Friday, December 30, 2011


From: Jonathan Overpeck <>
To: Darrell Kaufman <>, Nick McKay <>, Caspar Ammann <>, David Schneider <>, "Bette L. Otto-Bliesner" <>, Raymond Bradley <>, Miller Giff <>, Bo Vinther <>, Keith Briffa <>
Subject: Re: Arctic2k update?
Date: Sat, 05 Sep 2009 11:25:02 -0700
Cc: <>

D et al - Please write all emails as though they will be made public.
I would not rush and I would not respond to any of them until the best strategy is
developed - don't want to waste anyone's time, including yours or Mc's. Since the recon in
Science has an error, I think you do need to publish a correction in Science. In that, you
can very briefly not it didn't affect the calibration, nor the final result. I don't think
you have a choice here. And I don't think RealClimate alone is the place for this, although
RC could be good for the bigger list of issues. Don't do it on Mc;s blog. But, it would be
good to hear from Ray and Mike, since they have the most experience in getting it right.
Here are some other QUICK thoughts - don't count on me for the next week. Proposal hell and
Make sure you have Keith's feedback before saying anything about the dendro aspects.
Don't know about Dye3 issue
Error analysis should be done and be the topic of another paper - it wasn't included in
this paper, so it's something that should be done outside the peer-review process. There is
lots of new research to be done, and someone should do it as time allows. Don't get pushed
into something too rushed or preliminary, and your defense is that you wrote a paper that
reviewed well and was published. The goal wasn't to do everything in this paper.
#4 - your are absolutely right and that could be in a blog someplace, or just let them go
ahead and do a stupid thing. If this was a climate field recon it would be different, no?
#5 is tricky. Giving him the data would be good, but only if it is yours to give. You can't
give him data that you got from others and are not allowed to share. But, it would be nice
if he could have access to all the data that we used - that's the way science is supposed
to work. See what Mike and Ray say...
Be careful, very careful. But now you know why I advocated redoing all the analyses a few
months ago - to make sure we got it all right. We knew we'd get this scrutiny.
This paper has had great impact so far, so that's something to remember - its good work.
Thanks, peck
On 9/5/09 8:44 AM, "Darrell Kaufman" <[1]> wrote:

I received my first hate mail this AM, which helped me to realize that I shouldn't be
wasting time reading the blogs.
Regarding the "upside down man", as Nick's plot shows, when flipped, the Korttajarvi
series has little impact on the overall reconstructions. Also, the series was not
included in the calibration. Nonetheless, it's unfortunate that I flipped the
Korttajarvi data. We used the density data as the temperature proxy, as recommended to
me by Antii Ojala (co-author of the original work). It's weakly inversely related to
organic matter content. I should have used the inverse of density as the temperature
proxy. I probably got confused by the fact that the 20th century shows very high density
values and I inadvertently equated that directly with temperature.
This is new territory for me, but not acknowledging an error might come back to bite us.
I suggest that we nip it in the bud and write a brief update showing the corrected
composite (Nick's graph) and post it to RealClimate. Do you all agree?
There's other criticisms that have come up by McIntyre's group:
(1) We cherry-picked the tree-ring series in Eurasia. Apparently this is old ground, but
do we need to address why we chose the Yamal record over the Polar Urals? Apparently,
there's also a record from the Indigirka River region, which might not have been
published and doesn't seem to be included in Keith's recent summary. If we overlooked
any record that met our criteria, I suggest that we explain why. Keith: are you back?
Can Ray or Mike provide some advise?
(2) The correction for Dye-3 was criticized because the approach/rationale had not been
reviewed independently on its own. Bo: has this procedure now been published anywhere?
(3) We didn't publish any error analysis (e.g., leave-one-out ), but I recall that we
did do some of that prior to publication. Would it be worthwhile including this in our
update? The threshold-exceedence difference (O&B-style) does include a boot-strapped
estimate of errors. That might suffice, but is not the record we use for the temperature
(4) We selected records that showed 20th century warming. The only records that I know
of that go back 1000 years that we left out were from the Gulf of Alaska that are known
to be related strongly to precipitation, not temperature, and we stated this upfront. Do
we want to clarify that it would be inappropriate to use a record of precip to
reconstruct temperature? Or do we want to assume that precip should increase with
temperature and add those records in and show that the primary signals remain?
(5) McIntyre wrote to me to request the annual data series that we used to calculate the
10-year mean values (10-year means were up on the NOAA site the same AM as the paper was
published). The only "non-published" data are the annual series from the ice cores
(Agassiz, Dye-3, NGRIP, and Renland). We stated this in the footnote, but it does
stretch our assertion that all of the data are available publicly. Bo: How do you want
to proceed? Should I forward the annual data to McIntyre?
Please let me -- better yet, the entire group -- know whether you think we should post a
revision on RealScience, and whether we should include a reply to other criticism (1
through 5 above). I'm also thinking that I should write to Ojala and Tiljander directly
to apologize for inadvertently reversing their data.
Other thoughts or advise?
On Sep 4, 2009, at 5:24 PM, Nick McKay wrote:

The Korttajarvi record was oriented in the reconstruction in the way that McIntyre said.
I took a look at the original reference - the temperature proxy we looked at is x-ray
density, which the author interprets to be inversely related to temperature. We had
higher values as warmer in the reconstruction, so it looks to me like we got it wrong,
unless we decided to reinterpret the record which I don't remember. Darrell, does this
sound right to you?

This dataset is truncated at 1800, so it doesn't enter the calibration, nor does it
affect the recent warming trend.
The attached plot (same as before) shows the effect of re-orienting the record on the
reconstruction. It doesn't change any of our major or minor interpretations of course.

On Thu, Sep 3, 2009 at 4:45 PM, Nick McKay <[2]> wrote:

Hi all,
I haven't checked the original reference for it's interpretation, but I checked the code
and we did use it in the orientation that he stated. He's also right that flipping
doesn't affect any of the conclusions. Actually, flipping it makes it fit in better with
the 1900-year trend.

I've attached a plot of the original, and another with Korttajarvi flipped.


Jonathan T. Overpeck
Co-Director, Institute of the Environment
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences
Mail and Fedex Address:
Institute of the Environment
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: +1 520 622-9065
Email: [3]
PA Lou Regalado +1 520 792-8712
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