Section 1.6 Response
The terms of reference are as follows:
1.1 Examine the hacked e-mail exchanges, other relevant e-mail exchanges and any other information held at CRU to determine whether there is any evidence of the manipulation or suppression of data which is at odds with acceptable scientific practice and may therefore call into question any of the research outcomes.
ISSUES ARISING ON Para 1.1 OF THE TERMS OF REFERENCE
1. The allegation of ignoring potential problems in deducing palaeotemperatures from tree ring data that might undermine the validity of the so-called “hockey-stick” curve. In the late 20th century, the correlation between the tree ring record and instrumental record of temperature change diverges from that for the earlier period. The cause of this divergence does not appear to be understood. If the method used to deduce temperatures from tree ring proxy metrics for the earlier tree ring record is applied to the late 20th century tree ring series, then declining temperatures would be deduced for the late 20th century. It is alleged that if the cause of divergence between the tree ring and instrumental temperature record is unknown, it may have existed in earlier periods. Therefore if tree rings had similarly failed to reflect the warming of the early Middle Ages, they may significantly under- estimate the warming during the Medieval Warm Period, thus falsely enhancing the contrast between the recent warming and that earlier period. (It is this contrast that has led to statements that the late 20th century warming is unprecedented during at least the last 1000 years.)
QUESTIONS TO ADDRESS:
6. How does the tree ring evidence of the MWP compare with other proxy data?
The crutape letters's Blog 
February 13, 2010 at 7:15 am |
CA: http://climateaudit.org/category/other-multiproxy-studies/ for all the multi-proxy studies
0906042912, Mann to Jones, 17 Sep 1998:
“2) We all know the quality of proxies changes with time. Trees don’t have dating problems but do have the reduction in sample depths you talk about. Dendro people are much more open about this though than the coral and especially the ice core communitites… 4) Whilst we are taking bets, proxies will never be better than instrumental data. Corals will eventually extend the SOI series but never be better than it for the years after 1850. Similarly with the NAO. Instrumental data exists to extend this to about 1750 and the fact that such data is sitting out there is only just begining to be realised. A great NAO reconstruction could be produced if the real data extended over nearly 200 years, enabling the low-frequency aspects to be considered in much more detail than ever before ( a la Stahle with the SOI).”
0907695513 Oct 6, 1998 (Briffa to Overpeck, response to Overpeck) Peck: “3) regarding proxies, I wonder how much of the “quality” issue regarding ice cores and some other remote proxy records is due to there not being any instrumental stations near them (and at the same altitude)? Also, with >respect to coral records, I get the feeling most in the coral community now think there is something “funny” about long Galapagos record (age model, maybe more – I think a new record is being generated). Also, many coral 18O records (e.g., New Caledonia) are influenced by both temp and salinity variations.”
Briffa: “My first comment is that I agree with all of your general remarks and with your implied rebuke to Phil that we should be very wary of seeming to dam certain proxies and over hype others when we all know that there are real strengths and weaknesses associted with them all…that even within each of these sub-disciplines e.g. Dendro, coral etc. there is a large range of value , or concern with the external usage of our data…but perhaps there has been some reluctance to air them in sufficient depth or in the right situations where they will be heard/seen by those people who now seek to use the data . I believe that many of the modellers , having been blissfully unaware for years of the need to work with the palaeo-community, are now expecting too much…There is no doubt though, that many palaeo- types are not concerned with the ‘bigger issues’ of climate change , so it is up to those who do ,such as this group…I for one do not think the world revolves only around trees. The only sensible way forward is through interpretation of multiple proxies and we need much more work comparing and reconciling the different evidence they hold. Let’s have more balance in the literature and more constructive dialogue /debate between ourselves.”
0919310505 17 Feb 1999 (Simon Tett to Peter Stott, Phil Jones, Keith Briffa, others) is a long discussion of Proxy climate forcings:
“Proxy Climate data + comparision with obs and models.
Keith/Phil have 400 sites of high quality tree ring density data which there are willing to let HC (Mat) use to do a crude model/data comparision. Mat and Tim to liase on what they are doing. Note that funny things are happening in the density data post 1950. Also available may be some borehole data [Phil to talk to Pollock/Wang about possibility] which could use to compare with model — should consider using lower soil temperature rather than 1. m temp. There are a few sites with data from 0A to 2000 as well as many sites with data for 1700 to 2000 — should consider both. There may be some other tree ring data which tells us something about SW USA precip and thus ENSO.
Tim wants to compare patterns of temperature var from the proxy data and compare that with the models i.e compare “observed” and modelled covariance structure rather than just the variability. Also Tim wants to try and unpick Mann’s stuff…. HC to provide solar forced run from 1700 — Me to check if it goes from 1700!
Our approach will be to compare model data “directly” with Proxy data rather than do Interpolation a la GISST or Mann et al.”
1093794363 29 Aug 2004 (Marin Munroe to listserv): (whole email for technical discussion)
“This an attempt to tie up the loose ends from an earlier part of the
discussion, the idea that calibration of the radiocarbon timescale be
considered invalid, pending a better understanding of crossdating.
Some of the previous posts seem to imply that measurements of the C-14 half-life depend on the calibration; in fact it can be determined by
present-day laboratory measurements without reference to any old
material, simply by observing the decay rate in a known quantity of
the isotope.”
1107899057 2/4/2005 (Revkin to all):
At 02:14 PM 2/4/2005, Andy Revkin wrote:
Hi all,
There is a fascinating paper coming in Nature next week (Moberg of Stockholm Univ., et al) that uses mix of sediment and tree ring data to get a new view of last 2,000 years. Very warped hockeystick shaft (centuries-scale variability very large) but still pronounced ‘unusual’ 1990’s blade.”
1121871795 Jul 20, 2005 (Briffa to Osborn):
From: “Ricardo Villalba”
To: “Jonathan Overpeck” ,
“Edward R. Cook”
Cc: “Keith R. Briffa” ,
Subject: Re: the regional section and MWP Figure
“>>Thanks Ricardo and Ed! I personally am not a
>>big fan of the Jones and Mann SH recon. It is
>>based on so little. On the other hand, it is in
>>the literature. So, I leave it up to you and
>>Keith to decide – perhaps Eystein can weigh in
>>too.
>>
>>I do, however, think it would be really helpful
>>to included the borehole data (see prev.
>>emails) – either as a single SH curve, or
>>(probably better) two regional curves
>>(Australia and S. Africa). Is there a reason
>>this is not a good idea? Can’t complain about
>>snow bias down there…
>>
>>Thanks again – I look forward to seeing the
>>next draft and figure – complete w/ borehole I
>>hope.
>>
>>thx, Peck
>>
>>>Hi Keith,
>>>
>>>Please, find attached my last version of the SH temp. As you know, Ed Cook
>>>returned my original version of the SH with minor comments. Overall, he
>>>agreed with the text. Still I am waiting from him the Oroco Swamp data to
>>>include in the Figure, which first draft I sent you more than a month ago.
>>>
>>>In the last version I have included a first paragraph referring to the Jones and Mann (2003) temperature reconstruction for the SH. At that time we have to decide if we want to have the hemispheric (Jones and Mann) and the regional views (Tasmania, New Zealand, Patagonia, maybe include Antarctica (Ommem et al. 2005)), or just one of them. If we decide to stay with the hemispheric view, we should include Jones and Mann reconstruction at the bottom of one of your figures. In cases that we decide to maintain both hemispheric and regional views, we should include Jones and Mann at the bottom of my figure. Please, could you check with Peck and Eystein to see the best way to proceed?”
February 16, 2010 at 7:58 am |
CA: http://climateaudit.org/category/other-multiproxy-studies/ for all the multi-proxy studies
1143661010.txt
From: Tim Osborn
To: “Gustafson, Diane”
Subject: Re: Proxy time series
Date: Wed, 29 Mar 2006 14:36:50 +0100
Cc: Keith Briffa
Dear Diane / Mike / NRC Committee,
At 22:18 28/03/2006, Gustafson, Diane wrote:
>Dear Tim:
>
>Our National Research Council Committee on Surface Temperature
>Reconstructions has been considering your paper with Keith Briffa
>published in a recent issue of Science. Could you please elaborate
>on your criterion for selecting the proxy time series included in
>the analysis. We are interested in how you computed the correlation
>between the proxy time series and local temperature time series.
Reply:
We used records specifically from Mann and Jones (2003) and Esper et
al. (2002). In addition we included records from Mann et al. (2003),
which I think just adds the van Engelen documentary record from the
Low Countries in Europe, because the others were already in the Mann
and Jones set. We excluded duplicates, and our paper explains which
series we used where duplicates were present. We did not average the
Tornetrask, Yamal and Taimyr tree-ring records as done by Mann and
Jones, because we could see no reason not to use them as individual series.
The series used by Mann and Jones had already been correlated with
their local instrumental temperatures — using decadally-smoothed,
non-detrended, values — so we accepted this as an indication of some
temperature sensitivity. For the other series, we calculated our own
correlations against local instrumental temperatures, trying both
annual-mean or summer-mean temperatures. In our paper’s
supplementary information, we state that we used the HadCRUT2
temperatures for this purpose, which combines land air temperatures
with SST observations. …
February 16, 2010 at 8:34 am |
CA: http://climateaudit.org/category/other-multiproxy-studies/ for all the multi-proxy studies
https://crutapeletters.wordpress.com/section-1-responses/section-1-1-response/#comment-19 re: D’Arrigo also applies:
1051638938 4/29/03 Cook qutoed in Briffa to Cook. A longer chain mail:
Just when you think that you’ve heard of all the possible problems with tree rings, the newest issue comes from “positive” and “negative” responders to temperature within the same site. These issues are discussed in a number of articles by various post-docs associated with Jacoby and D’Arrigo with the latter as co-authors. So in fairness to them, they are not just ignoring the problem of the failure of tree rings to respond to post-1980 temperature – although the issue is dealt with more candidly in specialist articles than in the general literature. Also in fairness to Jacoby who I’ve criticized for failing to archive information (and will continue to criticize), unlike Mann, he’s collected a lot of information.
February 16, 2010 at 11:19 pm |
see also https://crutapeletters.wordpress.com/section-1-responses/section-1-2-response/#comment-107
February 16, 2010 at 11:26 pm |
0919310505.txt
Proxy Climate forcing.
Solar — Beer has a Be based proxy reconstruction of Solar ACTIVITY
which can be converted to irradiance changes. [Is it different from LBB
or H&S ?] Has the LBB dataset been updated? Has Svensmark got a better
handle on his proposed physical mechanisms to amplify solar irradiance
changes? [Someone to check at RMS meeting which I won’t be able to
attend] Want forcing back to 1600?? though HC would find it hard to
justify doing runs that early — me to see if John/Geoff think useful or
not.
Me to check with William the source of the rumour about problems with
the H&S dataset.
Volcanoes. Volcanoes are an important climate forcings [Issue for
IPCC??] Do volcanic erruptions cluster? Myles to “persuade” a student to
look at Phil/Keith’s dataset and see if there is evidence for this? Are
there other indices of volcanic activity? Is climate response to
volcanoes sensitive to mean state?? i.e. in cooler climate get bigger
response. [Gareth could see from our model if Krakota response
significantly different from Pinatubo]
Proxy Climate data + comparision with obs and models.
Keith/Phil have 400 sites of high quality tree ring density data which
there are willing to let HC (Mat) use to do a crude model/data
comparision. Mat and Tim to liase on what they are doing. Note that
funny things are happening in the density data post 1950. Also available
may be some borehole data [Phil to talk to Pollock/Wang about
possibility] which could use to compare with model — should consider
using lower soil temperature rather than 1. m temp. There are a few
sites with data from 0A to 2000 as well as many sites with data for 1700
to 2000 — should consider both. There may be some other tree ring data
which tells us something about SW USA precip and thus ENSO.
Tim wants to compare patterns of temperature var from the proxy data
and compare that with the models i.e compare “observed” and modelled
covariance structure rather than just the variability. Also Tim wants to
try and unpick Mann’s stuff…. HC to provide solar forced run from 1700
— Me to check if it goes from 1700!
Our approach will be to compare model data “directly” with Proxy data
rather than do Interpolation a la GISST or Mann et al.
From: Simon Tett
To: Peter Stott , Gareth Jones , Myles Allen , Phil Jones
, Keith Briffa
Subject: Tuesday Meeting
Date: Wed, 17 Feb 1999 23:01:45 +0000
February 16, 2010 at 11:31 pm |
0938031546.txt
Let me say that I don’t mind what you put in the policy makers summary if there is a general concensus. However some general discussion would be valuable . First , like Phil , I think that the supposed separation of the tree-ring reconstruction from the others on the grounds that it is not a true “multi-proxy” series is hard to justify. What is true is that these particular tree-ring data best represent SUMMER temperatures mostly at the northern boreal forest regions. By virtue of this , they also definately share significant variance with Northern Hemisphere land and land and marine ANNUAL temperatures – but at decadal and multidecadal timescales – simply by virtue of the fact that these series correlated with the former at these timescales. The multi proxy series (Mann et al . Jones et al) supposedly represent annual and summer seasons respectively, and both contain large proportions of tree-ring input. The latest tree-ring density curve ( i.e. our data that have been processed to retain low frequency information) shows more similarity to the other two series- as do a number of other lower resolution data ( Bradley et al, Peck et al ., and new Crowley series – see our recent Science piece) whether this represents ‘TRUTH’ however is a difficult problem. I know Mike thinks his series is the ‘best’ and he might be right – but he may also be too dismissive of other data and possibly over confident in his (or should I say his use of other’s). After all, the early ( pre-instrumental) data are much less reliable as indicators of global temperature than is apparent in modern calibrations that include them and when we don’t know the precise role of particular proxies in the earlier portions of reconstruction it remains problematic to assign genuine confidence limits…
From: Keith Briffa
To: “Folland, Chris” , ‘Phil Jones’
, “Michael E. Mann”
Subject: RE: IPCC revisions
Date: Wed Sep 22 16:19:06 1999
Cc: tkarl@ncdc.noaa.gov
February 18, 2010 at 6:19 pm |
1055512559.txt see also S&B https://crutapeletters.wordpress.com/section-5-responses/
> At 08:51 13/06/03 -0600, Tom Wigley wrote:
>
>> Phil,
>>
>> If W Greenland is based on isotopes, I note that the correlation
>> between these and temperature is very low. Do we really want to
>> perpetuate the myth that ice core isotopes are a good proxy for
>> temperature?
>>
>> Tom.
February 20, 2010 at 1:46 am |
By flipping the data opposite to the interpretation of Tiljander et al, Mann shows the Little Ice Age in Finland as being warmer than the MWP, 100% opposite to the interpretation of the authors and the paleoclimate evidence. The flipping is done because the increase in varve thickness due to construction and agricultural activities is interpreted by Mann et al as a “nonlocal statistical relationship” or “teleconnection” to world climate. Mann:
the EIV approach, which makes use of nonlocal statistical relationships, allowing temperature changes over distant regions to be effectively represented through their covariance with climatic changes recorded by the network
A more convincing example of spurious regression in “peer reviewed” literature will be hard to find. After reading through this, I keep expecting someone to say:
February 20, 2010 at 1:48 am |
The continued use of upside-down data by the Team is really quite remarkable. It’s not as though they were unaware of the issue.
The upside-down use of Tiljander data was originally observed at CA http://www.climateaudit.org/?p=3967). We know that Mann and Schmidt were monitoring CA because changes to Mann’s SI (always without attribution) were made soon after CA posts.
The use of upside-down data in MAnn et al 2008 was even published at PNAS earlier this year (McIntyre and McKitrick PNAS 2009 see here). In their response at PNAS, Mann et al described the claim that they used the data upside-down as “bizarre”, notwithstanding the fact that the correctness of the observation could be readily seen merely by plotting Mann’s data (and even in the data plots in the Mann et al 2008 SI).
February 20, 2010 at 1:57 am |
Notable omissions are the Mount Logan ice core and Jellowbean Lake sediment series. (See http://www.climateaudit.org/?p=2348, http://www.climateaudit.org/?p=806 for discussion of the Mount Logan proxies.) The Mount Logan ice core delO18 values decrease in the 20th century, contrary to the presumed increase. Although Mount Logan isotopes are as well resolved as the ice core isotopes used by Kaufman et al, they are excluded (along with a candidate sediment series) on the basis that the “bad” results for these proxies are due to changes in “moisture source” rather than temperature.
We excluded the isotope-based records from ices cores in the Saint Elias Mountains (S4) and from Jellybean Lake carbonate (S5), both in the Yukon, because the proxies are more strongly controlled by changes in moisture-source and atmospheric moisture transport patterns than by temperature.
The problem with this sort of reasoning is: if changes in moisture source cause isotope values to go down, they will also cause isotope values to go up.
Worsening this particular situation is the failure of Lonnie Thompson to report “adverse” results at Bona-Churchill (see the CA posts mentioned above.) Bona-Churchill, an ice core site near Mount Logan, was drilled in 2002. The unseemly delay in reporting results led me to speculate several years ago that these results were “bad” for Lonnie Thompson’s advocacy. This prediction was confirmed in a diagram presented in a workshop; the data itself remains unpublished to this day.
I note that the Dye-3 isotopes (#12) have been “corrected” to account for ice flow. In my opinion, the place for such adjustments should be in the original articles and not in multiproxy compilations. This will need to be assessed.
As has observed on many occasions at CA and on other critical blogs (it’s been independently noted by Jeff Id, David Stockwell and Lubos Motl as well as myself), when data sets are selected ex post according to whether they go up in the 20th century – as opposed to all the data sets, the results are subject to a very severe HS bias. David Stockwell published this result in 2006 (see here) (an article cited in McIntyre and McKitrick PNAS 2009) illustrating it as below (similar illustrations are available at Jeff Id’s and Luboš’):
February 20, 2010 at 2:01 am |
http://climateaudit.org/2009/10/02/atte-korhola-scientific-and-social-playground/ [the science paper is Kaufmann’s ]
Another example is a study recently published in the prestigious journal Science. It is concluded in the article that the average temperatures in the Arctic region are much higher now than at any time in the past two thousand years. The result may well be true, but the way the researchers ended up with this conclusion raises questions. Proxies have been included selectively, they have been digested, manipulated, filtered, and combined, for example, data collected from Finland in the past by my own colleagues has even been turned upside down such that the warm periods become cold and vice versa. Normally, this would be considered as a scientific forgery, which has serious consequences.
February 20, 2010 at 4:26 pm |
1057368583.txt Briffa/Eyestein and Money, too.
From: Eystein Jansen
To: Keith Briffa
Subject: Re: FP6-news?
Date: Fri, 4 Jul 2003 21:29:43 +0200
I agree with you that integration with biogeochemistry is not
straight forward with Holocene climate variability except for the
vegetation feedback which may be important.
I also know of one other palaeo-based initiative, ICON, dealing with
the thermohaline circulation, coordinated by Rainer Zahn. We are
involved. This will be submitted for the call just launched under the
hot spots in the climate system heading, but may be brought over to
the next call if unsuccessful (probably). We are involved there with
a number of modelling centres and many of the palaeoceanography labs.
I guess we should discuss a bit further after summer has passed what
to do. I am very keen on the science of Holclim and hope to be able
to develop this initiative with you and others.
Last thing – any idea of when the conference Brussels wants is going
to happen?.
I am away for two weeks on the Greek islands, but then I am back again.
Cheers,
Eystein
but I still feel strongly , on the evidence of other projects
>that I have heard are to be funded , that the need is for a sharper
>focus than was involved in our DOCC concept , and that the HOLIVAR
>approach is the optimum way forward. The problem will be scale of
>initiative (15-20 million seems a maximum likely request , with
>perhaps 12-15 a likely maximum award). The unified data / modelling
>route, as outlined in the HOLCLIM NoI seems the most likely
>candidate still. Obviously there remain difficulties even with this
>, such as geographic focus , use of the integrated data for defining
>future climate probabilities and links with socio-economic (impacts)
>community. This is also likely to clash with the direct interests of
>some major palaeoclimate scientists who focus on longer time scales
>and stronger climate and response signals. It is easier to think of
>climate forcings and the interaction of bio-geochemical cycles at
>glacial /interglacial time scales , but I am not convinced that this
>type of work would be a practical inclusion in this call. This is
>still my opinion , but an admittedly (unashamedly) biased one.
>Keith
February 20, 2010 at 6:19 pm |
1062592331.txt Ed Cook to Briffa not happy with Bradley 🙂
From: Edward Cook
To: Keith Briffa
Subject: An idea to pass by you
Date: Wed, 3 Sep 2003 08:32:11 -0400
Hi Keith,
After the meeting in Norway, where I presented the Esper stuff as
described in the extended abstract I sent you, and hearing Bradley’s
follow-up talk on how everybody but him has fucked up in
reconstructing past NH temperatures over the past 1000 years (this is
a bit of an overstatement on my part I must admit, but his air of
papal infallibility is really quite nauseating at times), I have come
up with an idea that I want you to be involved in. Consider the
tentative title:
“Northern Hemisphere Temperatures Over The Past Millennium: Where Are
The Greatest Uncertainties?”
Authors: Cook, Briffa, Esper, Osborn, D’Arrigo, Bradley(?), Jones
(??), Mann (infinite?) – I am afraid the Mike and Phil are too
personally invested in things now (i.e. the 2003 GRL paper that is
probably the worst paper Phil has ever been involved in – Bradley
hates it as well), but I am willing to offer to include them if they
can contribute without just defending their past work – this is the
key to having anyone involved. Be honest. Lay it all out on the table
and don’t start by assuming that ANY reconstruction is better than
any other.
Here are my ideas for the paper in a nutshell (please bear with me):
1) Describe the past work (Mann, Briffa, Jones, Crowley, Esper, yada,
yada, yada) and their data over-laps.
2) Use the Briffa&Osborn “Blowing Hot And Cold” annually-resolved
recons (plus Crowley?) (boreholes not included) for comparison
because they are all scaled identically to the same NH extra-tropics
temperatures and the Mann version only includes that part of the NH
(we could include Mann’s full NH recon as well, but he would probably
go ballistic, and also the new Mann&Jones mess?)
3) Characterize the similarities between series using unrotated
(maybe rotated as well) EOF analysis (correlation for pure
similarity, covariance for differences in amplitude as well) and
filtering on the reconstructions – unfiltered, 20yr high-pass, 100-20
bandpass, 100 lowpass – to find out where the reconstructions are
most similar and different – use 1st-EOF loadings as a guide, the
comparisons of the power spectra could also be done I suppose
4) Do these EOF analyses on different time periods to see where they
differ most, e.g., running 100-year EOF windows on the unfiltered
data, running 300-year for 20-lp data (something like that anyway),
and plot the 1st-EOF loadings as a function of time
5) Discuss where the biggest differences lie between reconstructions
(this will almost certainly occur most in the 100 lowpass data),
taking into account data overlaps
6) Point out implications concerning the next IPCC assessment and EBM
forcing experiments that are basically designed to fit the lower
frequencies – if the greatest uncertainties are in the >100 year
band, then that is where the greatest uncertainties will be in the
forcing experiments
7) Publish, retire, and don’t leave a forwarding address
Without trying to prejudice this work, but also because of what I
almost think I know to be the case, the results of this study will
show that we can probably say a fair bit about 100 year variability was like with any certainty (i.e. we know
with certainty that we know fuck-all).
Of course, none of what I have proposed has addressed the issue of
seasonality of response. So what I am suggesting is strictly an
empirical comparison of published 1000 year NH reconstructions
because many of the same tree-ring proxies get used in both seasonal
and annual recons anyway. So all I care about is how the recons
differ and where they differ most in frequency and time without any
direct consideration of their TRUE association with observed
temperatures.
I think this is exactly the kind of study that needs to be done
before the next IPCC assessment. But to give it credibility, it has
to have a reasonably broad spectrum of authors to avoid looking like
a biased attack paper, i.e. like Soon and Balliunas.
If you don’t want to do it, just say so and I will drop the whole
idea like a hot potato. I honestly don’t want to do it without your
participation. If you want to be the lead on it, I am fine with that
too.
Cheers,
Ed
February 20, 2010 at 6:23 pm |
1062618881.txt More on proxies Soon and Baliunas sent as an attachment so applies also to Section 5.
From: Tim Osborn
To: Keith Briffa , Edward Cook
Subject: Fwd: Re: Fwd: Soon & Baliunas
Date: Wed Sep 3 15:54:41 2003
Hi Ed,
first all, yes I agree that we need a paper that takes a more objective look at where we
are now and how we can take things forward in terms of NH temperature reconstructions (and
possibly global, SH, spatial etc.).
As Keith said, we (mainly I so far) have been planning our version of this (hopefully)
“objective assessment”, and by chance I was sketching out a vague outline of its possible
content. We’ve been keeping this fairly close to our chests for now, so please keep our
plans/ideas to yourself for the moment. There is partial overlap between our ideas and
yours, so it might be good to do this jointly. Anyway, my current ideas are a number of
forum articles, the first comparing existing reconstructions but without going into more
depth, and the other three looking at the way forward (i.e. what should we attempt to do to
improve them):
Forum piece (1): Comparison of existing reconstructions
This has most overlaps with your ideas, though I hadn’t thought of it being so
comprehensive. I was thinking more of:
(a) comparing original series.
(b) comparing them after our recalibration to common target data, including discussion of
why some things don’t change much (e.g. relative positioning of reconstructions), though
amplitudes can change – and of course the comparison of Mann et al. with and without
oceans/tropics.
(c) maybe a bit on comparison with boreholes, though maybe not.
(d) uncertainty estimates and how these may decrease with time scale and hence not all
reconstructions lie in the Mann et al. uncertainty ranges.
Forum piece (2): Selection of predictand and predictor data
(a) What to try to reconstruct and why it matters – e.g. will we get the wrong spectral
shape if we reconstruct ocean SST from land-based proxies. Plus some on seasonality,
though Jones, Osborn and Briffa cover part of that issue (are you aware of that paper, in
press with JGR?).
(b) What proxies should be used – e.g. does throwing in “poor” proxies cause a problem with
simple averaging, weighted averaging and multivariate regression approaches. Plus does
using precipitation proxies to reconstruct temperature result in the wrong spectral shape?
Forum piece (3): Reconstruction methods
Something here on different methods (simple averaging, multivariate regression type
approaches) and different implementation choices (e.g. calibration against trends/filtered
data). Not entirely sure about this, but it would not be new work, just would critically
appraise the methods used to date and what their theoretical/potential problems/advantages
might be.
Forum piece (4): Estimating uncertainty
Again, not entirely sure yet, but this must emphasise the absolute requirement to estimate
AND USE uncertainty when comparing reconstructions against observations or simulations
etc. Then something about how to do it, contrasting using calibration residuals,
verification residuals, parameter uncertainty, with the type of approach that you’ve taken
(bootstrap uncertainty, or measures of the EPS) to look at the common signal, with
additional uncertainty of how the common signal differs from the predictand.
So that’s it!! Perhaps rather ambitious, so maybe a reduction to certain key points might
be required. I was deliberately avoiding any review of tree-ring contributions and
low-frequency per se, thinking that you and Keith would be taking the lead on that kind of
review.
One final think to mention, is that the emails copied below and the attached file might be
of interest to you as an example of something that *might* go in a comparison paper of
existing reconstructions. It’s shows how the recalibrated average of existing
reconstructions differs from the average of existing calibrated reconstructions. You’ll
see from Mike Mann’s initial request below that he was thinking of it as a contribution to
the EOS rebuttal of Soon and Baliunas, but I’ve not heard much from him since. Also Tom
Crowley was very interests in this composite of the reconstructions, and I started to
converse with him about it but never finished estimating the uncertainty range on the
composite series and kind of stopped emailing him. But I guess either of them might
reproduce this idea sometime, if it suits them.
A visit to talk face to face about all these things would be good. Keith and I have been
talking about how to fit a visit in.
Cheers
Tim
Date: Wed, 12 Mar 2003 16:16:16 +0000
To: “Michael E. Mann” , Tom Crowley , Phil Jones
From: Tim Osborn
Subject: Re: Fwd: Soon & Baliunas
Cc: Malcolm Hughes , rbradley@geo.umass.edu,
mhughes@ltrr.arizona.edu, srutherford@gso.uri.edu, k.briffa@uea.ac.uk, mann@virginia.edu
This is an excellent idea, Mike, IN PRINCIPLE at least. In practise, however, it raises
some interesting results (as I have found when attempting this myself) that may be
difficult to avoid getting bogged down with discussing.
The attached .pdf figure shows an example of what I have produced (NB. please don’t
circulate this further, as it is from work that is currently being finished off –
however, I’m happy to use it here to illustrate my point).
I took 7 reconstructions and re-calibrated them over a common period and against an
observed target series (in this case, land-only, Apr-Sep, >20N – BUT I GET SIMILAR
RESULTS WITH OTHER CHOICES, and this re-calibration stage is not critical). You will
have seen figures similar to this in stuff Keith and I have published. See the coloured
lines in the attached figure.
In this example I then simply took an unweighted average of the calibrated series, but
the weighted average obtained via an EOF approach can give similar results. The average
is shown by the thin black line (I’ve ignored the potential problems of series covering
different periods). This was all done with raw, unsmoothed data, even though 30-yr
smoothed curves are plotted in the figure.
The thick black line is what I get when I re-calibrate the average record against my
target observed series. THIS IS THE IMPORTANT BIT. The *re-calibrated* mean of the
reconstructions is nowhere near the mean of the reconstructions. It has enhanced
variability, because averaging the reconstructions results in a redder time series
(there is less common variance between the reconstructions at the higher frequencies
compared with the lower frequencies, so the former averages out to leave a smoother
curve) and the re-calibration is then more of a case of fitting a trend (over my
calibration period 1881-1960) to the observed trend. This results in enhanced
variability, but also enhanced uncertainty (not shown here) due to fewer effective
degrees of freedom during calibration.
Obviously there are questions about observed target series, which series to
include/exclude etc., but the same issue will arise regardless: the analysis will not
likely lie near to the middle of the cloud of published series and explaining the
reasons behind this etc. will obscure the message of a short EOS piece.
It is, of course, interesting – not least for the comparison with borehole-based
estimates – but that is for a separate paper, I think.
My suggestion would be to stick with one of these options:
(i) a single example reconstruction;
(ii) a plot of a cloud of reconstructions;
(iii) a plot of the “envelope” containing the cloud of reconstructions (perhaps also the
envelope would encompass their uncertainty estimates), but without showing the
individual reconstruction best guesses.
How many votes for each?
Cheers
Tim
At 15:32 12/03/03, Michael E. Mann wrote:
p.s. The idea of both a representative time-slice spatial plot emphasizing the spatial
variability of e.g. the MWP or LIA, and an EOF analysis of all the records is a great
idea. I’d like to suggest a small modification of the latter:
I would suggest we show 2 curves, representing the 1st PC of two different groups, one
of empirical reconstructions, the other of model simulations, rather than just one in
the time plot.
Group #1 could include:
1) Crowley & Lowery
2) Mann et al 1999
3) Bradley and Jones 1995
4) Jones et al, 1998
5) Briffa et al 200X? [Keith/Tim to provide their preferred MXD reconstruction]
6) Esper et al [yes, no?–one series that differs from the others won’t make much of a
difference]
I would suggest we scale the resulting PC to the CRU 1856-1960 annual Northern
Hemisphere mean instrumental record, which should overlap w/ all of the series, and
which pre-dates the MXD decline issue…
Group #2 would include various model simulations using different forcings, and with
slightly different sensitivities. This could include 6 or so simulation results:
1) 3 series from Crowley (2000) [based on different solar/volcanic reconstructions],
2) 2 series from Gerber et al (Bern modeling group result) [based on different assumed
sensitivities]
1) Bauer et al series (Claussen group EMIC result) [includes 19th/20th century land use
changes as a forcing].
I would suggest that the model’s 20th century mean is aligned with the 20th century
instrumental N.Hem mean for comparison (since this is when we know the forcings best).
I’d like to nominate Scott R. as the collector of the time series and the performer of
the EOF analyses, scaling, and plotting, since Scott already has many of the series and
many of the appropriate analysis and plotting tools set up to do this.
We could each send our preferred versions of our respective time series to Scott as an
ascii attachment, etc.
thoughts, comments?
thanks,
mike
At 10:08 AM 3/12/2003 -0500, Michael E. Mann wrote:
Thanks Tom,
Either would be good, but Eos is an especially good idea. Both Ellen M-T and Keith
Alverson are on the editorial board there, so I think there would be some receptiveness
to such a submission.t
I see this as complementary to other pieces that we have written or are currently
writing (e.g. a review that Ray, Malcolm, and Henry Diaz are doing for Science on the
MWP) and this should proceed entirely independently of that.
If there is group interest in taking this tack, I’d be happy to contact Ellen/Keith
about the potential interest in Eos, or I’d be happy to let Tom or Phil to take the lead
too…
Comments?
mike
At 09:15 AM 3/12/2003 -0500, Tom Crowley wrote:
Phil et al,
I suggest either BAMS or Eos – the latter would probably be better because it is
shorter, quicker, has a wide distribution, and all the points that need to be made have
been made before.
rather than dwelling on Soon and Baliunas I think the message should be pointedly made
against all of the standard claptrap being dredged up.
I suggest two figures- one on time series and another showing the spatial array of
temperatures at one point in the Middle Ages. I produced a few of those for the Ambio
paper but already have one ready for the Greenland settlement period 965-995 showing the
regional nature of the warmth in that figure. we could add a few new sites to it, but
if people think otherwise we could of course go in some other direction.
rather than getting into the delicate question of which paleo reconstruction to use I
suggest that we show a time series that is an eof of the different reconstructions – one
that emphasizes the commonality of the message.
Tom
Dear All,
I agree with all the points being made and the multi-authored article would be a
good idea,
but how do we go about not letting it get buried somewhere. Can we not address the
misconceptions by finally coming up with definitive dates for the LIA and MWP and
redefining what we think the terms really mean? With all of us and more on the paper,
it should
carry a lot of weight. In a way we will be setting the agenda for what should be being
done
over the next few years.
We do want a reputable journal but is The Holocene the right vehicle. It is
probably the
best of its class of journals out there. Mike and I were asked to write an article for
the EGS
journal of Surveys of Geophysics. You’ve not heard of this – few have, so we declined.
However,
it got me thinking that we could try for Reviews of Geophysics. Need to contact the
editorial
board to see if this might be possible. Just a thought, but it certainly has a high
profile.
What we want to write is NOT the scholarly review a la Jean Grove (bless her soul)
that
just reviews but doesn’t come to anything firm. We want a critical review that enables
agendas to be set. Ray’s recent multi-authored piece goes a lot of the way so we need
to build on this.
Cheers
Phil
At 12:55 11/03/03 -0500, Michael E. Mann wrote:
HI Malcolm,
Thanks for the feedback–I largely concur. I do, though, think there is a particular
problem with “Climate Research”. This is where my colleague Pat Michaels now publishes
exclusively, and his two closest colleagues are on the editorial board and review editor
board. So I promise you, we’ll see more of this there, and I personally think there *is*
a bigger problem with the “messenger” in this case…
But the Soon and Baliunas paper is its own, separate issue too. I too like Tom’s latter
idea, of a more hefty multi-authored piece in an appropriate journal (Paleoceanography?
Holocene?) that seeks to correct a number of misconceptions out there, perhaps using
Baliunas and Soon as a case study (‘poster child’?), but taking on a slightly greater
territory too.
Question is, who would take the lead role. I *know* we’re all very busy,
mike
At 10:28 AM 3/11/03 -0700, Malcolm Hughes wrote:
I’m with Tom on this. In a way it comes back to a rant of mine
to which some of you have already been victim. The general
point is that there are two arms of climatology:
neoclimatology – what you do based on instrumental records
and direct, systematic observations in networks – all set in a
very Late Holocene/Anthropocene time with hourly to decadal
interests.
paleoclimatology – stuff from rocks, etc., where major changes
in the Earth system, including its climate, associated with
major changes in boundary conditions, may be detected by
examination of one or a handful of paleo records.
Between these two is what we do – “mesoclimatology” –
dealing with many of the same phenomena as neoclimatology,
using documentary and natural archives to look at phenomena
on interannual to millennial time scales. Given relatively small
changes in boundary conditions (until the last couple of
centuries), mesoclimatology has to work in a way that is very
similar to neoclimatology. Most notably, it depends on heavily
replicated networks of precisely dated records capable of
being either calibrated, or whose relationship to climate may
be modeled accuarately and precisely.
Because this distinction is not recognized by many (e.g.
Sonnechkin, Broecker, Karlen) we see an accumulation of
misguided attempts at describing the climate of recent
millennia. It would be better to head this off in general, rather
than draw attention to a bad paper. After all, as Tom rightly
says, we could all nominate really bad papers that have been
published in journals of outstanding reputation (although there
could well be differences between our lists).
End of rant, Cheers, Malcolm
> Hi guys,
>
> junk gets published in lots of places. I think that what could be
> done is a short reply to the authors in Climate Research OR a SLIGHTLY
> longer note in a reputable journal entitled something like “Continuing
> Misconceptions About interpretation of past climate change.” I kind
> of like the more pointed character of the latter and submitting it as
> a short note with a group authorship carries a heft that a reply to a
> paper, in no matter what journal, does not.
>
> Tom
>
>
>
> > Dear All,
> > Apologies for sending this again. I was expecting a stack of
> >emails this morning in
> > response, but I inadvertently left Mike off (mistake in pasting)
> >and picked up Tom’s old
> > address. Tom is busy though with another offspring !
> > I looked briefly at the paper last night and it is appalling –
> >worst word I can think of today
> > without the mood pepper appearing on the email ! I’ll have time to
> >read more at the weekend
> > as I’m coming to the US for the DoE CCPP meeting at Charleston.
> >Added Ed, Peck and Keith A.
> > onto this list as well. I would like to have time to rise to the
> >bait, but I have so much else on at
> > the moment. As a few of us will be at the EGS/AGU meet in Nice, we
> >should consider what
> > to do there.
> > The phrasing of the questions at the start of the paper
> >determine the answer they get. They
> > have no idea what multiproxy averaging does. By their logic, I
> >could argue 1998 wasn’t the
> > warmest year globally, because it wasn’t the warmest everywhere.
> >With their LIA being 1300-
> >1900 and their MWP 800-1300, there appears (at my quick first
> >reading) no discussion of
> > synchroneity of the cool/warm periods. Even with the instrumental
> >record, the early and late
> > 20th century warming periods are only significant locally at
> >between 10-20% of grid boxes.
> > Writing this I am becoming more convinced we should do
> >something – even if this is just
> > to state once and for all what we mean by the LIA and MWP. I think
> >the skeptics will use
> > this paper to their own ends and it will set paleo back a number of
> >
> >years if it goes
> > unchallenged.
> >
> > I will be emailing the journal to tell them I’m having
> >nothing more to do with it until they
> > rid themselves of this troublesome editor. A CRU person is on the
> >editorial board, but papers
> > get dealt with by the editor assigned by Hans von Storch.
> >
> > Cheers
> > Phil
> >
> > Dear all,
> > Tim Osborn has just come across this. Best to ignore
> >probably, so don’t let it spoil your
> > day. I’ve not looked at it yet. It results from this journal
> >having a number of editors. The
> > responsible one for this is a well-known skeptic in NZ. He has let
> >
> >a few papers through by
> > Michaels and Gray in the past. I’ve had words with Hans von Storch
> >
> >about this, but got nowhere.
> > Another thing to discuss in Nice !
> >
> > Cheers
> > Phil
> >Attachment converted: Macintosh HD:Soon & Baliunas 2003.pdf (PDF
February 20, 2010 at 10:54 pm |
1065125462.txt Mann not cultivating the press:
From: “Michael E. Mann”
To: “Robert Matthews”
Subject: Re:
Date: Thu, 02 Oct 2003 16:11:02 -0400
Cc: Phil Jones , Keith Briffa , Tim Osborn , ckfolland@meto.gov.uk, peter.stott@metoffice.com, d.viner@uea.ac.uk, m.hulme@uea.ac.uk
Dear Mr. Matthews,
Unfortunately Phil Jones is travelling and will probably be unable to offer a separate
reply. Since your comments involve work that is his as well, I have therefore taken the
liberty of copying your inquiry and this reply to several of his British colleagues.
The comparisons made in our paper are well explained therein, and your statements belie
the clearly-stated qualifications in our conclusions with regard to separate analyses of
the Northern Hemisphere, Southern Hemisphere, and globe.
An objective reading of our manuscript would readily reveal that the comments you refer to
are scurrilous. These comments have not been made by scientists in the peer-reviewed
literature, but rather, on a website that, according to published accounts, is run by
individuals sponsored by ExxonMobile corportation, hardly an objective source of
information.
Owing to pressures on my time, I will not be able to respond to any further inquiries from
you. Given your extremely poor past record of reporting on climate change issues, however,
I will leave you with some final words. Professional journalists I am used to dealing with
do not rely upon un-peer-reviewed claims off internet sites for their sources of
information. They rely instead on peer-reviewed scientific research, and mainstream, rather
than fringe, scientific opinion.
Sincerely,
Michael E. Mann
At 08:30 PM 10/2/2003 +0100, Robert Matthews wrote:
Dear Professor Mann
I’m putting together a piece on global warming, and I’ll be making reference to your
paper in Geophysical Research Letters
with Prof Jones on “Global surface temperatures over the past two millennia”.
When the paper came out, some critics argued that the paper actually showed that there
have been three periods in the last 2000 years which were warmer than today (one just
prior to AD 700, one just after, and one just prior to AD 1000). They also claimed that
the paper could only conclude that current temperatures were warmer if one compared the
proxy data with other data sets. (For an example of these arguments, see:
[1]http://www.co2science.org/journal/2003/v6n34c4.htm)
I’d be very interested to include your rebuttals to these arguments in the piece I’m
doing. I must admit to being confused by why proxy data should be compared to
instrumental data for the last part of the data-set. Shouldn’t the comparison be a
consistent one throughout ?
With many thanks for your patience with this
Robert Matthews
———————————————————————-
Robert Matthews
Science Correspondent, The Sunday Telegraph
February 20, 2010 at 10:56 pm |
1065128595.txt Followup to Matthews telegraph email in 1.6
From: “Michael E. Mann”
To: Phil Jones , Keith Briffa , Tim Osborn , ckfolland@meto.gov.uk, peter.stott@metoffice.com, d.viner@uea.ac.uk, m.hulme@uea.ac.uk
Subject: Re:
Date: Thu, 02 Oct 2003 17:03:15 -0400
For those of you who haven’t seen it, this is Robert Matthews last article on the topic.
Hence the fairly brusque tone taken…
mike
Middle Ages were warmer than today, say scientists
By Robert Matthews, Science Correspondent
(Filed: 06/04/2003)
Claims that man-made pollution is causing “unprecedented”
global warming
have been seriously undermined by new research which shows that the
Earth
was warmer during the Middle Ages.
From the outset of the global warming debate in the late 1980s,
environmentalists have said that temperatures are rising higher and
faster
than ever before, leading some scientists to conclude that greenhouse
gases
from cars and power stations are causing these
“record-breaking” global
temperatures.
Last year, scientists working for the UK Climate Impacts Programme said
that
global temperatures were “the hottest since records began”
and added: “We
are pretty sure that climate change due to human activity is here and
it’s
accelerating.”
This announcement followed research published in 1998, when scientists
at
the Climatic Research Unit at the University of East Anglia declared
that
the 1990s had been hotter than any other period for 1,000 years.
Such claims have now been sharply contradicted by the most
comprehensive
study yet of global temperature over the past 1,000 years. A review of
more
than 240 scientific studies has shown that today’s temperatures
are neither
the warmest over the past millennium, nor are they producing the most
extreme weather – in stark contrast to the claims of the
environmentalists.
The review, carried out by a team from Harvard University, examined the
findings of studies of so-called “temperature proxies” such as
tree rings,
ice cores and historical accounts which allow scientists to estimate
temperatures prevailing at sites around the world.
The findings prove that the world experienced a Medieval Warm Period
between
the ninth and 14th centuries with global temperatures significantly
higher
even than today.
They also confirm claims that a Little Ice Age set in around 1300,
during
which the world cooled dramatically. Since 1900, the world has begun to
warm
up again – but has still to reach the balmy temperatures of the Middle
Ages.
The timing of the end of the Little Ice Age is especially significant, as
it
implies that the records used by climate scientists date from a time
when
the Earth was relatively cold, thereby exaggerating the significance of
today’s temperature rise.
According to the researchers, the evidence confirms suspicions that
today’s
“unprecedented” temperatures are simply the result of
examining temperature
change over too short a period of time.
The study, about to be published in the journal Energy and Environment,
has
been welcomed by sceptics of global warming, who say it puts the claims
of
environmentalists in proper context. Until now, suggestions that the
Middle
Ages were as warm as the 21st century had been largely anecdotal and
were
often challenged by believers in man-made global warming.
Dr Philip Stott, the professor emeritus of bio-geography at the
University
of London, told The Telegraph: “What has been forgotten in all the
discussion about global warming is a proper sense of history.”
According to Prof Stott, the evidence also undermines doom-laden
predictions
about the effect of higher global temperatures. “During the Medieval
Warm
Period, the world was warmer even than today, and history shows
that it was
a wonderful period of plenty for everyone.”
In contrast, said Prof Stott, severe famines and economic collapse
followed
the onset of the Little Ice Age around 1300. He said: “When the
temperature
started to drop, harvests failed and England’s vine industry died. It
makes
one wonder why there is so much fear of warmth.”
The United Nation’s Intergovernmental Panel on Climate Change (IPCC),
the
official voice of global warming research, has conceded the possibility
that
today’s “record-breaking” temperatures may be at least
partly caused by the
Earth recovering from a relatively cold period in recent history. While
the
evidence for entirely natural changes in the Earth’s temperature
continues
to grow, its causes still remain mysterious.
Dr Simon Brown, the climate extremes research manager at the
Meteorological
Office at Bracknell, said that the present consensus among scientists on
the
IPCC was that the Medieval Warm Period could not be used to judge the
significance of existing warming.
Dr Brown said: “The conclusion that 20th century warming is not
unusual
relies on the assertion that the Medieval Warm Period was a global
phenomenon. This is not the conclusion of IPCC.”
He added that there were also doubts about the reliability of
temperature
proxies such as tree rings: “They are not able to capture the recent
warming
of the last 50 years,” he said.
© Copyright of Telegraph Group Limited 2003. Terms & Conditions of
reading.
Commercial information. Privacy Policy.
At 04:11 PM 10/2/2003 -0400, Michael E. Mann wrote:
Dear Mr. Matthews,
Unfortunately Phil Jones is travelling and will probably be unable to offer a separate
reply. Since your comments involve work that is his as well, I have therefore taken the
liberty of copying your inquiry and this reply to several of his British colleagues.
The comparisons made in our paper are well explained therein, and your statements belie
the clearly-stated qualifications in our conclusions with regard to separate analyses of
the Northern Hemisphere, Southern Hemisphere, and globe.
An objective reading of our manuscript would readily reveal that the comments you refer
to are scurrilous. These comments have not been made by scientists in the peer-reviewed
literature, but rather, on a website that, according to published accounts, is run by
individuals sponsored by ExxonMobile corportation, hardly an objective source of
information.
Owing to pressures on my time, I will not be able to respond to any further inquiries
from you. Given your extremely poor past record of reporting on climate change issues,
however, I will leave you with some final words. Professional journalists I am used to
dealing with do not rely upon un-peer-reviewed claims off internet sites for their
sources of information. They rely instead on peer-reviewed scientific research, and
mainstream, rather than fringe, scientific opinion.
Sincerely,
Michael E. Mann
At 08:30 PM 10/2/2003 +0100, Robert Matthews wrote:
Dear Professor Mann
I’m putting together a piece on global warming, and I’ll be making reference to your
paper in Geophysical Research Letters
with Prof Jones on “Global surface temperatures over the past two millennia”.
When the paper came out, some critics argued that the paper actually showed that there
have been three periods in the last 2000 years which were warmer than today (one just
prior to AD 700, one just after, and one just prior to AD 1000). They also claimed that
the paper could only conclude that current temperatures were warmer if one compared the
proxy data with other data sets. (For an example of these arguments, see:
[1]http://www.co2science.org/journal/2003/v6n34c4.htm)
I’d be very interested to include your rebuttals to these arguments in the piece I’m
doing. I must admit to being confused by why proxy data should be compared to
instrumental data for the last part of the data-set. Shouldn’t the comparison be a
consistent one throughout ?
With many thanks for your patience with this
Robert Matthews
———————————————————————-
Robert Matthews
Science Correspondent, The Sunday Telegraph
February 20, 2010 at 11:01 pm |
1065189366.txt Osborn to Matthews, MWP, Calibration with Instrumental
From: Tim Osborn
To: “Michael E. Mann” , “Robert Matthews”
Subject: Re: Mann and Jones, climate of the last two millennia
Date: Fri Oct 3 09:56:06 2003
Cc: Phil Jones , Keith Briffa , ckfolland@meto.gov.uk, peter.stott@metoffice.com, d.viner@uea.ac.uk, m.hulme@uea.ac.uk
Dear Mr. Matthews,
I have not read the criticism on the website you refer to, but will add to Mike Mann’s
response in a small, but hopefully helpful, way.
Comparison of the Mann and Jones proxy-based reconstruction with instrumental temperature
data *is* a valid comparison to make, provided that the reconstruction is *calibrated* to
represent the instrumental record and provided that the *uncertainties* in the calibration
are taken into account when making the comparison.
That is, after all, the purpose of calibration – to allow two different data sets to be
compared!
As is clear from their article, Mann and Jones do undertake a careful calibration and only
make comparisons after the calibration, and their comparison figure includes their
estimated uncertainty range. Thus the conclusions they draw (regarding whether recent
warming is unprecedented) are valid and are supported by their analysis.
This does not mean that future work, perhaps using new proxy records or different methods
for calibration or for estimating calibration uncertainties, will not change those
conclusions. But it remains true that their conclusions are supported by their analysis.
As an example of a poor comparison, see the piece by Fred Pearce on page 5 of 12 July 2003
issue of New Scientist. This is a short news article about the Mann and Jones paper, and
it unfortunately shows a comparison figure without the associated calibration
uncertainties. That is not a good comparison. I mention this in case you were thinking of
including a diagram in your article, perhaps showing the Mann and Jones results. If you
do, then it will only be valid for comparing the recent instrumental temperatures with the
proxy-based reconstruction of earlier temperatures if the reconstruction uncertainties are
included. Try to avoid the mistake that Fred Pearce made.
Regards
Tim
At 21:11 02/10/2003, Michael E. Mann wrote:
Dear Mr. Matthews,
Unfortunately Phil Jones is travelling and will probably be unable to offer a separate
reply. Since your comments involve work that is his as well, I have therefore taken the
liberty of copying your inquiry and this reply to several of his British colleagues.
The comparisons made in our paper are well explained therein, and your statements belie
the clearly-stated qualifications in our conclusions with regard to separate analyses of
the Northern Hemisphere, Southern Hemisphere, and globe.
An objective reading of our manuscript would readily reveal that the comments you refer
to are scurrilous. These comments have not been made by scientists in the peer-reviewed
literature, but rather, on a website that, according to published accounts, is run by
individuals sponsored by ExxonMobile corportation, hardly an objective source of
information.
Owing to pressures on my time, I will not be able to respond to any further inquiries
from you. Given your extremely poor past record of reporting on climate change issues,
however, I will leave you with some final words. Professional journalists I am used to
dealing with do not rely upon un-peer-reviewed claims off internet sites for their
sources of information. They rely instead on peer-reviewed scientific research, and
mainstream, rather than fringe, scientific opinion.
Sincerely,
Michael E. Mann
At 08:30 PM 10/2/2003 +0100, Robert Matthews wrote:
Dear Professor Mann
I’m putting together a piece on global warming, and I’ll be making reference to your
paper in Geophysical Research Letters
with Prof Jones on “Global surface temperatures over the past two millennia”.
When the paper came out, some critics argued that the paper actually showed that there
have been three periods in the last 2000 years which were warmer than today (one just
prior to AD 700, one just after, and one just prior to AD 1000). They also claimed that
the paper could only conclude that current temperatures were warmer if one compared the
proxy data with other data sets. (For an example of these arguments, see:
[1]http://www.co2science.org/journal/2003/v6n34c4.htm)
I’d be very interested to include your rebuttals to these arguments in the piece I’m
doing. I must admit to being confused by why proxy data should be compared to
instrumental data for the last part of the data-set. Shouldn’t the comparison be a
consistent one throughout ?
With many thanks for your patience with this
Robert Matthews
References
1. http://www.co2science.org/journal/2003/v6n34c4.htm
February 20, 2010 at 11:10 pm |
1065206624.txt More Matthews discussion. A lot of these apply to Response Sec. 2 in a general way also. Link placed in 8.3.2 because this is one clear example of the ‘bogging down’, interfering with research’ excuses used against FOI compliance. One excuse on one issue seems to translate to other areas. Just the holocaust denier statement in the emails can be studied as a first mention followed by extreme amplification…hmmm, a HS approach to everything.
From: Tim Osborn
To: “Michael E. Mann”
Subject: Re: Mann and Jones, climate of the last two millennia
Date: Fri Oct 3 14:43:44 2003
Hi Mike,
I agree completely with your analysis. I don’t get so many requests as you, but even so
get enough to mean that I ignore most – I just pick a few at random to respond to. As Phil
is away, I picked this. He’s already come back with a second request, which I answered,
but that’s all he’ll get from me. I’ll
At 13:56 03/10/2003, you wrote:
Tim,
Many kind thanks for going out of your way to respond to this. Colleagues have
increasingly been warning me against “taking the bait” too often (which this seems
another attempt at), and so I resisted giving the detailed response that you have nicely
provided (as well as I could have myself, I might add). They dried to bog Ben Santer
down with distractions, they’ve been trying to do the same to me, and its supposed to be
a warning to the rest of us. So the trick is to find the middle ground between
responding to most egregious and potentially damaging accusations, and not swinging at
every ball they throw your way. Its thus very helpful if friends and colleagues can take
up a bit of the slack now and then, as you have so graciously done…
This guy has written such trash before on the subject, that I assume he’s out to do a
hatchet job and there is little that we can do to change that. But your response was
very helpful. It will be interesting to see what comes of this,
thanks once again,
mike
p.s. I never saw the graph in Fred Pearce’s piece, since the online version didn’t show
it. But it does sound problematic from what you describe.
At 9:56 AM 10/3/2003 +0100, Tim Osborn wrote:
Dear Mr. Matthews,
I have not read the criticism on the website you refer to, but will add to Mike Mann’s
response in a small, but hopefully helpful, way.
Comparison of the Mann and Jones proxy-based reconstruction with instrumental
temperature data *is* a valid comparison to make, provided that the reconstruction is
*calibrated* to represent the instrumental record and provided that the *uncertainties*
in the calibration are taken into account when making the comparison.
That is, after all, the purpose of calibration – to allow two different data sets to be
compared!
As is clear from their article, Mann and Jones do undertake a careful calibration and
only make comparisons after the calibration, and their comparison figure includes their
estimated uncertainty range. Thus the conclusions they draw (regarding whether recent
warming is unprecedented) are valid and are supported by their analysis.
This does not mean that future work, perhaps using new proxy records or different
methods for calibration or for estimating calibration uncertainties, will not change
those conclusions. But it remains true that their conclusions are supported by their
analysis.
As an example of a poor comparison, see the piece by Fred Pearce on page 5 of 12 July
2003 issue of New Scientist. This is a short news article about the Mann and Jones
paper, and it unfortunately shows a comparison figure without the associated calibration
uncertainties. That is not a good comparison. I mention this in case you were thinking
of including a diagram in your article, perhaps showing the Mann and Jones results. If
you do, then it will only be valid for comparing the recent instrumental temperatures
with the proxy-based reconstruction of earlier temperatures if the reconstruction
uncertainties are included. Try to avoid the mistake that Fred Pearce made.
Regards
Tim
At 21:11 02/10/2003, Michael E. Mann wrote:
Dear Mr. Matthews,
Unfortunately Phil Jones is travelling and will probably be unable to offer a separate
reply. Since your comments involve work that is his as well, I have therefore taken the
liberty of copying your inquiry and this reply to several of his British colleagues.
The comparisons made in our paper are well explained therein, and your statements belie
the clearly-stated qualifications in our conclusions with regard to separate analyses of
the Northern Hemisphere, Southern Hemisphere, and globe.
An objective reading of our manuscript would readily reveal that the comments you refer
to are scurrilous. These comments have not been made by scientists in the peer-reviewed
literature, but rather, on a website that, according to published accounts, is run by
individuals sponsored by ExxonMobile corportation, hardly an objective source of
information.
Owing to pressures on my time, I will not be able to respond to any further inquiries
from you. Given your extremely poor past record of reporting on climate change issues,
however, I will leave you with some final words. Professional journalists I am used to
dealing with do not rely upon un-peer-reviewed claims off internet sites for their
sources of information. They rely instead on peer-reviewed scientific research, and
mainstream, rather than fringe, scientific opinion.
Sincerely,
Michael E. Mann
At 08:30 PM 10/2/2003 +0100, Robert Matthews wrote:
Dear Professor Mann
I’m putting together a piece on global warming, and I’ll be making reference to your
paper in Geophysical Research Letters
with Prof Jones on “Global surface temperatures over the past two millennia”.
When the paper came out, some critics argued that the paper actually showed that there
have been three periods in the last 2000 years which were warmer than today (one just
prior to AD 700, one just after, and one just prior to AD 1000). They also claimed that
the paper could only conclude that current temperatures were warmer if one compared the
proxy data with other data sets. (For an example of these arguments, see:
http://www.co2science.org/journal/20
03/v6n34c4.htm)
I’d be very interested to include your rebuttals to these arguments in the piece I’m
doing. I must admit to being confused by why proxy data should be compared to
instrumental data for the last part of the data-set. Shouldn’t the comparison be a
consistent one throughout ?
With many thanks for your patience with this
Robert Matthews
Dr Timothy J Osborn
February 20, 2010 at 11:21 pm |
1065723391.txt Mann to Crowley Borehole data discussion
From: “Michael E. Mann”
To: Tom Crowley
Subject: Re: draft
Date: Thu, 09 Oct 2003 14:16:31 -0400
Cc: Caspar Ammann , rbradley@geo.umass.edu, Keith Briffa , tcrowley@duke.edu, mhughes@ltrr.arizona.edu, omichael@princeton.edu, t.osborn@uea.ac.uk, jto@u.arizona.edu, Scott Rutherford , Kevin Trenberth , Tom Wigley , mann@virginia.edu
HI Tom,
My understanding of the papers from the borehole community ever since the 1997 GRL article
by Huang et al is that they no longer believe that the data has proper sensitivity to
variations prior to about AD 1500–in fact, I don’t believe anyone in that community now
feels they can meaningfully go farther back that that. Huang contributed the section on
boreholes in chapter 2 for IPCC (2001), and wrote the very words to that effect…
Now, the possible influences on boreholes might lead to inferred trends in GST that are
different from those in SAT is a different one. A number of independent recently published
papers by (Beltrami et al; Stiglitz et al; Mann and Schmidt) and others have demonstrated
that there should be expectations for significant differences between past SAT (what we
care about) and GST variations (what boreholes in the best case scenario see) due to
snowcover influences, etc. We don’t have time to discuss that in this very short piece, so
I tried, as briefly as possible, to cover our bases on this issue, in a way that doesn’t
really stir up the pot w/ the borehole folks…
I’m interested in any further thoughts on the above,
mike
At 12:38 PM 10/9/03 -0400, Tom Crowley wrote:
Hi, I don’t understand why we cannot cite the borehole data for the MWP – that in a
sense is the only legitimate data set that shows a ~1 C cooling from the MWP to the LIA
– forget the deforestation problem for the moment, that is later in time –
if the borehole data for the MWP are legitimate then there is still a case for
concluding that the MWP was significantly warmer than the LIA
tom
Thanks Phil,
a few brief responses and inquiries below…
cheers,
mike
At 04:17 PM 10/9/03 +0100, Phil Jones wrote:
Mike,
Away Oct 11-16, so here are a few comments. A few times the tone could be a little
less
antagonistic. We don’t want to inflame things any further. So remove the word laundry.
fair enough. You *should* have seen the first draft I wrote. This is quite toned down
now…
1. With the boreholes do we want to get one of the borehole group to sign up, eg Henry
Pollack?
Would add a lot of weight to the last 500 year argument.
this has merit. unfortunately though I think it might open up a hornets nest of the
author list is not identical to the original list of authors on the Eos article. Other
thoughts on this…
2. On the UHI, there was a paper in a very recent issue of J. Climate by Tom Peterson,
arguing
for the USA that this is non-existent. Issue with UHI is one of large versus local
scale. One
station doesn’t influence large-scale averages. All studies which look at the UHI
comprehensively
find very little effect (an order of magnitude smaller than the warming). Also the
warming
in the 20th century is very similar between the NH and SH and between the land and
ocean
components.
let me see if I can fit one or two sentences in on this and keep the article under the
length.
Also, if we can’t estimate temperature histories accurately, then SB can’t say it
was
warmer in their MWP period. They believe the 20th century instrumental data when they
want to.
yes, one of a large number of amazing contradictions in their reasoning…
3. Keith is away till next week. I doubt we will have the space to do the ‘tree issues’
justice.
Best just to say that there are an (equal) number of non tree-based proxy series??
I do think we need to address their spurious description of the putative biological
effects. Any way that you can get in touch w/ Keith for a response, perhaps just to
this one point? Also, Malcolm might want to comment on the current wording?
4. Ray, Malcolm and Henry Diaz have a Science Perspectives piece coming out in the next
couple of weeks on the MWP/E. This is also relevant.
good!
5. Don’t think we will get away with the last paragraph. Whether we want it is an issue
??
Shouldn’t we be sticking to the science.
ok, I wasn’t sure myself–yet it is a powerful rebuke, and reminds people that the
objection to the validity of their work goes beyond just our article–and that’s
important. Does someone want to try to rephrase this paragraph, maybe reducing it to a
couple sentences?
Cheers
Phil
At 21:37 08/10/2003 -0400, Michael E. Mann wrote:
Dear co-authors,
Attached is a draft response, incorporating suggestions Kevin, Tom W, and Michael. I’ve
aimed to be as brief as possible, but hard to go much lower than 750 words and still
address all the key issues. 750 words, by the way, is our allotted limit.
Looking forward to any comments. Feel free to send an edited version if you prefer, and
I’ll try to assimilate all of the suggested edits and suggestions into a single revised
draft. If you can get comments to me within the next couple days, that would be very
helpful as we’re working on a late October deadline for the final version.
Thanks for your continued help,
mike
February 22, 2010 at 3:21 pm |
Calibrating “Dr. Thompson’s Thermometer” Dec 10, 2009 by Hu McCulloch
“Some of the individual cores, such as Quelccaya and Dasuopu, are strongly correlated with temperature, while others, such as Sajama and Dunde, are not.”
“Even though Thompson’s LCZ series ends on a dramatic record high in the 1990s, when the series is correctly calibrated to temperature, the point estimate for the 1990s in fact comes in a little cooler than the 1940s.”
Update As noted in a 12/10 comment below, Matlab scipts, input data, and output arrays are now available via http://www.econ.ohio-state.edu/jhm/AGW/Thompson6/.
Update 12/14 My online working paper has been revised to include more material on alternative calibration procedures, including multiproxy calibration.
On inconsistencies in the Thompson ice core data, see also “Juckes, Yang, Thompson and PNAS: Guliya” (CA 12/3/06), “Dunde: Will the real Slim Shady please stand up?” (CA 4/12/07), “More Evasion by Thompson” (CA 5/10/07), “Irreproducible Results in PNAS” (CA 4/24/09).
Update 12/21 I have now updated my online working paper, “Posterior Confidence Intervals in Calibration Problems:
Calibrating the Thompson Ice Core Index”, at http://econ.ohio-state.edu/jhm/AGW/Thompson6/Thompson6Calib.pdf, to include comparison of my Bayesian CIs with the “classical” approach, as well as to treat the more powerful multiproxy sequential prior cases, without trying to implement these.
I’ve also toned down the title of this post somewhat.
Update 1/12/10. I’ve further updated my online working paper, showing that my approach is in fact a new derivation of a method proposed by Hunter and Lamboy (1981), and that my new derivation overcomes objections that were raised against the HL method by Hill and others when it first appeared.
I’ve also simplified the diagrams, so that the 1980s are simply represented by the 6-core index, and the 1990s by the 4-core index, with a red line connecting the last point to its predecessor.