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
e-mail: Phone: (434) 924-7770 FAX: (434) 982-2137

Prof. Phil Jones
Climatic Research Unit Telephone +44 (0) 1603 592090
School of Environmental Sciences Fax +44 (0) 1603 507784
University of East Anglia
Norwich Email

Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
e-mail: Phone: (434) 924-7770 FAX: (434) 982-2137


Thomas J. Crowley
Nicholas Professor of Earth Systems Science
Dept. of Earth and Ocean Sciences
Nicholas School of the Environment and Earth Sciences
Box 90227
103 Old Chem Building Duke University
Durham, NC 27708
919-684-5833 fax

Professor Michael E. Mann
Department of Environmental Sciences, Clark Hall
University of Virginia
Charlottesville, VA 22903
e-mail: Phone: (434) 924-7770 FAX: (434) 982-2137

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