About This Series -- Acknowledgements -- Abbreviations and Acronyms -- Contents -- Chapter 1: Summary for Decision Makers -- 1.1 Introduction -- 1.2 Observed Recent Climatic Change in the Southwest -- 1.3 Projected Future Climatic Change in the Southwest -- 1.4 Recent and Future Effects of Climatic Change in the Southwest -- Terrestrial and freshwater ecosystems -- Coastal systems -- Water -- Human health -- Additional effects of climate change -- 1.5 Choices for Adjusting to Climate and Climate Change -- 1.6 Key Unknowns -- References -- Chapter 2: Overview -- 2.1 Introduction -- What is an assessment? -- 2.2 Context and Scope -- 2.3 Other Southwest Region Climate Assessments -- 2.4 Sponsors and Authors of this Report -- 2.5 Characterizing and Communicating Uncertainty -- 2.6 Accountability and Review -- 2.7 Organization of This Report -- References -- Chapter 3: The Changing Southwest -- Executive Summary -- 3.1 Lay of the Land: Geographical Themes and Features -- Natural features -- Human geography -- Public lands -- Population -- Natural resource economy -- 3.2 Land Use and Land Cover -- Trends for urban and exurban development -- References -- Appendix -- Chapter 4: Present Weather and Climate: Average Conditions -- Executive Summary -- 4.1 Introduction -- 4.2 General Climate Characteristics -- Surface-air temperature -- Precipitation -- Snowfall, snowpack, and water resources -- 4.3 Major Climate and Weather Events -- Drought -- Winter storms -- Floods -- Thunderstorms -- Temperature extremes -- Air quality -- 4.4 Climate Variability -- References -- Chapter 5: Present Weather and Climate: Evolving Conditions -- Executive Summary -- 5.1 Introduction -- 5.2 Climate of the First Decade of the Twenty-first Century -- 5.3 Climate Trends for 1901-2010 -- 5.4 E xtreme Weather Variability During 1901-2010 -- 5.5 Summertime Drought During 1901-2010.

5.6 H ydroclimatic Variability During 1901-2010 -- 5.7 Paleoclimate of the Southwest United States -- Paleotemperature -- Paleodrought -- Paleostreamflow -- 5.8 Future Monitoring and Science Needs -- References -- Appendix -- Chapter 6: Future Climate: Projected Average -- Executive Summary -- 6.1 Global Climate Models: Statistical and Dynamical Downscaling -- 6.2 Climate Scenarios -- 6.3 Data Sources -- 6.4 Temperature Projections -- 6.5 Projections of Other Temperature Variables -- 6.6 Precipitation Projections -- 6.7 Atmospheric Circulation Changes -- 6.8 N orth American Monsoon -- 6.9 Changes in Precipitation-related Measures -- References -- Chapter 7: Future Climate: Projected Extremes -- Executive Summary -- 7.1 Introduction -- 7.2 Heat Waves -- Heat wave index -- Projections -- 7.3 W intertime Cold Outbreaks -- 7.4 Precipitation -- General results and key uncertainties -- North American monsoon (NAM) -- Atmospheric rivers -- Hail on the Colorado Front Range -- 7.5 Surface Hydrology -- Flooding -- Drought -- 7.6 Fire Weather -- Santa Ana winds -- 7.7 Discussion of Key Uncertainties -- Irreversible changes and tipping points -- References -- Chapter 8: Natural Ecosystems -- Executive Summary -- 8.1 Introduction: Climate, Climate Change, and Ecosystems of the Southwest -- 8.2 Phenology and Species Interactions -- Phenology and interactions among species in terrestrial systems -- Interactions in freshwater systems -- 8.3 Southwestern Deserts -- 8.4 Southwestern Forests -- Temperature, precipitation, and pests and pathogens -- Fire -- References -- Chapter 9: Coastal Issues -- Executive Summary -- 9.1 Coastal Assets -- 9.2 Observed Threats -- Overview -- Threats to the physical environment -- Threats to the built environment -- 9.3 Ocean and Coastal Impacts to Ecosystems -- Overview -- Sea-level rise -- Changes in ocean temperature and dynamics.

Ocean acidification -- 9.4 Coastal Impacts to Communities -- Overview -- Airport infrastructure -- Vehicular transportation infrastructure -- Economy, culture, and identity -- 9.5 Managing Coastal Climate Risks -- Overview -- Adaptation options -- Level of preparedness and engagement in adaptation planning -- Barriers to adaptation -- References -- Appendix -- Chapter 10: Water: Impacts, Risks, and Adaptation -- Executive Summary -- 10.1 Introduction -- 10.2 Physical Changes to the Water Cycle -- 10.3 Human and Natural Systems Impacts, Risks and Vulnerabilities -- 10.4 Water Sector Adaptation Activities -- 10.5 Planning Techniques and Stationarity -- 10.6 Potential Supply and Demand Strategies and Solutions -- 10.7 Barriers to Climate Change Adaptation -- 10.8 Federal Adaptation Initiatives -- 10.9 SECURE Water Act Overview -- 10.10 W estern States Federal Agency Support Team (WestFAST) -- 10.11 Climate Change and Water Working Group (CCAWWG) -- 10.12 State Adaptation Efforts -- 10.13 Regional and Municipal Adaptation Efforts -- References -- Chapter 11: Agriculture and Ranching -- Executive Summary -- 11.1 Distinctive Features of Southwestern Agriculture -- 11.2 Implications for Specialty Crops -- 11.3 On-farm Water Management -- 11.4 System-wide Water Management: Lessons from Programming Models of Water Allocation -- Sustained drought in California -- Water availability and crop yields in California -- Effects of adaptation measures in California -- Economic and land-use projections in California -- Agriculture in Nevada's Great Basin -- Water transfers in Rio Grande Basin -- Severe drought in Rio Grande Basin -- Drought and Arizona's agriculture -- Reduced water supplies across the Southwest -- Lessons from simulation studies -- 11.5 Ranching Adaptations to Multi-year Drought -- 11.6 Disaster Relief Programs and Climate Adaptation -- References.

Chapter 12: Energy: Supply, Demand, and Impacts -- Executive Summary -- 12.1 Introduction -- 12.2 Energy in the Southwest: Past and Present -- 12.3 Potential Climate Impacts on Energy -- Climate-induced impacts to peak and annual electricity demand -- Vulnerability of electricity generation to climate impacts -- Vulnerability of electricity distribution to climate impacts -- Vulnerability of infrastructure to indirect climate impacts -- Climate impacts on renewable source intensity -- Evolution of the energy sector -- Climate impacts on primary energy production -- Cost of climate change -- References -- Chapter 13: Urban Areas -- Executive Summary -- 13.1 Cities in the Southwest -- Observed changes in climatic trends in major cities in the Southwest -- Urban processes that contribute to climate change -- Government characteristics of large metropolitan regions in the Southwest -- Southwest cities as distinctive federal creations -- 13.2. Pathways Through which Climate Change Will Affect Cities in the Southwest -- Fire hazards -- The built environment -- Climate change and urban water -- 13.3 Critical Missing Data and Monitoring in Cities -- References -- Chapter 14: Transportation -- Executive Summary -- 14.1 Introduction -- 14.2 Passenger Transportation Trends in the Southwest -- 14.3 Freight Movement in the Southwest -- 14.4 Impacts of Climate Change -- Direct impacts -- Indirect impacts -- 14.5 Major Vulnerabilities and Uncertainties -- Disruptions to the transportation system -- References -- Chapter 15: Human Health -- Executive Summary -- 15.1 Introduction -- 15.2 Current Climate-Related Health Concerns in the Southwest -- Air quality -- Heat extremes -- Wildfires -- Permissive ecology -- 15.3 Climate Change and Potential Health Implications -- Emissions and air pollution -- Increases in extreme events -- Long-term warming trend.

15.4 O bserved and Predicted Effects on Health from Climate Change -- Air quality -- Heat-related mortality and morbidity -- Vector-borne disease -- 15.5 Uncertainties -- Availability of high-quality health data -- Climate data -- Disease complexity -- New disease introduction -- 15.6 Public Health Planning for Climate Change -- Adaptation -- Co-benefits -- References -- Chapter 16: Climate Change and U.S.-Mexico Border Communities -- Executive Summary -- 16.1 Introduction -- 16.2 Definition of the Border Region -- 16.3 Border Region Climate Variability, Climate Change, and Impacts -- Temperature -- Precipitation -- Drought -- 16.4 Understanding Vulnerability, Risk, and Adaptive Capacity in the Border Region -- Definitions and concepts -- Key drivers of border vulnerability -- Socioeconomic drivers -- Urbanization, infrastructure, and economy -- Institutional and governance drivers -- Drivers of biophysical changes and their impacts -- 16.5 Sectoral Analysis of Border Vulnerability -- Water supply and sectoral vulnerability -- Agriculture and ranching -- Wildfire -- References -- Chapter 17: Unique Challenges Facing Southwestern Tribes -- Executive Summary -- 17.1 Introduction -- 17.2 The Effects of Marginal Living Conditions and Extreme Climatic Environments -- 17.3 Current Impacts on Native Lands -- 17.4 Potential Rangeland Impacts -- Sand and dust storms -- 17.5 Adaptation Strategies and Adaptation Planning -- Floods and disaster planning -- Droughts and drought mitigation planning -- 17.6 Challenges for Adaptation Planning -- 17.7 V ulnerability from Economic, Political, and Legal Stresses -- Vulnerability and adaptive capacity -- Water rights -- 17.8 Climate Change Mitigation Strategies -- References -- Chapter 18: Climate Choices for a Sustainable Southwest -- Executive Summary -- 18.1 Introduction.

18.2 Defining a Sustainable Approach to Climate Change in the Southwest.