CLIMATE
INTERVENTION
Carbon Dioxide Removal and
Reliable Sequestration
Committee on Geoengineering Climate:
Technical Evaluation and Discussion of Impacts
Board on Atmospheric Sciences and Climate
Ocean Studies Board
Division on Earth and Life Studies
NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES
THE NATIONAL ACADEMIES PRESS
Washington, D.C.
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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.
This study was supported by the U.S. Department of Energy under Contract Number DE-SC0011701, the National Aeronautics and Space Administration under Contract Number NNX13A041G, the National Oceanic and Atmospheric Administration under Contract Number WC133R-11-CQ-0048, the National Academy of Sciences’ Arthur L. Day Fund, and the intelligence community. Any opinions, findings, and conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the sponsoring agencies or any of their subagencies.
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THE NATIONAL ACADEMIES
Advisers to the Nation on Science, Engineering, and Medicine
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. Ralph J. Cicerone 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. C. D. Mote, Jr., 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. Victor J. Dzau 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 Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. C. D. Mote, Jr., are chair and vice chair, respectively, of the National Research Council.
COMMITTEE ON GEOENGINEERING CLIMATE:
TECHNICAL EVALUATION AND DISCUSSION OF IMPACTS
MARCIA K. MCNUTT (Chair), Science, Washington, DC
WALEED ABDALATI, University of Colorado, Boulder
KEN CALDEIRA, Carnegie Institution for Science, Stanford, California
SCOTT C. DONEY, Woods Hole Oceanographic Institution, Massachusetts
PAUL G. FALKOWSKI, Rutgers, The State University of New Jersey, New Brunswick
STEVE FETTER, University of Maryland, College Park
JAMES R. FLEMING, Colby College, Waterville, Maine
STEVEN P. HAMBURG, Environmental Defense Fund, Boston, Massachusetts
M. GRANGER MORGAN, Carnegie Mellon University, Pittsburgh, Pennsylvania
JOYCE E. PENNER, University of Michigan, Ann Arbor
RAYMOND T. PIERREHUMBERT, University of Chicago, Illinois
PHILIP J. RASCH, Pacific Northwest National Laboratory, Richland, Washington
LYNN M. RUSSELL, Scripps Institution of Oceanography, La Jolla, California
JOHN T. SNOW, University of Oklahoma, Norman
DAVID W. TITLEY, Pennsylvania State University, University Park
JENNIFER WILCOX, Stanford University, California
NRC Staff
EDWARD DUNLEA, Senior Program Officer
CLAUDIA MENGELT, Senior Program Officer
KATHERINE THOMAS, Program Officer
AMANDA PURCELL, Research Associate
SHELLY FREELAND, Administrative and Financial Assistant
ROB GREENWAY, Program Associate
BOARD ON ATMOSPHERIC SCIENCES AND CLIMATE
A.R. RAVISHANKARA (Chair), Colorado State University, Fort Collins
GERALD A. MEEHL (Vice Chair), National Center for Atmospheric Research, Boulder, Colorado
LANCE F. BOSART, State University of New York, Albany
MARK A. CANE, Columbia University, Palisades, New York
SHUYI S. CHEN, University of Miami, Florida
HEIDI CULLEN, Climate Central, Princeton, New Jersey
PAMELA EMCH, Northrup Grumman Aerospace Systems, Redondo Beach, California
ARLENE FIORE, Columbia University, Palisades, New York
WILLIAM B. GAIL, Global Weather Corporation, Boulder, Colorado
LISA GODDARD, Columbia University, Palisades, New York
MAURA HAGAN, National Center for Atmospheric Research, Boulder, Colorado
TERRI S. HOGUE, Colorado School of Mines, Golden
ANTHONY JANETOS, Joint Global Change Research Institute, College Park, Maryland
EVERETTE JOSEPH, SUNY at Albany, New York
RONALD “NICK” KEENER, JR., Duke Energy Corporation, Charlotte, North Carolina
JOHN R. NORDGREN, The Kresge Foundation, Troy, Michigan
JONATHAN OVERPECK, University of Arizona, Tucson
STEPHEN W. PACALA, Princeton University, New Jersey
ARISTIDES A.N. PATRINOS, New York University, Brooklyn
S.T. RAO, North Carolina State University, Raleigh
DAVID A. ROBINSON, Rutgers, The State University of New Jersey, Piscataway
CLAUDIA TEBALDI, Climate Central, Princeton, New Jersey
Ocean Studies Board Liaison
DAVID HALPERN, Jet Propulsion Laboratory, Pasadena, California
Polar Research Board Liaison
JENNIFER FRANCIS, Rutgers, The State University of New Jersey, Marion, Massachusetts
NRC Staff
AMANDA STAUDT, Director
EDWARD DUNLEA, Senior Program Officer
LAURIE GELLER, Senior Program Officer
KATHERINE THOMAS, Program Officer
LAUREN EVERETT, Associate Program Officer
AMANDA PURCELL, Research and Financial Associate
RITA GASKINS, Administrative Coordinator
SHELLY FREELAND, Administrative and Financial Assistant
ROB GREENWAY, Program Associate
OCEAN STUDIES BOARD
ROBERT A. DUCE (Chair), Texas A&M University, College Station
E. VIRGINIA ARMBRUST, University of Washington, Seattle
KEVIN R. ARRIGO, Stanford University, California
CLAUDIA BENETIZ-NELSON, University of South Carolina, Columbia
EDWARD A. BOYLE, Massachusetts Institute of Technology, Cambridge
RITA R. COLWELL, University of Maryland, College Park
SARAH W. COOKSEY, State of Delaware, Dover
CORTIS K. COOPER, Chevron Corporation, San Ramon, California
ROBERT HALLBERG, NOAA/GFDL and Princeton University, New Jersey
DAVID HALPERN, Jet Propulsion Laboratory, Pasadena, California
SUSAN E. HUMPHRIS, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
BONNIE J. MCCAY, Rutgers University, New Brunswick, New Jersey
STEVEN A. MURAWSKI, University of South Florida, St. Petersburg
JOHN A. ORCUTT, Scripps Institution of Oceanography, La Jolla, California
H. TUBA ÖZKAN-HALLER, Oregon State University, Corvallis
STEVEN E. RAMBERG, Penn State Applied Research Lab, Washington, DC
MARTIN D. SMITH, Duke University, Durham, North Carolina
MARGARET SPRING, Monterey Bay Aquarium, Monterey, California
DON WALSH, International Maritime Incorporated, Myrtle Point, Oregon
DOUGLAS WARTZOK, Florida International University, Miami
LISA D. WHITE, University of California, Berkeley, and San Francisco State University
Ex-Officio
MARY (MISSY) H. FEELEY, ExxonMobil Exploration Company (retired), Houston, Texas
NRC Staff
SUSAN ROBERTS, Board Director
DEBORAH GLICKSON, Senior Program Officer
CLAUDIA MENGELT, Senior Program Officer
STACEE KARRAS, Research Associate
PAMELA LEWIS, Administrative Coordinator
SHUBHA BANSKOTA, Financial Associate
PAYTON KULINA, Senior Program Assistant
Preface
The signs of a warming planet are all around us: rising seas, melting ice sheets, record-setting temperatures, with impacts cascading to ecosystems, humans, and our economy. At the root of the problem, anthropogenic greenhouse gas emissions to the atmosphere continue to increase, a substantial fraction of which diffuse into the ocean, causing ocean acidification and threatening marine ecosystems. Global climate is changing faster than at any time since the rise of human civilization, challenging society to adapt to those changes. If the current dependence on fossil fuel use continues, evidence from previous periods of high atmospheric greenhouse gas concentrations indicates that our release of fossil fuel carbon into Earth’s atmosphere in the form of CO2 will be recorded in the rock record as a major planet-wide event, marked by transgressions of shorelines, extinctions of biota, and perturbations of major biogeochemical cycles.
The specific topic of this report, “climate geoengineering,” was often framed in terms of a last-ditch response option to climate change if climate change damage should produce extreme hardship. Such deliberate intervention in the climate system was often considered a taboo subject. Although the likelihood of eventually considering last-ditch efforts to address damage from climate change grows with every year of inaction on emissions control, there remains a lack of information on these ways of potentially intervening in the climate system. In 2012 the U.S. government, including several of the science agencies, asked the National Academy of Sciences to provide advice on this subject. The National Research Council (NRC) committee assembled in response to this request realized that carbon dioxide removal and albedo modification (i.e., modification of the fraction of short-wavelength solar radiation reflected from Earth back into space) have traditionally been lumped together under the term “geoengineering” but are sufficiently different that they deserved to be discussed in separate volumes.
Carbon dioxide removal strategies, discussed in the first volume, are generally of lower risk and of almost certain benefit given what is currently known of likely global emissions trajectories and the climate change future. Currently, cost and lack of technical maturity are factors limiting the deployment of carbon dioxide removal strategies for helping to reduce atmospheric CO2 levels. In the future, such strategies could, however, contribute as part of a portfolio of responses for mitigating climate warming and ocean acidification. In the meantime, natural air CO2 removal processes (sinks) con-
sume the equivalent of over half of our emissions, a feature that might be safely and cost-effectively enhanced or augmented as explored in the first volume.
In contrast, albedo modification approaches show some evidence of being effective at temporarily cooling the planet, but at a currently unknown environmental price. The committee is concerned that understanding of the ethical, political, and environmental consequences of an albedo modification action is relatively less advanced than the technical capacity to execute it. In fact, one serious concern is that such an action could be unilaterally undertaken by a nation or smaller entity for their own benefit without international sanction and regardless of international consequences. A research basis is currently lacking to understand more about the potential results and impacts of albedo modification to help inform such decisions. These approaches are discussed in the second volume.
The committee’s very different posture concerning the currently known risks of carbon dioxide removal as compared with albedo modification was a primary motivation for separating these climate engineering topics into two separate volumes.
Terminology is very important in discussing these topics. “Geoengineering” is associated with a broad range of activities beyond climate (e.g., geological engineering), and even “climate engineering” implies a greater level of precision and control than might be possible. The committee concluded that “climate intervention,” with its connotation of “an action intended to improve a situation,” most accurately describes the strategies covered in these two volumes. Further, the committee chose to avoid the commonly used term of “solar radiation management” in favor of the more physically descriptive term “albedo modification” to describe a subset of such techniques that seek to enhance the reflectivity of the planet to cool the global temperature. Other related methods that modify the emission of infrared energy to space to cool the planet are also discussed in the second volume.
Transparency in discussing this subject is critical. In that spirit of transparency, this study was based on peer-reviewed literature and the judgments of the committee members involved; no new research was done as part of this study and all data and information used in this study are from entirely open sources. Moving forward, the committee hopes that these two new reports will help foster an ethos in which all research in this area is conducted openly, responsibly, and with transparent goals and results.
It is the committee’s sincere hope that these topics will receive the attention and investment commensurate with their importance to addressing the coming potential climate crises. By helping to bring light to this topic area, carbon dioxide removal tech-
nologies could become one more viable strategy for addressing climate change, and leaders will be far more knowledgeable about the consequences of albedo modification approaches before they face a decision whether or not to use them.
In closing, I would like to thank my fellow committee members for all of their hard work to summarize the existing, fragmented science and to work toward consensus on extremely complex issues. As well, we greatly appreciate all of the time and effort volunteered by our colleagues who generously gave their time and talent to review these reports, speak at our committee meetings, and communicate with us during the study process. We would also like to thank the NRC staff for their superb efforts to assemble and make sense of the many moving parts of two separate reports.
Marcia McNutt, Chair
Committee on Geoengineering Climate:
Technical Evaluation and Discussion of Impacts
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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 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. The committee wishes to thank the following individuals for their review of this report:
DAVID VICTOR, University of California, San Diego
CLIVE HAMILTON, Centre for Applied Philosophy and Public Ethics, Canberra, Australia
GREG RAU, University of California, Santa Cruz
EDWARD PARSON, University of California, Los Angeles
TIM LENTON, University of Exeter, UK
AH-HYUNG (ALISSA) PARK, Columbia University, New York, New York
DANIEL SIGMAN, Princeton University, New Jersey
DAVID KEITH, Harvard University, Cambridge, Massachusetts
MICHAEL HANEMANN, University of California, Berkeley
PETER KELEMAN, Lamont-Doherty Earth Observatory, Palisades, New York
JAMES A. EDMONDS, Joint Global Change Research Institute, College Park, Maryland
Although the reviewers listed above have provided constructive comments and suggestions, they were not asked to endorse the views of the committee, nor did they see the final draft of the report before its release. The review of this report was overseen by Warren M. Washington, National Center for Atmospheric Research, Boulder, Colorado, and James W. C. White, University of Colorado, Boulder; appointed by the NRC, they were 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 panel and the institution.
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Contents
Carbon Dioxide Removal and Albedo Modification within a Portfolio of Climate Responses
Carbon Dioxide Removal Ready for Increased Research and Development
Albedo Modification Presents Poorly Understood Risks
The Need for More Research on Albedo Modification
Decarbonizing the Energy System
Carbon Dioxide Removal and Albedo Modification
3 Assessment of Possible Carbon Dioxide Removal and Long-Term Sequestration Systems
Afforestation and Reforestation
Carbon Sequestration on Agricultural Lands
Summary of Land Management Approaches
Accelerated Weathering Methods and Mineral Carbonation
Scaling and Environmental Issues
Bioenergy with Carbon Capture and Sequestration and Direct Air Capture and Sequestration
Bioenergy with Carbon Capture and Sequestration
Direct Air Capture and Sequestration
Geological Sequestration of Carbon Dioxide