date: Thu Jul  3 16:52:36 2003
from: Tim Osborn <t.osborn@uea.ac.uk>
subject: Fwd: 03-19 Mann - climate change press release - first draft
to: k.briffa@uea

   Keith - you might want to take a close look at this press release, in case (i) it is
   inappropriate, or (ii) you want to be contacted by the media because Phil & Mike are in
   Japan.
   Cheers
   Tim

     Date: Thu, 03 Jul 2003 11:04:26 -0400
     From: Harvey Leifert <HLeifert@agu.org>
     Organization: AGU
     User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.3.1) Gecko/20030425
     X-Accept-Language: en-us, en
     To: "Michael E. Mann" <mann@virginia.edu>
     CC: f028 <P.Jones@uea.ac.uk>, tim Osborn <t.osborn@uea.ac.uk>
     Subject: 03-19 Mann - climate change press release - first draft
     Hi Mike,
     Thanks for the background information, some of which I have incorporated into the draft
     below. Please send me your corrections and/or suggestions asap. In particular, is the
     title ok or too strong regarding human activity? I also need contact information (phone
     and email) for whichever authors you think should be able to handle media queries
     resulting from this release. In the case of you and Phil, I need Sapporo numbers, as
     well as your permanent ones. (Not all authors are AGU members, it seems, and therefore
     not in our database.) If the changes are not major, I'll just make them and issue the
     release; if you want to see a second draft, let me know. Thanks!
     Regards,
     Harvey
     *****
     [Title] Leading Climate Scientists Reaffirm View That Late 20th Century Warming Was
     Unusual and Resulted From Human Activity
     WASHINGTON - A group of leading climate scientists has reaffirmed the "robust consensus
     view" emerging from the peer reviewed literature that the warmth experienced on at least
     a hemispheric scale in the late 20th century was an anomaly in the previous millennium
     and that human activity likely played an important role in causing it. In do doing, they
     refuted recent claims that the warmth of recent decades was not unprecedented in the
     context of the past thousand years.
     Writing in the 8 July issue of the American Geophysical Union publication Eos, Michael
     Mann of the University of Virginia and 12 colleagues in the United States and United
     Kingdom endorse the position on climate change and greenhouse gases taken by AGU in
     1998. Specifically, they say that "there is a compelling basis for concern over future
     climate changes, including increases in global-mean surface temperatures, due to
     increased concentrations of greenhouse gases, primarily from fossil-fuel burning."
     The Eos article is a response to two recent and nearly identical papers by Drs. Willie
     Soon and Sallie Baliunas of the Harvard-Smithsonian Center for Astrophysics, published
     in Climate Research and Energy & Environment (the latter paper with additional
     co-authors). They challenge the generally accepted view that natural factors cannot
     fully explain recent warming and must have been supplemented by significant human
     activity, and their papers have received attention in the media and in the U.S. Senate.
     Requests from reporters to top scientists in the field, seeking comment on the Soon and
     Baliunas position, lead to memoranda that were later expanded into the current Eos
     article, which was itself peer reviewed.
     Mann and his colleagues rely on instrumental data for the past 150 years and "proxy"
     indicators, such as tree rings, ice cores, corals, and lake sediments to reconstruct the
     climate of earlier times. Most of the available data pertain to the northern hemisphere
     and show, according to the authors, that the warmth of the northern hemisphere over the
     past few decades is likely unprecedented in the last 1,000 years and quite possibly in
     the preceding 1,000 years as well.
     Climate model simulations cannot explain the anomalous late 20th century warmth without
     taking into account the contributions of human activities, the authors say. They make
     three major points regarding Soon and Baliunas's recent assertions challenging these
     findings.
     First, in using proxy records to draw inferences about past climate, it is essential to
     assess their actual sensitivity to temperature variability. In particular, the authors
     say, Soon and Baliunas misuse hydrological data in their effort to determine
     temperature.
     Second, it is essential to distinguish between regional temperature anomalies and
     hemispheric mean temperature, which must represent an average of estimates over a
     sufficiently large number of distinct regions. For example, Mann and his co- authors
     say, the concepts of a "Little Ice Age" and "Medieval Warm Period" arose from the
     Eurocentric origins of historic climatology. The specific periods of coldness and warmth
     differed from region to region and as compared with data for the northern hemisphere as
     a whole.
     Third, according to Mann and his colleagues, it is essential to define carefully the
     modern base period with which past climate is to be compared and to identify and
     quantify uncertainties. For example, they say, the most recent report of the
     Intergovernmental Panel on Climate Change (IPCC) carefully compares data for recent
     decades with reconstructions of past temperatures, taking into account the uncertainties
     in those reconstructions. IPCC concluded that late 20th century warmth in the northern
     hemisphere likely exceeded that of any time in the past millennium. The method used by
     Soon and Baliunas, they say, considers mean conditions for the entire 20th century as
     the base period and determines past temperatures from proxy evidence not capable of
     resolving trends on a decadal basis. It is therefore, they say, of limited value in
     determining whether recent warming in anomalous in a long term and large scale context.
     The Eos article started as a memorandum that Michael Oppenheimer and Mann drafted to
     help inform colleagues who were being contacted by members of the media regarding the
     Soon and Baliunas papers and wanted an opinion from climate scientists and
     paleoclimatologists (scientists who study ancient climates) who were directly familiar
     with the underlying issues.
     Mann and Oppenheimer learned that a number of other colleagues, including Tom Wigley of
     the University Corporation for Atmospheric Research (UCAR) in Boulder, Colorado; Philip
     Jones of the University of East Anglia's Climatic Research Unit in Norwich, United
     Kingdom; and Raymond Bradley of the University of Massachusetts in Amherst were
     receiving similar media requests for their opinions on the matter. Their original
     memorandum evolved into a more general position paper jointly authored by a larger group
     of leading scientists in the field.
     Mann says he sees the resulting Eos article as representing an even broader consensus of
     the viewpoint of the mainstream climate research community on the question of late 20th
     century warming and its causes. The goal of the authors, he says, is to reaffirm support
     for the AGU position statement on climate change and greenhouse gases and clarify what
     is currently known from the paleoclimate record of the past one-to-two thousand years
     and, in particular, what the bearing of this evidence is on the issue of the detection
     of human influence on recent climate change.
     **********
     Notes for Journalists:
     The article, "On Past Temperatures and Anomalous Late-20th Century Warmth. appears in
     Eos, Volume 84, No. 27, 8 July 2003, page 256.
     Authors (full list):
     Michael Mann, University of Virginia, Charlottesville, Virginia;
     Caspar Ammann and Kevin Trenberth, National Center for Atmospheric Research, Boulder,
     Colorado;
     Raymond Bradley, University of Massachusetts, Amherst, Massachusetts;
     Keith Briffa, Philip Jones, and Tim Osborn, Climatic Research Unit, University of East
     Anglia, Norwich, United Kingdom;
     Tom Crowley, Nicholas School of the Environment and Earth Science, Duke University,
     Durham, North Carolina;
     Malcolm Hughes, Laboratory of Tree-Ring Research, University of Arizona, Tucson,
     Arizona;
     Michael Oppenheimer, Princeton University, Princeton, New Jersey;
     Jonathan Overpeck, Department of Geosciences and Institute for the Study of Planet
     Earth, University of Arizona, Tucson, Arizona;
     Scott Rutherford, University of Rhode Island, Narragansett, Rhode Island;
     Tom Wigley, University Corporation for Atmospheric Research and National Center for
     Atmospheric Research, Boulder, Colorado.
     Journalists may obtain a pdf copy of this article by request to Harvey Leifert
     (hleifert@agu.org). Please provide your name, name of publication, phone, and email
     address.
     AGU's position statement, Climate Change and Greenhouse Gases (1998), may be read at
     [1]http://www.agu.org/sci_soc/policy/climate_change_position.html. A peer reviewed
     article, discussing the scientific background to the position statement appeared in Eos,
     Volume 80, No 39, September 28, 1999, page 453, and may be read at
     [2]http://www.agu.org/eos_elec/99148e.html.
     Contact information for authors:
     [TO COME]
     ###
     --
     Harvey Leifert
     Public Information Manager
     American Geophysical Union
     2000 Florida Avenue, N.W.
     Washington, DC 20009, USA
     Phone: +1-202-777-7507
     Fax: +1-202-328-0566
     Email: hleifert@agu.org
     Web: [3]http://www.agu.org/sci_soc/media.html
     ###

