UNIVERSITY OF CALIFORNIA, IRVINE Fossil Fuel Emissions of Carbon Dioxide: Feedbacks and Forecasting DISSERTATION submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in Earth System Science by Dawn L. Woodard Dissertation Committee: Professor James T. Randerson, Chair Professor Steven J. Davis, Co-chair Professor Michael L. Goulden Professor Nathan M. Mueller 2020 Chapter2 © 2019 Dawn L. Woodard and coauthors All other materials © 2020 Dawn L. Woodard DEDICATION This thesis is dedicated to the teachers who taught me to be curious and who gave me the tools to begin answering all my questions. \Every major national science academy in the world has reported that global warming is real, caused mostly by humans, and requires urgent action. The cost of acting goes far higher the longer we wait | we can't wait any longer to avoid the worst and be judged immoral by coming generations." { James Hansen ii TABLE OF CONTENTS Page LIST OF FIGURESv LIST OF TABLES vi ACKNOWLEDGMENTS vii CURRICULUM VITAE viii ABSTRACT OF THE DISSERTATION xii 1 Introduction1 1.1 Climate and the carbon cycle .......................... 1 1.2 Fossil fuel emissions of carbon dioxide...................... 3 1.3 Modeling the carbon cycle............................ 5 1.4 Organization of research............................. 6 2 Economic carbon cycle feedbacks may offset additional warming from natural feedbacks9 2.1 Introduction.................................... 9 2.2 Materials and methods.............................. 13 2.3 Results....................................... 16 2.3.1 Climate and carbon cycle impacts.................... 16 2.3.2 Feedback effects.............................. 19 2.4 Discussion..................................... 19 3 Estimating Carbon Cycle Feedbacks on Fossil Fuel Emissions 24 3.1 Introduction.................................... 24 3.2 An extension of the feedback framework .................... 30 3.3 Decomposing the gain of the carbon-climate feedback............. 32 3.4 Decoupling models ................................ 35 3.5 Estimates from simple models.......................... 40 3.6 Discussion..................................... 46 4 Near Term Forecasts of US Fossil Fuel Emissions with a Vector Autore- gression Model 50 4.1 Introduction.................................... 50 4.2 Methods...................................... 54 4.2.1 Data selection and processing ...................... 54 4.2.2 Model selection and design........................ 56 4.2.3 Model evaluation............................. 59 4.3 Results....................................... 59 iii 4.4 Discussion..................................... 62 4.4.1 Lessons for prediction .......................... 62 4.4.2 Comparison with other modeling approaches.............. 64 4.4.3 Lessons for global predictability..................... 66 4.5 Conclusions.................................... 67 5 Conclusions 68 Bibliography 71 A Supplementary Methods for Chapter 2 85 A.1 Carbon cycle box model ............................. 85 A.2 Simulation design................................. 89 A.3 Estimating the gain of the climate-carbon feedback .............. 91 A.4 Climate-economy relationships.......................... 92 A.4.1 Influence of climate on population.................... 92 A.4.2 Temperature impacts on per capita gross domestic product . 93 A.4.3 Temperature impact on the energy intensity of GDP ......... 94 A.4.4 Temperature impact on carbon intensity of energy........... 96 iv LIST OF FIGURES Page 1.1 Global carbon cycle fluxes............................ 2 2.1 Diagram of economic and natural carbon cycle processes ........... 11 2.2 Net effects of economic and natural feedbacks ................. 15 2.3 Model results compared across all scenarios................... 18 2.4 Response of the carbon-climate gain to a range of economic damages . 21 3.1 Carbon cycle feedbacks in ocean, land, managed land, and fossil fuel carbon pools........................................ 26 3.2 Pathways of carbon-climate and carbon-concentration feedbacks on the vari- ous carbon pools ................................. 39 3.3 Fossil fuel feedback effect on model output................... 41 3.4 Carbon-climate and carbon-concentration feedbacks in Woodard et al. model 43 3.5 Feedback responses between DICE-Burke and Woodard et al. models . 45 3.6 Comparison of estimating feedback parameters based on a fully-coupled or decoupled baseline in Woodard et al. model .................. 47 4.1 US fossil fuel emissions sources and trends................... 52 4.2 Monthly predictor data used in analysis..................... 54 4.3 Correlations between fossil fuel emissions and each predictor......... 55 4.4 Theoretical timeline of US data availability and modeling approaches . 57 4.5 Raw and seasonal forecast results with one-month lead time ......... 60 4.6 Forecast error across models by length of forecast............... 62 4.7 Annual forecasts to the end of the current year and one and two years ahead 63 4.8 Comparison of predictors over forecasts in 2009, 2010, 2011 and 2015 . 65 4.9 Comparison of end-of-year forecasts between this model and EIA forecasts . 66 v LIST OF TABLES Page 3.1 Model scenarios for carbon cycle analysis.................... 36 3.2 DICE-Burke and Woodard et al. results across carbon and climate variables 44 4.1 Data availability and temporal lags for emissions data and economic, climate, and energy predictor data............................. 56 4.2 Out-of-sample statistics for a one-month forecast compared to benchmark models....................................... 61 4.4 Frequency of occurrence of each predictor in the best 25 VAR models . 64 vi ACKNOWLEDGMENTS This dissertation is based upon work in part supported by the National Science Foundation Graduate Research Fellowship Program under Grant DGE-1321846. I would like to express so much gratitude to my committee chair, James Randerson, who has had patience throughout all of my ups and downs the past five and a half years, and who was always interested in whatever idea I had for a research topic, no matter the subject, and provided me with so many opportunities to advance my career and build professional connections. He has constantly been there to advocate for me and provide support when needed and has always helped me find the story in my research and the interesting direction to pursue in my analysis whenever I was floundering. I also want to thank my committee co-chair Steven Davis for all of his advice and support, particularly for his creativity and design ideas for making my figures interesting and readable, and his suggestions for structuring papers for flow and a clear story. I want to thank the other members of my committee, Nathan Mueller and Michael Goulden, for providing additional perspectives on this work, and for their useful input and advice along the way. And I could not have done any of this without my friends, partners, and of course my parents. My friends have kept me sane, commiserated over stress and deadlines and coding errors, and provided much needed distractions after work. My partners have been endlessly supportive throughout everything and I cannot put into words how much their constant presence and faith in me has meant. And, finally, my parents who have been there in all the little ways like cards and care packages and encouragement and listening to my venting about whatever hurdle I was currently facing, but also throughout my life in all the bigger ways, like providing me with all the best educational opportunities and always believing in me and supporting me in whatever direction my interests turned. vii VITA Dawn L. Woodard EDUCATION Doctor of Philosophy in Earth System Science 2020 University of California, Irvine Irvine, California Master of Science in Earth System Science 2018 University of California, Irvine Irvine, California Bachelor of Science in Mathematics 2010 Appalachian State University Boone, North Carolina RESEARCH EXPERIENCE Graduate Student Researcher Fall 2014 - Winter 2020 University of California, Irvine, Irvine, CA Research Assistant Fall 2012 - Summer 2014 Appalachian State University, Boone, NC Student Researcher Summer 2013 Bishop Heber College, Tiruchirapalli, Tamil Nadu, India REU Student Summer 2012 National Institute of Mathematical and Biological Synthesis University of Tennessee Knoxville, Knoxville, TN REU Student Summer 2011 North Carolina Agricultural and Technical State University, Greensboro, NC RESEARCH PUBLICATIONS Woodard, D. L., Davis, S. J., & Randerson, J. T., (2019). Economic carbon cycle feedbacks may offset additional warming from natural feedbacks. Proceedings of the National Academy of Sciences, 116(3), 759-764. Hogue, S., Marland, E., Andres, R. J., Marland, G., & Woodard, D. (2016). Uncertainty in gridded CO2 emissions estimates. Earth's Future, 4(5), 225-239. LoPresti, A., Charland, A., Woodard, D., Randerson, J., Diffenbaugh, N., Davis, S. (2015). Rate and velocity of climate change caused by cumulative carbon emissions. Environmental Research Letters, 10 (9), 095001. Woodard, D., Branham, M., Buckingham, G., Hogue, S., Hutchins, M., Gosky, R., Mar- land, G., Marland, E. (2014). A spatial uncertainty metric for anthropogenic CO2 emissions. Greenhouse Gas Measurement and Management, 4(2-4), 139-160. Singer, A., Branham, M., Hutchins, M., Welker, J., Woodard, D., Badurek, C., Ruseva, T., viii Marland, E., Marland, G. (2014). The Role of CO2 Emissions from Large Point Sources in Emissions Totals, Responsibility,