cc: Keith Briffa , Tim Osborn , Raymond Bradley , Philip D Jones , mann@virginia.edu date: Sun, 06 Jul 2003 02:33:54 -0400 from: "Michael E. Mann" subject: Re: 03-19 Mann - climate change press release - first draft to: Harvey Leifert Hi Harvey, Here is Phil's information: Sapporo Prince Hotel (room #610), phone: (011) 511-3131 Phil and I have discussed various options for making ourselves available to the press on the 8th. The IUGG press office probably won't be of much use here, given time zone differences. Given the 13 hour time difference, the most sensible approach is that Phil and I will make sure to be available to receive phone calls in our respective hotel rooms Tuesday the 8th evening Sapporo time (i.e,. Tuesday the 8th morning U.S. east coast time). Phil can be available 9-11 PM Sapporo Time which corresponds to 8-10 AM U.S. morning of the 8th east coast time). while I can try to be available until a bit later (say, 9-12 PM Sapporo time, which is approximately 8-11 AM U.S. east coast). Unfortunately, because of the time zone change, it would be difficult for us to be available any later than that on morning/afternoon of the 8th east coast time, but if the press can be informed of the above early morning windows during which we can be reached in Japan, hopefully they can reach us for comment then. Otherwise, Ray, Tim, and Keith can all field inquiries and, of course, both Phil and I can respond to email inquiries more flexibily. Let us know if this sounds workable. Re, the press release itself, Phil and I have the following five minor comments. Otherwise, we're very happy with it: 1) first paragraph, 2nd sentence, typo "In do doing" should be "In so doing"... 2) 3rd paragraph, 2nd sentence, change "They challenge" to "These authors challenged" to clarify that it is Soon, Baliunas that are being referred to here, not us! 3) 4th paragraph, 1st sentence, change "Mann and his colleagues" to "Paleoclimatologists generally" to clarify that this is the mainstream approach, more general than just Mann and colleagues... 4) 6th paragraph, 2nd sentence: see comment from my previous email about wording (use of term 'hydrological") 5) 9th paragraph, 2nd sentence: parenthetical statement "scientists who study ancient climates" should be moved to first usage of the term 'paleoclimatologists' above (see comment #3). At 11:04 AM 7/3/2003 -0400, you wrote: 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 ### ______________________________________________________________ Professor Michael E. Mann Department of Environmental Sciences, Clark Hall University of Virginia Charlottesville, VA 22903 _______________________________________________________________________ e-mail: mann@virginia.edu Phone: (434) 924-7770 FAX: (434) 982-2137 [4]http://www.evsc.virginia.edu/faculty/people/mann.shtml