Alleged CRU Emails - 25 results below

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From: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
To: Jonathan Overpeck <jto@u.arizona.edu>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>,

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From: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
To: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>
Subject: Re: Urgent Re: latest version of my responses
Date: Tue Aug 1 15:48:xxx xxxx xxxx
Cc: Tim Osborn <t.osborn@xxxxxxxxx.xxx>, jto@u.arizona.edu,Fortunat Joos <joos@xxxxxxxxx.xxx>,Valerie.Masson@xxxxxxxxx.xxx,Ricardo Villalba <ricardo@xxxxxxxxx.xxx>

Dear all
attached is my latest (currently definitive) version of the responses to the
"sky-blue-highlighted" comments on text and Figures.
PLEASE NOTE THAT THESE HAVE CHANGED IN VARIOUS PLACES FROM WHAT I SENT EARLIER AS WELL AS
BEING UPDATED. I would suggest that they be cut and pasted into the document rather than
just including the new ones. Sorry , but I had to reconsider a number of responses and
edit others to remove typos etc.
Even though marked in blue - a few were not relevant to me. Two have been marked with
"Valerie " - xxx xxxx xxxx, xxx xxxx xxxx) . Those marked PECK xxx xxxx xxxxthrough xxx xxxx xxxx; ie 7 comments) are
best dealt with by he. The comment xxx xxxx xxxxis for Stefan. The comments marked F are those I
sent from Fortunat before and I also sent the edited version of Ricardo's. The two
outstanding ones he marked for me/Tim are here xxx xxxx xxxxand xxx xxxx xxxx)
xxx xxxx xxxxNoted - this issue will be reviewed , though the discussion of forcings must come
before that of comparison of simulation results.
xxx xxxx xxxxNoted - the text is intended to provide examples only and will be modified to refer
to Table 6.2 , where details of all simulations used are provided.
I think that should be OK as far as my stuff goes. I will send minor changes to text
(separate message) that have arisen in dealing with final comments.
Cheers
Keith
At 10:37 01/08/2006, Eystein Jansen wrote:

Hi Keith,
could you send me responses to the reviewers

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From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Re: response to your question
Date: Tue, 1 Aug 2006 22:05:xxx xxxx xxxx
Cc: "Susan Solomon" <Susan.Solomon@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

<x-flowed>
Hi Keith - thanks. This makes sense to me. I'll
cc Susan so she understands the issue better, and
also can advise on any strategy we should adopt
to make sure we communicate effectively.

thanks again

best, peck

>Peck,
>
>The TAR was, in my opinion, wrong to say
>anything about the precedence (or lack thereof)
>of the warmth of the individual year 1998.
>
>The reason is that all reconstructions have very
>wide uncertainty ranges bracketing
>individual-year estimates of part temperature.
>Given this, it is hard to dismiss the
>possibility that individual years in the past
>did exceed the measured 1998 value. These errors
>on the individual years are so wide as to make
>any comparison with the 1998 measured value very
>problematic, especially when you consider that
>most reconstructions do not include it in their
>calibration range (curtailed predictor network
>in recent times) and the usual estimates of
>uncertainty calculated from calibration (or
>verification) residual variances would not
>provide a good estimate of the likely error
>associated with it even if data did exist.
>
>I suspect that many/most reconstructions of NH
>annual mean temperature have greater fidelity at
>decadal to multidecadal timescales (based on
>examination of the covariance spectrum of the
>actual and estimated data over the calibration
>period. This is the reason many studies
>implicitly (Hegerl et al.,) or explicitly (Esper
>et a;., Cook et al.) choose to calibrate
>directly against decadally-smoothed data.
>
>The exception is the Briffa et al (tree-ring
>density network based) reconstruction back to ~
>1400. This has probably the best year-to-year
>fidelity

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From: Anders Moberg <anders.moberg@xxxxxxxxx.xxx>
To: Martin Juckes <m.n.juckes@xxxxxxxxx.xxx>
Subject: McIntyre, McKitrick & MITRIE ...
Date: Fri, 04 Aug 2006 09:18:24 +0100
Cc: Anders <anders@xxxxxxxxx.xxx>, Eduardo.Zorita@xxxxxxxxx.xxx, hegerl@xxxxxxxxx.xxx, esper@xxxxxxxxx.xxx, k.briffa@xxxxxxxxx.xxx, m.allen1@xxxxxxxxx.xxx, weber@xxxxxxxxx.xxx, t.osborn@xxxxxxxxx.xxx

<x-flowed>
Dear Martin and all others,

Having read the new manuscript, I would like to draw the attention of
all of you to the section about McIntyre&McKitrick vs Mann et al. I am
not entirely happy with this section. It may be that I am not fully
updated about all details on their dispute, but it appears to be some
mistakes in this section of our manuscript. Therefore, I ask all of you
to check how this section can be improved and clarified. This is very
important! If we refer incorrectly to the MM-Mann dispute, I am
convinced that all of us will be involved in lengthy frustrating e-mail
discussions later on. I anticipiate this from personal experience! Let's
do our best to avoid this.

The problematic bit of text starts on p. 16, para 4: ("The failure of
MM2003 ... is partly due to a misunderstanding of the stepwise
reconstruction method") and slightly below: ("MM2003 only calculate
principal components for the period when all chronologies are present").

I read through the MM2003 paper yesterday. From what is written there,
on p. xxx xxxx xxxx, it appears that they were well aware of the stepwise
method. On p. 763, about at the middle of the page, they write:
"Following the description of MBH98 ... our construction is done
piecewise for each of the periods listed in Table 8, using the roster of
proxies available through the period and the selection of TPCs for each
period listed in Table 8".

This is clearly at odds to what is written in our manuscript. Has it
been documented somewhere else that MM2003, despite what they wrote,
really misunderstood the stepwise technique? If it is so, we need to
insert a reference. If this is not the case, we need to omit the lines
about the misunderstanding. We also need to explain better why the
MM2003 calculations differ from MBH.

Moreover, our sentence ("MM2003 only calculate principal components for
the period when all chronologies are present") imply that MM2003 only
calculated PCs for the period 1xxx xxxx xxxx, as this would be the period
when all chronologies are present according to the MM2003 Table 8.
Obviously, they calculated PCs beyond 1820, as their calculations
actually extend back to 1400.

The problem continues in the legend to our Fig. 2. (" Each of the 212
data series is shown ... The red rectangle indicates the single block
used by MM2003, neglecting all data prior to 1619"). The last sentence
is inconsistent with the information in MM2003 in three ways; a) MM2003
clearly show in their Table 8 that they analysed the same blocks of data
as MBH. b) The year 1619 as a starting point of a data block is
inconsistent with MM Table 8. Where does the year 1619 come from? It is
not mentioned anywhere in MM2003. c). The red block implies that MM2003
made calculations back only to 1619, but they did back to 1400.

Moreover, the numbers given in the graph of our Fig. 2 indicate that the
total number of series is 211, whereas the text in the legend and also
in the main text on p. 16 says 212. Which number is correct?

I suppose that some of you others will know this subject much better
than I. I have just read the MM2003 paper, and find our reference to it
to be inconsistent with it. I hope you all can make efforts to make this
bit crystal clear. If not, I fear we will get problems!

Finally, I would like to draw your attention to the related sentence in
our conclusions on p. 26: ("Papers which claim to refute ... have been
reviewed and found to contain serious flaws"). Are all of you happy with
this statement? Would it sound better with a somewhat less offending
sentence, something like:

"Papers which claim to refute ... have been reviewed and found to
essentially contribute with insignificant information that does not
affect the consensus, and even to include some flaws."

I attach the MM2003 paper.

I will send some comments to the other parts of the text in a separate mail.

Cheers,
Anders



Martin Juckes wrote:
> Hello All,
>
> here is another draft. I've added a new reconstruction, using 19 independent
> proxies series from Jones et al., Mann et al., Esper et al. and Moberg et al.
> This gives a good fit to the calibration data, such that 2 recent years exceed
> the maximum pre-industrial estimate by 4 sigma levels. I've included this
> because without it I found it hard to draw precise and useful conclusions
> from the 4 partially overlapping reconstructions I had done before.
>
> cheers,
> Martin
>
> ------------------------------------------------------------------------
>
> documentclass[cpd,11pt]{egu}
>
> input macs
> voffset 5cm
> hoffset 1.5cm
>
> begin{document}
>
> title
> {bf Millennial Temperature Reconstruction Intercomparison and Evaluation
> }
>
> runningtitle{Millennial Temperature}
> runningauthor{M.~N.~Juckes et al}
> author{Martin Juckes$^{(1)}$,
> Myles Allen$^{(2)}$,
> Keith Briffa$^{(3)}$,
> Jan Esper$^{(4)}$,
> Gabi Hegerl$^{(5)}$,
> Anders Moberg$^{(6)}$,
> Tim Osborn$^{(3)}$,
> Nanne Weber$^{(7)}$,
> Eduardo Zorita$^{(8)}$}
> correspondence{Martin Juckes (M.N.Juckes@xxxxxxxxx.xxx)}
> affil{
> British Atmospheric Data Centre, SSTD,
> Rutherford Appleton Laboratory
> Chilton, Didcot,
> Oxfordshire, OX11 0QX,
> United Kingdom
> }
>
> affil{1: Rutherford Appleton Laboratory,
> 2: University of Oxford,
> 3: University of East Anglia,
> 4: Swiss Federal Research Institute,
> 5: Duke University,
> 6: Stockholm University,
> 7: Royal Netherlands Meteorological Institute (KNMI),
> 8: GKSS Research Centre
> }
> date{Manuscript version from 31 Oct 2005 }
> msnumber{xxxxxx}
>
> pubyear{}
> pubvol{}
> pubnum{}
>
> received{}
> %pubacpd{} % ONLY applicable to ACP
> revised{}
> accepted{}
>
> firstpage{1}
>
> maketitle
>
> begin{abstract}
> There has been considerable recent interest in paleoclimate reconstructions of the temperature history of
> the last millennium. A wide variety of techniques have been used.
> The interrelation among the techniques is sometimes unclear, as different studies often
> use distinct data sources as well as distinct methodologies.
> Recent work is reviewed with an aim to clarifying the import of
> the different approaches.
> A range of proxy data collections used by different authors are passed
> through two reconstruction algorithms: firstly, inverse regression and,
> secondly, compositing followed by variance matching.
> It is found that the first method tends to give large weighting to
> a small number of proxies and that the second approach is more robust
> to varying proxy input.
> A reconstruction using 19 proxy records extending back to 1000AD shows a
> maximum pre-industrial temperature of 0.227K (relative to the 1866 to 1970 mean).
> The standard error on this estimate, based on the residual in the calibration
> period is 0.149K. Two recent years (1998 and 2005) have exceeded the pre-industrial
> estimated maximum by more than 4 standard errors.
> end{abstract}
>
>
> %%openup 1jot
>
> introductionlabel{sec:intro}
>
> The climate of the last millennium has been the subject of much
> debate in recent years, both in the scientific literature
> and in the popular media.
> This paper reviews reconstructions of past temperature,
> on the global, hemispheric, or near-hemispheric scale, by
> citet{jones_etal1998} [JBB1998],
> citet{mann_etal1998a} [MBH1998],
> citet{mann_etal1999} [MBH1999],
> citet{huang_etal2000} [HPS2000],
> citet{crowley_lowery2000} [CL2000],
> citet{briffa_etal2001} [BOS2001],
> citet{esper_etal2002b} [ECS2002],
> citet{mann_jones2003} [MJ2003],
> citet{moberg_etal2005} [MSH2005],
> citet{oerlemans2005} [OER2005],
> citet{hegerl_etal2006+} [HCA2006].
> %%The criticism
> %%directed at them (mainly MBH1999) by citet{mcintyre_mckitrick2003} [MM2003] and others.
>
>
> Climate variability can be partitioned into contributions from
> internal variability of the climate system and response to forcings,
> which the forcings being further partitioned in natural and
> anthropogenic.
> The dominant change in forcing in the late 20th century
> arises from human impact in the form of
> greenhouse gases citep[primarily carbon dioxide, methane and
> chloro-fluoro carbons:][]{IPCC2001}.
> The changes in concentration of these gases in the atmosphere
> are well documented and their radiative properties which reduce,
> for a given temperature difference, radiative loss of heat to space
> from the mid and lower troposphere
> citep[for carbon dioxide, this was first documented by][]{arrhenius1896}
> are beyond dispute.
>
> However, there remains some uncertainty on two issues:
> firstly, how much of the observed change is due to greenhouse forcing as
> opposed to natural forcing and internal variability;
> secondly, how significant, compared to past natural changes, are the
> changes which we now observe and expect in the future?
>
> The first question is not answered by the IPCC conclusion cited above because
> that conclusion only compares the anthropogenic forcing of the late 20th century
> with the natural forcings of the same period. Further back in the past, it is
> harder to make definitive statements about the amplitude of variability in natural
> forcings. The second question reflects the uncertainty in the response of the
> climate system to a given change in forcing. In the last century both the
> variations in forcing and the variations in response have been measured with
> some detail, yet there remains uncertainty about the contribution of
> natural variability to the observed temperature fluctuations.
> In both cases, investigation is hampered by the fact that
> estimates of global mean temperature based on reliable direct measurements
> are only available from 1856 onwards citep{jones_etal1986}.
>
> Climate models are instrumental in addressing both questions,
> but they are still burdened with
> some level of uncertainty and there is a need for more detailed knowledge
> of the behaviour of the actual climate on multi-centennial timescales
> both in order to evaluate the climate models and in order to address the
> above questions directly.
>
> The scientific basis for proxy based climate reconstructions may be stated simply: there are
> a number of physical indicators
> which contain information about the past environmental variability.
> As these are not direct measurements, the term proxy is used.
>
>
> citet{jones_mann2004} review evidence for climate change in
> the past millennium and conclude that there had been a
> global mean cooling since the 11th century
> until the warming period initiated in the 19th century, but the issue remains
> controversial. This paper reviews recent contributions and evaluates the impact
> of different methods and different data collections used.
>
> Section 2 discusses recent contributions, which have developed a range of new
> methods to address aspects of the problem.
> Section 3 discusses the technique used by MBH1998/9
> in more detail in the context of criticism by citet{mcintyre_mckitrick2003}
> (hereafter MM2003).
> Section 4 presents some new results using the data collections from 5 recent studies.
>
>
> section{A survey of recent reconstructions}
>
> This section gives brief reviews of recent
> contributions, displayed in Fig.~1.
> Of these, 5 are estimates of the Northern Hemisphere mean temperature
> (MBH1999, HPS2000, CL2000, MSH2005, HCA2006),
> 2 of the Northern Hemisphere extra tropical mean temperature (BOS2001, ECS2002)
> and 3 of the global mean temperature (JBB1998, MJ2003, OER2005).
> All, except the inherently low resolution reconstructions of HPS2000 and OER2005,
> have been smoothed with a 40 year running mean.
> With the exception of HPS2000 and OER2005, the reconstructions
> use partly overlapping methods and data, so they
> cannot be viewed as independent from a statistical viewpoint.
> In addition to exploiting a range of different data sources,
> the above works also use a range of techniques.
> The subsections below cover different scientific themes,
> ordered according to the date of key publications.
> Some reconstructions which do not extend all the way
> back to 1000AD are included because of their
> importance in addressing specific issues.
> The extent to which the global, northern hemisphere and northern hemisphere
> extratropical reconstructions might be expected to agree
> is discussed in Sect.~2.10 below.
>
> subsection{High-resolution paleoclimate records}
>
> citet{jones_etal1998} [JBB1998] present the first annually resolved
> reconstructions of temperatures back to 1000AD, using
> a composite of standardised 10 proxies for the northern hemisphere and 7 for the southern,
> with variance damped in the early part of the series to account for the
> lower numbers of proxies present (6 series extend back to 1000AD), following citet{osborn_etal1997}.
> The composites are
> scaled by variance matching (Appendix A) against the annual mean summer temperatures for 1xxx xxxx xxxx.
> Climate models are also employed to investigate the temperature coherency
> between proxy sites and it is shown that there are strong large scale
> coherencies in the proxy data which are not reproduced by
> the climate model. An evaluation of each individual
> proxy series against instrumental data from 1881 to 1980
> shows that tree-rings and historical reconstructions
> are more closely related to temperature than those
> from corals and ice-cores.
>
> With regard to the temperatures of the last millennium,
> the primary conclusion of JBB1998 is that
> the twentieth century was the warmest of the millennium.
> There is clear evidence of a cool period from 1500 to 1900,
> but no strong ``Medieval Warm Period" [MWP] (though the second warmest
> century in the northern hemisphere reconstruction is
> the 11th). The MWP is discussed further in Sect.~2.4 below.
>
> JBB1998 draw attention to the limitations of some of the proxies
> on longer timescales (see Sect.~3.5 below).
> Homogeneity of the data record and
> its relation with temperature may not be guaranteed on longer timescale.
> This is an important issue, since
> many climate reconstructions assume a constant relationship between
> temperature anomalies and the proxy indicators
> (there are also problems associated with timescale-dependency in the
> relationship which are discussed further in Sect.~2.6 below).
>
> MJ2003 include some additional proxy series and extend to study period back a
> further millennium and conclude that the late 20th century warmth
> is unprecedented in the last two millennia.
>
> subsection{Climate field reconstruction}
>
> citet{mann_etal1999} published
> the first reconstruction of the last thousand years northern hemispheric mean
> temperature which included objective error bars,
> based on the analysis of the residuals in the calibration period.
> The authors concluded not only
> that their estimate of the temperature over the whole period 1000AD to 1860AD
> was colder than the late twentieth century, but also that 95% certainty limits
> were below the last decade of the twentieth century.
> The methods they used were presented in MBH1998
> which described a reconstruction back to 1400AD.
>
> MBH1998 use a collection of 415 proxy time indicators, many more than used in citet{jones_etal1998},
> but many of these are too close geographically to be considered
> as independent, so they are combined into a smaller number of representative
> series.
> The number of proxies also decreases significantly with age:
> only 22 independent proxies extend back to 1400AD,
> and, in
> MBH1999, 12 extend back to 1000AD (7 in the Northern Hemisphere).
> MBH1998 and MBH1999 have been the subject of much debate since the latter was cited
> in the IPCC (2001) report, though the IPCC
> conclusionsfootnote{citet{IPCC2001} concluded that
> ``The 1990s are likely to have been the warmest decade of the millennium in
> the Northern Hemisphere, and 1998 is likely to have been the warmest
> year," where ``likely'' implies a greater than 66% probability.
> Since 2001 it has been recognised that there is a need to explicitly
> distinguish between an expression of confidence, as made by the IPCC in this quote,
> which should include expert assessment of the robustness of statistical methods
> employed, and simple citation of the results of statistical test.
> In the language of
> citet{manning_etal2004} we can say that MBH1999 carried out statistical
> tests which concluded that the 1990s have been the warmest decade of the
> millenium with 95% likelihood, while IPCC (2001), after assessing all
> available evidence had a 66% confidence in the same statement.}
> were weaker than those of MBH1999.
>
> This work also differ from Jones et al. (1998) in using spatial patterns of temperature
> variability rather than hemispheric mean temperatures. In this way the study aims
> to exploit proxies which are related to temperature indirectly: for
> instance, changes in temperature may be associated with changes in
> wind and rainfall which might affect proxies more strongly than
> temperature. Since wind and rainfall are correlated with
> changes in temperature patterns, it is argued, there may be important non-local
> correlations between proxies and temperature.
>
> Different modes of atmospheric variability are evaluated through an
> Empirical Orthogonal Function [EOF] analysis of the time period 1902 to 1980,
> expressing the global field as a sum of spatial patterns (the EOFs) multiplied by
> Principal Components (PCs -- representing the temporal evolution).
> Earlier instrumental data are too sparse to be used for this purpose:
> instead they are used in a validation calculation to determine how
> many EOFs should be included in the reconstruction.
> Time series for each mode of variability are then reconstructed from the proxy data using
> a optimal least squares inverse regression.
>
> Finally, the skill of the regression of each PC is tested using the
> 1856 to 1901 validation data.
> Prior to 1450AD it is determined that only
> one PC can be reconstructed with
> any accuracy. This means that the main advantage of the
> Climate Field Reconstruction method does not apply at earlier dates.
> The methodology will be discussed further in Sect.~3 below.
>
> The reconstructed temperature evolution (Fig.~1) is rather less variable than that of Jones et al. (1998),
> but the differences are not statistically significant.
> The overall picture is of gradual cooling until the mid 19th century,
> followed by rapid warming matching that evaluated by the earlier work.
>
> subsection{Borehole temperatures}
>
> citet{huang_etal2000} [HPS2000] estimate northern hemisphere temperatures
> back to 1500AD using
> measurements made in 453 boreholes (their paper also presents global and
> southern hemisphere results using an additional 163 southern hemisphere boreholes).
> The reconstruction is included here, even though it does not extend back to 1000AD,
> because it has the advantage of being completely
> independent of the other reconstructions shown.
> Temperature fluctuations at the surface propagate slowly downwards, so that measurements
> made in the boreholes at depth contain a record of past surface temperature fluctuations.
> HPS2000 used measurements down to around 300m.
> The diffuse nature of the temperature anomaly means that short time scale fluctuations
> cannot be resolved. Prior to the 20th century, the typical resolution is about 100 years.
>
> citet{mann_etal2003} analyse the impact of changes in land use and snow cover
> on borehole temperature reconstructions and conclude that
> it results in significant errors.
> This conclusions has been refuted by
> citet{pollack_smerdon2004} (on statistical grounds), citet{gonzalez-rouco_etal2003}
> (using climate simulations) and citet{huang2004} (using an expanded network of 696
> boreholes in the northern hemisphere).
>
> subsection{Medieval Warm Period}
>
> Despite much discussion
> citep[e.g.][]{hughes_diaz1994, bradley_etal2003}, there is no clear quantitative
> understanding of what is meant by the ``Medieval Warm Period'' [MWP].
> citet{crowley_lowery2000}
> [CL2000] discuss the evidence for a global MWP, which they interpret as
> a period of unusual warmth in the 11th century. All the reconstructions
> of the 11th century temperature shown
> in Fig.~1 estimate that century to have been warmer than most of the
> past millennium. However, the question of practical importance is not
> whether it was warmer than the 12th to 19th centuries, which is
> generally accepted, but whether it was a period of comparable
> warmth to the late 20th century. MBH1999 concluded, with 95% confidence, that
> this was not so. CL2000 revisit the question
> using 15 proxy records, of which 9 were not used in the studies
> described above. Several of the series used have extremely low temporal resolution.
> %%CL2000 sought to select tree ring chronologies with consistent quality
> %%throughout their length, as measured by the "sample replication"
> %%citep{cook_etal2004}.
> %%[check usage of "sample replication" -- cook etal (QSR) is available from Jan's website]]
>
> They draw attention to the spatial localization of the MWP in their proxy series:
> it is strong in North America, North Atlantic and Western Europe, but not
> clearly present elsewhere. Periods of unusual warmth
> do occur in other regions, but these are short and asynchronous.
>
> Their estimate of northern hemispheric temperature over the past millennium is consistent
> with the works discussed above. They conclude that the occurrence of decades of
> temperatures similar to those of the late 20th century cannot be unequivocally ruled
> out, but that there is, on the other hand, no evidence to support the claims
> that such an extended period of large-scale warmth occurred.
>
> citet{soon_baliunas2003} carry out an analysis of local climate reconstructions.
> They evaluate the number of such reconstructions which show (a) a sustained ``climate
> anomaly" during xxx xxxx xxxxAD, (b) a sustained ``climate
> anomaly" during 1xxx xxxx xxxxAD and (c)
> their most anomalous 50 year period in the 20th century.
> Their definition of a ``sustained climate anomaly" is 50 years of warmth,
> wetness or dryness for (a) and (c) and 50 years of coolness, wetness
> or dryness in (b).
> It should be noted that they do not carry out evaluations which allow direct comparison between
> the 20th century and earlier times:
> they compare the number of extremes occurring in the 20th century with the
> number of anomalies occurring in periods of 3 and 4 centuries in the past.
> Both the use of sampling periods of differing length and different selection criteria make interpretation
> of their results problematic.
> They have also been criticised for interpreting
> regional extremes which occur at distinct times as being indicative of a global
> climate extremes citep{jones_mann2004}. This issue is discussed further in
> Sect.~2.9 below.
> citet{osborn_briffa2006} perform a systematic analysis along the lines of citet{soon_baliunas2003}
> and conclude that the proxy records alone, by-passing the problem of proxy calibration
> against instrumental temperatures, show an unprecedented anomaly in the 20th century.
>
> subsection{Segment length curse}
>
> citet{briffa_etal2001} and citet{briffa_etal2002} discuss the impact of
> the ``segment length curse'' citep{cook_etal1995a, briffa_etal1996, briffa2000} on
> temperature reconstructions from tree rings.
> Tree rings have been shown to have much greater sensitivity
> than other proxies on short timescales (JBB1998), but there is a concern that this may not
> be true on longer timescales. Tree ring chronologies are often made up of
> composites of many trees of different ages at one site.
> The width of the annual growth ring
> depends not only on environmental factors but also on the age of the
> tree. The age dependency on growth is often removed by subtracting
> a growth curve from the tree ring data for each tree. This process,
> done empirically, will not only remove age related trends but also any environmental
> trends which span the entire life of the tree.
> citet{briffa_etal2001} use a more sophisticated method
> (Age Band Decomposition [ABD], which
> forms separate chronologies from tree rings in different age bands,
> and then averages all the age-band chronologies)
> to construct northern hemisphere
> temperatures back to 1400AD, and show that
> a greater degree of long term variability is preserved.
> The reconstruction lies between those
> of MBH1999 and JBB1998, showing the cold 17th century of the former,
> but the relatively mild 19th century of the latter.
>
> The potential impact of the segment length limitations is analysed further
> by citet{esper_etal2002b, esper_etal2003}, using `Regional Curve Standardisation' (RCS)
> citep{briffa_etal1992}.
> In RCS composite growth curves (different curves reflecting
> different categories of growth behaviour) are obtained from all the trees
> in a region and this, rather than a fitted curve, is subtracted
> from each individual series. Whereas ABD circumvents the need to
> subtract a growth curve, RCS seeks to evaluate a growth curve which
> is not contaminated by climate signals.
> The ECS2002 analysis agrees well with that of MBH1999 on short
> time scales, but has greater centennial variability citep{esper_etal2004}.
> ECS2002 suggest that this may be partly due to the lack of tropical proxies
> in their work, which they suggest should be regarded as an extratropical
> Northern Hemisphere estimate. The extratropics are known to have
> greater variability than the tropics.
> %[check]:from eduardo:: Table 1 in MBH GRL 99 --add ref??
> However, it has to be also noted that among the proxies used by MBH1999
> (12 in total), just 2 of them are located in the tropics, both at one location
> (see table 1 below).
>
> citet{cook_etal2004} study the data used by ECS2002 and pay particular attention
> to potential loss of quality in the earlier parts of tree-ring chronologies
> when a relatively small number of tree samples are available. Their analysis
> suggests that tree ring chronologies prior to 1200AD should be treated with
> caution.
>
> subsection{Separating timescales}
>
> citet{moberg_etal2005} follow BOS2001 and ECS2002 in trying to address
> the ``segment length curse'', but rather than trying to improve the
> tree-ring chronologies by improving the standardizations,
> they discard low frequency component of the tree-ring data,
> and replace this with low-frequency information from proxies with lower temporal resolution.
> A wavelet analysis is used to filter different temporal scales.
>
> Each individual proxy series is first scaled to unit variance and then wavelet transformed.
> Averaging of the wavelet transforms is made separately for tree ring data
> and the low-resolution data.
> The average wavelet transform of tree-ring data for timescales less than 80
> years is combined with the averaged wavelet transform of the low-resolution data for
> timescales longer than 80 years to form one single wavelet transform covering all timescales.
> This composite wavelet transform is inverted to create a dimensionless temperature
> reconstruction, which is calibrated against the instrumental record of
> northern hemisphere mean temperatures, AD 1xxx xxxx xxxx, using a variance matching method.
>
> Unfortunately, the calibration period is too short to independently calibrate the
> low frequency component. The variance matching represents a form of cross-calibration.
> In all calibrations against instrumental data, the long period (multi-centennial)
> response is determined by a calibration which is dominated by
> sub-centennial variance. The MSH2005 approach makes this explicit and
> shows a level of centennial variability which is much larger than in
> MBH1999 reconstruction and
> similar to that in simulations of the past millennium with two
> different climate models, ECHO-G citep{storch_etal2004} and NCAR CSM
> (``Climate System Model'') citep{mann_etal2005}.
>
> subsection{Glacial advance and retreat}
>
> citet{oerlemans2005} provides another independent estimate of the global mean temperature
> over the last 460 years from an analysis of glacial advance and retreat.
> As with the bore hole based estimate of HPS2000, this work uses a
> physically based model rather than an empirical calibration.
> The resulting curve lies within the
> range spanned by the high-resolution proxies, roughly midway between
> the MBH1999 Climate Field Reconstruction and the HPS2000 bore hole estimate.
>
> Unlike the borehole estimate, but consistent with most other works presented
> here, this analysis shows a cooling trend prior to 1850, related to glacial
> advances over that period.
> It should be noted that
> the technique used to generate the bore hole estimate citep{pollack_etal1998}
> assumes a constant temperature prior to 1500AD. The
> absence of a cooling trend after this date may be influenced by this
> boundary condition.
>
> subsection{Regression techniques}
>
> Many of the reconstructions listed above depend on empirical relationships
> between proxy records and temperature. citet{storch_etal2004} suggest
> that the regression technique used by MBH1999
> under-representsfootnote{This is sometimes referred to as ``underestimating'',
> which will mean the same thing to many people, but something slightly different
> to statisticians. Any statistical model (that is, a set of assumptions about the
> noise characteristics of the data being examined) will deliver estimates of
> an expected value and variability. The variability of the expected value is
> not generally the same as the expected value of the variability.}
> the variability of past climate.
> This conclusion is drawn after a applying a method similar to that of MBH1999 to output from a
> climate model using a set of pseudo-proxies: time series generated from
> the model output and degraded with noise which is intended to match the noise
> characteristics of actual proxies.
> citet{mann_etal2005} use the same approach and arrive at a different conclusion:
> namely, that their regression technique is sound.
> citet{mann_etal2005} show several implementations of their
> Climate Field Reconstruction Method in the CSM simulation, using different levels
> of white noise in their synthetic pseudo proxies.
> For a case of pseudo-proxies with a realistic signal-to-noise ratio of 0.5, they use
> a calibration period (1xxx xxxx xxxx) which is longer than that
> used in MBH1998 and MBH1999 (1xxx xxxx xxxx).
> It turns out that the difference in the length of the calibration period is critical
> for the skill of the method (Zorita, personal communication et al., submitted).
> % (I think you can refer to Buerger et al 2006 here. Check with Eduardo if this is OK.
> % By the way, update the reference list: Tellus, 58A, xxx xxxx xxxx) [AM]
>
> There is some uncertainty about the true nature of noise on the proxies, and
> on the instrumental record, as will be discussed further below.
> The optimal least squares estimation technique of MBH1998 effectively
> neglects the uncertainties in the proxy data relative to uncertainties
> in the temperature.
> Instead,
> citet{hegerl_etal2006+} use total least squares regression citep{allen_stott2003, adcock1878}.
> This approach
> allows the partitioning of noise between instrumental temperatures
> and proxy records to be estimated, on the assumption that the instrumental
> noise is known. citet{hegerl_etal2006+} show that this approach leads to greater variability in the reconstruction.
>
> citet{rutherford_etal2005} take a different view. They compare reconstructions
> from 1400AD to present using a regularised expectation maximisation technique citep{schneider2001}
> and the MBH1998 climate field reconstruction method and find only minor differences.
> Standard regression techniques assume that we have a calibration period, in which
> both sets of variables are measured, and a reconstruction (or prediction) period
> in which one variable is estimated, by regression, from the other.
> The climate reconstruction problem is more complex:
> there are hundreds of instrumental records
> which are all of different lengths, and similar numbers of proxy records,
> also of varying length. The expectation maximisation technique
> citep{little_rubin1987}
> is well suited to deal with this: instead of imposing an
> artificial separation between a calibration period and a reconstruction
> period, it fills in the gaps in a way which exploits all data present.
> Regularised expectation maximisation is a generalisation
> developed by citet{schneider2001} to deal with ill posed problems.
> Nevertheless, there is still a simple regression equation at the heart of the technique.
> That used by citet{rutherford_etal2005} is similar to that used by
> %new: corrected
> MBH1998, so the issue raised by citet{hegerl_etal2006+} is unanswered.
>
> subsection{Natural variability and forcings}
>
> Global temperature can fluctuate through internally generated variability of
> the climate system (as in the El Ni~no phenomenon), through
> variability in natural forcings (solar insolation, volcanic aerosols,
> natural changes to greenhouse gas concentrations) and human changes.
> Reconstructions of variations in the external forcings for the last
> millenium have been
> put forward citep{crowley2000}, although recent studies have
> suggested a lower amplitude
> of low-frequency solar forcing citep{lean_etal2002, foukal_etal2004}.
>
> Analysis of reconstructed temperatures of MBH1999 and CL2000 and
> simulated temperatures using reconstructed solar and volcanic forcings
> shows that changes in the forcings can explain the reconstructed long
> term cooling through most of the millenium
> and the warming in the late 19th century citep{crowley2000}.
> The relatively cool climate in the second half of the 19th century may be
> attributable to cooling from deforestation citep{bauer_etal2003}.
> citet{hegerl_etal2003} analyse the correlations between four
> reconstructions (MBH1999, BOS2001, ECS2002, and a modified version of
> CL2000)
> and estimated forcings citep{crowley2000}.
> They find that that natural forcing, particularly by
> volcanism, explains a substantial fraction of decadal variance.
> Greenhouse gas forcing is detectable
> with high significance levels in all analyzed reconstructions except
> MSH2005, which ends in 1925.
> citet{weber2005b} carries out a similar analysis with a wider range
> of reconstructions. It is shown that the regression of reconstructed
> global temperatures on the forcings has a similar dependence on timescale
> as regressions derived from the climate model. The role of solar forcing is
> found to be larger for longer timescales, whereas volcanic forcing dominates
> for decadal timescales.
> The trend component over the period 1000 to 1850 is, however, in all
> reconstructions larger than the trend implied by the forcings.
>
> The methods employed by
> citet{hegerl_etal2006+} attribute about a third of the early 20th
> century warming, sometimes
> more, in high-variance reconstructions to greenhouse gas forcing.
> These results indicate that enhanced variability in the past does not
> make it more difficult to detect greenhouse warming, since a large
> fraction of the variability can be attributed to external forcing.
> Quantifying the influence of external forcing on the proxy records is
> therefore more relevant to understanding climate variability and its
> causes than determining if past periods were possibly as warm as the
> 20th century.
>
> citet{goosse_etal2005} investigate the role of internal variability using
> an ensemble of 25 climate model simulations of the last millennium
> and forcing estimates from citet{crowley2000}.
> They conclude that internal variability dominates local and regional
> scale temperature anomalies, implying that most of the variations
> experienced by a region such as Europe over the last millennium could
> be caused by internal variability. On the hemispheric and global scale,
> however, the forcing dominates.
> This agrees with results from a long
> solar-forced model simulation by citet{weber_etal2004}.
> %%similar This reinforces similar statements made by JOS1998. [where does this come from?]
> citet{goosse_etal2005}
> make the new point, that noise can lead to regional temperature anomalies
> peaking at different times to the forcing, so that disagreements in
> timing between proxy series should not necessarily be interpreted as
> meaning there is no common forcing.
>
> subsection{The long view}
>
> The past sections have drawn attention to the problems of calibrating
> temperature reconstructions using a relatively short
> period over which instrumental records are available.
> For longer reconstructions, with lower temporal resolution,
> other methods are available. Pollen
> reconstructions of climate match the ecosystem types with those
> currently occurring at different latitudes. The changes in
> ecosystem can then be mapped to the temperatures at which
> they now occur citep[e.g.][]{bernabo1981, gajewski1988}.
> These reconstructions cannot resolve decadal variability,
> but they provide an independent estimate of local low-frequency
> temperature variations. The results of citet{weber_etal2004}
> and
> citet{goosse_etal2005} suggest that such estimates
> centennial mean temperatures can provide some information about
> global mean anomalies, as they strongly reflect the external forcings on
> centennial and longer timescales. However, there has, as yet,
> been no detailed intercomparison between the pollen based
> reconstructions and the higher resolution reconstructions.
>
>
> section{Critics of the IPCC consensus on millennial temperatures}
>
> The temperature reconstructions described in the previous section
> represent (including their respective differences and similarities)
> the scientific consensus, based on objective analysis
> of proxy data sources which are sensitive to temperature.
> Nevertheless, there are many who are strongly attached to the view that past
> temperature variations were significantly larger and that, consequently,
> the warming trend seen in recent decades should not be considered
> as unusual.
>
>
> The criticism has been directed mainly at the citet{mann_etal1998a, mann_etal1999}
> work.
> Therefore, this section focuses mainly on this criticism.
> %new
> Though some of the critics identify the consensus with the MBH1998 work,
> this is not the case: the consensus rests on a broader body of work, and
> as formulated by IPCC2001 is less strong than the conclusions of
> MBH1998 (Sect.~3.2).
> citet{mcintyre_mckitrick2003} [MM2003]
> criticize MBH1998 on many counts, some related to deficiencies
> in the description of the data used and possible irregularities in the data
> themselves. These issues have been largely resolved in citet{mann_etal2004}.
> %%footnote{ftp://holocene.evsc.virginia.edu/pub/MANNETAL1998}.
>
> As noted above, the MBH1998 analysis is considerably more complex than others,
> and uses a greater volume of data.
> There are 3 main stages of the algorithm: (1) sub-sampling of
> regions with disproportionate numbers of proxies, (2) regression,
> (3) validation and uncertainty estimates.
>
> Stage (1) is necessary because some parts of the globe, particularly
> North America and Northern Europe, have a disproportionate number of
> proxy records. Other authors have dealt with this by using only
> a small selection of the available data or using regional
> averages citep[BOS2001;][]{hegerl_etal2006+}. MBH1998
> use a principal component analysis to extract the common signal from the records in
> densely sampled regions.
>
> The failure of MM2003 to replicate the MBH1998 results is partly due to
> a misunderstanding of the stepwise reconstruction method. MBH1998 use
> different subsets of their proxy database for different time periods.
> This allows more data to be used for more recent periods.
>
> For example, Fig.~2 illustrates
> how the stepwise approach applies to the North American tree ring network.
> Of the total of 212 chronologies, only 66 extend back beyond 1400AD.
> MM2003 only calculate principal components for the period when all
> chronologies are present. Similarly, MBH1998 use one principal
> component calculated from 6 drought sensitive tree-rings chronologies from South West Mexico
> and this data is omitted in MM2003.
> %%[is this clear now?? (AM)]]
> %new
> %%Table 7 of MM2003 indicates only 20 series for the region, as the
> %%supplementary information provided with MBH2003 omitted 2
> %%citep{mann_etal2004}.
> %endnew
> citet{mcintyre_mckitrick2005a} [MM2005] continue the criticism of the techniques
> used by MBH1998 and introduce a ``hockey stick index": defined in terms of the ratio
> of the variance at the end of a time series
> to the variance over the remainder of the series.
> MM2005 argue that the way in which
> a principal component analysis is carried out in MBH generates an artificial
> bias towards a high ``hockey-stick index" and that the statistical significance of
> the MBH results may be lower that originally estimated.
>
> The issue arises because the tree ring chronologies are standardized:
> this involves subtracting a mean and dividing by a variance.
> MBH1998 use the mean and variance of the detrended series evaluated
> over the calibration period. MM2005 are of the view that this is
> incorrect.
> They suggest that each series should be standardised with respect to the
> mean and variance its full length.
>
> The code used by MM2005 is not, at the time of writing available,
> but the code fragments included in the text imply
> that their calculation used data which had been
> centred (mean removed) but had not been normalized to unit variance (standardised).
> Figure 3 shows the effect of the changes, applied to the
> North American tree ring sub-network of the data used by MBH1998,
> using those chronologies which extend back to 1400AD.
> The calculation used here does not precisely reproduce the archived MBH1998
> result, but the differences may be due to small differences in
> mathematical library routines used to do the decomposition.
> The effect of replacing the MBH1998 approach with centering and
> standardising on the whole time series is small, the effect of
> omitting the standardisation as in MM2005 is much larger:
> this omission causes the 20th century trend to be removed from the
> first principal component.
>
> citet{storch_zorita2005} look at some of the claims made in MM2005
> and analyses them in the context of a climate simulation.
> They find the impact of the modifications suggested by McIntyre and McKitrick to
> be minor.
> citet{mcintyre_mckitrick2005b} clarify their original claim, stating that the
> standardisation technique used by MBH98 does not create the ``hockey-stick" structure
> but does ``steer" the selection of this structure in principal component
> analysis.
>
> citet{mcintyre_mckitrick2005c} [MM2005c] revisit the MM2003 work and correct
> their earlier error by taking the stepwise reconstruction technique into account.
> They assert that the results of MM2003, which show a 15th century
> reconstruction 0.5K warmer than found by MBH1998,
> are reproduced with only minor changes to the MBH1998 proxy data base.
> Examination of the relevant figures, however, shows that this is not entirely
> true. The MM2005c predictions for
> the 15th century are 0.3K warmer than the MBH1998
> result: this is still significant, but, unlike the discredited MM2003 result, it
> would not make the 15th century the warmest on record.
>
> MM20005c and citet{wahl_ammann2005} both find that
> excluding the north American bristlecone pine data from the proxy
> data base removes the skill from the 15th century reconstructions.
> MM2005c justify this removal on the grounds that the first principal component
> of the North American proxies, which is dominated by the
> bristlecone pines, is a statistical outlier with respect to the joint distribution
> of $R^2$ and the difference in mean between 1400 to 1450 and 1902 to 1980.
> %%first ref to table 1
> Table 1, which lists a range of proxies extending back to 1000,
> shows that the North American first principal component (``ITRDB [pc01]'' in that table)
> is not an outlier
> in terms of its coherence with northern hemispheric mean temperature from 1856 to 1980.
>
> begin{table}[t]
> small
> %% output from mitrie/pylib/multi_r2.py, editted
> begin{tabular}{|p{7.0cm}|r|r|l|r|l|}
> hline
> Name & Lat. & Lon. & Id & $R^2$ & Type cr
> hline
> GRIP: borehole temperature (degC) (Greenland)$^1$ & 73 & -38 & *,Mo & 0.67 & [IC] cr
> China: composite (degC)$^2$ & 30 & 105 & *,Mo & 0.63 & [MC] cr
> Taymir (Russia) & 72 & 102 & He & 0.60 & [TR C] cr
> Eastern Asia & 35 & 110 & He & 0.58 & [TR C] cr
> Polar Urals$^3$ & 65 & 67 & Es, Ma & 0.51 & [TR] cr
> Tornetraesk (Sweden)$^4$ & 58 & 21 & Mo & 0.50 & [TR] cr
> ITRDB [pc01] & 40 & -110 & Ma & 0.49 & [TR PC] cr
> Mongolia & 50 & 100 & He & 0.46 & [TR C] cr
> Arabian Sea: Globigerina bull$^5$ & 18 & 58 & *,Mo & 0.45 & [CL] cr
> Western Siberia & 60 & 60 & He & 0.44 & [TR C] cr
> Northern Norway & 65 & 15 & He & 0.44 & [TR C] cr
> Upper Wright (USA)$^6$ & 38 & -119 & *,Es & 0.43 & [TR] cr
> Shihua Cave: layer thickness (degC) (China)$^7$ & 40 & 116 & *,Mo & 0.42 & [SP] cr
> Western Greenland & 75 & -45 & He & 0.40 & cr
> Quelcaya 2 [do18] (Peru)$^8$ & -14 & -71 & *,Ma & 0.37 & [IC] cr
> Boreal (USA)$^6$ & 35 & -118 & *,Es & 0.32 & [TR] cr
> Tornetraesk (Sweden)$^9$ & 58 & 21 & *,Es & 0.31 & [TR] cr
> Taymir (Russia)$^{10}$ & 72 & 102 & *,Es, Mo & 0.30 & [TR] cr
> Fennoscandia$^{11}$ & 68 & 23 & *,Jo,Ma & 0.28 & [TR] cr
> Yamal (Russia)$^{12}$ & 70 & 70 & *,Mo & 0.28 & [TR] cr
> Northern Urals (Russia)$^{13}$ & 66 & 65 & *,Jo & 0.27 & [TR] cr
> hline
> end{tabular}
> caption{Continued overleaf.}
> end{table}
>
> renewcommand{thetable}{arabic{table}}
> addtocounter{table}{-1}
> begin{table}[t]
> small
> begin{tabular}{|p{7.0cm}|r|r|l|r|l|}
> hline
> Name & Lat. & Lon. & Id & $R^2$ & Type cr
> hline
> ITRDB [pc02] & 42 & -108 & Ma & 0.21 & [TR PC] cr
> Lenca (Chile)$^{14}$ & -41 & -72 & Jo & 0.18 & [TR] cr
> Crete (Greenland)$^{15}$ & 71 & -36 & *,Jo & 0.16 & [IC] cr
> Methuselah Walk (USA) & 37 & -118 & *,Mo & 0.14 & [TR] cr
> Greenland stack$^{15}$ & 77 & -60 & Ma & 0.13 & [IC] cr
> Morocco & 33 & -5 & *,Ma & 0.13 & [TR] cr
> North Patagonia$^{16}$ & -38 & -68 & Ma & 0.08 & [TR] cr
> Indian Garden (USA) & 39 & -115 & *,Mo & 0.04 & [TR] cr
> Tasmania$^{17}$ & -43 & 148 & Ma & 0.04 & [TR] cr
> ITRDB [pc03] & 44 & -105 & Ma & -0.03 & [TR PC] cr
> Chesapeake Bay: Mg/Ca (degC) (USA)$^{18}$ & 38 & -76 & *,Mo & -0.07 & [SE] cr
> Quelcaya 2 [accum] (Peru)$^{8}$ & -14 & -71 & *,Ma & -0.14 & [IC] cr
> France & 44 & 7 & *,Ma & -0.17 & [TR] cr
> hline
> end{tabular}
> caption{(continued)
> The primary reference for each data set is indicated by the superscript in the first column as
> follows:
> 1: citep{dahl-jensen_etal1998}, 2: citet{yang_etal2002}, 3: citet{shiyatov1993}, 4: citet{grudd_etal2002}, 5: citet{gupta_etal2003},
> 6: citet{lloyd_graumlich1997}, 7: citet{tan_etal2003}, 8: citet{thompson1992},
> 9: citet{bartholin_karlen1983}, 10: citet{naurzbaev_vaganov1999}, 11: citet{briffa_etal1992},
> 12: citet{hantemirov_shiyatov2002}, 13: citet{briffa_etal1995}, 14: citet{lara_villalba1993},
> 15: citet{fisher_etal1996}, 16: citet{boninsegna1992}, 17: citet{cook_etal1991}, 18: citet{cronin_etal2003}.
> the "Id" in column 4 refers to the reconstructions in which the data were used.
> The type of proxy is indicated in column 6:: tree-ring [TR], tree-ring composite [TR C],
> tree-ring principle component [TR PC], coral [CL], sediment [SE], ice core [IC],
> multi-proxy composite [MC]. The 19 proxy series marked with a "*" in column 4 are used in the
> ``Union'' reconstruction.
> }
> end{table}
>
> citep[][; MM2005c]{briffa_osborn1999} suggest that
> rising CO$_2$ levels may have contributed significantly to the
> 19th and 20th century increase in growth rate in some trees,
> particularly the bristlecone pines, but such an
> effect has not been reproduced in controlled experiments with mature trees
> citep{korner_etal2005}.
>
> Once a time series purporting to represent past temperature has been obtained,
> the final, and perhaps, most important, step is to verify its
> and estimate uncertainty limits. This is discussed further in the next section.
>
> section{Varying methods vs. varying data}
>
> One factor which complicates the evaluation of the various reconstructions is
> that different authors have varied both method and data collections. Here we will
> run a representative set of proxy data collections through two algorithms:
> inverse regression and scaled composites. These two methods, and the different
> statistical models from which they may be derived, are explained in the
> Appendix A.
>
> Esper et al. (2005) investigated the differing calibration approaches used in the recent literature, including
> regression and scaling techniques, and concluded that the methodological differences in calibration result in differences
> in the reconstructed temperature amplitude/variance of about 0.5K.
> This magnitude is equivalent to the mean annual temperature change for the Northern Hemisphere reported in the last
> IPCC report for the 1xxx xxxx xxxxperiod.
> citet{burger_etal2006} take another approach and investigate a family of 32 different regression algorithms
> derived by adjusting 5 binary switches, using pseudo-proxy data.
> They show that these choices, which
> have all been defended in the literature, can lead to a wide variety of different
> reconstructions given the same data.
> They also point out that the uncertainty is greater when we
> attempt to estimate the climate of periods which lie outside the range experienced
> during the calibration period. The relevance of this point to the last millennium is
> under debate: the glacier based temperature estimates of OER2005 suggest that the
> coldest northern hemisphere mean temperatures occurred close to the start of
> the instrumental record, in the 19th century. The borehole reconstructions,
> however, imply that there were colder temperatures experienced in the 16th to 18th centuries.
> For the question as to whether the warmth of the latter part of the calibration
> period has been experienced in the past, however,
> this particular issue is not directly relevant.
>
> As noted above, much of the MBH1999 algorithm is irrelevant to reconstructions
> prior to AD 1450, because before that date the data only suffice,
> according to estimates in that paper, to determine one degree of freedom.
> Hence, we will only look at direct evaluation of the hemispheric mean temperature.
>
> Several authors have evaluated composites and calibrated those composites
> against instrumental temperature. Many of the composites contain more samples in later
> periods, so that the calibration may be dominated by samples which do
> not extend into the distant past. Here, we will restrict attention to
> records which span the entire reconstruction period.
> The data series used are listed in table 1.
>
> subsection{Proxy data quality issues}
>
> As noted previously, their has been especially strong criticism of
> MBH1998, 1999, partly concerning some aspects of their data collection.
> Figures 4 and 5 show reconstructions made using the MBH1999 and MBH1998 data respectively.
> Regression against northern hemispheric mean temperature from 1856 to 1980 is used
> instead of regression against principal components of
> temperature from 1902 to 1980. There are differences, but key features remain.
> MM2003 draw attention to the fact that one time series,
> ``CANA036" in the ITRDB classification, contributed
> by Gasp'e, appears twice in the MBH1998 database.
> This error is corrected in the red dashed curve of Fig.~5,
> which is almost identical to the green curve, which retains the duplication.
>
> subsection{Reconstruction using a union of proxy collections}
>
> The following subsection will discuss a range of reconstructions using different
> data collections. The first 5 of these collections are defined as those proxies used by
> JBB1998, MBH1999, ECS2002, MSH2005 and HCA2006, respectively, which extend back to 1000AD.
> These will be referred to below as the JBB, MBH, ECS, MSH, HCA composites below
> to distinguish them from the composites used in the published articles, which include
> additional, shorter, proxy data series.
> Finally there is a `Union' composite made using 19 independent northern
> hemisphere proxy series marked with ``*" in table 1. Apart from the China composite
> record, all the data used are individual series. The PCs used by MBH1999 have been
> omitted in favour of individual series used in other studies.
> Two southern hemisphere tropical series, both from the Quelcaya glacier, Peru,
> are included ensure adequate representation of tropical temperatures.
> This 'Union' collection contains 11 tree-ring series, 4 ice-cores, and one each of
> coral, speleothem, lake sediment and a composite record including historical data.
>
> subsection{Intercomparison of proxy collections}
>
> Figure 6 shows reconstructions back to 1000AD using
> composites of proxies and variance matching [CVM] (for the proxy
> principal components in the MBH1998, MBH1999 data collections the sign
> is arbitrary: these series have, where necessary, had the sign reversed so that
> they have a positive correlation with the northern hemisphere
> temperature record).
> Surprisingly, the `Union' does not lie in the range spanned by the other reconstructions,
> and reaches colder temperatures than any of them. It does, however, fit the calibration period
> data better than any of the sub-collections.
>
> The reconstructions shown in Fig.~7 use the same data is used: this time
> using inverse regression [INVR] (Appendix A), as used by MBH1998
> (the method used here differs from that of MBH1998 in using northern hemisphere
> temperature to calibrate against, having a longer calibration period,
> and reconstructing only a single variable instead of multiple EOFs).
> The spread of values is substantially increased relative to the CVM reconstruction.
>
> With INVR, only one reconstruction (that using the ECS2001
> data) shows temperatures warmer than the mid 20th century.
> The inverse regression technique applies weights to the
> individual proxies which are proportional to the
> correlation between the proxies and the calibration temperature
> signature.
> For this time series the 5 proxies are weighted as:
> 1.7 (Boreal); 2.9 (Polar Urals); 1.7 (Taymir); 1.8 (Tornetraesk); and 2.3 (Upper Wright).
> Firstly, it should be noted that this collection samples North America and the
> Eurasian arctic only. The bias towards the arctic is strengthened by the weights
> generated by the inverse regression algorithm, such that the reconstruction has poor geographical coverage.
>
> The MBH1999 and HPS2000 published reconstructions are shown in Fig.~6 for comparison: the MBH1999
> reconstruction lies near the centre of the spread of estimates, while the HPS2000 reconstruction
> is generally at the lower bound.
>
> Much of the current debate revolves around the level of
> centennial scale variability in the past.
> The CVM results generally suggest
> a low variance scenario comparable to MBH1999. The inverse regression
> results, however, suggest greater variability. It should be noted
> that the MBH1999 inverse regression result use greater volumes of
> data for recent centuries, so that the difference in Fig.~7 between the
> dashed red curve and the full green curve in the 17th
> century is mainly due to reduced proxy data input in the latter
> (there is also a difference because MBH1999 used inverse regression
> against temperature principle components rather than northern hemisphere
> mean temperature as here).
>
> Table 2 shows the cross correlations of the reconstructions in Fig.~6,
> for high pass (upper right) and low pass (lower left) components
> of the series, with low pass being defined by a 40 year running mean.
> The low pass components are highly correlated.
>
> begin{table}[t]
> %% output from mitrie/pylib/pp.py
> begin{tabular}{|l|c|c|c|c|c|c|}
> hline
> & Ma & Mo & Es & Jo & He & Unioncr
> hline
> Ma & -- & 14% & 25% & 60% & 20% & 61% cr
> Mo & 69% & -- & 37% & 11% & 13% & 60% cr
> Es & 64% & 77% & -- & 14% & 36% & 57% cr
> Jo & 62% & 51% & 46% & -- & 11% & 35% cr
> He & 72% & 75% & 85% & 53% & -- & 26% cr
> Union & 67% & 71% & 62% & 45% & 84% & -- cr
> hline
> end{tabular}
> caption{Cross correlations between reconstructions from
> different proxy data bases: Mann et al (Ma), Moberg et al (Mo),
> Esper et al (Es), Jones et al (Jo), Hegerl et al (He).
> Lower left block correspond to low pass filtered series,
> upper right to high pass filtered.}
> end{table}
>
> The significance of the correlations between these five proxy data samples
> and the instrumental temperature data during the calibration period (1xxx xxxx xxxx)
> has been evaluated using a Monte-Carlo simulation
> with (1) a first order Markov model and (2) random time series
> which reproduces the lag correlation structure of the data samples (see Appendix A).
> Figure 8 shows the lag correlations. The instrumental record had a pronounced
> anti-correlation on the 40 year time-scale. This may be an artifact of the short
> data record, but it is retained in the significance calculation as the best available
> estimate which is independent of the proxies.
> The `Union' composite shows multi-centennial correlations which are not present in the other data.
> The MBH and JBB composites clearly underestimate the decadal scale correlations, while
> the HCA and 'Union' composites overestimate it.
> %%first ref to table 3
> Results are shown in table 3.
> If the full lag correlation structure of the data were known, it would be true,
> as argued by MM2005, that the first order approach generally
> leads to an overestimate of significance. Here, however, we only have a
> estimated correlation structure based on a small sample. Using this finite
> sample correlation is likely to overestimate long-term correlations and hence
> lead to an underestimate of significance. Nevertheless, results are presented here
> to provide a cautious estimate of significance.
> For the MBH and JBB composites, which have short lag-correlations, the difference
> between the two methods is minimal. For other composites there is a substantial difference.
> In all cases the $R^2$ values exceed the 99% significance level. When
> detrended data are used the $R^2$ values are lower, but still above the 95%
> level -- with the exception of the Hegerl et al. data. This data has only decadal
> resolution, so the lower significance in high frequency variability is to be expected.
>
>
> begin{table}[t]
> %% output from mitrie/pylib/sum_ac.py
> begin{tabular}{|l||c|c||c|c||c||c|p{1.1cm}|}
> hline
> Source & $R^2_{95|h}$ & $R^2_{95|AR}$ & $R^2$ & $R^2_{detr}$ & $sigma$ & Signif. & Signif. (detrended) cr
> hline
> Mann et al. & 0.205 & 0.170 & 0.463 & 0.286 & 0.186 & 99.99% & 98.75%cr
> hline
> Moberg et al., (hi+lo)/2 & 0.225 & 0.183 & 0.418 & 0.338 & 0.153 & 99.87% & 99.25%cr
> hline
> Esper et al. & 0.335 & 0.220 & 0.613 & 0.412 & 0.158 & 99.96% & 98.11%cr
> hline
> Jones et al. & 0.187 & 0.180 & 0.371 & 0.274 & 0.203 & 99.93% & 99.17%cr
> hline
> Hegerl et al. & 0.440 & 0.266 & 0.618 & 0.357 & 0.133 & 99.56% & 90.13%cr
> hline
> Union & 0.337 & 0.236 & 0.655 & 0.414 & 0.149 & 99.98% & 97.91%cr
> hline
> end{tabular}
> caption{
> $R^2$ values evaluated using the Northern Hemisphere mean temperature (1856 to 1980) and various
> proxy records.
> Columns 2 and 3 show $R^2$ values for the 95% significance
> levels, evaluated using a Monte Carlo simulation with 10,000 realisations. In columns
> 2, 7 and 8 the full lag-correlation structure of the data is used, in column
> 3 a first order auto-regressive model is used, based on the lag one auto-correlation.
> Column 4 shows the $R^2$ value obtained from the data and column 5 shows the same
> using detrended data.
> Column 6 shows the standard error (root-mean-square residual) from the calibration
> period. Columns 7 and 8 show significance levels, estimated using
> Monte Carlo simulations as in column 2, for the full and detrended $R^2$ values.
> }
> end{table}
>
> Figure 9 plots this reconstruction,
> with the instrumental data
> in the calibration period.
> The composite tracks the changes in northern hemisphere temperature well,
> capturing the steep rise between 1910 and 1950 and much of the decadal
> scale variability. This is reflected in the significance scores (Tab.~3)
> which are high both for the full series and for the detrended series.
> The highest temperature in the reconstructed data, relative to the 1xxx xxxx xxxxmean is
> 0.227K in 1091AD. This temperature was first exceeded in the instrumental record in 1878,
> again in 1937 and frequently thereafter. The instrumental record has not gone below this level since 1986.
> Taking $sigma=0.149$ as the root-mean-square residual in the calibration period
> 1990 is the first year when the 1091 maximum was exceed by $2sigma$.
> This happened again in 1995 and every year since 1997.
> 1998 and every year since 2001 have exceeded the preindustrial maximum by $3sigma$.
>
> conclusionslabel{sec:end}
>
> There is general agreement that global temperatures cooled
> over the majority of the last millennium and have risen sharply
> since 1850. In this respect, the recent literature has not produced
> any change to the conclusions of JBB1998, though there remains
> substantial uncertainty about the magnitude of centennial scale variability
> superimposed over longer term trends.
>
> The IPCC 2001 conclusion that temperatures of the past millennium
> are unlikely to have been as warm, at any time prior to the 20th
> century, as the last decades of the 20th century is supported
> by subsequent research and by the results obtained here.
>
> The greatest range of disagreement among independent
> assessments occurs during the coolest centuries, from 1500 to
> 1900, when the departure from recent climate conditions
> was strongest and may have been outside the range of
> temperatures experienced during the later
> instrumental period.
>
> There are many areas of uncertainty and disagreement within
> the broad consensus outlined above, and also some who
> dissent from that consensus. Papers which claim to refute the
> IPCC2001 conclusion on the climate of the past millennium have been
> reviewed and found to contain serious flaws.
>
> A major area of uncertainty concerns the accuracy of the long time-scale
> variability in the reconstructions. This is particularly
> so for timescale of a century and longer. There does not appear to be any
> doubt that the proxy records would capture rapid change on
> a 10 to 50 year time scale such as we have experienced in recent decades.
>
> Using two different reconstruction methods on a range of proxy data
> collections, we have found that inverse regression
> tends to give large weighting to
> a small number

Original Filename: 1155150358.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
To: cbaisan@xxxxxxxxx.xxx
Subject: Re: help with an idea?
Date: Wed Aug 9 15:05:xxx xxxx xxxx

Dear Chris
just wondering what became of my forwarded request (from you to Tony) ? Have not received
any feedback and still anxious to follow this up
cheers
Keith
At 15:53 17/10/2003, you wrote:

Keith,
I am inclined to forward your note to Tony Caprio - any objections?
He has the best temperature sensitive foxtail pine material I am
aware of.
I have some sense that there is a change in regional climate
patterns prior to 1000AD in the western US. Not sure what or
why...
Matt Salzer and Malcolm Hughes are working on 3k yr material
from temperature sensitive upper tree-line sites in the west.
John King knows a great deal about the Sierra collections and
data.
MaryBeth Keifer and Andrea Loyd-Faste collected the Sierra
Foxtail you referred to.
Chris B.
> Hi Lisa and Chris and Ed
>
> The first point of this message is to ask for access to the raw data
> for the Boreal and Camp Hill Foxtail pine chronologies (Lisa) that I
> believe you and/or your students produced and similar data that you
> may have (Chris). for the area inland of the Santa Barbara Basin ,
> California. I am also trying to stimulate your interest and hopefully
> start a joint collaboration (Lisa , Chris and Ed). Please allow me to
> explain . I was reading some papers on the putative link between North
> Atlantic temperatures (oxygen isotope record from Greenland) and
> climate (bio-turbation index) in the Santa Barbara basin , on the
> 1000-year time scale (papers by Boyle and Leuschner et al. in the
> PAGES QSR Volume published in 2000). It got me to thinking whether a
> robust regional temperature chronology for North west Scandinavia
> might show any associations with any climate factors as represented in
> either high or low elevation tree-ring chronologies in Western
> California , at higher temporal resolution (perhaps decades to
> century) - and hence whether there is any evidence for a thermohaline
> link (or other more direct dynamic atmospheric connection) operating
> on various time scales. Of course there are problems with what
> specific climate response one would investigate (in terms of season
> and variable). However, as a first look I compared our Tornetrask
> temperature reconstruction (JJA in Northern Sweden) with a (very) few
> series I had for the west US - among which were the chronologies
> mentioned above from AD 800 that Jan Esper and Ed produced for their
> Science paper, using data supplied by Lisa I believe .
> Now I don't actually like the general way they applied the RCS ( -
> using
> a very large scale standardisation curve based on disparate data from
> a very wide expanse of sites across the Northern Hemisphere - but as
> Ed might say " it seems to work "). However, the association between
> the Tornetrask series and the curves for Boreal/ Upper Wright have
> stimulated me to try to look deeper and solicit your interest and
> help. In my opinion, for the 600-year period between AD 1100 and 1700
> the similarity in the 5 circa 120-year cycles that make up these
> series certainly warrant serious further study. The similarity is not
> apparent before this but the two California series themselves show
> little agreement in the earlier 300 years of data that I have seen,
> implying that the common signal at the regional level may not be well
> represented in either anyway. This could be a standardisation issue
> though. By producing more robust mean series and especially by
> extending the series back before the post Christian era we could
> significantly extend the power of the comparison. I would like to
> establish well replicated series (using more-local RCS curves based
> applied to more, and longer, data) for both the Tornetrask (and
> possibly Northern Finnish) region and the combined set from Upper
> Wright and Boreal and any other nearby Foxtail data ( from the region
> of the 118 degrees west 36 degrees north) . We have earlier (than
> circa AD 800 ) data for Tornetrask and Finland , showing good inter
> region coherence . If we can establish stronger evidence of a North
> Atlantic/Eastern Pacific link (at different time scales perhaps) we
> can look at other high resolution records to establish the nature of
> the likely forcing and the possible climate dynamic mechanisms. What
> do you think? Can I play with your data to this end ? Whatever you
> think , I would appreciate it if you would treat this as confidential
> and any thoughts on the idea , or pointers to relevant data sets are
> still welcome.
> All the very best
> Keith
>
> --
> Professor Keith Briffa,
> Climatic Research Unit
> University of East Anglia
> Norwich, NR4 7TJ, U.K.
>
> Phone: xxx xxxx xxxx
> Fax: xxx xxxx xxxx
>
> [1]http://www.cru.uea.ac.uk/cru/people/briffa/
>
):)) ) )) )) ) )).)) ) )) ) )) ) ).))
Christopher Baisan
Sr. Research Specialist
Laboratory of Tree-Ring Research
University of Arizona, Tucson 85721
email: cbaisan@xxxxxxxxx.xxx
tel: xxx xxxx xxxx
Fax: xxx xxxx xxxx
).)) ) )) ) ) )) ).) )) ) )) ) ) )).) ) )) )))

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

Phone: xxx xxxx xxxx
Fax: xxx xxxx xxxx
[2]http://www.cru.uea.ac.uk/cru/people/briffa/

References

1. http://www.cru.uea.ac.uk/cru/people/briffa/
2. http://www.cru.uea.ac.uk/cru/people/briffa/

Original Filename: 1155333435.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
To: Hans von Storch <hvonstorch@xxxxxxxxx.xxx>
Subject: Re: open data access?
Date: Fri Aug 11 17:57:xxx xxxx xxxx

Hans
just too bogged down with stuff to even read their crap - but I have no intention of
withholding anything. Will supply the stuff when I get five minutes!! no idea what the
so-called update stuff is about
Keith
At 11:19 05/08/2006, you wrote:

Dear Keith,
I read this comment on the prometheus-weblog of Roger Pielke jr:
"Ask Briffa for site identifications for Briffa et al 2001? While you're at it, ask him
for the measurement data for Taimyr, Tornetrask update and Yamal? Ask Briffa why he
didn't publish the updated Polar Urals results."
The background of this inquiry seems to be the replicability of your studies. I think
this is a reasonable request, but some people claim that you would "stonewall" any such
attempts. ("The issue of data access was discussed in the dendro conference in Beijing -
some people suggesting that withholding data was giving the trade a black eye. Industry
leaders, such as presumably Briffa, said that they were going to continue
stonewalling.") I can not believe this claim, and I would greatly appreciate if you
would help me to diffuse any such suspicions.
As you possibly have heard, I had a chance to hear a lot what is said on Capitol Hill
(see attachment) - and I am concerned if we do not apply a truly open data and
algorithm-policy, our credibility will be severly damaged, not only in the US but also
in Europe. "Open" means also to provide data to groups which are hostile to our work -
we have done so with our ECHO-G data, which resulted in two hostile comments in
"science", which were, however, useful as they helped to clarify some issues.
All the best,
Hans
--
Hans von Storch
hvonstorch@xxxxxxxxx.xxx; skype: hvonstorch
presently: Kaspervej 2, 4673 R

Original Filename: 1155346370.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Hans von Storch <hvonstorch@xxxxxxxxx.xxx>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Re: open data access?
Date: Fri, 11 Aug 2006 21:32:50 +0200
Cc: Hans von Storch <hans.von.storch@xxxxxxxxx.xxx>, Hans Graf <hfg21@xxxxxxxxx.xxx>

Dear Keith,

I think we have to take this talking and questioning seriously. what we do is important and we have to allow for replication. when we were confronted with such requests concering the ERIK-simulations, we were initially reluctant, but now we gove teh data to verybpody. Got us two critical comments in "science" but I think it was worth it.

Do you mind if I publish your response? Would be the prometheus weblog.
I could ask what is meant with "update" - I do know not what is meant; I had just quoted a request which I find in principle not unreasonable - and I am happy to hear that you in principle agree.

Regards,
Hans



> -----Urspr

Original Filename: 1155402164.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: "Wahl, Eugene R" <wahle@xxxxxxxxx.xxx>
To: "Keith Briffa" <k.briffa@xxxxxxxxx.xxx>
Subject: RE: confidential
Date: Sat, 12 Aug 2006 13:02:xxx xxxx xxxx

Hi Keith:

Thanks so much for the chance to look over this section. I think the long section you added on pp 6-5 and 6-6 reads well, and makes good sense according to what I know. Indeed, reading the whole section is a good review for me!

I suggested addition of a phrase in lines xxx xxxx xxxxon page 6-3 regarding MM 2003 and analysis of it by Wahl-Ammann 2006. I also suggest a (logically useful) change from singular to plural in line 42 of that page. The changes are in RED/BOLD font.

[I should note that AW 2006 is still in "in press" status, and its exact publication date will be affected by publication of an editorial designed to go with it that Caspar and I are submitting this weekend. Thus I cannot say it is certain this article will come out in 2006, but its final acceptance for publication as of 2/28/06 remains completely solid.]

Also, I added the full information for the Wahl-Ritson-Ammann 2006 Science article in the references section, also in RED/BOLD font.


By the way, is the "AJS" NCAR-CSM model in Fig. xxx xxxx xxxxthe one Caspar did? I couldn't tell this for sure from the information in the text. If it is, perfect. If not, is there a way to include his millenium run?


Thanks to you and all the authors for you painstaking work.


Peace, Gene
Dr. Eugene R. Wahl
Asst. Professor of Environmental Studies
Alfred University

xxx xxxx xxxx
1 Saxon Drive
Alfred, NY 14802

________________________________

From: Keith Briffa [mailto:k.briffa@xxxxxxxxx.xxx]
Sent: Mon 7/31/2006 10:29 AM
To: Wahl, Eugene R
Subject: RE: confidential



First Gene - let me say that I never intended that you should spend
so much time on this - though I really appreciate your take on these
points. The one you highlight here - correctly warns me that in
succumbing to the temptation to be lazy in the sense of the brief
answer that I have provided - I do give an implied endorsement of
the sense of the whole comment. This is not, of course what I
intended. I simply meant to agree that some reference to the
"divergence" issue was necessitated . I will revise the reply to say
briefly that I do not agree with the interpretation of the reviewer.
I am attaching what I have done (see blue highlighting) to the
section in response to comments (including the addition of the needed
extra section on the "tree-ring issues" called for by several
people). I have had no feedback yet on this as it has not been
generally circulated , but thought you might like to see it. PLEASE
REMEMBER that this is "for your eyes only " . Please do NOT feel that
I am asking /expecting you to go through this in any detail - but
given the trouble you have taken,I thought it reasonable to give
you a private look. Cheers
Keith

At 07:16 27/07/2006, you wrote:
>Hi Keith:
>
>Here is the text with my comments. I will go over the "stolen"
>parts (highlighted in blue outline) for a final time tomorrow
>morning, but I wanted to get this to you ASAP. The main new point I
>have to make is added in bold/blue font on pp. xxx xxxx xxxx. I question
>the way the response to the comment there is currently worded, as it
>seems to imply that the divergence issue really does invalidate any
>dendro-based reconstructions before about 1850--which I imagine is
>not what you would like to say. I give a series of arguments
>against this as a general conclusion. Maybe I got over-bold in
>doing so, as in my point (1) I'm examining issues that are at the
>very core of your expertise! Excuse me that one, but I decided to
>jump in anyway. Let me know if I got it wrong in any way!
>
>There are other quite minor suggestions (mostly focused on
>referencing other responses in a few places) that are also in
>bold/blue. These go on into the "120's" in terms of page numbers.
>
>This is really a lot of work you've taken on, and I REALLY
>appreciate what you and the others are doing!
>
>[I've also been a lot involved with helping to get a person from the
>Pew Center for Global Climate Change ready to testify in front of
>the House Energy and Environment Committee tomorrow. That is why I
>couldn't get this done and sent to you earlier today. Send Mike
>Mann and Jay Gulledge (Pew Center) all good thoughts for strength and clarity.]
>
>
>NB -- "r" towards the end of the filename stands for my middle initial.
>
>
>Peace, Gene
>Dr. Eugene R. Wahl
>Asst. Professor of Environmental Studies
>Alfred University
>
>xxx xxxx xxxx
>1 Saxon Drive
>Alfred, NY 14802
>
>________________________________
>
>From: Keith Briffa [mailto:k.briffa@xxxxxxxxx.xxx]
>Sent: Mon 7/24/2006 3:16 PM
>To: Wahl, Eugene R
>Subject: RE: confidential
>
>
>
>
>
>Gene
>here is where I am up to now with my responses (still a load to do) -
>you can see that I have "borrowed (stolen)" from 2 of your responses
>in a significant degree - please assure me that this OK (and will not
>later be obvious) hopefully.
>You will get the whole text(confidentially again ) soon. You could
>also see that I hope to be fair to Mike - but he can be a little
>unbalanced in his remarks sometime - and I have had to disagree with
>his interpretations of some issues also.
>
>Please do not pass these on to anyone at all.
>Keith
>
>
>
>Will pass all comments to you before they are fixed in stone- nothing
>from review article will be mentioned.
>Really grateful to you - thanks
>Keith
>
>At 05:08 22/07/2006, you wrote:
> >Hi Keith:
> >
> >Glad to help. (!)
> >
> >If I could get a chance to look over the sections of my text you
> >would post to the comments before you do, I would appreciate it. If
> >this is a burden/problem let me know and we'll work it out.
> >
> >If it is anything from the Wahl-Ammann paper, of course that is fine
> >to use at once since it is publicly available. There will only be
> >exceedingly minor/few changes in the galleys, including a footnote
> >pointing to the extended RE benchmarking analysis contained in the
> >Ammann-Wahl review article.
> >
> >What I am concerned about for the time being is that nothing in the
> >review article shows up anywhere. It is just going in, and
> >confidentiality is important. The only exception to this are the
> >points I make in my blue comments in the big review file on page
> >104, concerning the MM way of benchmarking the RE statistic. Those
> >comments are fine to repeat at this point. [Please excuse my
> >hesitance in this way.]
> >
> >Actually, all the other blue comments I made in the big review file
> >are also fine to use at once.
> >
> >
> >Again, if this request is in any way a problem, let me know and
> >we'll figure out something.
> >
> >
> >Peace, Gene
> >Dr. Eugene R. Wahl
> >Asst. Professor of Environmental Studies
> >Alfred University
> >
> >________________________________
> >
> >From: Keith Briffa [mailto:k.briffa@xxxxxxxxx.xxx]
> >Sent: Fri 7/21/2006 2:00 PM
> >To: Wahl, Eugene R
> >Subject: RE: confidential
> >
> >Gene
> >your comments have been really useful and reassuring that I am not
> >doing MM a disservice. I will use some sections of your text in my
> >comments that will be eventually archived so hope this is ok with
> >you. I will keep the section in the chapter very brief - but will
> >cite all the papers to avoid claims of bias. I really would like to
> >discuss the whole issue of the reconstruction differences at a later
> >, less stressful time. I completely accept the arguments about the
> >limitation in the r2 and the value of capturing longer-term variance
> >. I think I will have to stop now as the temp and humidity are killing here.
> >
> >Thanks a lot again
> >
> >Keith
> >
> >At 18:39 21/07/2006, you wrote:
> > >Hi Keith:
> > >
> > >I'm sorry that there is a bit to digest...although I know it is just
> > >a result of the nature of things.
> > >
> > >By the way, copied below is a synopsis that I sent this morning to a
> > >person in DC who is working on all this with regard to the House of
> > >Representative hearings. Evidently, there is to be at least one
> > >more hearing next week, and Mike Mann will go. The person I sent
> > >this to is trying to understand the importance of the proxy PC
> > >issues --especially how, no matter what way the PC extraction is
> > >done, the reconstructions converge if the structures actually
> > >present in the data are not tossed out by truncating the number
> > >retained PCs at a too low level. What I've copied is this
> > >synopsis. I think it is straightforward -- maybe a bit dense, but
> > >at least brief.
> > >
> > >Also, let me know if I can help on the issue of RE vs r^2. I could
> > >write a few brief sentences as something for you to look at if you
> > >would like. Wahl-Ammann show very clearly that there is objectively
> > >demonstrated skill at the low-frequency level of the verification
> > >period mean for all the MBH segments, although the earlier MBH
> > >segments do have really low r^2 values (indicating very little skill
> > >at the interannual level). Our argument that to throw out the
> > >reconstruction completely based on the fastest varying frequency,
> > >when it has objectively demonstrable meaning at lower frequencies,
> > >is to me quite reasonable. That it is some how entirely ad hoc, as
> > >McIntyre claims in one (more?) of his comments, is neither logical
> > >nor factual in my perspective. The idea of frequency dependent
> > >skill/non-skill is not new to the literature, and the independent
> > >re-reviewer that Steve Schneider had look over Wahl-Ammann said s/he
> > >had experienced this issue in his/her work. G.
> > >
> > >
> > >****************************** COPIED TEXT ******************************
> > >
> > >What it boils down to in the end is as follows:
> > >
> > >1) The different reference periods used to calculate proxy PCs from
> > >N. America (calibration only for MBH, full period for MM) only have
> > >the effect of re-arranging how the hockey stick shape appears across
> > >the rank ordering of PCs. In MBH it is concentrated in PC1. In the
> > >full-period method, it is spread over PCs 1 and 2. If one adds PCs
> > >1 and 2 (either arithmetically or as vectors) from either
> > >convention, you get an essentially IDENTICAL time series, only the
> > >amplitudes are a bit different. [Note that the input data were
> > >centered AND standardized before being put into the PC calculation
> > >algorithm. This is important, as shown below.]
> > > WHEN ACTUALLY USED IN THE RECONSTRUCTION, THE DIFFERENCE
> > > IS MINISCULE -- MBH is colder over 1xxx xxxx xxxxby 0.05 degrees!
> > >
> > >2) IF the data are centered but NOT standardized and are input into
> > >in a PCA algorithm using the variance-covariance matrix and not the
> > >correlation matrix (the way MM did it), then the hockey stick shape
> > >shows up in PC4. MM in fact reported this first in their 2005
> > >Energy and Environment article. In effect, the first two PCs are
> > >ARE ACTING TO DO THE STANDARDIZING OF THE DATA not done as a
> > >pre-processing step. [When the correlation matrix is used instead
> > >in the PCA algorithm, then the standardization is in effect done by
> > >the algorithm, because all the correlations are "standardized" by
> > >construction--they all range between 0 and 1.]
> > > When 4 PCs from this calculation method are used rather
> > > than 2 PCs calculated as above, then the RECONSTRUCTION CONVERGES
> > > TO THE SAME AS ABOVE.
> > >
> > >3) Thus, all the different "flavors" for PC extraction have
> > >essentially no effect on reconstruction when one does the exercise
> > >of adding PCs sequentially from 2 to 5 for any flavor. In the case
> > >of (1), the reconstructions converge by the second PC. In the case
> > >of (2), they converge by PC4. They don't change with higher order
> > PCs added.
> > > THIS SHOULD BE EXPECTED FROM FIRST PRINCIPLES. That is,
> > > the same underlying information is there in all cases, it is only
> > > how the structures present in these data are spread across the rank
> > > order of PCs, as explained. The simple exercise of taking the
> > > reconstructions to convergence across the number of PCs used shows
> > > this clearly.
> > >
> > >4) In fact, MM essentially say all this in the 2005 EE
> > >article--INCLUDING ABOUT THE RECONSTRUCTION RESULTS -- but they
> > >strongly claim that the movement of the hockey stick shape to the
> > >4th PC shows it is not a leading pattern of variance as MBH claim,
> > >and thus should not be used. This might be logical if their
> > >analysis was an apples-apples comparison, but it is not, due to the
> > >PCA method they use and applying it on NON-standardized data.
> > > THESE TWO DIFFERENCES (which one can only fully get
> > > from their actual code, not in the articles published) DRIVE THEIR
> > > ENTIRE ARGUMENT ON THIS PARTICULAR ISSUE. What they do not say is
> > > that convergence to something like the MBH result is expectable,
> > > and indeed MUST happen given the data used, because the hockey
> > > stick shape is actually IN the data, it is NOT an artifact of PC
> > > calculation procedure.
> > >
> > >
> > >5) FINALLY, note that all of this rests on the foundation that
> > >keeping the bristlecone pine records in the data is appropriate,
> > >which Caspar and I find can be reasonable presumption. If one
> > >believes that the bristlecone data should be removed, then the
> > >1xxx xxxx xxxxreconstruction does not pass verification testing with the
> > >RE statistic, and the MBH reconstruction should commence from 1450 on out.
> > >
> > >Although there are a number of reasons to keep the bristlecone data
> > >in, maybe the most compelling reason they are a NON-ISSUE is that,
> > >over the common period of overlap (1xxx xxxx xxxx), the reconstruction
> > >based on using them from 1xxx xxxx xxxxis very close to the
> > >reconstruction based on omitting them from 1xxx xxxx xxxx. Since the
> > >issues about the bristlecone response to climate are primarily about
> > >1850 onwards, especially 1900 onwards [KEITH -- PLEASE LET ME KNOW
> > >IF I AM NOT ACCURATE IN THIS], there is no reason to expect that
> > >their behavior during 1xxx xxxx xxxxis in any way anomalous to their
> > >behavior from 1xxx xxxx xxxx. Thus, THERE IS NO REASON TO THINK THAT THE
> > >BRISTLECONES ARE SOMEHOW MAKING THE 1xxx xxxx xxxxSEGMENT OF THE MBH
> > >RECONSTRUCTION BE INAPPROPRIATELY SKEWED.
> > >
> > >
> > >****************************** END OF COPIED TEXT *******************
> > >
> > >Peace, Gene
> > >Dr. Eugene R. Wahl
> > >Asst. Professor of Environmental Studies
> > >Alfred University
> > >
> > >xxx xxxx xxxx
> > >1 Saxon Drive
> > >Alfred, NY 14802
> > >
> > >________________________________
> > >
> > >From: Keith Briffa [mailto:k.briffa@xxxxxxxxx.xxx]
> > >Sent: Fri 7/21/2006 4:51 AM
> > >To: Wahl, Eugene R
> > >Subject: RE: confidential
> > >
> > >
> > >
> > >Gene
> > >thanks a lot for this - I need to digest and I will come back to you.
> > >
> > >thanks again
> > >Keith
> >
> >--
> >Professor Keith Briffa,
> >Climatic Research Unit
> >University of East Anglia
> >Norwich, NR4 7TJ, U.K.
> >
> >Phone: xxx xxxx xxxx
> >Fax: xxx xxxx xxxx
> >
> >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: xxx xxxx xxxx
>Fax: xxx xxxx xxxx
>
>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: xxx xxxx xxxx
Fax: xxx xxxx xxxx

http://www.cru.uea.ac.uk/cru/people/briffa/



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From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, t.osborn@xxxxxxxxx.xxx, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>
Subject: Fwd: Tett et al. paper
Date: Sun, 13 Aug 2006 15:32:xxx xxxx xxxx
Cc: IPCC-WG1 <ipcc-wg1@xxxxxxxxx.xxx>

Hi Mel - thanks. Since chap 6 CA Tim Osborn is an author on this paper, I'm sure he and
Keith have made the right call.

Thanks again, Peck

X-Sieve: CMU Sieve 2.2
Date: Thu, 10 Aug 2006 09:44:xxx xxxx xxxx

From: IPCC-WG1 <ipcc-wg1@xxxxxxxxx.xxx>
X-Accept-Language: en-us, en
To: Jonathan Overpeck <jto@u.arizona.edu>,
Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>
Subject: Tett et al. paper

Hi Peck and Eystein,
Although the deadline for additional accepted papers has now passed, this submission
comes from a CLA (Gabi Hegerl) so am forwarding on. Official acceptance of the Tett et
al. paper was 2 June. My understanding is that you already have a copy, but will forward
the copy sent in by Simon just in case.
Cheers,
Mel

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
IPCC WGI TSU
NOAA Chemical Sciences Division
325 Broadway DSRC CSD08
Boulder, CO 80305, USA
Phone: xxx xxxx xxxx
Fax: xxx xxxx xxxx/5628
Email: [1]ipcc-wg1@xxxxxxxxx.xxx

--

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences
Mail and Fedex Address:
Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/

Attachment Converted: "c:eudoraattachTett_etal.pdf"

References

1. mailto:ipcc-wg1@xxxxxxxxx.xxx

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From: Eduardo Zorita <Eduardo.Zorita@xxxxxxxxx.xxx>
To: m.n.juckes@xxxxxxxxx.xxx, " Moberg; Anders " <anders.moberg@xxxxxxxxx.xxx>, Gabi Hegerl <hegerl@xxxxxxxxx.xxx>, esper@xxxxxxxxx.xxx, " Briffa; Keith " <k.briffa@xxxxxxxxx.xxx>, " Osborn; Tim " <t.osborn@xxxxxxxxx.xxx>, m.allen1@xxxxxxxxx.xxx, weber@xxxxxxxxx.xxx
Subject: comments to mitrie manuscript
Date: Thu, 17 Aug 2006 12:31:28 +0200



?

Due to the ongoing debate, this has turned an even more difficult manuscript. In general, I think Martin did a very good job in the review of the literature. Concerning the new reconstructions and the evaluation of McIntyre work, I would not fully agree with some of the conclusions, which I thin do not follow from the material presented in the text. I have some remarks on this which you may consider useful. But I think that I am not the one that should give the manuscript the final shape, as Martin is the person in charge of the project. Please, consider the following comments as suggestions.

eduardo



Consensus: I would tend to avoid the word 'consensus', since it is not a well defined concept.
Depending on the meaning of consensus, each would agree with it to a certain degree. I would prefer to refer to a particular IPCC conclusion, or something similar. I think this review of the literature is very well written and informative, but I am not sure that each one of us will agree with each one of the concussions of each of the papers.

Page 12, section 2.8. I think the text is somewhat vague here, and it could be misunderstood.
Mann et al (2005) tested the RegEM method, not the original MBH98 method. It is true that applied to the
real proxies both methods, according to Mann, yield very similar results. But strictly speaking , Mann did not test the MBH98 method in the CSM simulation. The MBH98 method is thereby only by implication

I tested the the sensitivity of the MBH98, and not of RegEM, to the length of the calibration period. It may be the RegEM is less sensitive or not at all. Figure 4 and 5, if I understood well, support this dependency of MBH to the calibration period. Am I correct to interpret the large differences between the original MBH reconstruction (dashed red) and the black curve as due to the different calibration period (1xxx xxxx xxxxversus 1xxx xxxx xxxx) and to the use of the leading PC or NHT as calibration target? At least in the period prior to 1600 I think these are the only methodological differences between both curves (?).
My interpretation of this figure is also somewhat different. If the final reconstructions differs so strongly by using a longer calibration period (in general yielding stronger decadal variability in the reconstruction) I would tend to think that the method based on these proxies is quite unstable. What would happen if the calibration period could have been extended to 1800, for instance?.


Page 15: top. The role of forcing on the global or NH T is also recognized in the correlation between the NHT simulated by ECHO-G and CSM for the millennium. For the case of a second ECHO-G simulation /Gonzalez-Rouco et al.) the agreement is very close at 30-year timescale.

Section 3, beginning.
In my opinion, MM05 stress the inadequacies and uncertainties in the MBH work, but they not put forward their own reconstruction implying a warmer-than-today MWP. They believe that this is true, but in their works so far, at least to my knowledge, they do not assert that the MWP was warmer than present, only that the uncertainties are too large for such a claim.

Section 3: Consensus. This paragraph may be problematic. Again what is the consensus? If we look at the recent NAS report, which again not every one would agree with, the 'consensus' is reduced to the past 400 years in comparison to IPCC, leaving ample space for speculation before this period. Does the NAS report belong to the consensus? perhaps partially, but I am not sure to what extent.

Section 3, discussion of MM05 and hockey-stick index. I have here a certain level of disagreement with these paragraphs. The issue raised by MM05 would be that the de-centering of the proxies prior to the calculations of the principal components tends to produce hockey-stick-shaped leading PC. I think this effect is true, at least with spatially uncorrelated red-noise series . It can be easily verified and it has been recognized in the NAS, the Wegman report and by Francis Zwiers. To be fair, following this issue is the problem of the truncation- just to keep the leading PC or further Pcs down the hiercharchy, and if this is done, the final differences could be probably minor. in the final reconstructions. But the paragraph implies, in my opinion, that this criticism by MM05 has no grounds, which as I said is problematic and could open the manuscript with criticisms based on these recent reports.

I think that the calculation shown in Figure 3 is very useful, as it boils down to the issue raised by MM05: how relevant is the de-centering and standardization with real proxies?. Apparently, I get a different message from Figure3 (although I may have misinterpreted the text). I see quite large differences in the 20th century between the original MBH leading PC and the 'correct' calculation (whole period centering and standarization,blue line). Only the original MBH PC shows a positive trend in the 20th century. The blue lines seems even to show a negative trend or no trend at all. If this PCs were to be used in the MBH regression model (with trend included in the calibration) the results could be quite different. I would tend to think that this figure actually supports the MM05 criticism, since the hockey-stick shape of the leading PC disappears.

Section 3, end, bristlecone pines. I am also worried by this paragraph. The recent NAS report clearly states that the bristlecone pines should not be used for reconstructions in view of their potential problems. They cite previous analysis on this issue. I think that to refer to just one study indicating no fertilization effect could not be enough. However, I am not a dendroclimatologist. This could open the door to potential problems.

Section 4 , end. years 1997 and onwards were the warmest in the millennium. I see here also potential problems with this claim, and I do not see the need to make our lives more complicated. The NAS report expressed that the uncertainties are too large for this type of conclusion and certainly this conclusion would attract some attention from the reader. I see two lines of criticism on this: one is that the standard errors have been calculated with the calibration residuals and these are an underestimation of the true uncertainties. A reviewer may require that the uncertainty range be calculated by cross-calibration or bootstraping. In the case of CVM perhaps this effect is not very important, as there is just one free parameter, but in the case of inverse regression there are much many more free parameters and the true uncertainties can be quite different from those estimated from the calibration residuals. This potential criticism could be exacerbated by the fact that the new reconstruction has not been tested in a validation period.
The other line of criticism could be that the calibration period has been, as in all reconstructions, a priori truncated -data after 1980 are not considered as the proxies are known to not follow the temperature. Strictly speaking this truncation can be only justified by a credible physical explanation about the cause of this divergence. Statistically, I think it is not correct to a priori ignore some data because they do not fit. If one does so, I think the uncertainty range should be enlarged to encompass the possibility that this divergence could have happened in the past, i.e. an additional standard deviation of the instrumental NH T in the period 1xxx xxxx xxxx(or perhaps more correct, the square root of the sum of the error variance and the NHT variance in 1xxx xxxx xxxx). Alternatively, one could include the period 1xxx xxxx xxxxin the calibration and due to the divergence the standard errors would grow, but perhaps this is practically not possible as the proxy time series may not have been archived for the last 20 years.

Section 5, conclusions.

I share the worry of Anders Moberg about the wording 'serious flaws' in the analysis of MM05. This sentence would be based on Figure 3, if I understood properly, but as I said I think Figures 3 actually does not support this conclusion.


Finally, I think it would strategically better to avoid conflicts on the particular point of whether some particular year was the warmest of the millennium or not, and to stress the fact that all reconstructions, also the new ones presented in the manuscript (with one exception) show MWP temperatures lower than late 20th century temperatures.


Another conclusion could be, in my view, that the average temperature in the cold centuries in the millennium seems to be still quite uncertain. The new reconstructions, or the calculation of the leading PCs of the proxies, seem to be still quite sensitive to particular choices in the statistical set-up.

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From: "Michael E. Mann" <mann@xxxxxxxxx.xxx>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: ECHO-G?
Date: Wed, 23 Aug 2006 08:07:xxx xxxx xxxx
Reply-to: mann@xxxxxxxxx.xxx
Cc: Scott Rutherford <srutherford@xxxxxxxxx.xxx>

<x-flowed>
HI Keith,

If the offer still stands, we wanted to get from you the ECHO-G surface
temperature field, so we can do some tests of RegEM with this. So far
we've only tested on CSM 1.4 and it would be nice to test this on on
ECHO-G, especially since other groups apparently now also have the
ECHO-G outpout (e.g. Mark Cane's group and Francis Zwiers' group).

Thanks in advance for any help w/ this,

mike

--
Michael E. Mann
Associate Professor
Director, Earth System Science Center (ESSC)

Department of Meteorology Phone: (8xxx xxxx xxxx
503 Walker Building FAX: (8xxx xxxx xxxx
The Pennsylvania State University email: mann@xxxxxxxxx.xxx
University Park, PA 16xxx xxxx xxxx

http://www.met.psu.edu/dept/faculty/mann.htm


</x-flowed>

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From: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Fwd: Chpt 6 - last 1000 yrs
Date: Wed, 30 Aug 2006 21:43:25 +0200
Cc: Jonathan Overpeck <jto@u.arizona.edu>

Hi Keith,

John should have the latest versions of the comments file and the chapter text, i.e. the
ones that went out for LA review this summer. I believe he is after some more specific
answers in the comments and not so much changes to the text, and has selected the
bristlecone issue, the divergency issue and the verification and robustness issues. If you
are unsure what comments or tetx he refers to, I think the best thing is for to ask John
for the specific comments he thinks are not adequate, or the specific lines of text which
he suggests changed. It seems he needs some reassurance rather than you writing much new in
terms of comments and text, so the best would be to talk to him and ask what he needs you
to do to the documents.

Best wishes,

Eystein

Envelope-to: Eystein.Jansen@xxxxxxxxx.xxx
Date: Wed, 30 Aug 2006 15:31:12 +0100
To: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>

From: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Fwd: Chpt 6 - last 1000 yrs
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Eystein
John sent these remarks - have not talked with him yet - but not sure what is now
required
Keith

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Subject: Chpt 6 - last 1000 yrs
Date: Wed, 16 Aug 2006 16:14:52 +0100
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Thread-Topic: Chpt 6 - last 1000 yrs
Thread-Index: AcbBRrj0FPNJH9bQTyCswuNw7Ln3bw==
From: "Mitchell, John FB (Chief Scientist)" <john.f.mitchell@xxxxxxxxx.xxx>
To: "Keith Briffa" <k.briffa@xxxxxxxxx.xxx>
Cc: "Mitchell, John FB (Chief Scientist)" <john.f.mitchell@xxxxxxxxx.xxx>
X-UEA-Spam-Score: 2.1
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Hi Keith
I have tried to cindense what I think the main issues for the and what the response is
below. The weakest area seems to be statistical significance and by implication the
likely/ very likely statements. I can't think of any easy solution - in the TAR for
detection and attribution we used 95% limits on stats tests and them downrated them to
allow for other uncertainties.
I am interested in your comments
John
Issues
1. Reliance on Bristlecone pine -
Response - the issues are in calibration period- they agree with other indicators for
the rest of the record
2. Centring of principle components leads to "hockeysticks"-
Response - this makes only a small difference when standardised data used.
Comment - Would be useful to know which reconstructions do and donot make this
assumption- this could strengthen the response
3. The divergence issue-
Response - it is only apparent in high latitudes, and only with some trees.
Comment- Do we know what happens if we eliminate those records with a divergence
problem. The wider issue is whether or not it is reasonable to extend the
reconstructions outside the calibration range.
4. There are different ways of verifying reconstructions and assigning significance
levels( calibration period or seprate verifying period, different statistics)
Response ?
Comment- it is difficult in the text to gauge how well reconstructions are validated -
eg using the calibration period to estimate errors as opposed to an independent period
clearly makes a difference. This is important where "likely", "very likely"are used-
based on what statistics? I think this is the area where I think the current response is
weakest
5. Robustness- Burger and Cubasch show a wide range of results using different
assumptions-
Response ?
Mann makes a reasoned defence- there are other checks and tests which would rule out
many of the arbitrary assumptions explored by Cubasch and Burger, but this is not clear
in the response to M&M etc

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

Phone: xxx xxxx xxxx
Fax: xxx xxxx xxxx
http://www.cru.uea.ac.uk/cru/people/briffa/

--

______________________________________________________________
Eystein Jansen
Professor/Director
Bjerknes Centre for Climate Research and
Dep. of Earth Science, Univ. of Bergen
All

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From: David Rind <drind@xxxxxxxxx.xxx>
To: Jonathan Overpeck <jto@u.arizona.edu>
Subject: Re: urgent IPCC need
Date: Thu, 31 Aug 2006 21:28:xxx xxxx xxxx
Cc: joos <joos@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, cddhr@xxxxxxxxx.xxx, rahmstorf@xxxxxxxxx.xxx, Keith Briffa <k.briffa@xxxxxxxxx.xxx>

<x-flowed>
Jonathan,

I haven't looked at these in great detail, but I
have a problem with Martin making suggestions
about the TSU Exec Summary for chap 6. Weren't
these decided by consensus among the Chap 6
authors? Why does Martin have any say about this?
Clarification is one thing, but some of these
suggestions seem to be 'leading'. I think we
should be very cautious about changing anything
substantive here at the last moment. [This is the
expurgated version of what I really thing.]

David


At 4:55 PM -0600 8/31/06, Jonathan Overpeck wrote:
>Hi all - We need to submit our latest chap 6
>Exec Summary to TSU tomorrow if we can. We can
>still make changes, but I wanted to update with
>Martin's suggestions taken into account. See the
>attached and please comment regarding my strike
>throughs and additions (yellow highlight).
>Martin's comments are in yellowish text, and my
>questions to you (especially FORTUNAT) are
>higlighted in PURPLE.
>
>Please send by tomorrow aft if you can.
>
>Not that I've sent to those I think are on-line
>right now. Will send to the whole team later
>with more edited text.
>
>Thanks, Peck
>--
>Jonathan T. Overpeck
>Director, Institute for the Study of Planet Earth
>Professor, Department of Geosciences
>Professor, Department of Atmospheric Sciences
>
>Mail and Fedex Address:
>
>Institute for the Study of Planet Earth
>715 N. Park Ave. 2nd Floor
>University of Arizona
>Tucson, AZ 85721
>direct tel: xxx xxxx xxxx
>fax: xxx xxxx xxxx
>http://www.geo.arizona.edu/
>http://www.ispe.arizona.edu/
>
>Attachment converted:
>Toltec:Ch06_FinalDraft_ExecSumV3.doc (WDBN/

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From: Jonathan Overpeck <jto@u.arizona.edu>
To: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>
Subject: Re: urgent IPCC need
Date: Fri, 1 Sep 2006 15:25:xxx xxxx xxxx
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, Stefan Rahmstorf <rahmstorf@xxxxxxxxx.xxx>, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, david.adelman@xxxxxxxxx.xxx

Hi all - today has been a hectic one, with lots of good input from multiple folks. In the
end, we agreed to stick with our existing bullets, which changes only where they would
improve the clarity of what we were saying. Please check the attached - need Fortunat's
detailed look in particular. Changes are all in yellow highlight. Two special issues:

1) There is still concern that this bullet is too vague to be as useful as it could be:

o It is very likely that the global warming of 4 to 7

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From: "Mitchell, John FB (Chief Scientist)" <john.f.mitchell@xxxxxxxxx.xxx>
To: "Stefan Rahmstorf" <rahmstorf@xxxxxxxxx.xxx>, "Keith Briffa" <k.briffa@xxxxxxxxx.xxx>
Subject: RE: Fwd: Re: [Wg1-ar4-ch06] NEW DRAFT FOR LA REVIEW
Date: Tue, 5 Sep 2006 12:29:08 +0100
Cc: "Eystein Jansen" <Eystein.Jansen@xxxxxxxxx.xxx>, "Jonathan Overpeck" <jto@u.arizona.edu>, "Jean Jouzel" <jouzel@xxxxxxxxx.xxx>

Keith, Stefan



Its not my role as review editor to tell you what to write, just to make sure you have
responded to the reviewers comments. For what its worth,
I did find Keith's text quite involved. However, you do need to respond the the reviewers
comments on Burger etc - if the flaws in von Storch paper cast doubt on the subsequent
papers, then why not include a sentence in the chapter that says so, and list just the key
papers affected.

I hope this helps

john



Professor John Mitchell OBE FRS Chief Scientist,
Met Office FitzRoy Road Exeter EX1 3PB United Kingdom
Tel. +44(0)1392884604 Fax:+44 xxx xxxx xxxx
E-mail: john.f.mitchell@xxxxxxxxx.xxx [1]http://www.metoffice.gov.uk


______________________________________________________________________________________

From: Stefan Rahmstorf [mailto:rahmstorf@xxxxxxxxx.xxx]
Sent: 01 September 2006 13:02
To: Keith Briffa
Cc: Mitchell, John FB (Chief Scientist); Eystein Jansen; Jonathan Overpeck
Subject: Re: Fwd: Re: [Wg1-ar4-ch06] NEW DRAFT FOR LA REVIEW

Dear Keith,
you disagree with my proposed revision of the paragraph re. the Von Storch papers, but you
do not give any reasons or arguments for that. I think there are some good reasons to
shorten this discussion and to clarify it, and I would welcome to hear your reasons against
it.
Firstly, I think your original discussion was too long and complex to understand for
non-specialists, and, at this level of detail, not policy-relevant. It took up a
disproportionate amount of space for what we can learn from it.
Secondly, I don't think we need to cite all those Storch-spinoff papers by B

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From: "Michael E. Mann" <mann@xxxxxxxxx.xxx>
To: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
Subject: Re: followup
Date: Wed, 06 Sep 2006 08:34:xxx xxxx xxxx
Reply-to: mann@xxxxxxxxx.xxx
Cc: Scott Rutherford <srutherford@xxxxxxxxx.xxx>, Keith Briffa <k.briffa@xxxxxxxxx.xxx>

<x-flowed>
Tim, thanks a bunch. This all sounds very good. We're finalizing a
pseudoproxy paper for JGR based on the various tests w/ the CSM
simulation I showed in Wengen, and will send you a guys a copy once its
finalized. A natural followup would be a similar analysis applying to
the ECHO-G simulation, and we would enjoy collaborating w/ you and Keith
on this. We were also thinking of doing some "mixed signal" analyses,
where the pseudoproxies represent a combinatiiion of temp and precip
(including limiting cases of pure temp and pure precip). This might be a
natural way to incorporate the ECHO-G results. We'll let you know if we
have any trouble w/ format, etc.

thanks again,

mike

Tim Osborn wrote:

> Hi Mike and Scott,
>
> below are details about accessing the ECHO-G data from the SO&P
> web-archive. There are time series plots of various variables and
> regions that might be useful for a quick overview of what's going on,
> plus the temperature fields (and fields for other variables) can be
> accessed in netCDF format (hope that format is ok, if not I can make a
> conversion for you but that won't be till next week).
>
> I'd like to add to Keith's reasons why we'd like to be involved in the
> outcome of analysis of these data. The extra reason is that we
> (Keith/me) are free to use these data and thus by extension you can
> too provided we collaborate. Fidel Gonzalez-Rouco or GKSS aren't yet
> ready to make them completely open access, preferring to consider each
> 3rd party request and decide on that basis. I did ask Eduardo Zorita
> about making them available for pseudo-proxy challenge after the
> Wengen meeting, but I haven't yet followed up to find out his
> decision. The bottom line is that they might well make them available
> for you to do your own thing with, but if you are happy to collaborate
> with us then you can definitely use them immediately.
>
> The data are available from here:
>
> http://www.cru.uea.ac.uk/cru/projects/soap/data/model/echog.htm
>
> Near the bottom you will find the link to the password-protected model
> data (this includes the time series plots too). The login details for
> this are:
>
> soapech
> od2004
>
> The 2m air temperature is 3rd in the list of variables. 'Erik' is the
> simulation will all forcings, 'Enat' just has natural forcings through
> to the present. The easiest way to get all the monthly 2m air
> temperature fields for Erik is to use 'wget'. There is help for how
> to use 'wget' if you aren't familiar.
>
> The site was designed to be fairly self explanatory; hope you find it
> so. If not, please just ask.
>
> Best wishes
>
> Tim
>
> At 18:30 05/09/2006, Michael E. Mann wrote:
>
>> sure thing Keith, thanks. and of course, we'll keep you fully in the
>> loop on our findings. I'm copying to Scott, as he's the one who will
>> probably obtain the data from Tim. Thanks again, got to go teach now...
>>
>> mike
>>
>> Keith Briffa wrote:
>>
>>> mike
>>> simply missed the first and been away since second message -
>>> forwarding to Tim to arrange access to these data ( I am assuming
>>> Hans will not mind but best not say anything yet ) we wish to be
>>> involved in this follow up please as it will be a SOAP product and
>>> Tim (especially) and I did stuff to get these data produced and in a
>>> form for dissemination. I am rushing now to Austria for a week .
>>> cheers
>>> Keith
>>>
>>> At 13:51 28/08/2006, you wrote:
>>>
>>>> Keith, I didn't receive a response to my previous inquiry so I'm
>>>> resending. Also copying to Phil in case you haven't been reading
>>>> email for some reason.
>>>>
>>>> We would like to run our RegEM analysis through the ECHO-G
>>>> simulation results. It appears that the results of that simulation
>>>> have been widely disseminated to other groups, and yet they are not
>>>> publically available to our knowledge.
>>>>
>>>> As per your previous suggestion, we would be grateful if we could
>>>> acquire the surface temperature field for the simulation from you
>>>> for some analyses we're doing.
>>>>
>>>> Thanks in advance for any help,
>>>>
>>>> mike
>>>>
>>>> --
>>>> Michael E. Mann
>>>> Associate Professor
>>>> Director, Earth System Science Center (ESSC)
>>>>
>>>> Department of Meteorology Phone: (8xxx xxxx xxxx
>>>> 503 Walker Building FAX: (8xxx xxxx xxxx
>>>> The Pennsylvania State University email: mann@xxxxxxxxx.xxx
>>>> University Park, PA 16xxx xxxx xxxx
>>>>
>>>> http://www.met.psu.edu/dept/faculty/mann.htm
>>>
>>>
>>> --
>>> Professor Keith Briffa,
>>> Climatic Research Unit
>>> University of East Anglia
>>> Norwich, NR4 7TJ, U.K.
>>>
>>> Phone: xxx xxxx xxxx
>>> Fax: xxx xxxx xxxx
>>>
>>> http://www.cru.uea.ac.uk/cru/people/briffa/
>>
>>
>>
>>
>> --
>> Michael E. Mann
>> Associate Professor
>> Director, Earth System Science Center (ESSC)
>>
>> Department of Meteorology Phone: (8xxx xxxx xxxx
>> 503 Walker Building FAX: (8xxx xxxx xxxx
>> The Pennsylvania State University email: mann@xxxxxxxxx.xxx
>> University Park, PA 16xxx xxxx xxxx
>>
>> http://www.met.psu.edu/dept/faculty/mann.htm
>>
>
> Dr Timothy J Osborn, Academic Fellow
> Climatic Research Unit
> School of Environmental Sciences, University of East Anglia
> Norwich NR4 7TJ, UK
>
> e-mail: t.osborn@xxxxxxxxx.xxx
> phone: xxx xxxx xxxx
> fax: xxx xxxx xxxx
> web: http://www.cru.uea.ac.uk/~timo/
> sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm
>
> **Norwich -- City for Science:
> **Hosting the BA Festival 2-9 September 2006
>


--
Michael E. Mann
Associate Professor
Director, Earth System Science Center (ESSC)

Department of Meteorology Phone: (8xxx xxxx xxxx
503 Walker Building FAX: (8xxx xxxx xxxx
The Pennsylvania State University email: mann@xxxxxxxxx.xxx
University Park, PA 16xxx xxxx xxxx

http://www.met.psu.edu/dept/faculty/mann.htm


</x-flowed>

Original Filename: 1158153059.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Re:
Date: Wed, 13 Sep 2006 09:10:xxx xxxx xxxx
Cc: rahmstorf@xxxxxxxxx.xxx, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, cddhr@xxxxxxxxx.xxx, joos <joos@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, "Ricardo Villalba" <ricardo@xxxxxxxxx.xxx>, t.osborn@xxxxxxxxx.xxx

Keith - thanks for this and the earlier updates. Stefan is not around this week, but
hopefully the others on this email can weight in. My thoughts...

1) We MUST say something about individual years (and by extension the 1998 TAR statement) -
do we support it, or not, and why.

2) a paragraph would be nice, but I doubt we can do that, so..

3) I suggest putting the first sentence that Keith provides below as the last sentence, in
the last (summary) para of 6.6.1.1. To make a stand alone para seems like a bad way to end
the very meaty section.

4) I think the second sentence could be more controversial - I don't think our team feels
it is valid to say, as they did in TAR, that "It is also likely that, in the Northern
Hemisphere,... 1998 was the warmest year" in the last 1000 years. But, it you think about
it for a while, Keith has come up with a clever 2nd sentence (when you insert "Northern
Hemisphere" language as I suggest below). At first, my reaction was leave it out, but it
grows on you, especially if you acknowledge that many readers will want more explicit prose
on the 1998 (2005) issue.

Greater uncertainty associated with proxy-based temperature estimates for individual years
means that it is more difficult to gauge the significance, or precedence, of the extreme
warm years observed in the recent instrumental record. However, there is no new evidence to
challenge the statement made in the TAR that 1998 (or the subsequent near-equivalent 2005)
was likely the warmest of Northern Hemisphere year over the last 1000 years.

5) I strongly agree we can't add anything to the Exec Summary.

6) so, if no one disagrees or edits, I suggest we insert the above 2 sentences to end the
last (summary) para of 6.6.1.1. Or should we make it a separate, last para - see point #3
above why I don't favor that idea as much. But, it's not a clear cut issue.

Thoughts? Thanks all, Peck

Eystein and Peck
I have thought about this and spent some time discussing it with Tim. I have come up
with the following

Greater uncertainty associated with proxy-based temperature estimates for individual
years means that it is more difficult to gauge the significance, or precedence, of the
extreme warm years observed in the recent instrumental record. However, there is no new
evidence to challenge the statement made in the TAR that 1998 (or the subsequent
near-equivalent 2005) was likely the warmest in the last 1000 years.
This should best go after the paragraph that concludes section 6.6.1.1
I believe we might best omit the second sentence of the suggested new paragraph - but
you might consider this too subtle (or negative) then. I think the second sentence is
very subtle also though - because it does not exclude the possibility that the same old
evidence that challenges the veracity of the TAR statement exists now , as then!
I think this could go in the text where suggested , but I think it best NOT to have a
bullet about this point.We need to check exactly what was saidin the TAR . Perhaps a
reference to the Academy Report could also be inserted here?
Anyway, you asked for a straw-man statement for all to argue about so I suggest we send
this to Stefan, David , Betty and whoever else you think.
cheers
Keith

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

Phone: xxx xxxx xxxx
Fax: xxx xxxx xxxx
http://www.cru.uea.ac.uk/cru/people/briffa/

--

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences
Mail and Fedex Address:
Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/

Original Filename: 1158175939.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
To: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>, Jonathan Overpeck <jto@u.arizona.edu>
Subject: No Subject
Date: Wed, 13 Sep 2006 15:32:19 +0100

Eystein and Peck
I have thought about this and spent some time discussing it with Tim. I have come up with
the following
Greater uncertainty associated with proxy-based temperature estimates for individual years
means that it is more difficult to gauge the significance, or precedence, of the extreme
warm years observed in the recent instrumental record. However, there is no new evidence to
challenge the statement made in the TAR that 1998 (or the subsequent near-equivalent 2005)
was likely the warmest in the last 1000 years.
This should best go after the paragraph that concludes section 6.6.1.1
I believe we might best omit the second sentence of the suggested new paragraph - but you
might consider this too subtle (or negative) then. I think the second sentence is very
subtle also though - because it does not exclude the possibility that the same old evidence
that challenges the veracity of the TAR statement exists now , as then!
I think this could go in the text where suggested , but I think it best NOT to have a
bullet about this point.We need to check exactly what was saidin the TAR . Perhaps a
reference to the Academy Report could also be inserted here?
Anyway, you asked for a straw-man statement for all to argue about so I suggest we send
this to Stefan, David , Betty and whoever else you think.
cheers
Keith

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

Phone: xxx xxxx xxxx
Fax: xxx xxxx xxxx
[1]http://www.cru.uea.ac.uk/cru/people/briffa/

References

1. http://www.cru.uea.ac.uk/cru/people/briffa/

Original Filename: 1158180188.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: David Rind <drind@xxxxxxxxx.xxx>
To: Jonathan Overpeck <jto@u.arizona.edu>
Subject: Re:
Date: Wed, 13 Sep 2006 16:43:xxx xxxx xxxx
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, rahmstorf@xxxxxxxxx.xxx, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, cddhr@xxxxxxxxx.xxx, joos <joos@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, "Ricardo Villalba" <ricardo@xxxxxxxxx.xxx>, t.osborn@xxxxxxxxx.xxx

Leaving aside for the moment the resolution issue, the statement should at least be
consistent with our figures. Fig. xxx xxxx xxxxlooks like there were years around 1000 AD that
could have been just as warm - if one wants to make this statement, one needs to expand
the vertical scale in Fig. xxx xxxx xxxxto show that the current warm period is 'warmer'.

Now getting back to the resolution issue: given what we know about the ability to
reconstruct global or NH temperatures in the past - could we really in good conscience say
we have the precision from tree rings and the very sparse other data to make any definitive
statement of this nature (let alone accuracy)? While I appreciate the cleverness of the
second sentence, the problem is everybody will recognize that we are 'being clever' - at
what point does one come out looking aggressively defensive?

I agree that leaving the first sentence as the only sentence suggests that one is somehow
doubting the significance of the recent warm years, which is probably not something we want
to do. What I would suggest is to forget about making 'one year' assessments; what Fig.
xxx xxxx xxxxshows is that the recent warm period is highly anomalous with respect to the record of
the last 1000 years. That would be what I think we can safely conclude the last 1000 years
really tells us.

David

At 9:10 AM -0600 9/13/06, Jonathan Overpeck wrote:

Keith - thanks for this and the earlier updates. Stefan is not around this week, but
hopefully the others on this email can weight in. My thoughts...

1) We MUST say something about individual years (and by extension the 1998 TAR
statement) - do we support it, or not, and why.

2) a paragraph would be nice, but I doubt we can do that, so..

3) I suggest putting the first sentence that Keith provides below as the last sentence,
in the last (summary) para of 6.6.1.1. To make a stand alone para seems like a bad way
to end the very meaty section.

4) I think the second sentence could be more controversial - I don't think our team
feels it is valid to say, as they did in TAR, that "It is also likely that, in the
Northern Hemisphere,... 1998 was the warmest year" in the last 1000 years. But, it you
think about it for a while, Keith has come up with a clever 2nd sentence (when you
insert "Northern Hemisphere" language as I suggest below). At first, my reaction was
leave it out, but it grows on you, especially if you acknowledge that many readers will
want more explicit prose on the 1998 (2005) issue.

Greater uncertainty associated with proxy-based temperature estimates for individual
years means that it is more difficult to gauge the significance, or precedence, of the
extreme warm years observed in the recent instrumental record. However, there is no new
evidence to challenge the statement made in the TAR that 1998 (or the subsequent
near-equivalent 2005) was likely the warmest of Northern Hemisphere year over the last
1000 years.

5) I strongly agree we can't add anything to the Exec Summary.

6) so, if no one disagrees or edits, I suggest we insert the above 2 sentences to end
the last (summary) para of 6.6.1.1. Or should we make it a separate, last para - see
point #3 above why I don't favor that idea as much. But, it's not a clear cut issue.

Thoughts? Thanks all, Peck

Eystein and Peck
I have thought about this and spent some time discussing it with Tim. I have come up
with the following

Greater uncertainty associated with proxy-based temperature estimates for individual
years means that it is more difficult to gauge the significance, or precedence, of the
extreme warm years observed in the recent instrumental record. However, there is no new
evidence to challenge the statement made in the TAR that 1998 (or the subsequent
near-equivalent 2005) was likely the warmest in the last 1000 years.

This should best go after the paragraph that concludes section 6.6.1.1
I believe we might best omit the second sentence of the suggested new paragraph - but
you might consider this too subtle (or negative) then. I think the second sentence is
very subtle also though - because it does not exclude the possibility that the same old
evidence that challenges the veracity of the TAR statement exists now , as then!
I think this could go in the text where suggested , but I think it best NOT to have a
bullet about this point.We need to check exactly what was saidin the TAR . Perhaps a
reference to the Academy Report could also be inserted here?
Anyway, you asked for a straw-man statement for all to argue about so I suggest we send
this to Stefan, David , Betty and whoever else you think.
cheers
Keith

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

Phone: xxx xxxx xxxx
Fax: xxx xxxx xxxx
http://www.cru.uea.ac.uk/cru/people/briffa/

--

Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences
Mail and Fedex Address:
Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/

--

///////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////

Original Filename: 1158204073.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>
To: Jonathan Overpeck <jto@u.arizona.edu>, David Rind <drind@xxxxxxxxx.xxx>
Subject: Re:
Date: Wed, 13 Sep 2006 23:21:13 +0200
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, rahmstorf@xxxxxxxxx.xxx, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, cddhr@xxxxxxxxx.xxx, joos <joos@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, "Ricardo Villalba" <ricardo@xxxxxxxxx.xxx>, t.osborn@xxxxxxxxx.xxx

Hi all,

My take on this is similar to what Peck wrote. My suggestion is to write:

Greater uncertainty associated with proxy-based temperature estimates for individual years
means that it is more difficult to gauge the significance, or precedence, of the extreme
warm individual years observed in the recent instrumental record, such as 1998 and 2005,
in the context of the last millennium.

I think this is scientifically correct, and in essence means that we, as did the NAS panel
say, feel the TAR statement was not what we would have said. I sympatise with those who say
that it is not likely that any individual years were warmer, as Stefan has stated, but I
don

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From: Jonathan Overpeck <jto@u.arizona.edu>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Re: 1988/2005
Date: Fri, 15 Sep 2006 08:55:xxx xxxx xxxx
Cc: David Rind <drind@xxxxxxxxx.xxx>, rahmstorf@xxxxxxxxx.xxx, Bette Otto-Bleisner <ottobli@xxxxxxxxx.xxx>, cddhr@xxxxxxxxx.xxx, Ricardo Villalba <ricardo@xxxxxxxxx.xxx>, t.osborn@xxxxxxxxx.xxx, joos <joos@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>, <oyvind.paasche@xxxxxxxxx.xxx>

<x-flowed>
Thanks Keith, Tim and Fortunat for your input.
We'll go with what we have then - Eystein's
suggestion minus the second "individual".

Eystein and

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From: Tim Osborn <t.osborn@xxxxxxxxx.xxx>
To:

Original Filename: 1158680269.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Jonathan Overpeck <jto@u.arizona.edu>
To: Gabi Hegerl <hegerl@xxxxxxxxx.xxx>
Subject: Re: cheers!
Date: Tue, 19 Sep 2006 11:37:xxx xxxx xxxx
Cc: Keith Briffa <k.briffa@xxxxxxxxx.xxx>, Eystein Jansen <eystein.jansen@xxxxxxxxx.xxx>

<x-flowed>
Hi Gabi - we do loose quite a bit (e.g., boreholes and other proxies)
back beyond 500, so that's why we drew the "very likely" line there.
But, we did stay as strong as the TAR back 1300, so that was our
compromise on certainty. I believe the forcing series also start to
get more uncertain pretty fast back beyond even 400 years ago, but
I'm pretty impressed with the match between simulated and observed NH
climate back ca. 700 years (e.g., our Figs 6.13 and 6.14). Thus, I
bet you are right that we know back to 700 pretty well, but not well
enough to go with "very likely" in the all important chap 6 bullet.

Not sure this helps, but we do need to pay attention as we do the SPM
to get the right balance.

I'll cc to Keith in case he wants to chime in, which would be appreciated.

thanks, peck

>p.s. hope you are all recovered etc!
>I have one chapter question: We were waffling back and forth if we
>SHOULD go with the chapter 6
>assessment on the last 500 being better reconstructed than say last
>700, but in the end, we stuck with
>last 700 because some results rely on using a long timehorizon to
>separate like ghg and solar signals.
>To say that very likely a substantial fraction of the variance on
>those records is externally forced (nother
>words, detectable external signals in reconstructions).
>Does this seem ok to you? In the SPM session we had some waffling
>about 5 vs 7 centuries.
>
>Gabi
>
>Jonathan Overpeck wrote:

--
Jonathan T. Overpeck
Director, Institute for the Study of Planet Earth
Professor, Department of Geosciences
Professor, Department of Atmospheric Sciences

Mail and Fedex Address:

Institute for the Study of Planet Earth
715 N. Park Ave. 2nd Floor
University of Arizona
Tucson, AZ 85721
direct tel: xxx xxxx xxxx
fax: xxx xxxx xxxx
http://www.geo.arizona.edu/
http://www.ispe.arizona.edu/
</x-flowed>

Original Filename: 1158770262.txt | Return to the index page | Permalink | Earlier Emails | Later Emails

From: Gabi Hegerl <hegerl@xxxxxxxxx.xxx>
To: Keith Briffa <k.briffa@xxxxxxxxx.xxx>
Subject: Re: 5 to 7 centuries
Date: Wed, 20 Sep 2006 12:37:xxx xxxx xxxx
Cc: Eystein Jansen <Eystein.Jansen@xxxxxxxxx.xxx>, Jonathan Overpeck <jto@u.arizona.edu>, Francis Zwiers <Francis.Zwiers@xxxxxxxxx.xxx>

<x-flowed>
I asked Tom about it, he says (but I realize he is one sample of the
volcano enthusiasts) it could
have been El Chichon, the eruption seems to be huge, but there is
concerns that different physics
would apply to such a large eruption making it cause different climate
impacts (he cites a paper
for that that I promplty forgot).
I am always slightly nervous about the fact that this one doesnt show up
in the data, and wondering
if there is a sliver of circularity, but I think results like my
detection stuff and probably also EPOCH
stuff (I could try) are quite robust to missing an eruption, even a biggie.

Greetings everybody!

Gabi

Keith Briffa wrote:

> Hi everyone - just been at a meeting all day so just seen this . I
> agree with Eystein et al . so no problems . Interested to know what
> you mean Gabi about the 1256 eruption - we have been looking at the
> empirical evidence for a contemporaneous cooling with ambiguous results
> cheers
> Keith
>
>
>
> At 20:16 19/09/2006, Eystein Jansen wrote:
>
>> Hi Gabi,
>> this is fine with me and does not seem to contradict Ch6.
>> Eystein
>>
>>
>>
>>
>> At 15:xxx xxxx xxxx, Gabi Hegerl wrote:
>>
>>> SOunds good - since forcing and temperature reconstrucitons are
>>> independent,
>>> I think it was defensible to make a statement about role of forced
>>> response 700 yrs back in Ch9.
>>> Is it ok to keep 700 yrs about significant externally forced
>>> component in SPM?
>>> Susan is finetuning that bullet right now so thats why i thought it
>>> would be good to know if you guys are
>>> happy.
>>> We justified ch9's assessment based on your figure 6.13 showing
>>> model and recon agreement, and on few detection
>>> studies and some qualitatative agreement studies all saying the
>>> agreement is not spurious.
>>> One issue going beyond further is 1256 eruption, which is not that
>>> well understood,
>>> so it gets a bit dicey beyond I think!
>>>
>>> Gabi
>>>
>>> Jonathan Overpeck wrote:
>>>
>>>> Hi Gabi - we do loose quite a bit (e.g., boreholes and other
>>>> proxies) back beyond 500, so that's why we drew the "very likely"
>>>> line there. But, we did stay as strong as the TAR back 1300, so
>>>> that was our compromise on certainty. I believe the forcing series
>>>> also start to get more uncertain pretty fast back beyond even 400
>>>> years ago, but I'm pretty impressed with the match between
>>>> simulated and observed NH climate back ca. 700 years (e.g., our
>>>> Figs 6.13 and 6.14). Thus, I bet you are right that we know back to
>>>> 700 pretty well, but not well enough to go with "very likely" in
>>>> the all important chap 6 bullet.
>>>>
>>>> Not sure this helps, but we do need to pay attention as we do the
>>>> SPM to get the right balance.
>>>>
>>>> I'll cc to Keith in case he wants to chime in, which would be
>>>> appreciated.
>>>>
>>>> thanks, peck
>>>>
>>>>> p.s. hope you are all recovered etc!
>>>>> I have one chapter question: We were waffling back and forth if we
>>>>> SHOULD go with the chapter 6
>>>>> assessment on the last 500 being better reconstructed than say
>>>>> last 700, but in the end, we stuck with
>>>>> last 700 because some results rely on using a long timehorizon to
>>>>> separate like ghg and solar signals.
>>>>> To say that very likely a substantial fraction of the variance on
>>>>> those records is externally forced (nother
>>>>> words, detectable external signals in reconstructions).
>>>>> Does this seem ok to you? In the SPM session we had some waffling
>>>>> about 5 vs 7 centuries.
>>>>>
>>>>> Gabi
>>>>>
>>>>> Jonathan Overpeck wrote:
>>>>
>>>>
>>>
>>> --
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> Gabriele Hegerl Division of Earth and Ocean Sciences, Nicholas
>>> School for the Environment and Earth Sciences,
>>> Box 90227
>>> Duke University, Durham NC 27708
>>> Ph: xxx xxxx xxxx, fax xxx xxxx xxxxemail: hegerl@xxxxxxxxx.xxx,
>>> http://www.env.duke.edu/faculty/bios/hegerl.html
>>
>>
>>
>> --
>> ______________________________________________________________
>> Eystein Jansen
>> Professor/Director
>> Bjerknes Centre for Climate Research and
>> Dep. of Earth Science, Univ. of Bergen
>> All

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From: "Saffron O'Neill" <s.o-neill@xxxxxxxxx.xxx>
To: <t.osborn@xxxxxxxxx.xxx>
Subject: panel meeting and ice extent modelling
Date: Mon, 2 Oct 2006 10:46:26 +0100

<x-flowed>
Hi Tim

I've found some 'communicating cc' ref's which I've attached - nothing too
hard going! Futerra's 'rules of the game' is a good intro to what climate
change communicators should be working towards in terms of best practice.
Sophie's poster is a summary of the main findings of her PhD research from a
couple of years back in ENV, and is a message that some NGOs in particular
would still do well to heed! Finally, the communicating CC document is an
outline of Defra's recent initiative, as followed on from Futerra's
consultancy work.

PhD stuff: at the last panel meeting, we agreed to meet again in early
October. However, I think this meeting would best be delayed until we know
exactly what info we can obtain for the expert elicitation as r.e. ice
extent maps, time series etc.

I forwarded on the email from Xiangdong Zhang a few days ago - he's happy to
give me some plots showing 2-D distribution of sea ice concentrations around
2050 and also animations from 1xxx xxxx xxxxunder the A1B scenario.

How is the ice modelling going? Do you think you'd be able to get some plots
say by w/c 9th Oct so we could talk about them in the meeting?

Cheers

Saffron

</x-flowed>

Attachment Converted: "c:documents and settingstim osbornmy documentseudoraattachcommunicating_climate_change.pdf"

Attachment Converted: "c:documents and settingstim osbornmy documentseudoraattachPOSTER SNC.pdf"

Attachment Converted: "c:documents and settingstim osbornmy documentseudoraattachRulesOfTheGame.pdf"