From: "Michael E. Mann" <mann@meteo.psu.edu>
To: Tim Osborn <t.osborn@uea.ac.uk>
Subject: Re: [Fwd: u seen?]
Date: Wed, 30 Nov 2005 11:04:40 -0500
Reply-to: mann@psu.edu
Cc: Phil Jones <p.jones@uea.ac.uk>, Keith Briffa <k.briffa@uea.ac.uk>

<x-flowed>
fair enough, I'll go w/ flimsy. The real problem is the fairly 
inflammatory wording of this, and the really flawed interpretations 
w.r.t. implicatinos for natural vs. anthropogenic variaiblity.

normally I'd ignore, but the fact that Andy Revkin received this 
suggests they are trying to publicize this review paper, which I find a 
bit odd...

mike

Tim Osborn wrote:

> Hi Mike,
>
> I've seen this before (and probably Keith has too) because our EU 
> "SOAP" project supported Rob Wilson, the second author.  I'd say that 
> it is "flimsy" rather than "shoddy"!  Still, it's only supposed to be 
> a "viewpoint" rather than new science.
>
> Tim
>
> At 15:31 30/11/2005, Michael E. Mann wrote:
>
>> thought you guys would be interested. pretty shoddy stuff in my view...
>>
>> mike
>>
>> -- 
>> Michael E. Mann
>> Associate Professor
>> Director, Earth System Science Center (ESSC)
>>
>> Department of Meteorology              Phone: (814) 863-4075
>> 503 Walker Building                    FAX:   (814) 865-3663
>> The Pennsylvania State University      email:  mann@psu.edu
>> University Park, PA 16802-5013
>>
>> http://www.met.psu.edu/dept/faculty/mann.htm
>>
>>
>>
>>
>> Return-Path: <anrevk@nytimes.com>
>> X-Original-To: mann@meteo.psu.edu
>> Delivered-To: mann@meteo.psu.edu
>> Received: from tr12n04.aset.psu.edu (tr12g04.aset.psu.edu 
>> [128.118.146.130])
>>         by mail.meteo.psu.edu (Postfix) with ESMTP id 2027520401A
>>         for <mann@meteo.psu.edu>; Wed, 30 Nov 2005 10:15:10 -0500 (EST)
>> Received: from nytimes.com (nat-hq-gate-02.nytimes.com 
>> [199.181.175.222])
>>         by tr12n04.aset.psu.edu (8.13.2/8.13.2) with ESMTP id 
>> jAUFF8P22437280
>>         for <mann@psu.edu>; Wed, 30 Nov 2005 10:15:08 -0500
>> Message-Id: <6.1.2.0.2.20051130101420.02d14460@smtp-store.nytimes.com>
>> X-Sender: anrevk@smtp-store.nytimes.com
>> X-Mailer: QUALCOMM Windows Eudora Version 6.1.2.0
>> Date: Wed, 30 Nov 2005 10:14:45 -0500
>> To: mann@psu.edu
>> From: Andy Revkin <anrevk@nytimes.com>
>> Subject: u seen?
>> Mime-Version: 1.0
>> Content-Type: multipart/alternative;
>>         boundary="=====================_79165303==.ALT"
>> X-NYTOriginatingHost: , 10.149.64.222
>> X-Virus-Scanned: amavisd-sophos
>> X-PSU-Spam-Flag: NO
>> X-PSU-Spam-Hits: 0.695
>> X-PSU-Spam-Level: *
>> X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on 
>> mail.meteo.psu.edu
>> X-Spam-Level:
>> X-Spam-Status: No, score=-1.6 required=5.0 
>> tests=AWL,BAYES_00,HTML_00_10,
>>         HTML_MESSAGE,MIME_QP_LONG_LINE autolearn=no version=3.0.2
>>
>> purely fyi.. u seen?
>>
>>
>>> Quaternary Science Reviews, Volume 24, Issues 20-21 , November 2005, 
>>> Pages 2164-2166
>>> http://tinyurl.com/b95ee
>>>
>>> Climate: past ranges and future changes
>>>
>>> Jan Esper a), Robert J.S. Wilson b), David C. Frank a), Anders 
>>> Moberg c), Heinz Wanner d) and Jürg Luterbacher d)
>>>
>>> a) Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland
>>> b) School of GeoSciences, Grant Institute, Edinburgh University, 
>>> Edinburgh, UK
>>> c) Department of Meteorology, Stockholm University, 10691 Stockholm, 
>>> Sweden
>>> d) NCCR Climate and Institute of Geography, University of Bern, 3012 
>>> Bern, Switzerland
>>>
>>> Abstract
>>>
>>> Comparison of large-scale temperature reconstructions over the past 
>>> millennium reveals agreement on major climatic episodes, but 
>>> substantial divergence in reconstructed (absolute) temperature 
>>> amplitude. We here detail several research priorities to overcome 
>>> this 'amplitude desideratum', and discuss the relevance of this 
>>> effort for the prediction of future temperature changes and the 
>>> meaning of the Kyoto protocol.
>>>
>>> Persisting controversy (Regalado, 2005) surrounding a pioneering 
>>> northern hemisphere temperature reconstruction (Mann et al., 1999) 
>>> indicates the importance of such records to understand our changing 
>>> climate. Such reconstructions, combining data from tree rings, 
>>> documentary evidence and other proxy sources are key to evaluate 
>>> natural forcing mechanisms, such as the sun's irradiance or volcanic 
>>> eruptions, along with those from the widespread release of 
>>> anthropogenic greenhouse gases since about 1850 during the 
>>> industrial (and instrumental) period. We here demonstrate that our 
>>> understanding of the shape of long-term climate fluctuations is 
>>> better than commonly perceived, but that the absolute amplitude of 
>>> temperature variations is poorly understood. We argue that the 
>>> knowledge of this amplitude is critical for predicting future 
>>> trends, and detail four research priorities to solve this 
>>> incertitude: (i) reduce calibration uncertainty, (ii) preserve 
>>> 'colour' in proxy data, (iii) utilize accurate instrumental data, 
>>> and (iv) update old and develop new proxy data.
>>>
>>> When matching existing temperature reconstructions (Jones et al., 
>>> 1999; Mann et al., 1999; Briffa, 2000; Esper et al., 2002; Moberg, 
>>> et al., 2005) over the past 1000 years, although substantial 
>>> divergences exist during certain periods, the timeseries display a 
>>> reasonably coherent picture of major climatic episodes: 'Medieval 
>>> Warm Period', 'Little Ice Age' and 'Recent Warming' (Fig. 1). 
>>> However, when calibrated against instrumental temperature records, 
>>> these same reconstructions splay outwards with temperature 
>>> amplitudes ranging from  0.4 to 1.0 °C for decadal means (Moberg et 
>>> al., 2005). Further, a comparison of commonly used regression and 
>>> scaling approaches shows that the reconstructed absolute amplitudes 
>>> easily vary by over 0.5 °C, depending on the method and instrumental 
>>> target chosen (Esper et al., 2005). Overall, amplitude discrepancies 
>>> are in the order of the total variability estimated over the past 
>>> millennium, and undoubtedly confuse future modelled temperature 
>>> trends via parameterisation uncertainties related to inadequately 
>>> simulated behaviour of past variability.
>>>
>>> Fig. 1. Course of temperature variations. Large-scale temperature 
>>> reconstructions scaled to the same mean and variance over the common 
>>> period 1000-1979 AD, and their arithmetic mean. The normalisation 
>>> highlights the similarity between the records, but broadly ignores 
>>> the differing calibration statistics with instrumental data, and 
>>> their particular 'shapes' and distribution of variance, e.g. during 
>>> the instrumental and pre-instrumental periods. The average 
>>> correlation between the original reconstructions is 0.47, and 0.64 
>>> after smoothing (as done in the figure using a 40-year low-pass 
>>> filter). Lag-1 autocorrelations range from 0.52 (Jones98) to 0.93 
>>> (Moberg05; with no variability <4 years represented).
>>>
>>>
>>> Solutions to reduce calibration uncertainty include the use of 
>>> pseudo-proxy experiments (Osborn and Briffa, 2004; von Storch et 
>>> al., 2004) derived from ensemble simulations of different models 
>>> (Knutti et al., 2002; Stainforth et al., 2005) to test statistical 
>>> calibration methods, e.g. principal component (Cook et al., 1994) 
>>> and timescale-dependent (Osborn and Briffa, 2000) regression. Such 
>>> analyses, however, should mimic the character of empirical proxy 
>>> data, e.g. the decline of replication (numbers of sites, quality per 
>>> site) back in time, and the addition of noise typical to empirical 
>>> proxy data (i.e., not just white; Mann and Rutherford, 2002). 
>>> Further, reconstructions from areas such as Europe (Luterbacher et 
>>> al., 2004; Xoplaki et al., 2005), where long instrumental series and 
>>> high densities of proxy records exist, allow extended calibration 
>>> periods and increased degrees of freedom enabling the assessment of 
>>> robust relationships at all timescales (i.e., low and high 
>>> frequency), both critical to reduce calibration uncertainty. 
>>> Subsequent comparison of such regional records with hemispheric 
>>> reconstructions that can be downscaled should provide greater 
>>> understanding of reconstructed amplitudes at larger spatial scales.
>>>
>>> Accurate preservation and assessment of low-to-high frequency 
>>> variation ('colour') in proxy data, and a selected use of certain 
>>> frequency bands that best fit those of instrumental data (Moberg et 
>>> al., 2005), are further desirable when compiling large-scale 
>>> reconstructions that seek to yield the true absolute temperature 
>>> amplitude. This approach, however, requires a comprehensive 
>>> examination of regional proxy data including the seasonality of 
>>> temperature signals, and a selection of only those records that 
>>> effectively capture low-frequency climate variation. Inclusion of 
>>> regional tree ring records in which long-term trends are not 
>>> preserved, should be avoided in efforts to reconstruct low frequency 
>>> temperature variations (Esper et al., 2004; Melvin, 2004). In these 
>>> data, such limitations primarily occur when age-related biases from 
>>> tree-ring series are individually estimated and removed ('the 
>>> segment length curse' Cook et al., 1995). Similar considerations 
>>> apply to documentary evidence, long isotope records and other proxy 
>>> sources that should, on a site-by-site basis, be examined for 
>>> potential low-frequency limitations.
>>>
>>> The instrumental target data chosen (Esper et al., 2005), and 
>>> adjustments made to these data are also vital to the reconstructed 
>>> amplitude. A recent analysis of a carefully homogenised instrumental 
>>> network from the Alps and surrounding areas (Böhm et al., 2001), for 
>>> example, shows the annual temperature trend over the last ca 110 
>>> years to be 1.1 °C-twice that observed over the same alpine 
>>> gridboxes in the global dataset provided by the Climatic Research 
>>> Unit (Jones et al., 1999). Such changes in the character of 
>>> observational data, resulting from homogeneity adjustments and 
>>> methodology differences (Moberg et al., 2003), directly affect the 
>>> temperature amplitude in proxy-based reconstructions, since 
>>> instrumental calibration sets the pulse in these paleorecords 
>>> (Büntgen et al., 2005). Accurate instrumental data are therefore 
>>> crucial to the reconstructed amplitude, and this again argues for 
>>> regional studies where mutual verification between proxy and 
>>> instrumental records is viable (Frank and Esper, 2005; Wilson et 
>>> al., 2005).
>>>
>>> Finally, more proxy data covering the full millennium and 
>>> representing the same spatial domain as the instrumental target data 
>>> (e.g., hemisphere) are required to solve the amplitude puzzle. The 
>>> current pool of 1000-year long annually resolved temperature proxies 
>>> is limited to a handful of timeseries, with some of them also 
>>> portraying differing seasonal (e.g., summer or annual) responses. 
>>> Furthermore, the strength of many of these local records and 
>>> literally all tree ring chronologies varies and almost always 
>>> declines back in time (Cook et al., 2004). The reasons are manifold 
>>> and include dating uncertainty, loss of signal fidelity in the 
>>> recent period, assumptions about signal stationarity, reduction of 
>>> sample replication, etc., and are generally not considered in the 
>>> uncertainty estimates of combined large-scale reconstructions. Also, 
>>> data from the most recent decades, absent in many regional proxy 
>>> records, limits the calibration period length and hinders tests of 
>>> the behaviour of the proxies under the present 'extreme' temperature 
>>> conditions. Calibration including the exceptional conditions since 
>>> the 1990s would, however, be necessary to estimate the robustness of 
>>> a reconstruction during earlier warm episodes, such as the Medieval 
>>> Warm Period, and would avoid the need to splice proxy and 
>>> instrumental records together to derive conclusions about recent 
>>> warmth.
>>>
>>> So, what would it mean, if the reconstructions indicate a larger 
>>> (Esper et al., 2002; Pollack and Smerdon, 2004; Moberg et al., 2005) 
>>> or smaller (Jones et al., 1998; Mann et al., 1999) temperature 
>>> amplitude? We suggest that the former situation, i.e. enhanced 
>>> variability during pre-industrial times, would result in a 
>>> redistribution of weight towards the role of natural factors in 
>>> forcing temperature changes, thereby relatively devaluing the impact 
>>> of anthropogenic emissions and affecting future predicted scenarios. 
>>> If that turns out to be the case, agreements such as the Kyoto 
>>> protocol that intend to reduce emissions of anthropogenic greenhouse 
>>> gases, would be less effective than thought. This scenario, however, 
>>> does not question the general mechanism established within the 
>>> protocol, which we believe is a breakthrough.
>>>
>>> doi:10.1016/j.quascirev.2005.07.001
>>> Copyright © 2005 Elsevier Ltd All rights reserved.
>>
>>
>>
>> Andrew C. Revkin, Science Reporter, The New York Times
>> 229 West 43d St. NY, NY   10036
>> Tel:   212-556-7326, 914-441-5556 (mobile); Fax:  509-357-0965
>> Recent Arctic coverage: www.nytimes.com/pages/science/sciencereport
>> Book on the Amazon: The Burning Season ( www.islandpress.org/burning )
>> Acoustic-Roots Band: www.sonicbids.com/unclewade
>
>
> Dr Timothy J Osborn
> Climatic Research Unit
> School of Environmental Sciences, University of East Anglia
> Norwich  NR4 7TJ, UK
>
> e-mail:   t.osborn@uea.ac.uk
> phone:    +44 1603 592089
> fax:      +44 1603 507784
> web:      http://www.cru.uea.ac.uk/~timo/
> sunclock: http://www.cru.uea.ac.uk/~timo/sunclock.htm
>


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

Department of Meteorology              Phone: (814) 863-4075
503 Walker Building                    FAX:   (814) 865-3663
The Pennsylvania State University      email:  mann@psu.edu
University Park, PA 16802-5013

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


</x-flowed>

