Reconciling Observations of Global Temperature Change
Panel on Reconciling Temperature Observations
Climate Research Committee
Board on Atmospheric Sciences and Climate
Commission on Geosciences, Environment, and Resources
National Research Councilbreak
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NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.
Support for this project was provided by the National Oceanic and Atmospheric Administration under Contract No. 50-DKNA-7-90052 and by Alcoa. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the NOAA or any of its sub-agencies or of Alcoa.
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Cover: Surface and lower to mid-tropospheric temperature trends for the period 1979–1998. The surface data (left panel) are comprised of surface air temperature over land and the temperature of water at the ocean's surface, and have been subjected to a slight additional smoothing to simplify the pattern (Jones et al., 1999). The lower to mid-tropospheric data (right panel) are derived from satellite observations from the Microwave Sounding Unit Channel 2 (the so-called "MSU 2LT") (Christy et al., 2000). For both datasets, the trends are computed using the method of ordinary least squares. The color key is the same as in Figure 6.2. The map views on the front cover are centered at 30° N and 110° W and the views on the back cover are centered at 30° S and 70° E. For the globe as a whole (see Figures 6.2 and 7.1 inside), warming has been prevalent at the earth's surface, but much less so in the lower to mid-troposphere.
Copyright 2000 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America
First Printing, January 2000
Second Printing, February 2000break
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THE NATIONAL ACADEMIES
National Academy of Sciences
National Academy of Engineering
Institute of Medicine
National Research Council
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences.
The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. William A. Wulf is president of the National Academy of Engineering.
The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine.
The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academics and the Institute of Medicine. Dr. Bruce M. Alberts and Dr. William A. Wulf are chairman and vice chairman, respectively, of the National Research Council.break
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PANEL ON RECONCILING TEMPERATURE OBSERVATIONS
Members
JOHN M. WALLACE (Chair), University of Washington, Seattle
JOHN R. CHRISTY, University of Alabama in Huntsville
DIAN J. GAFFEN, NOAA/Air Resources Laboratory, Silver Spring, Maryland
NORMAN C. GRODY, NOAA/NESDIS, Camp Springs, Maryland
JAMES E. HANSEN, NASA Goddard Institute for Space Studies, New York, New York
DAVID E. PARKER, Hadley Centre, Meteorological Office, Bracknell, United Kingdom
THOMAS C. PETERSON, NOAA/National Climatic Data Center, Asheville, North Carolina
BENJAMIN D. SANTER, Lawrence Livermore National Laboratory, Livermore, California
ROY W. SPENCER, NASA Marshall Space Flight Center, Huntsville, Alabama
KEVIN E. TRENBERTH, National Center for Atmospheric Research, Boulder, Colorado
FRANK J. WENTZ, Remote Sensing Systems, Santa Rosa, California
Consultant
TODD MITCHELL, University of Washington, Seattle
NRC Staff
PETER A. SCHULTZ, Study Director
DIANE L. GUSTAFSON, Administrative Assistantbreak
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CLIMATE RESEARCH COMMITTEE
Members
EUGENE M. RASMUSSON (Chair), University of Maryland, College Park
EDWARD S. SARACHIK (Vice-Chair), University of Washington, Seattle
MAURICE BLACKMON, National Center for Atmospheric Research, Boulder, Colorado
JEFF DOZIER, University of California, Santa Barbara
JAMES GIRAYTYS, Consultant, Winchester, Virginia
JAMES E. HANSEN, NASA Goddard Institute for Space Studies, New York, New York
PHILIP E. MERILEES, Naval Research Laboratory, Monterey, California
ROBERTA BALSTAD MILLER, CIESIN, Columbia University, Palisades, New York
S. ICHTIAQUE RASOOL, International Consultant, Paris, France
STEVEN W. RUNNING, University of Montana, Missoula
ANNE M. THOMPSON, NASA Goddard Space Flight Center, Greenbelt, Maryland
ANDREW WEAVER, University of Victoria, British Columbia
ERIC F. WOOD, Princeton University, New Jersey
Ex Officio Members
W. LAWRENCE GATES, Lawrence Livermore National Laboratory, Livermore, California
DOUGLAS G. MARTINSON, Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York
JOHN O. ROADS, Scripps Institution of Oceanography, La Jolla, California
NRC Staff
PETER A. SCHULTZ, Program Director
CARTER W. FORD, Project Assistantbreak
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BOARD ON ATMOSPHERIC SCIENCES AND CLIMATE
Members
ERIC J. BARRON (Co-Chair), Pennsylvania State University, University Park
JAMES R. MAHONEY (Co-Chair), Consultant, McLean, Virginia
SUSAN K. AVERY, Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder
LANCE F. BOSART, State University of New York, Albany
MARVIN A. GELLER, State University of New York, Stony Brook
CHARLES E. KOLB, Aerodyne Research, Inc., Billerica, Massachusetts
ROGER A. PIELKE, JR., National Center for Atmospheric Research, Boulder, Colorado
ROBERT T. RYAN, WRC-TV, Washington, D.C.
MARK R. SCHOEBERL, NASA Goddard Space Flight Center, Greenbelt, Maryland
JOANNE SIMPSON, NASA Goddard Space Flight Center, Greenbelt, Maryland
NIEN DAK SZE, Atmospheric and Environmental Research, Inc., Cambridge, Massachusetts
ROBERT A. WELLER, Woods Hole Oceanographic Institution, Massachusetts
ERIC F. WOOD, Princeton University, New Jersey
Ex Officio Members
DONALD S. BURKE, Johns Hopkins University, Baltimore, Maryland
DARA ENTEKHABI, Massachusetts Institute of Technology, Cambridge
MICHAEL C. KELLEY, Cornell University, Ithaca, New York
JOHN O. ROADS, Scripps Institution of Oceanography, La Jolla, California
EUGENE M. RASMUSSON, University of Maryland, College Park
PAUL WINE, Georgia Institute of Technology, Atlanta
NRC Staff
ELBERT W. (JOE) FRIDAY, JR., Director
LAURIE S. GELLER, Program Officerbreak
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PETER A. SCHULTZ, Program Officer
DIANE L. GUSTAFSON, Administrative Assistant
ROBIN MORRIS, Financial Associate
TENECIA A. BROWN, Senior Program Assistant
CARTER W. FORD, Project Assistantbreak
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COMMISSION ON GEOSCIENCES, ENVIRONMENT, AND RESOURCES
Members
GEORGE M. HORNBERGER (Chair), University of Virginia, Charlottesville
RICHARD A. CONWAY, Union Carbide Corporation (Retired), S. Charleston, West Virginia
THOMAS E. GRAEDEL, Yale University, New Haven, Connecticut
THOMAS J. GRAFF, Environmental Defense Fund, Oakland, California
EUGENIA KALNAY, University, of Maryland, College Park
DEBRA KNOPMAN, Progressive Policy Institute, Washington, D.C.
KAI N. LEE, Williams College, Williamstown, Massachusetts
BRAD MOONEY, J. Brad Mooney Associates, Ltd., Arlington, Virginia
HUGH C. MORRIS, El Dorado Gold Corporation, Vancouver, British Columbia
H. RONALD PULLIAM, University of Georgia, Athens
MILTON RUSSELL, Joint Institute for Energy and Environment and University of Tennessee (Emeritus), Knoxville
THOMAS C. SCHELLING, University of Maryland, College Park
ANDREW R. SOLOW, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
VICTORIA J. TSCHINKEL, Landers and Parsons, Tallahassee, Florida
E-AN ZEN, University of Maryland, College Park
MARY LOU ZOBACK, U.S. Geological Survey, Menlo Park, California
NRC Staff
ROBERT M. HAMILTON, Executive Director
GREGORY H. SYMMES, Associate Executive Director
JEANETTE SPOON, Administrative and Financial Officer
DAVID FEARY, Scientific Reports Officer
SANDI FITZPATRICK, Administrative Associate
MARQUITA SMITH, Administrative Assistant/Technology Analystbreak
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ACKNOWLEDGMENTS
This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the NRC's Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making the published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The review comments and draft manuscript remain confidential to protect the integrity of the deliberative process. We thank the following individuals for their participation in the review of this report:
JAMES ANGELL, NOAA/Air Resources Laboratory
ALAN BASIST, NOAA/National Climatic Data Center
LENNART BENGTSSON, Max Planck Institute for Meteorology
SIMON BROWN, Hadley Centre, Meteorological Office, United Kingdom
JAMES HOLTON, University of Washington
JAMES HURRELL, National Center for Atmospheric Research
EUGENIA KALNAY, University of Maryland
RICHARD LINDZEN, Massachusetts Institute of Technology
NEVILLE NICHOLLS, Australian Bureau of Meteorology Research Centre
EUGENE M. RASMUSSON, University of Marylandbreak
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While the individuals listed above have provided constructive comments and suggestions, it must be emphasized that responsibility for the final content of this report rests entirely with the authoring committee and the institution.
The panel wishes to thank Todd Mitchell at the University of Washington for his contributions and insight in the presentation of the report's complex data, Jay Lawrimore at the National Climatic Data Center for supplying figures and data, and David Feary at the National Research Council for his editorial guidance.break
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PREFACE
A National Research Council panel was convened to examine observed trends of temperature near the surface and in the lower to midtroposphere (the atmospheric layer extending from the earth's surface up to about 8 km). The objectives of this panel were to:
(1) summarize the state of the science in the measurement of temperature from space, from radiosondes, and from surface instrumentation;
(2) assess the biases and uncertainties in the data;
(3) describe the major conflicts in the trends; and
(4) define the actions required to reduce the uncertainties and biases.
The panel, which is under the purview of the Board on Atmospheric Sciences and Climate's (BASC) Climate Research Committee (CRC), included individuals with expertise on all relevant technical facets of the issue.
The panel's report, presented here, is structured in a layered fashion, providing the reader with an increasing level of technical detail. The Executive Summary gives a very brief overview of the report's findings and recommendations and is targeted towards non-scientists. Part I of the main body of the report is intended for the public, policy-making, and scientific communities and is also written in a relatively non-technicalcontinue
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fashion. Part I includes a chapter outlining the key questions (Introduction) and another that provides an overview of the relevant measurement types and their observations (Background). Part I concludes with chapters on the panel's Findings and Recommendations. Part II more fully articulates the scientific basis for the discussion and conclusions that are presented in Part I, by detailing the major, relevant measurement systems and their temperature records. It does so in chapters on Surface Temperature Observations, MSU Observations, and Radiosonde Observations. Part II concludes with a chapter that compares the temperature records of the three types of observations and presents possible reasons for the observed temperature trend differences.break
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CONTENTS
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