Sea-Level Rise for the Coasts of
California, Oregon, and Washington:


Past, Present, and Future



Committee on Sea Level Rise in California, Oregon, and Washington

Board on Earth Sciences and Resources and Ocean Studies Board

Division on Earth and Life Studies

NATIONAL RESEARCH COUNCIL
OF THE NATIONAL ACADEMIES



THE NATIONAL ACADEMIES PRESS
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Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future Committee on Sea Level Rise in California, Oregon, and Washington Board on Earth Sciences and Resources and Ocean Studies Board Division on Earth and Life Studies

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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 was supported by the California Department of Water Resources, Contract No. 4600008602; the National Oceanic and Atmospheric Administration, Contract No. DG133R08CQ0062; the U.S. Army Corps of Engineers, Contract No. W912HQ-09-P-0155; and the United States Geological Survey, Grant/ Cooperative Agreement No. G09AP00152. Any opinions, findings, or conclusions expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project. International Standard Book Number-13: 978-0-309-25594-3 International Standard Book Number-10: 0-309-25594-5 Additional copies of this report are available from the National Academies Press, 500 Fifth Street, NW, Keck 360, Washington, DC 20001; (800) 624-6242 or (202) 334-3313 (in the Washington metropolitan area); http://www.nap.edu. Cover: Lighthouse Point, Santa Cruz, California. SOURCE: Courtesy of Shmuel Thaler, Santa Cruz Sentinel. Copyright 2012 by the National Academy of Sciences. All rights reserved. Printed in the United States of America.

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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. Charles M. Vest 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. Harvey V. Fineberg 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 advis- ing 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. Charles M. Vest are chair and vice chair, respectively, of the National Research Council. www.national-academies.org

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COMMITTEE ON SEA LEVEL RISE IN CALIFORNIA, OREGON, AND WASHINGTON ROBERT A. DALRYMPLE, Chair, Johns Hopkins University, Baltimore, Maryland LAURENCE C. BREAKER, Moss Landing Marine Laboratories, California BENJAMIN A. BROOKS, University of Hawaii, Manoa DANIEL R. CAYAN, Scripps Institution of Oceanography, San Diego, California GARY B. GRIGGS, University of California, Santa Cruz WEIQING HAN, University of Colorado, Boulder BENJAMIN P. HORTON, University of Pennsylvania, Philadelphia CHRISTINA L. HULBE, Portland State University, Oregon JAMES C. MCWILLIAMS, University of California, Los Angeles PHILIP W. MOTE, Oregon State University, Corvallis WILLIAM TAD PFEFFER, University of Colorado, Boulder DENISE J. REED, University of New Orleans, Louisiana C.K. SHUM, Ohio State University, Columbus Ocean Studies Board Liaison ROBERT A. HOLMAN, Oregon State University, Corvallis National Research Council Staff ANNE M. LINN, Study Director, Board on Earth Sciences and Resources MARTHA MCCONNELL, Program Officer, Ocean Studies Board (through September 2011) COURTNEY R. GIBBS, Program Associate, Board on Earth Sciences and Resources JASON R. ORTEGO, Research Associate, Board on Earth Sciences and Resources v

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BOARD ON EARTH SCIENCES AND RESOURCES CORALE L. BRIERLEY, Chair, Brierley Consultancy LLC, Highlands Ranch, Colorado WILLIAM E. DIETRICH, University of California, Berkeley WILLIAM. L. GRAF, University of South Carolina, Columbia RUSSELL J. HEMLEY, Carnegie Institution of Washington, Washington, D.C. MURRAY W. HITZMAN, Colorado School of Mines, Golden EDWARD KAVAZANJIAN, Jr., Arizona State University, Tempe DAVID R. MAIDMENT, The University of Texas, Austin ROBERT B. MCMASTER, University of Minnesota, Minneapolis M. MEGHAN MILLER, UNAVCO, Inc., Boulder, Colorado ISABEL P. MONTAEZ, University of California, Davis CLAUDIA INS MORA, Los Alamos National Laboratory, New Mexico BRIJ M. MOUDGIL, University of Florida, Gainesville CLAYTON R. NICHOLS, Idaho National Engineering and Environmental Laboratory (retired), Ocean Park, Washington HENRY N. POLLACK, University of Michigan, Ann Arbor DAVID T. SANDWELL, University of California, San Diego, La Jolla PETER M. SHEARER, University of California, San Diego, La Jolla REGINAL SPILLER, Azimuth Investments LLC, Texas TERRY C. WALLACE, Jr., Los Alamos National Laboratory, New Mexico National Research Council Staff ELIZABETH A. EIDE, Director ANNE M. LINN, Senior Program Officer SAMMANTHA L. MAGSINO, Senior Program Officer MARK D. LANGE, Program Officer JENNIFER T. ESTEP, Financial and Administrative Associate NICHOLAS D. ROGERS, Financial and Research Associate COURTNEY R. GIBBS, Program Associate JASON R. ORTEGO, Research Associate ERIC J. EDKIN, Senior Program Assistant CHANDA IJAMES, Senior Program Assistant vi

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OCEAN STUDIES BOARD DONALD F. BOESCH, Chair, University of Maryland, Cambridge EDWARD A. BOYLE, Massachusetts Institute of Technology, Cambridge RITA R. COLWELL, University of Maryland, College Park SARAH COOKSEY, Delaware Department of Natural Resources and Environmental Control, Dover CORTIS K. COOPER, Chevron Corporation, San Ramon, California JORGE E. CORREDOR, University of Puerto Rico, Lajas KEITH R. CRIDDLE, University of Alaska, Fairbanks JODY W. DEMING, University of Washington, Seattle ROBERT HALLBERG, National Oceanic and Atmospheric Administration, Princeton, New Jersey ROBERT A. HOLMAN, Oregon State University, Corvallis KIHO KIM, American University, Washington, D.C. BARBARA A. KNUTH, Cornell University, Ithaca, New York GEORGE I. MATSUMOTO, Monterey Bay Aquarium Research Institute, California JOHN A. ORCUTT, University of California, San Diego JAY S. PEARLMAN, IEEE, Port Angeles, Washington STEVEN E. RAMBERG, National Defense University Pennsylvania State University, Washington, D.C. ANDREW A. ROSENBERG, Conservation International, Arlington, Virginia DANIEL L. RUDNICK, Scripps Institution of Oceanography, San Diego, California PETER L. TYACK, University of Saint Andrews, Scotland, United Kingdom DON WALSH, International Maritime Inc., Myrtle Point, Oregon DAWN J. WRIGHT, Oregon State University, Corvallis JAMES A. YODER, Woods Hole Oceanographic Institution, Massachusetts National Research Council Staff SUSAN J. ROBERTS, Director DEBORAH A. GLICKSON, Senior Program Officer CLAUDIA MENGELT, Senior Program Officer KIM J. WADDELL, Senior Program Officer SHERRIE FORREST, Senior Program Associate GRAIG R. MANSFIELD, Financial Associate PAMELA A. LEWIS, Administrative Coordinator LAUREN L. HARDING, Senior Program Assistant vii

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Preface P rojections of sea-level rise are increasingly being nerability and response to sea-level rise; to improve incorporated into coastal planning at national, models and forecasts; to develop research priorities; state, and local levels. This assessment of sea- and to develop decision support tools for a variety of level rise for the California, Oregon, and Washington users, including the public. Finally, the USACE needs coasts was requested by 10 state and federal agencies: sea-level information to guide water resource invest- ment decisions. California Department of Water Resources Assessments of sea-level rise at state and regional California Energy Commission levels are challenging because data on the geophysical California Department of Transportation processes involved are relatively sparse and there are no California State Water Resources Control Board agreed-upon models or approaches for projecting future California Ocean Protection Council sea-level rise. Consequently, in addition to searching Oregon Watershed Enhancement Board the scientific literature, it was necessary to consult Washington Department of Ecology widely with colleagues and to carry out original data National Oceanic and Atmospheric Administration analyses. The results were discussed during four com- (NOAA) mittee meetings in 2011 and countless teleconference U.S. Army Corps of Engineers (USACE) and email discussions. U.S. Geological Survey (USGS) The committee used standard statistical techniques to calculate means, trends, and uncertainties associated At the committee's first meeting, each agency de- with sea-level rise, and to extrapolate recent data into scribed its needs for sea-level information.1 The state the future. To ensure that the calculated results were agencies need estimates and projections of sea-level rise sound, the committee verified its results in several ways. in their areas to assess coastal risk; to plan investments Calculations performed using standard statistical pack- in water, transportation, energy, and pollution-control ages or the equations and data presented in the report infrastructure; to modify design and construction stan- were cross-checked by one or two committee members. dards; to develop adaptation strategies that will protect This process was used to check the means and uncer- the environment and infrastructure against increased tainties of the various components of sea-level rise, the salt-water intrusion, coastal erosion, and inundation; tide gage and satellite altimetry measurement errors and to identify necessary changes in state law or policy. and corrections, vertical land motion observations and NOAA and the USGS need sea-level information at models, and estimates of the effect of gravitational state, national, and global scales to assess coastal vul- attraction. Calculations that required specialized soft- ware, including extracting the steric contribution from 1 Presentations to the committee by the 10 sponsor agencies on model results, calculating trends from satellite measure- January 12, 2011. ix

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x PREFACE ments and glacial isostatic adjustment (GIA) models, the ice extrapolations; James Foster, who compiled and and projecting future sea-level rise, were carried out or analyzed leveling data in California; Richard Peltier, checked by a colleague or student of the lead committee who provided details of his GIA models and computed member. The method for extrapolating the cryospheric past and future predictions of relative sea-level changes contribution to sea-level rise was developed in collabo- in Washington, Oregon, and California; and Jerry ration with a statistician, who also verified the results. Mitrovica, who provided gravity fingerprints along the Where possible, the data and equations for these cal- U.S. west coast for Alaska, Greenland, and Antarctica. culations are provided in the report or the public-access The committee also thanks the students, postdocs, and file, enabling an independent check from reviewers. colleagues who crunched numbers, validated results, The committee would like to thank the indi viduals and created (and recreated) figures, including Jianbin who briefed the committee; supplied data, figures, or Duan, Zhenwei Huang, Chungyen Kuo, Darrin Sharp, model results; or provided other input or feedback: Scott Waibel, and Yuchan Yi. Without the hard work Jonathan Allan, Brian Atwater, Patrick Barnard, Laura and contributions of all these individuals, it would have Brophy, John Church, Abe Doherty, Catia Domingues, been difficult to complete this report. Peter Gleckler, Chris Goldfinger, Dominic Gregorio, Finally, I thank all the members of the committee Jonathan Gregory, Eric Grossman, Junyi Guo, Erica for their service, some of whom had to go way beyond Harris, Greg Hood, Masayoshi Ishii, Ian Joughin, that usually required for an NRC committee because of Jeanine Jones, Tom Kendall, Paul Komar, Eli Levitt, the short study period and the complexity of the task. Sydney Levitus, Becky Lunde, Anne Pardaens, Archie Finally, I thank Anne Linn for her tireless efforts as Paulson, Stephan Rahmstorf, Eric Rignot, Peter Study Director and for bringing the report to fruition. Ruggiero, Carl Safina, Ingo Sasgen, Armand Thibault, Wouter van der Wal, Hansheng Wang, Kelin Wang, Robert A. Dalrymple, Chair Jeff Weber, Josh Willis, Frank Wu, Patrick Wu, Jianjun Committee on Sea Level Rise in Yin, and Phoebe Zarnetske. Special thanks go to Balaji California, Oregon, and Washington Rajagopalan, who developed the statistical approach for

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Acknowledgments T his report has been reviewed in draft form by Antony R. Orme, University of California, Los individuals chosen for their diverse perspec- Angeles tives and technical expertise, in accordance W. Richard Peltier, University of Toronto, Canada with procedures approved by the NRC's Report Review Stephen Price, Los Alamos National Laboratory, Committee. The purpose of this independent review New Mexico is to provide candid and critical comments that will Claudia Tebaldi, Climate Central, Princeton, assist the institution in making its published report as New Jersey, and Palo Alto, California sound as possible and to ensure that the report meets John M. Wallace, University of Washington, institutional standards for objectivity, evidence, and re- Seattle sponsiveness to the study charge. The review comments Joshua K. Willis, Jet Propulsion Laboratory, and draft manuscript remain confidential to protect the Pasadena, California integrity of the deliberative process. We wish to thank the following individuals for their participation in the Although the reviewers listed above have provided review of this report: many constructive comments and suggestions, they were not asked to endorse the conclusions or recom- Linda K. Blum, University of Virginia, mendations nor did they see the final draft of the Charlottesville report before its release. The review of this report was Roland Brgmann, University of California, overseen by Ken Brink, Woods Hole Oceanographic Berkeley Institution, and Warren Washington, National Center John A. Church, Centre for Australian Weather for Atmospheric Research. Appointed by the National and Climate Research, Hobart, Tasmania Research Council, they were responsible for making Peter J. Gleckler, Lawrence Livermore National certain that an independent examination of this report Laboratory, California was carried out in accordance with institutional pro- Peter H. Gleick, Pacific Institute for Studies in cedures and that all review comments were carefully Development, Environment, and Security, considered. Responsibility for the final content of this Oakland, California report rests entirely with the authoring committee and Mark F. Meier, emeritus, University of Colorado, the institution. Boulder Jerry X. Mitrovica, Harvard University, Cambridge, Massachusetts xi

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Contents SUMMARY1 1INTRODUCTION 9 Committee Approach, 11 Overview of Sea-Level Change, 13 Geographic Variation Along the U.S. West Coast, 17 Organization of the Report, 19 2 MEASURED GLOBAL SEA-LEVEL RISE 23 Proxy Measurements, 23 Tide Gages, 23 Satellite Altimetry, 28 Gravity Recovery and Climate Experiment (GRACE), 28 Conclusions, 30 3 CONTRIBUTIONS TO GLOBAL SEA-LEVEL RISE 33 Thermal Expansion, 33 Glaciers, Ice Caps, and Ice Sheets, 40 Terrestrial Water Storage, 50 Conclusions, 53 4SEA-LEVEL VARIABILITY AND CHANGE OFF THE CALIFORNIA, OREGON, AND WASHINGTON COASTS 55 Changes in Ocean Circulation, 55 Short-Term Sea-Level Rise, Storm Surges, and Surface Waves, 59 Sea-Level Fingerprints of Modern Land Ice Change, 64 Vertical Land Motion Along the U.S. West Coast, 68 West Coast Tide Gage Records, 78 Conclusions, 81 xiii

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xiv CONTENTS 5 PROJECTIONS OF SEA-LEVEL CHANGE 83 Recent Global Sea-Level Projections, 83 Committee Projections of Global Sea-Level Rise, 88 Previous Projections of U.S. West Coast Sea-Level Rise, 95 Committee Projections of Sea-Level Rise Along the California, Oregon, and Washington Coasts, 96 Uncertainty, 101 Rare Extreme Events, 103 Conclusions, 107 6 RESPONSES OF THE NATURAL SHORELINE TO SEA-LEVEL RISE 109 Coastal Cliffs and Bluffs, 109 Beaches, 111 Coastal Dunes, 114 Retreat of Cliffs and Beaches Under Sea-Level Rise, 115 Estuaries and Tidal Marshes, 121 Opportunities for Marsh Restoration and the Effect of Marshes on Storm Wave Attenuation, 130 Conclusions, 135 REFERENCES137 APPENDIXES A Vertical Land Motion and Sea-Level Data Along the West Coast of the United States 153 B Sea-Level Rise in the Northeast Pacific Ocean 163 C Analysis of Sea-Level Fingerprint Effects 175 D Long-Term Tide Gage Stability from Leveling Data 179 E Cryosphere Extrapolations 191 F Biographical Sketches of Committee Members 197 G Acronyms and Abbreviations 201