Climate Science and Candor

Editor's note: The following are emails we've selected from more than 3,000 emails and documents that were hacked last week from computers at the University of East Anglia's Climate Research Unit in the United Kingdom. The CRU is the data repository for much of the world's climate research and is a major source for the judgments reached by the U.N.'s climate reports. A nearby editorial ("Global Warming With the Lid Off") puts the emails in their political and scientific context, but readers may want to browse for themselves to get a flavor of the thinking of scientists who are the leading advocates for the belief that global warming is man-made and that nations must re-order the world economy to stop it. We've removed the email addresses and phone numbers, and we've inserted paragraph breaks in some places. The emails are otherwise unedited. The ellipses are the authors' own.
On freedom of information rules and deleting files:
From: Phil Jones
To: "Michael E. Mann"
Subject: IPCC & FOI
Date: Thu May 29 11:04:11 2008
Mike,
Can you delete any emails you may have had with Keith re AR4? Keith will do likewise. He's not in at the moment - minor family crisis. Can you also email Gene and get him to do the same? I don't have his new email address. We will be getting Caspar to do likewise.
I see that CA claim they discovered the 1945 problem in the Nature paper!!
Cheers
Phil
Prof. Phil Jones
Climatic Research Unit
School of Environmental Sciences
University of East Anglia
Norwich
----------------------------------------------------------------------------
From: Phil Jones
Sent: Wednesday, September 12, 2007 11:30 AM
To: Wahl, Eugene R; Caspar Ammann
Subject: Wahl/Ammann
Gene/Caspar,
Good to see these two out. Wahl/Ammann doesn't appear to be in CC's online first, but comes up if you search. You likely know that McIntyre will check this one to make sure it hasn't changed since the IPCC close-off date July 2006! Hard copies of the WG1 report from CUP have arrived here today. Ammann/Wahl - try and change the Received date! Don't give those skeptics something to amuse themselves with.
Cheers
Phil
At 09:41 AM 2/2/2005, Phil Jones wrote:
Mike,
I presume congratulations are in order - so congrats etc !
Just sent loads of station data to Scott. Make sure he documents everything better this time! And don't leave stuff lying around on ftp sites - you never know who is trawling them. The two MMs have been after the CRU station data for years. If they ever hear there is a Freedom of Information Act now in the UK, I think I'll delete the file rather than send to anyone. Does your similar act in the US force you to respond to enquiries within 20 days?—our does! The UK works on precedents, so the first request will test it. We also have a data protection act, which I will hide behind. Tom Wigley has sent me a worried email when he heard about it - thought people could ask him for his model code. He has retired officially from UEA so he can hide behind that. IPR should be relevant here, but I can see me getting into an argument with someone at UEA who'll say we must adhere to it!
Are you planning a complete reworking of your paleo series? Like to be involved if you are. Had a quick look at Ch 6 on paleo of AR4. The MWP side bar references Briffa, Bradley, Mann, Jones, Crowley, Hughes, Diaz - oh and Lamb ! Looks OK, but I can't see it getting past all the stages in its present form. MM and SB get dismissed. All the right emphasis is there, but the wording on occasions will be crucial. I expect this to be the main contentious issue in AR4. I expect (hope) that the MSU one will fade away. It seems the more the CCSP (the thing Tom Karl is organizing) looks into Christy and Spencer's series, the more problems/issues they are finding. I might be on the NRC review panel, so will keep you informed.
Rob van Dorland is an LA on the Radiative Forcing chapter, so he's a paleo expert by GRL statndards.
Cheers
Phil
From: Phil Jones
To: Gavin Schmidt
Subject: Re: Revised version the Wengen paper
Date: Wed Aug 20 09:32:52 2008
Cc: Michael Mann
Gavin,
Almost all have gone in. Have sent an email to Janice re the regional freshening. On the boreholes I've used mostly Mike's revised text, with bits of yours making it read a little better. Thinking about the final bit for the Appendix. Keith should be in later, so I'll check with him - and look at that vineyard book. I did rephrase the bit about the 'evidence' as Lamb refers to it. I wanted to use his phrasing—he used this word several times in these various papers. What he means is his mind and its inherent bias(es).
Your final sentence though about improvements in reviewing and traceability is a bit of a hostage to fortune. The skeptics will try to hang on to something, but I don't want to give them something clearly tangible. Keith/Tim still getting FOI requests as well as MOHC and Reading. All our FOI officers have been in discussions and are now using the same exceptions not to respond —advice they got from the Information Commissioner. As an aside and just between us, it seems that Brian Hoskins has withdrawn himself from the WG1 Lead nominations. It seems he doesn't want to have to deal with this hassle.
The FOI line we're all using is this. IPCC is exempt from any countries FOI—the skeptics have been told this. Even though we (MOHC, CRU/UEA) possibly hold relevant info the IPCC is not part our remit (mission statement, aims etc) therefore we don't have an obligation to pass it on.
Cheers
Phil
On opposing views and their appearance in science journals or reviews:
From: "Michael E. Mann"
To: Phil Jones, Ray Bradley, Malcolm Hughes, S. Rutherford
Subject: Re: Fwd: Soon & Baliunas
Date: Tue, 11 Mar 2003 08:14:49 -0500
Cc: Keith Briffa, Jonathan Overpeck, Keith Alverson, Michael C. MacCracken
Thanks Phil,
(Tom: Congrats again!)
The Soon & Baliunas paper couldn't have cleared a 'legitimate' peer review process anywhere. That leaves only one possibility—that the peer-review process at Climate Research has been hijacked by a few skeptics on the editorial board. And it isn't just De Frietas, unfortunately I think this group also includes a member of my own department...
The skeptics appear to have staged a 'coup' at "Climate Research" (it was a mediocre journal to begin with, but now its a mediocre journal with a definite 'purpose').
Folks might want to check out the editors and review editors:
[1]http://www.int-res.com/journals/cr/crEditors.html
In fact, Mike McCracken first pointed out this article to me, and he and I have discussed this a bit. I've cc'd Mike in on this as well, and I've included Peck too. I told Mike that I believed our only choice was to ignore this paper. They've already achieved what they wanted—the claim of a peer-reviewed paper. There is nothing we can do about that now, but the last thing we want to do is bring attention to this paper, which will be ignored by the community on the whole...
It is pretty clear that thee skeptics here have staged a bit of a coup, even in the presence of a number of reasonable folks on the editorial board (Whetton, Goodess, ...). My guess is that Von Storch is actually with them (frankly, he's an odd individual, and I'm not sure he isn't himself somewhat of a skeptic himself), and without Von Storch on their side, they would have a very forceful personality promoting their new vision.
There have been several papers by Pat Michaels, as well as the Soon & Baliunas paper, that couldn't get published in a reputable journal. This was the danger of always criticising the skeptics for not publishing in the "peer-reviewed literature". Obviously, they found a solution to that--take over a journal!
So what do we do about this? I think we have to stop considering "Climate Research" as a legitimate peer-reviewed journal. Perhaps we should encourage our colleagues in the climate research community to no longer submit to, or cite papers in, this journal. We would also need to consider what we tell or request of our more reasonable colleagues who currently sit on the editorial board...
What do others think?
mike
From: Tom Wigley
To: Timothy Carter
Subject: Re: Java climate model
Date: Thu, 24 Apr 2003 09:17:29 -0600
Cc: Mike Hulme, Phil Jones
Tim,
I know about what Matthews has done. He did so without contacting Sarah or me. He uses a statistical emulation method that can never account for the full range of uncertainties. I would not trust it outside the calibration zone -- so I doubt that it can work well for (e.g.) stabilization cases. As far as I know it has not been peer reviewed. Furthermore, unless he has illegally got hold of the TAR version of the model, what he has done can only be an emulation of the SAR version.
Personally, I regard this as junk science (i.e., not science at all). Matthews is doing the community a considerable disservice.
Tom.
PS Re CR, I do not know the best way to handle the specifics of the editoring. Hans von Storch is partly to blame—he encourages the publication of crap science 'in order to stimulate debate'. One approach is to go direct to the publishers and point out the fact that their journal is perceived as being a medium for disseminating misinformation under the guise of refereed work. I use the word 'perceived' here, since whether it is true or not is not what the publishers care about—it is how the journal is seen by the community that counts.
I think we could get a large group of highly credentialed scientists to sign such a letter -- 50+ people. Note that I am copying this view only to Mike Hulme and Phil Jones. Mike's idea to get editorial board members to resign will probably not work—must get rid of von Storch too, otherwise holes will eventually fill up with people like Legates, Balling, Lindzen, Michaels, Singer, etc. I have heard that the publishers are not happy with von Storch, so the above approach might remove that hurdle too.
From: Phil Jones
To: Ben Santer
Subject: Re: See the link below
Date: Thu Mar 19 17:02:53 2009
Ben,
I don't know whether they even had a meeting yet - but I did say I would send something to their Chief Exec. In my 2 slides worth at Bethesda I will be showing London's UHI and the effect that it hasn't got any bigger since 1900. It's easy to do with 3 long time series. It is only one urban site (St James Park), but that is where the measurements are from. Heathrow has a bit of a UHI and it has go bigger. I'm having a dispute with the new editor of Weather. I've complained about him to the RMS Chief Exec. If I don't get him to back down, I won't be sending any more papers to any RMS journals and I'll be resigning from the RMS. The paper is about London and its UHI!
Cheers
Phil
On disputes over data and how to handle such disagreements:
From: "Michael E. Mann"
To: Tim Osborn
Subject: Re: reconstruction errors
Date: Thu, 31 Jul 2003 11:18:24 -0400
Tim,
Attached are the calibration residual series for experiments based on available networks
back to:
AD 1000
AD 1400
AD 1600
I can't find the one for the network back to 1820! But basically, you'll see that the residuals are pretty red for the first 2 cases, and then not significantly red for the 3rd case--its even a bit better for the AD 1700 and 1820 cases, but I can't seem to dig them up.In any case, the incremental changes are modest after 1600--its pretty clear that key predictors drop out before AD 1600, hence the redness of the residuals, and the notably larger uncertainties farther back...
You only want to look at the first column (year) and second column (residual) of the files. I can't even remember what the other columns are!
Let me know if that helps. Thanks,
mike
p.s. I know I probably don't need to mention this, but just to insure absolutely clarify on this, I'm providing these for your own personal use, since you're a trusted colleague. So please don't pass this along to others without checking w/ me first. This is the sort of "dirty laundry" one doesn't want to fall into the hands of those who might potentially try to distort things...
From: Ben Santer
To: Leopold Haimberger
Subject: Re: Update on response to Douglass et al., Dian, something like this?
Date: Thu, 10 Jan 2008 19:07:03 -0800
Cc: Peter Thorne , Dian Seidel, Tom Wigley, Karl Taylor, Thomas R Karl, John Lanzante, Carl Mears, David C. Bader, Francis W. Zwiers, Frank Wentz, Melissa Free , Michael C. MacCracken, Phil Jones, Steve Sherwood, Steve Klein, Susan Solomon, Tim Osborn, Gavin Schmidt, James J. Hack
Dear Leo,
Thanks very much for your email. I can easily make the observations a bit more prominent in Figure 1. As you can see from today's (voluminous!) email traffic, I've received lots of helpful suggestions regarding improvements to the Figures. I'll try to produce revised versions of the Figures tomorrow. On the autocorrelation issue: The models have a much larger range of lag-1 autocorrelation coefficients (0.66 to 0.95 for T2LT, and 0.69 to 0.95 for T2) than the UAH or RSS data (which range from 0.87 to 0.89). I was concerned that if we used the model lag-1 autocorrelations to guide the choice of AR-1 parameter in the synthetic data analysis, Douglass and colleagues would have an easy opening for criticising us ("Aha! Santer et al. are using model results to guide them in their selection of the coefficients for their AR-1 model!") I felt that it was much more difficult for Douglass et al. to criticize what we've done if we used UAH data to dictate our choice of the AR-1 parameter and the "scaling factor" for the amplitude of the temporal variability. As you know, my personal preference would be to include in our response to Douglass et al. something like the Figure 4 that Peter has produced. While inclusion of a Figure 4 is not essential for the purpose of illuminating the statistical flaws in the Douglass et al. "consistency test", such a Figure would clearly show the (currently large) structural uncertainties in radiosonde-based estimates of the vertical profile of atmospheric temperature changes. I think this is an important point, particularly in view of the fact that Douglass et al. failed to discuss versions 1.3 and 1.4 of your RAOBCORE data - even though they had information from those datasets in their possession.
However, I fully agree with Tom's comment that we don't want to do anything to "steal the thunder" from ongoing efforts to improve sonde-based estimates of atmospheric temperature change, and to better quantify structural uncertainties in those estimates.Your group, together with the groups at the Hadley Centre, Yale, NOAA ARL and NOAA GFDL, deserve great credit for making significant progress on a difficult, time-consuming, yet important problem.
I guess the best solution is to leave this decision up to all of you (the radiosonde dataset developers). I'm perfectly happy to include a version of Figure 4 in our response to Douglass et al. If we do go with inclusion of a Figure 4, you, Peter, Dian, Melissa, Steve Sherwood and John should decide whether you feel comfortable providing radiosonde data for such a Figure. I will gladly abide by your decisions. As you note in your email, our use of a Figure 4 would not preclude a more detailed and thorough comparison of simulated and observed amplification in some later publication. Once again, thanks for all your help with this project, Leo.
With best regards,
Ben
From: Tom Wigley
To: Phil Jones
Subject: 1940s
Date: Sun, 27 Sep 2009 23:25:38 -0600
Cc: Ben Santer
Phil,
Here are some speculations on correcting SSTs to partly explain the 1940s warming blip. If you look at the attached plot you will see that the land also shows the 1940s blip (as I'm sure you know). So, if we could reduce the ocean blip by, say, 0.15 degC, then this would be significant for the global mean—but we'd still have to explain the land blip. I've chosen 0.15 here deliberately. This still leaves an ocean blip, and i think one needs to have some form of ocean blip to explain the land blip (via either some common forcing, or ocean forcing land, or vice versa, or all of these). When you look at other blips, the land blips are 1.5 to 2 times (roughly) the ocean blips—higher sensitivity plus thermal inertia effects. My 0.15 adjustment leaves things consistent with this, so you can see where I am coming from.
Removing ENSO does not affect this. It would be good to remove at least part of the 1940s blip, but we are still left with "why the blip". Let me go further. If you look at NH vs SH and the aerosol effect (qualitatively or with MAGICC) then with a reduced ocean blip we get continuous warming in the SH, and a cooling in the NH—just as one would expect with mainly NH aerosols. The other interesting thing is (as Foukal et al. note—from MAGICC) that the 1910-40 warming cannot be solar. The Sun can get at most 10% of this with Wang et al solar, less with Foukal solar. So this may well be NADW, as Sarah and I noted in 1987 (and also Schlesinger later). A reduced SST blip in the 1940s makes the 1910-40 warming larger than the SH (which it currently is not)—but not really enough.
So ... why was the SH so cold around 1910? Another SST problem? (SH/NH data also attached.) This stuff is in a report I am writing for EPRI, so I'd appreciate any comments you (and Ben) might have.
Tom.
From: Gary Funkhouser
To: Keith Briffa
Subject: kyrgyzstan and siberian data
Date: Thu, 19 Sep 1996 15:37:09 -0700
Keith,
Thanks for your consideration. Once I get a draft of the central and southern siberian data and talk to Stepan and Eugene I'll send it to you.
I really wish I could be more positive about the Kyrgyzstan material, but I swear I pulled every trick out of my sleeve trying to milk something out of that. It was pretty funny though - I told Malcolm what you said about my possibly being too Graybill-like in evaluating the response functions—he laughed and said that's what he thought at first also. The data's tempting but there's too much variation even within stands. I don't think it'd be productive to try and juggle the chronology statistics any more than I already have—they just are what they are (that does sound Graybillian). I think I'll have to look for an option where I can let this little story go as it is. Not having seen the sites I can only speculate, but I'd be optimistic if someone could get back there and spend more time collecting samples, particularly at the upper elevations. Yeah, I doubt I'll be over your way anytime soon. Too bad, I'd like to get together with you and Ed for a beer or two. Probably someday though.
Cheers, Gary
Gary Funkhouser
Lab. of Tree-Ring Research
The University of Arizona
From: Michael Mann
To: Phil Jones
Subject: Re: Straight to the Point
Date: Thu, 6 May 1999 13:09:36 -0400 (EDT)
Cc: Keith Briffa, Malcolm Hughes, Ray Bradley, Tim Osborn
Hi Phil,
SOrry that you have taken such a negative spin from this. I had hoped it was all resolved pretty amicably, and emphasized to Keith and Tim that I was being perhaps overly picky this time PRECISELY to avoid the misunderstanding that happened last time around w/ Science.
Trust that I'm certainly on board w/ you that we're all working towards a common goal. That is what is distressing about commentarys (yours from last year, and potentially, without us having had approprimate input, Keith and Tim's now) that appear to "divide and conquer". The skeptics happily took your commentary last year as reason to doubt our results! In fact, your piece was references in several commentaries (mostly on the WEB, not published) attacking our work. So THAT is what this is all about. It is in the NAME of the common effort we're all engaged in, that I have voiced concerns about language and details in this latest commentary--so as to avoid precisely that scenario. Please understand the above to be a complete and honest statement about the source of my concerns. It really doesn't have anything to do about who did what first, etc. I trust that history will give us all proper credit for what we're doing here.
The millennial-scale trend issue appears to be a source of contention. Malcolm can address the replication issue better than any of us--it's not a problem w/ our reconstruction. Furthermore, WE HAVE EXPLICITLY TAKEN INTO ACCOUNT THE LOSS OF LOW-FREQUENCY VARIANCE IN OUR ESTIMATES OF UNCERTAINTY. I don't know how many times I need to stress this. It is of fundamental importance in framing our conclusions. Our own analysis convinces me that things are already quite uncertain a millennium back in time. With regard to longer timescale variations, the evidence is all over the place. At EGS I saw some convincing evidence that many new paleo proxies indicate steadily decline at least over several millennia, and so do, in large part, the available long borehole estimates (though we should all take that w/ a good dose of NaCl). So I'm skeptical of estimates more than a millennium back in time until we have multiple proxies we can trust at that timescale, and can verify somehow the DC component of the estimates, or at least replicate them. This was my concern about the latest 2000 year recon that was shown. You are right, the Milankovitch forcing argument is ONLY A NULL HYPOTHESIS. I hope I haven't argued anything more than that. That our millennial scale trend, which we reasonably trust, and have some idea of the uncertainties in, is in line w/ that null hypothesis is information that cannot be ignored. That Kutzbach, Berger, and others are showing increasingly convincing model integrations over several millennia suggesting this, is more evidence.In the real word, anything *could* have happened. But lets not loose site of the appropriate null hypothesis here.
I hope the above clears things up somewhat. I'm sorry things have been construed in more negative light than I had ever intended. Call me anytime to discuss, here at the office (not sure how well our schedules overlap though).
Thanks, and sorry for the miscommunication here,
mike
_______________________________________________________________________
From: Phil Jones
To: Tom Wigley
Subject: Re: MBH
Date: Fri Oct 22 15:13:20 2004
Cc: Ben Santer
Tom,
Just got the Science attachments for the von Storch et al. paper for Tim and Keith, so I thought you might like to see them. I've just sent a reply to von Storch as he claims his model is a better representation of reality than MBH. How a model that is only given past forcing histories can be better than some proxy data is beyond me, but Hans seems to believe this. The ERA-40 report and JGR paper are relevant here. ERA-40 is not of climate quality. There are differences and trends with CRU data before the late 1970s and again around the mid-1960s that should include other variables that are calculated. It is so bad in the Antarctic that ERA-40 rejects most of the surface obs (because they get little weight) and they don't begin to get accepted until the late 1970s. Conclusion is that you can't consider ERA-40 for climate purposes. Maybe the next generation, with a considerable efforts in getting all the missing back data in and changes to weights given to surface data might mean the 3rd generation is better. I shouldn't rabbit on about this as I have to go home to drive with Ruth to Gatwick for our week in Florence. A lot of people criticise MBH and other papers Mike has been involved in, but how many people read them fully - or just read bits like the attached. The attached is a complete distortion of the facts. M&M are completely wrong in virtually everything they say or do. I have sent them countless data series that were used in the Jones/Mann Reviews of Geophysics papers. I got scant thanks from them for doing this—only an email saying I had some of the data series wrong, associated with the wrong year/decade.
I wasted a few hours checking what I'd done and got no thanks for pointing their mistake out
to them. If you think M&M are correct and believable then go to this web site
[1]http://cgi.cse.unsw.edu.au/~lambert/cgi-bin/blog/
It will take a while to get around these web pages and you've got to be a bit of nerd and know the jargon, but it lists all the mistakes McKittrick has made in various papers. I bet there isn't a link to this on his web site. The final attachment is a comment on a truly awful paper by McKittirck and Michaels. I can't find the original, but it's reference is in this. The paper didn't consider spatial autocorrelation at all. Fortunately a longer version of the paper did get rejected by IJC—it seems a few papers are rejected! Point I'm trying to make is you cannot trust anything that M&M write. MBH is as good a way of putting all the data together as others.We get similar results in the work in the Holocene in 1998 (Jones et al) and so does Tom Crowley in a paper in 1999. Keith's reconstruction is strikingly similar in his paper from JGR in 2001. Mike's may have slightly less variability on decadal scales than the others (especially cf Esper et al), but he is using a lot more data than the others. I reckon they are all biased a little to the summer and none are truly annual —I say all this in the Reviews of Geophysics paper!
Bottom line - their is no way the MWP (whenever it was) was as warm globally as the last 20 years. There is also no way a whole decade in the LIA period was more than 1 deg C on a global basis cooler than the 1961-90 mean. This is all gut feeling, no science, but years of experience of dealing with global scales and varaibility. Must got to Florence now. Back in Nov 1.
Cheers
Phil
From: Tom Wigley
To: Doug Martinson
Subject: Re: Your help, please?
Date: Mon, 12 Aug 1996 10:07:42 -0600 (MDT)
Cc: Kevin Trenberth, Byron Boville, Grant Branstator, Jeff Kiehl, FP Bretherton, Ralph Cicerone, C. Covey, Tom Crowley, J Curry, pdadd@xxxx.xxx, Larry Gates, Lisa Graumlich, Dennis Hartmann, barafu@xxxx.xxx, Thomas Karl, Richard Lindzen, W. Timothy Liu, Joel Sloman, Jerry Marks, Robert Malone , Gerald Meehl, Berrien Moore, Dick Moritz, J. David Neelin, Reginald Newell, Gerald North, James J. O'Brien, W. R. Peltier, Raymond Pierrehumbert, V. Ramanathan, Dave Randall, Eugene M. Rasmusson, David Rind, Alan Cohn, njrosenberg@xxx.gov, Ed Sarachik, Michael E. Schlesinger, Edwin Schneider, Jagadish Shukla, Eric Smith, rsomervi@xxx.edu, Richard Turco, Duane Waliser, Mike Wallace, John Walsh, Wei-Chyung Wang, "P.D. Jones" , Edward Cook, Keith Briffa, Malcolm Hughes, Ray Bradley, Tim Barnett, Jay Fein, Ben Santer ,
Dear Doug,
In response to Jay Fein's e-mail re den-cen, here are some points (which may merely echo where you are already).
(1) Why study den-cen? Reason is: improve understanding of climate system to aid in detection and prediction. You should read Ch. 8 (detection) of IPCC WGI SAR in this regard.
(2) How to study den-cen? Models and observed data are equally important. Models (coupled O/AGCMs) can only give the internal component of variability, instrumental and paleodata give internal-plus-external.
(3) How useful are paleodata?I support the continued collection of such data, but I am disturbed by how some people in the paleo community try to oversell their product. A specific example is the ice core isotope record, which correlates very poorly with temperature on the annual to decadal timescale (and possibly also on the century timescale)---question, how do we ever demonstrate the usefulness or otherwise of ice core isotopes on this timescale?
There are other well known proxy data issues that need careful thought...
(a) Sedimentary records---dating. Are 14C-dated records of any value at all (unless wiggle matched)?
(b) Seasonal specificity---how useful is a proxy record that tells us about a single season (or only part of the year)?
(c) Climate variance explained by the proxy variable--close to zero for ice core isotopes, up to 50% for tree rings, somewhere in between for most other indicators. How valuable are such partially explained records in helping explain the past?
(d) Signal-to-noise problems---a key issue is, what role has external forcing had on climate over the past 10,000 years. There is a tendency to interpret observed changes as evidence of external forcing—usually unjustifiably. Few workers in the area realize that paleo interpretation has a detection aspect, just like interpreting the past 100+ years---only much more difficult. More work is needed on this.
(e) Frequency dependence of explained variance---the classic example here is tree rings, where it is exceedingly difficult to get out a credible low frequency (50+ year time scale) message. Work in this area could reap useful rewards.
(f) Coverage---what about den-cen data from the oceans? We need much more of this, especially in regions that might provide insights into mechanisms (like NADW changes).
(4) Causes. Here, ice cores are more valuable (CO2, CH4 and volcanic aerosol changes). But the main external candidate is solar, and more work is required to improve the "paleo" solar forcing record and to understand how the climate system responds both globally and regionally to solar forcing.
I hope these very hasty ramblings are helpful
Cheers,
Tom
P.S. I've added Ben Santer, Tim Barnett, Ed Cook, Keith Briffa, Malcolm Hughes, Ray Bradley and Phil Jones to your mailing list.