CALIFORNIA’S FOURTH CLIMATE CHANGE ASSESSMENT Statewide Summary Report Coordinating Agencies: Introduction to California’s Fourth Climate Change Assessment alifornia is a global leader in using, investing in, and advancing research to set proactive climate change policy, and its Climate Change Assessments provide the scientifc foundation for understanding climate- related vulnerability at the local scale and informing resilience actions. The Climate Change Assessments C directly inform State policies, plans, programs, and guidance to promote effective and integrated action to safeguard California from climate change. California’s Fourth Climate Change Assessment (Fourth Assessment) advances actionable science that serves the growing needs of state and local-level decision-makers from a variety of sectors. Tis cutting-edge research initiative is comprised of a wide-ranging body of technical reports, including rigorous, comprehensive climate change scenarios at a scale suitable for illuminating regional vulnerabilities and localized adaptation strategies in California; datasets and tools that improve integration of observed and projected knowledge about climate change into decision- making; and recommendations and information to directly inform vulnerability assessments and adaptation strategies for California’s energy sector, water resources and management, oceans and coasts, forests, wildfres, agriculture, biodiversity and habitat, and public health. In addition, these technical reports have been distilled into summary reports and a brochure, allowing the public and decision-makers to easily access relevant fndings from the Fourth Assessment. • A concise summary of the Fourth Assessment’s most important fndings and conclusions. • An in-depth report on how California’s people, built KEY FINDINGS environment, and ecosystems will be impacted by climate change and how we can proactively adapt, based on the Fourth Assessment’s fndings. • Reports summarizing Fourth Assessment fndings to STATEWIDE SUMMARY provide a state of the science for nine regions, the ocean and coast, tribal communities, and climate justice in California. SUMMARIES FOR REGIONS AND COMMUNITIES • Academic research that provides robust and detailed results on resilience and vulnerability to climate change. ORIGINAL RESEARCH TO • A shared foundation of updated climate change INFORM POLICY AND ACTION projections, data and ecosystem models developed for use by Assessment authors to permit cross-comparability of results and ensure the fndings consider a robust range ASSESSMENT FOUNDATION: UPDATED CLIMATE PROJECTIONS AND DATA of future climate conditions. These data are available to the public via Cal-Adapt.org. All research contributing to the Fourth Assessment was peer-reviewed to ensure scientifc rigor as well as, where applicable, appropriate representation of the practitioners and stakeholders to whom each report applies. For the full suite of Fourth Assessment research products, please visit: www.ClimateAssessment.ca.gov Fourth Climate Change Assessment Statewide Summary Report | 2 California Regions CLIMATE NORTH JUSTICE COAST REGION SACRAMENTO TRIBAL VALLEY COMMUNITIES REGION SIERRA SAN FRANCISCO NEVADA BAY AREA REGION REGION SAN JOAQUIN VALLEY REGION CENTRAL COAST OCEAN REGION AND COAST COMMUNITIES INLAND DESERTS LOS ANGELES REGION REGION SAN DIEGO REGION The Statewide Summary Report presents an overview of the main fndings from California’s Fourth Climate Change Assessment. Produced as part of a volunteer initiative by leading climate experts, this summary report aims to translate the state of climate science into useful information for decision-makers and practitioners to catalyze action that will beneft regions, the ocean and coast, frontline communities, and tribal and indigenous communities. The Statewide Summary Report presents fndings in the context of existing climate science, including strategies to adapt to climate impacts and key research gaps needed to spur additional progress on safeguarding California from climate change. Fourth Climate Change Assessment Statewide Summary Report | 3 Statewide Summary Report Authors COORDINATING LEAD CONTRIBUTING Chris Jones John Radke AUTHORS AUTHORS UC Berkeley UC Berkeley Julie Kalansky David Roland-Holst Louise Bedsworth, David Ackerly UC Berkeley Scripps Institution of UC Berkeley California Governor’s Oceanography John Andrew Scott Samuelson Offce of Planning and California Department of Dan Kammen UC Irvine Research Water Resources UC Berkeley Alan Sanstad Surabhi Karambelkar Lawrence Berkeley Dan Cayan, Maximilian Aufammer UC Berkeley University of Arizona National Laboratory Scripps Institution of Rupa Basu Nuin-Tara Key Benjamin Sleeter Oceanography California Ofce of California Governor’s US Geological Survey Environmental Health Ofce of Planning and David Stoms Guido Franco, Hazard Assessment Research California Energy California Energy Neil Berg Michael Kleeman Commission Commission UC Los Angeles UC Davis James Torne Hilda Blanco Millie Levin UC Davis LEAD AUTHORS University of Southern California Ofce of Jason Vargo California Emergency Services California Department of Leah Fisher, Carolyn Cook Jay Lund Public Health California Governor’s California Department of UC Davis Max Wei Offce of Planning and Food and Agriculture Amber Mahone Lawrence Berkeley E3 National Laboratory Research Ivana Cvijanovic Lawrence Livermore Michael L. Mann Leroy Westerling Sonya Ziaja, National Laboratory Te George Washington UC Merced California Public Utilities Larry Dale University Susan Wilhelm Lawrence Berkeley Commission Josué Medellín-Azuara California Energy National Laboratory UC Merced Commission Eric Fournier Nicole Meyer-Morse A. Park Williams UC Los Angeles California Ofce of Lamont-Doherty Earth Christina Greene Emergency Services Observatory of Columbia University of Arizona Meredith Millet University Amrith Gunasekara California Department of Xiangmei Wu California Department of Public Health California Ofce of Food and Agriculture Max Moritz Environmental Health Hazard Assessment Ellen Hanak UC Santa Barbara Public Policy Institute of Jennifer Phillips Erika Zavaleta California California Ocean UC Santa Cruz Michael Hanemann Protection Council Arizona State University David Pierce Jelena Hartman Scripps Institution of California State Water Oceanography Resources Control Board Fourth Climate Change Assessment Statewide Summary Report | 4 8/2018 PEER REVIEW COMMITTEE MEMBERS ACKNOWLEDGMENTS Chair: Robert Lempert, Creation of this report would not have been possible RAND Corporation without the contributions of many people. First, we would like to thank all of the contributing authors Phil Duffy, who took time to develop content, review material, Woods Hole Research Center and support the development of this report. We would also like to thank the Fourth Assessment State Team, Chris Field, including Susan Wilhelm, Jim Torne, Joey Wraithwall, Stanford University Jamie Anderson, and Grayson Hough for their coordination and technical editing support, and Della Juliette Finzi Hart, Gilleran and her design team. A huge thank you to Beth U.S. Geological Survey Hotchkiss, who provided critical support on references David Graves, and generating a bibliography for this report. Saintsbury Winery Tis report also benefted from the thoughtful comments and insights of the peer review committee, who reviewed Lara Kueppers, and provided feedback on earlier drafs. Tank you to University of California, Berkeley Rob Lempert who chaired this committee, and to all of Robert A. Leiter, FAICP the committee members listed here. California’s Fourth Climate Change Assessment was supported by funding Peter Moyle, from the California Energy Commission (CEC), the University of California, Davis California Natural Resources Agency (CNRA), and contributions from researchers supported by external Jonathan Parfrey, funds (see Appendix A for the complete research Climate Resolve portfolio). Stephanie Pincetl, Any errors that remain in this report are the University of California, Los Angeles responsibility of the coordinating lead authors. Margaret Torn, Lawrence Berkeley National Laboratory CITATION: Bedsworth, Louise, Dan Cayan, Guido Franco, Leah Fisher, Sonya Ziaja. (California Governor’s Sarah White, Ofce of Planning and Research, Scripps Institution California Workforce Development Board of Oceanography, California Energy Commission, California Public Utilities Commission). 2018. Statewide Summary Report. California’s Fourth Climate Change Assessment. Publication number: SUM- CCCA4-2018-013. This report summarizes the results of work sponsored by the California Natural Resources Agency and California Energy Commission, in the context of broader scientifc literature. The information presented here does not necessarily represent the views of the funding agencies or the State of California. Fourth Climate Change Assessment Statewide Summary Report | 5 8/2018 Table of Contents Introduction to California’s Fourth Climate Change Assessment ...........................................................................................2 California Regions ...............................................................................................................................................................3 Statewide Summary Report Authors .................................................................................................................................4 Summary of Key Findings from the Fourth Assessment ..........................................................................................................8