The Effects of Solar Variability
on Earth’s Climate
A Workshop Report
Committee on the Effects of Solar Variability on Earth’s Climate
Space Studies Board
Division on Engineering and Physical Sciences
NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES
THE NATIONAL ACADEMIES PRESS
THE NATIONAL ACADEMIES PRESS 500 Fifth Street, NW Washington, DC 20001
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.
This study is based on work supported by Contract NNH06CE15B between the National Academy of Sciences and the National Aeronautics and Space Administration and Grant No. AGS-1106426 between the National Academy of Sciences and the National Science Foundation. Any views or observations expressed in this publication are those of the authors and do not necessarily reflect the views of the agencies that provided support for the project.
International Standard Book Number-13: 978-0-309-26564-5
International Standard Book Number-10: 0-309-26564-9
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Limited copies of these reports are available free of charge from:
Space Studies Board
National Research Council
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COMMITTEE ON THE EFFECTS OF SOLAR VARIABILITY ON EARTH’S CLIMATE
GERALD R. NORTH, Texas A&M University, Chair
DANIEL N. BAKER, University of Colorado, Boulder
RAYMOND S. BRADLEY, University of Massachusetts
PETER FOUKAL, Heliophysics, Inc.
JOANNA D. HAIGH, Imperial College, London
ISAAC M. HELD, National Oceanic and Atmospheric Administration Geophysical Fluid Dynamics Laboratory
GERALD A. MEEHL, National Center for Atmospheric Research
LARRY J. PAXTON, Johns Hopkins University
PETER PILEWSKIE, University of Colorado, Boulder
CAROLUS J. SCHRIJVER, Lockheed Martin Advanced Technology Center
KA-KIT TUNG, University of Washington
ABIGAIL A. SHEFFER, Associate Program Officer, Study Director
ARTHUR A. CHARO, Senior Program Officer
CATHERINE A. GRUBER, Editor
AMANDA R. THIBAULT, Research Associate
TERRI M. BAKER, Senior Program Assistant (through April 6, 2012)
DIONNA WILLIAMS, Program Associate
DANIELLE PISKORZ, Lloyd V. Berkner Space Policy Intern
MICHAEL BARTON, Lloyd V. Berkner Space Policy Intern
MICHAEL H. MOLONEY, Director, Space Studies Board
SPACE STUDIES BOARD
CHARLES F. KENNEL, Scripps Institution of Oceanography, University of California, San Diego, Chair
JOHN KLINEBERG, Space Systems/Loral (retired), Vice Chair
MARK R. ABBOTT, Oregon State University
JAMES ANDERSON, Harvard University
JAMES BAGIAN, University of Michigan
YVONNE C. BRILL, Aerospace Consultant
ELIZABETH R. CANTWELL, Lawrence Livermore National Laboratory
ANDREW B. CHRISTENSEN, Dixie State College of Utah
ALAN DRESSLER, The Observatories of the Carnegie Institution
THOMAS R. GAVIN, California Institute of Technology
HEIDI B. HAMMEL, AURA
FIONA A. HARRISON, California Institute of Technology
JOSEPH S. HEZIR, EOP Group, Inc.
ANTHONY C. JANETOS, University of Maryland
JOAN JOHNSON-FREESE, U.S. Naval War College
ROBERT P. LIN, University of California, Berkeley
MOLLY K. MACAULEY, Resources for the Future, Inc.
JOHN F. MUSTARD, Brown University
ROBERT T. PAPPALARDO, Jet Propulsion Laboratory, California Institute of Technology
MARCIA J. RIEKE, University of Arizona
DAVID N. SPERGEL, Princeton University
MEENAKSHI WADHWA, Arizona State University
CLIFFORD M. WILL, Washington University
THOMAS H. ZURBUCHEN, University of Michigan
MICHAEL H. MOLONEY, Director
CARMELA J. CHAMBERLAIN, Administrative Coordinator
TANJA PILZAK, Manager, Program Operations
CELESTE A. NAYLOR, Information Management Associate
CHRISTINA O. SHIPMAN, Financial Officer
SANDRA WILSON, Financial Assistant
Experts on solar physics, solar variability, climate science, climate models, paleoclimatology, atmospheric science, and experts on other stars came together on September 8-9, 2011, at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, to discuss how the Sun’s variability over time has affected Earth’s climate. The National Research Council was asked by program managers at the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA) to organize an interdisciplinary public workshop to examine the state of knowledge of Earth’s climate response to solar variability and to explore some of the outstanding science questions that might guide future research endeavors. As noted above, this particular topic touches upon a number of diverse research areas; a workshop such as this brings together scientists that do not always have an opportunity to interact as a group.
A Committee on the Effects of Solar Variability on Earth’s Climate was formed and met on April 25, 2011, at the National Academies Keck Center in Washington, D.C., to develop an agenda for the workshop. Speakers were invited to submit abstracts, and these talks were organized into sessions by the committee. The workshop was advertised to the public through various media. During the workshop, the audience was encouraged to interact with the speakers and discuss the issues from different viewpoints. A final panel discussion was lead by chairs of the sessions, and the entire group was encouraged to share their thoughts on open research questions in these fields.
A complete statement of task and workplan for the project can be found in Appendix A. The workshop featured presentations on a variety of topics related to solar variability and climate change, organized as follows:
The Sun and Solar Variability: Past and Present
- —Overview of solar and heliospheric variability
- —Observations of the Sun’s variable outputs
- —Techniques for revealing past solar changes
Sun-Climate Connections on Different Timescales
- —Evidence of solar influences in the troposphere and stratosphere
- —How the climate system works and how it might respond to solar influences
- —Indications of influence based on paleoclimate records
Mechanisms for Sun-Climate Connections
- —Mechanisms connecting variations in total solar irradiance directly to the troposphere
- —Mechanisms that influence upper parts of the atmosphere, such as variations in solar ultraviolet radiation and possibly solar energetic particles
- —Mechanisms that link variations in galactic cosmic rays to climate change.
This workshop report contains no recommendations, findings, or statements of consensus. Instead, this workshop report summarizes the views expressed by individual workshop participants (invited speakers and guests). Also included is background information intended to provide context to the reader on both the solar and climate science topics presented at the workshop; however, this is not intended to be an exhaustive review of the current state of the science. Although the committee is responsible for the overall quality and accuracy of the report as a record of what transpired at the
workshop, the views contained in the report are not necessarily those of all workshop participants, the committee, or the National Research Council.
The committee thanks the NCAR Mesa Laboratory, in particular, Gerald Meehl, Stephanie Shearer, and Eron Brennan, for providing meeting space and excellent technical support.
Acknowledgment of Reviewers
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 National Research Council’s (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 its 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 wish to thank the following individuals for their review of this report:
Lennard Fisk, University of Michigan,
Philip Judge, National Center for Atmospheric Research,
Fabrizio Sassi, Naval Research Laboratory, and
Nathan Schwadron, University of New Hampshire.
Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse any of the viewpoints or observations detailed in this report, nor did they see the final draft of the report before its release. The review of this report was overseen by Joyce Penner, University of Michigan. Appointed by the NRC, she was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the institution.
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