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 thisâonly 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 IJCâit 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 âI 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 forcingâusually 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.