SAN DIEGO COUNTY ECOSYSTEMS: ECOLOGICAL IMPACTS OF CLIMATE CHANGE ON A BIODIVERSITY HOTSPOT A Report for: California’s Fourth Climate Change Assessment Prepared By: Megan K. Jennings, San Diego State University Dan Cayan, Scripps Institution of Oceanography Julie Kalansky, Scripps Institution of Oceanography Amber D. Pairis, Climate Science Alliance South Coast Dawn M. Lawson, Space and Naval Warfare Systems Center Pacific (SSCPAC) Alexandra D. Syphard, Conservation Biology Institute Udara Abeysekera, Climate Science Alliance-South Coast Rachel E.S. Clemesha, Scripps Institution of Oceanography Alexander Gershunov, Scripps Institution of Oceanography Kristen Guirguis, Scripps Institution of Oceanography John M. Randall, The Nature Conservancy, California Chapter Eric D. Stein, Southern California Coastal Water Research Project Sula E. Vanderplank, San Diego State University Additional Contributors: Horacio de la Cueva, Centro de Investigacin Científica y de Educacin Superior de Ensenada, Baja California Shasta Gaughen, Pala Band of Mission Indians i Janin Guzman-Morales, Scripps Institution of Oceanography Laura Hampton, Climate Science Alliance-South Coast David W. Pierce, Scripps Institution of Oceanography Hiram Rivera Huerta, Universidad Autnoma de Baja California Rob Roy, La Jolla Band of Luiseno Indians DISCLAIMER This report was prepared as part of California’s Fourth Climate Change Assessment, however the research represented was not directly sponsored by the California Energy Commission or the Natural Resources Agency. It does not necessarily represent the views of the Energy Commission, the Natural Resources Agency, its employees or the State of California. The Energy Commission, Natural Resources Agency, the State of California, its employees, contractors and subcontractors make no warrant, express or implied, and assume no legal liability for the information in this report; nor does any party represent that the uses of this information will not infringe upon privately owned rights. This document has not been approved or disapproved by the California Energy Commission or the Natural Resources Agency nor has the California Energy Commission or the Natural Resources Agency passed upon the accuracy or adequacy of the information in this document. Edmund G. Brown Jr., Governor August 2018 CCCA4-EXT-2018-010 ii ACKNOWLEDGEMENTS The San Diego region has a diverse community of land managers, consultants, researchers, and policy makers and we thank those who contributed thoughts and insights to this work both as we developed this report and over our careers. The wealth of citations of local work throughout this document is a testament to the vibrant research community addressing basic and applied science on a multitude of projects driven by the need to solve complex resource conservation and management problems. The institutions represented include federal, state, local, and non- governmental organizations as well as consulting firms. First, we thank the institutions of each of the authors that provided in-kind support for our time to contribute to this unfunded collaboration. This includes San Diego State University, Scripps Institution of Oceanography, Climate Science Alliance – South Coast, CA Department of Fish and Wildlife, Space and Naval Warfare Systems Center Pacific, Conservation Biology Institute, the CA Chapter of the Nature Conservancy (TNC), and the Southern Coastal Water Research Project. Further, our additional contributors represented Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Universidad Autónoma Baja California (UABC), the Pala Band of Mission Indians, and the La Jolla Band of Luiseo Indians. We appreciate that these organizations recognized the value of this work and supported our efforts. We acknowledge the National Oceanic and Atmospheric Administration’s Regional Integrated Science Assessment (NOAA RISA) Program (NA11OAR4310150), for supporting Cayan’s and Kalansky’s time, and the NOAA Coastal and Ocean Climate Applications (COCA) program (NA15OAR4310114) for Clemesha’s and Guirguis’s work. In addition, we would like to acknowledge Climate Education Partners (NSF Grant #DUE-1239797) for support of Gershunov, Clemesha and Guirguis, the University of California Office of the President (UCOP)-funded Multicampus Research Programs and Initiatives (MRPI) Project "Drought and Public Health in a Warming CA” for supporting Gershunov and Guzman-Morales, and the CA Energy Commission and the Southwest Climate Science Center for supporting downscaling and regional climate change efforts of Pierce and Cayan. We also recognize the colleagues and collaborators who generously provided data, information, and thoughtful discussion about the topics in this report: Kris Preston, United States Geological Survey (USGS) and the San Diego Management and Monitoring Program; Erin Riordan, University of California, Los Angeles (UCLA); Cara Lacey and Trish Smith of TNC, CA Chapter; Sara Baguskas, San Francisco State University; Danielle Boudreau, Tijuana River National Estuarine Research Reserve (TRNERR); Amy Vandergast, USGS; Christy Wolf, Naval Weapons Station Seal Beach Detachment Fallbrook; Kimberly O’Connor, Commander Pacific Fleet; Deborah Bieber, Marine Corps Installation-West and Marine Corps Base Camp Pendleton; John Sanborn, San Diego Natural History Museum, and Paul Zedler, University of Wisconsin, Madison. Finally, we are appreciative of the encouragement and financial support we have received from the Southwest Climate Science Center (G17AP00197) to develop outreach materials for this work and host a symposium in March 2018 featuring the results from this assessment. This work would not have been possible without the firm belief of each of the contributing authors that this work would be a valuable contribution to researchers, managers, planners, and 3 decision makers in the San Diego region and beyond. As such, we would like to recognize the authors’ contributions to this report: Jennings, Cayan, and Kalansky conceived of this assessment and sought out ecologists and climatologists to contribute; Jennings organized meetings, set timelines and tasks for work, and generally kept us on track; Pairis, Jennings, Jennings, Syphard, and Lawson each led the writing of one or more section, keeping authors organized and managing editing; Jennings, Pairis, Kalansky, Lawson, Randall, Cayan, Abeysekera, Stein, and Vanderplank all contributed substantial material to more than one section of the report; Guirguis, Gershunov, Pierce, Rivera-Huerta, JGM, Clemesha, Gaughen, and De La Cueva all made significant contributions to a single section; Pierce provided the downscaled climate data that appear in figures and were the basis for much of the climate- related discussion in this assessment; Hampton developed all map-based figures presented here; Abeysekera worked tirelessly on the many references cited herein; and Jennings, Kalansky, Syphard, Cayan, and Abeysekera worked on compiling sections, formatting, and editing the final report. Finally, we appreciate the input from three anonymous reviewers and Jim Thorne, UC Davis, who improved this report. i PREFACE California’s Climate Change Assessments provide a scientific foundation for understanding climate-related vulnerability at the local scale and informing resilience actions. These Assessments contribute to the advancement of science-based policies, plans, and programs to promote effective climate leadership in California. In 2006, California released its First Climate Change Assessment, which shed light on the impacts of climate change on specific sectors in California and was instrumental in supporting the passage of the landmark legislation Assembly Bill 32 (Nez, Chapter 488, Statutes of 2006), California’s Global Warming Solutions Act. The Second Assessment concluded that adaptation is a crucial complement to reducing greenhouse gas emissions (2009), given that some changes to the climate are ongoing and inevitable, motivating and informing California’s first Climate Adaptation Strategy released the same year. In 2012, California’s Third Climate Change Assessment made substantial progress in projecting local impacts of climate change, investigating consequences to human and natural systems, and exploring barriers to adaptation. Under the leadership of Governor Edmund G. Brown, Jr., a trio of state agencies jointly managed and supported California’s Fourth Climate Change Assessment: California’s Natural Resources Agency (CNRA), the Governor’s Office of Planning and Research (OPR), and the California Energy Commission (Energy Commission). The Climate Action Team Research Working Group, through which more than 20 state agencies coordinate climate-related research, served as the steering committee, providing input for a multisector call for proposals, participating in selection of research teams, and offering technical guidance throughout the process. 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. It includes research to develop 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