Monday, June 11, 2012

5089.txt

date: Thu Oct 2 16:44:13 2008
from: Keith Briffa <k.briffaatXYZxyz.ac.uk>
subject: Re: recognize this?!
to: Edward Cook <drdendroatXYZxyzo.columbia.edu>

Ed
I truly hope for this also - and that you may eventually end up as a lead author or
convening lead author on the hoped-for palaeo chapter. I would certainly promote this to
the best of my ability.
Keith
At 16:20 02/10/2008, you wrote:

Hi Keith,
I think we are all in basic agreement here. My beef with IPCC is
perhaps a bit unfair. It is probably more so an issue with the way the
debate over past and present warming has been conducted, as you also
suggest. The science is indeed moving past the point where the only
issue to discuss and debate was one related to temperature change, and
IPCC is responding to it as you say. Hopefully, IPCC will still
include an explicit paleo chapter in the next report to enable a more
complete synthesis to be made concerning past and present
hydroclimatic variability. There will be a tremendous amount of
exciting new results coming out over the next couple of years in that
regard. I certainly hope you and Tim can work with me on some of this
stuff. It will be fun to do.
Cheers,
Ed
==================================
Dr. Edward R. Cook
Doherty Senior Scholar and
Director, Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, New York 10964 USA
Email: drdendroatXYZxyzo.columbia.edu
Phone: 845-365-8618
Fax: 845-365-8152
==================================
On Oct 2, 2008, at 10:58 AM, Keith Briffa wrote:

Dear Ed
Thanks for these comments - and while I agree with them , I do not
necessarily concur on the "fashionable" opinion these days that IPCC
has made a mistake in stressing the temperature issue and the rank
magnitudes of late Holocene warm periods. It is undeniable that
hydroclimatic variability , past and future, is of enormous
scientific and societal importance. However, the IPCC must follow
the published literature and to a large extent the assessment must
maintain a reasonable degree of continuity. Just as it is vital to
understand spatial variability and mechanisms concerning
temperature (and precipitation) changes, the extent of published
knowledge has not, as yet, supported a strong emphasis on these
topics. The focus on the MWP was perhaps to some degree a response
to the misinformation peddled by certain climate warming sceptics,
but I believe it was justified to devote the amount of limited space
allotted to this section to the area of large-scale temperature
reconstructions, especially considering the extent of the recent
literature and the attacks on the TAR hockey stick. I hope we did a
reasonable job in assessing the evidence honestly. I am in no doubt
that future IPCC reports will reflect a growing body of evidence
for the existence of large natural variability in moisture
conditions and , hopefully, the dynamic mechanisms whereby
temperature and moisture have varied over space in recent millennia.
In our defence I would also say that the AR4 clearly pointed to the
importance of the issue of natural drought occurence and cited the
best relevant work demonstrating this - ie your own.
My beef with Esper is not because his conclusion is wrong - merely
that his piece wrongly impugns the IPCC. Through a subtle
combination of selective focus, blatant misrepresentation of the
text, and a complete failure to acknowledge the circumspect language
and explicit caveats therein, he builds a straw man and succeeds in
publishing a trivial, unoriginal idea.
cheers
Keith
At 14:48 01/10/2008, you wrote:

Hi Keith and Tim,
I have quickly read through the Esper paper and have the following
comments to make. First, I hadn't seen it before, so it is all new
to me. It is certainly true that Jan did not do a proper job citing
Briffa et al. (1992). That was a clear mistake, especially given
that Douglass (1929) was cited for crossdating. I also note that
Jan did not cite Osborn et al. (1997) on adjusting the variance in
series for sample size changes. That too was an clear oversight
given that Frank et al. (2007) was cited. Hopefully, neither was
done intentionally. I tend to give people the benefit of a doubt on
that unless it is a chronic problem in their publications. The
latter issue of variance adjustment is also relevant to the
discussion concerning spatial homogeneity or lack thereof. Am I
correct in assuming that some form of variance adjustment was made
to the series used in the AR4 report? I haven't read the report
closely enough to recall if that was done. If it was done, that
would tend to force the data towards an appearance of greater
homogeneity, I would guess, hence the relative stability of the
bootstrap intervals, etc.. In any case, I do tend to agree with Jan
that nothing very definitive can be said about the spatial
homogeneity of the putative MWP until we get more records to look
at that truly express temperature and not something else.
The whole issue of whether or not the MWP was more spatially
heterogeneous or not is a huge "red herring" in my opinion anyway.
A growing body of evidence clearly shows that hydroclimatic
variability during the putative MWP (more appropriately and
inclusively called the "Medieval Climate Anomaly" or MCA period)
was more regionally extreme (mainly in terms of the frequency and
duration of megadroughts) than anything we have seen in the 20th
century, except perhaps for the Sahel. So in certain ways the MCA
period may have been more climatically extreme than in modern
times. The problem is that we have been too fixated on temperature,
especially hemispheric and global average temperature, and IPCC is
enormously guilty of that. So the fact that evidence for "warming"
in tree-ring records during the putative MWP is not as strong and
spatially homogeneous as one would like might simply be due to the
fact that it was bloody dry too in certain regions, with more
spatial variability imposed on growth due to regional drought
variability even if it were truly as warm as today. The Calvin
cycle and evapotranspiration demand surely prevail here: warm-dry
means less tree growth and a reduced expression of what the true
warmth was during the MWP.
That is my take on the Esper and Frank paper, with obvious
editorial comments included as well.
Cheers,
Ed
==================================
Dr. Edward R. Cook
Doherty Senior Scholar and
Director, Tree-Ring Laboratory
Lamont-Doherty Earth Observatory
Palisades, New York 10964 USA
Email: <[1]mailto:drdendro@ldeo.columbia.edu>drdendro@ldeo.columbia.edu
Phone: 845-365-8618
Fax: 845-365-8152
==================================
On Sep 29, 2008, at 11:06 AM, Keith Briffa wrote:

X-Mailer: QUALCOMM Windows Eudora Version 7.1.0.9
Date: Mon, 29 Sep 2008 09:50:59 +0100
To: Keith Briffa <<[2]mailto:k.briffa@uea.ac.uk>k.briffa@uea.ac.uk>
From: Tim Osborn <<[3]mailto:t.osborn@uea.ac.uk>t.osborn@uea.ac.uk>
Subject: recognize this?!
Dr Timothy J Osborn, Academic Fellow
Climatic Research Unit
School of Environmental Sciences
University of East Anglia
Norwich NR4 7TJ, UK
e-mail: <[4]mailto:t.osborn@uea.ac.uk>t.osborn@uea.ac.uk
phone: +44 1603 592089
fax: +44 1603 507784
web: <[5]http://www.cru.uea.ac.uk/~timo/>[6]http://www.cru.uea.ac.uk/~timo/
sunclock:
<[7]http://www.cru.uea.ac.uk/~timo/sunclock.htm>[8]http://www.cru.uea.ac.uk/~timo/sunclo
ck.htm

--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.
Phone: +44-1603-593909
Fax: +44-1603-507784
<[9]http://www.cru.uea.ac.uk/cru/people/briffa/>[10]http://www.cru.uea.ac.uk/cru/people/
briffa/ <esper frank IPCC on MWP hetero 2008.pdf>

--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.
Phone: +44-1603-593909
Fax: +44-1603-507784
[11]http://www.cru.uea.ac.uk/cru/people/briffa/

--
Professor Keith Briffa,
Climatic Research Unit
University of East Anglia
Norwich, NR4 7TJ, U.K.

Phone: +44-1603-593909
Fax: +44-1603-507784
[12]http://www.cru.uea.ac.uk/cru/people/briffa/

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