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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

Reflecting Sunlight

Recommendations for Solar Geoengineering
Research and Research Governance

Committee on Developing a Research Agenda and Research Governance
Approaches for Climate Intervention Strategies that Reflect Sunlight tos
Cool Earth

Board on Atmospheric Sciences and Climate

Division on Earth and Life Studies

Committee on Science, Technology, and Law

Policy and Global Affairs

A Consensus Study Report of

images

THE NATIONAL ACADEMIES PRESS
Washington, DC
www.nap.edu

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

THE NATIONAL ACADEMIES PRESS•500 Fifth Street, NW•Washington, DC 20001

This activity was supported by contracts between the National Academy of Sciences and the BAND Foundation, the Christopher Reynolds Foundation, the Department of Energy, the MacArthur Foundation, the National Academy of Sciences’ Arthur L. Day Fund, the National Aeronautics and Space Administration, the National Oceanic and Atmospheric Administration, and the V. Kann Rasmussen Foundation. Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of any organization or agency that provided support for the project.

International Standard Book Number-13: 978-0-309-67605-2
International Standard Book Number-10: 0-309-67605-3
Digital Object Identifier: https://doi.org/10.17226/25762

Cover Photo: Lake Fairfax, Reston, Virgina by Quinn S. Jackson.

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Suggested citation: National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight:Recommendations for Solar Geoengineering ResearchandResearchGovernance. Washington, DC: The National Academies Press. https://doi.org/10.17226/25762.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

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The National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, nongovernmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president.

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The National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president.

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Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

Image

Consensus Study Reports published by the National Academies of Sciences, Engineering, and Medicine document the evidence-based consensus on the study’s statement of task by an authoring committee of experts. Reports typically include findings, conclusions, and recommendations based on information gathered by the committee and the committee’s deliberations. Each report has been subjected to a rigorous and independent peer-review process and it represents the position of the National Academies on the statement of task.

Proceedings published by the National Academies of Sciences, Engineering, and Medicine chronicle the presentations and discussions at a workshop, symposium, or other event convened by the National Academies. The statements and opinions contained in proceedings are those of the participants and are not endorsed by other participants, the planning committee, or the National Academies.

For information about other products and activities of the National Academies, please visit www.nationalacademies.org/about/whatwedo.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

COMMITTEE ON DEVELOPING A RESEARCH AGENDA AND RESEARCH GOVERNANCE APPROACHES FOR CLIMATE INTERVENTION STRATEGIES THAT REFLECT SUNLIGHT TO COOL EARTH

CHRISTOPHER FIELD (NAS) (Chair), Stanford University

WILLIAM W.L. CHEUNG, The University of British Columbia

LISA DILLING, University of Colorado, Boulder

PETER C. FRUMHOFF, Union of Concerned Scientists

HENRY (HANK) T. GREELY, Stanford Law School

MARION E. HOURDEQUIN, Colorado College

JAMES HURRELL, Colorado State University

ANDREW LIGHT, George Mason University and World Resources Institute (until January 2021)

ALBERT LIN, University of California, Davis School of Law

DOUGLAS MacMARTIN, Cornell University

ROBERT McHENRY, Bright Silicon Technologies

JUAN MORENO-CRUZ, University of Waterloo

KATHARINE RICKE, University of California, San Diego

LYNN RUSSELL, Scripps Institution of Oceanography

AMBUJ SAGAR, Indian Institute of Technology, Delhi

PAUL WENNBERG (NAS), California Institute of Technology

National Academies of Sciences, Engineering, and Medicine Staff

LAURIE GELLER, Senior Program Officer, Board on Atmospheric Sciences and Climate

STEVEN KENDALL, Program Officer, Committee on Science, Technology, and Law

KATIE THOMAS, Senior Program Officer, Board on Atmospheric Sciences and Climate (until February 2020)

ANITA EISENSTADT, Program Officer, Board on Science, Technology, and Economic Policy (until February 2020)

AMANDA STAUDT, Senior Director, Board on Atmospheric Sciences and Climate

ANNE-MARIE MAZZA, Senior Director, Committee on Science, Technology, and Law

RACHEL SILVERN, Associate Program Officer, Board on Atmospheric Sciences and Climate

ERIN MARKOVICH, Research Associate, Board on Atmospheric Sciences and Climate (until February 2021)

ROB GREENWAY, Program Associate, Board on Atmospheric Sciences and Climate

MICHAEL HUDSON, Senior Program Assistant/Research Assistant, Board on Atmospheric Sciences and Climate (until April 2020)

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

BOARD ON ATMOSPHERIC SCIENCES AND CLIMATE

A.R. RAVISHANKARA (NAS) (Chair), Colorado State University

MARY GLACKIN (Vice Chair), The Weather Company, an IBM Business (Ret.)

CYNTHIA S. ATHERTON, Heising-Simons Foundation

CECILIA BITZ, University of Washington

JOHN C. CHIANG, University of California, Berkeley

BRADLEY R. COLMAN, The Climate Corporation

BARTHOLOMEW E. CROES, California Air Resources Board

ROBERT B. DUNBAR, Stanford University

EFI FOUFOULA-GEORGIOU (NAE), University of California, Irvine

PETER C. FRUMHOFF, Union of Concerned Scientists

VANDA GRUBISIC, National Center for Atmospheric Research

EVERETTE JOSEPH, National Center for Atmospheric Research

ROBERT KOPP, Rutgers, The State University of New Jersey

RUBY LEUNG (NAE), Pacific Northwest National Laboratory

JONATHAN MARTIN, University of Wisconsin-Madison

ALLISON STEINER, University of Michigan

DAVID W. TITLEY, U.S. Navy (Ret.), Pennsylvania State University

National Academies of Sciences, Engineering, and Medicine Staff

AMANDA STAUDT, Senior Director

LAUREN EVERETT, Senior Program Officer

SHELLY FREELAND, Financial Business Partner

RITA GASKINS, Administrative Coordinator

LAURIE GELLER, Senior Program Officer

ROB GREENWAY, Program Associate

ERIN MARKOVICH, Research Associate

APRIL MELVIN, Senior Program Officer

AMANDA PURCELL, Senior Program Officer

ALEX REICH, Associate Program Officer

RACHEL SILVERN, Associate Program Officer

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

COMMITTEE ON SCIENCE, TECHNOLOGY, AND LAW

DAVID BALTIMORE (NAS/NAM) (Co-Chair), California Institute of Technology

DAVID S. TATEL (Co-Chair), U.S. Court of Appeals for the District of Columbia Circuit

JOE S. CECIL, University of California, Berkeley School of Law

ERWIN CHEMERINSKY, University of California, Berkeley School of Law

ELLEN WRIGHT CLAYTON (NAM), Vanderbilt University Medical Center

JOHN S. COOKE, Federal Judicial Center

JOHN DABIRI, California Institute of Technology

JENNIFER EBERHARDT (NAS), Stanford University

FEI-FEI LI (NAE/NAM), Stanford University

JUDITH MILLER, Independent Consultant

MARTHA MINOW, Harvard Law School

KIMANI PAUL-EMILE, Fordham University School of Law

NATALIE RAM, University of Maryland Francis King Carey School of Law

LISA RANDALL (NAS), Harvard University

PAUL M. ROMER, New York University

WILLIAM B. SCHULTZ, Zuckerman Spaeder LLP

JOSHUA SHARFSTEIN (NAM), Johns Hopkins Bloomberg School of Public Health

SUSAN S. SILBEY, Massachusetts Institute of Technology

SRI SRINIVASAN, U.S. Court of Appeals for the District of Columbia Circuit

GREGORY STONE, Munger, Tolles & Olson LLP

SUSAN R. WESSLER (NAS), University of California, Riverside

National Academies of Sciences, Engineering, and Medicine Staff

ANNE-MARIE MAZZA, Senior Director

STEVEN KENDALL, Program Officer

DOMINIC LOBUGLIO, Senior Program Assistant

Page viii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

Acknowledgments

This Consensus Study Report was reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise. The purpose of this independent review is to provide candid and critical comments that will assist the National Academies of Sciences, Engineering, and Medicine in making each published report as sound as possible and to ensure that it meets the institutional standards for quality, 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 review of this report:

WALEED ABDALATI, University of Colorado Boulder

DONALD C. BINGAMAN, VPE Aerospace Consulting, LLC

DANIEL M. BODANSKY, Arizona State University

TRACY HESTER, University of Houston

SIKINA JINNAH, University of California, Santa Cruz

FRANK N. KEUTSCH, Harvard University

DUNCAN MCLAREN, University of Lancaster

HELENE MURI, Norwegian University of Science and Technology

SIMON NICHOLSON, American University

NICK PIDGEON, Cardiff University

ALAN ROBOCK, Rutgers University

SIMONE TILMES, National Center for Atmospheric Research

DAVID G. VICTOR, University of California, San Diego

KYLE WHYTE, University of Michigan

ROBERT WOOD, University of Washington

Although the reviewers listed above provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations of this report nor did they see the final draft before its release. The review of this report was overseen by Antonio J. Busalacchi (NAE), University Corporation for Atmospheric Research, and Andrew R. Solow, Woods Hole Oceanographic Institution. They were responsible for making certain that an independent examination of this report was carried out in accordance with the standards of the National Academies and that all

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

review comments were carefully considered. Responsibility for the final content rests entirely with the authoring committee and the National Academies.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

Preface

In 2015, the National Research Council published a two-volume report that provided a technical evaluation and discussion of the impacts of geoengineering climate. One volume addressed technologies for removing carbon dioxide from the atmosphere. The other explored prospects for cooling the planet by albedo modification—increasing the reflection of solar radiation. A central conclusion from the 2015 study is that the two families of approaches for geoengineering climate differ greatly in terms of scientific understanding, technical feasibility, risks, and societal implications. In particular, understanding of prospects for and issues with albedo modification is nascent. This led that committee to recommend that “albedo modification at scales sufficient to alter climate should not be deployed at this time “ (NRC, 2015, p. 9). Noting that the urgency of the climate crisis underscores the importance of understanding the full range of options, however, the committee also recommended a program of further research on albedo modification and the development of a framework for governing that research.

Since 2015, the motivation for understanding the full range of options for dealing with the climate crisis has gotten even stronger. Globally, 2015–2019 were the 5 warmest years in the instrumental record. Understanding of the link between warming and extreme heat, wildfires, drought, hurricanes, and diverse socioeconomic impacts is stronger than ever. As I write this in September 2020, my home in California’s Bay Area is experiencing record-breaking temperatures and has been blanketed with wildfire smoke for more than 3 weeks. But despite overwhelming evidence that the climate crisis is real and pressing, emissions of greenhouse gases continue to increase, with global emissions of fossil carbon dioxide rising 10.8 percent from 2010 through 2019. The total for 2020 is on track to decrease in response to decreased economic activity related to the COVID-19 pandemic. The pandemic is thus providing frustrating confirmation of the fact that the world has made little progress in separating economic activity from carbon dioxide emissions.

The creation of this study committee is one response to the need for understanding the full range of options for dealing with the climate crisis. Its mandate flows directly from the recommendations of the 2015 report but with an urgency reinforced by the world’s slow progress on climate. The undertaking of this report should not, however, be interpreted as an indication of giving up on decarbonization. Rapidly reducing emissions of carbon dioxide and other greenhouse gases remains a top priority, as

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
×

explicitly recommended in the 2015 report. Throughout the committee’s discussions, the focus was always on evaluating whether and how, in the context of a global emphasis on emissions reductions and carbon dioxide removal, other approaches might be explored.

The committee that carried out this study was remarkably diverse. With expertise ranging from atmospheric chemistry to philosophy and experiences ranging from space-based and airborne measurement campaigns to global climate negotiations, all of us needed to make real investments in stepping outside our communities and learning the language and perspectives of colleagues from very different backgrounds. Committee members arrived with a wide array of thoughts not only about the topic but also about the best path forward for building knowledge. Often, there was as much discussion about who needs to be in the conversation as there was about the design and oversight of a research program. I greatly admire the willingness of every member of the committee to explain and defend but also challenge their own perspectives.

Chris Field, Chair

Page xiii Cite
Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Dedication

This report is dedicated to Paul J. Crutzen (1933-2021) and Steve Rayner (1953–2020).

Paul Crutzen and Steve Rayner were pioneering researchers, widely recognized for diverse contributions. Both made foundational contributions to solar geoengineering scholarship.

Paul Crutzen was, more than anything, a student of human impacts on Earth. He was a meteorologist best known for his research on stratospheric ozone depletion, work that earned him the 1995 Nobel Prize in Chemistry. Crutzen’s coining of the term “Anthropocene” underscores the focus of his scholarship on impacts. His 2006 essay on solar geoengineering set the stage for future discussions in stark, memorable terms, laying out the risks from climate disruption, the challenges of decarbonization, and the pros and cons of solar geoengineering.

Steve Rayner, who called himself an “undisciplined” scholar, made major contributions to the understanding of how science and technology shape the relationship between societies and nature. Much of his focus was on the social science of addressing climate change. Deeply interested in the role of science in governance and the governance of science, Rayner was a strong proponent of ambitious action on climate but a harsh critic of the Kyoto Protocol. He established much of the framework for thinking about governance of solar geoengineering, especially through his role as lead author of the Oxford Principles for Geoengineering Governance.

Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Suggested Citation:"Front Matter." National Academies of Sciences, Engineering, and Medicine. 2021. Reflecting Sunlight: Recommendations for Solar Geoengineering Research and Research Governance. Washington, DC: The National Academies Press. doi: 10.17226/25762.
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Climate change is creating impacts that are widespread and severe for individuals, communities, economies, and ecosystems around the world. While efforts to reduce emissions and adapt to climate impacts are the first line of defense, researchers are exploring other options to reduce warming. Solar geoengineering strategies are designed to cool Earth either by adding small reflective particles to the upper atmosphere, by increasing reflective cloud cover in the lower atmosphere, or by thinning high-altitude clouds that can absorb heat. While such strategies have the potential to reduce global temperatures, they could also introduce an array of unknown or negative consequences.

This report concludes that a strategic investment in research is needed to enhance policymakers' understanding of climate response options. The United States should develop a transdisciplinary research program, in collaboration with other nations, to advance understanding of solar geoengineering's technical feasibility and effectiveness, possible impacts on society and the environment, and social dimensions such as public perceptions, political and economic dynamics, and ethical and equity considerations. The program should operate under robust research governance that includes such elements as a research code of conduct, a public registry for research, permitting systems for outdoor experiments, guidance on intellectual property, and inclusive public and stakeholder engagement processes.

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