Climate Change in the Northwest: Implications for Our Landscapes, Waters, and Communities is aimed at assessing the state of knowledge about key climate impacts and consequences to various sectors and communities in the northwest United States. It draws on a wealth of peer-reviewed literature, earlier state-level assessment reports conducted for Washington (2009) and Oregon (2010), as well as a risk-framing workshop. As an assessment, it aims to be representative (though not exhaustive) of the key climate change issues as reflected in the growing body of Northwest climate change science, impacts, and adaptation literature now available. This report will serve as an updated resource for scientists, stakeholders, decision makers, students, and community members interested in understanding and preparing for climate change impacts on Oregon, Washington, and Idaho. This more detailed, foundational report is intended to support the key findings presented in the Northwest chapter of the Third National Climate Assessment.  "[Climate Change in the Northwest] is a lucid, engaging precis of climate change science and impacts in the Pacific Northwest." ― Choice Climate Change in the Northwest Implications for Our Landscapes, Waters, and Communities By Meghan M. Dalton, Philip W. Mote, Amy K. Snover ISLAND PRESS Copyright © 2013 Oregon Climate Change Reasearch Institute All rights reserved. ISBN: 978-1-61091-428-4 Contents Executive Summary, CHAPTER 1 INTRODUCTION: THE CHANGING NORTHWEST, CHAPTER 2 CLIMATE: VARIABILITY AND CHANGE IN THE PAST AND THE FUTURE, CHAPTER 3 WATER RESOURCES: IMPLICATIONS OF CHANGES IN TEMPERATURE AND PRECIPITATION, CHAPTER 4 COASTS: COMPLEX CHANGES AFFECTING THE NORTHWEST'S DIVERSE SHORELINES, CHAPTER 5 FORESTS ECOSYSTEMS: VEGETATION, DISTURBANCE, AND ECONOMICS, CHAPTER 6 AGRICULTURE: IMPACTS, ADAPTATION, AND MITIGATION, CHAPTER 7 HUMAN HEALTH: IMPACTS AND ADAPTATION, CHAPTER 8 NORTHWEST TRIBES: CULTURAL IMPACTS AND ADAPTATION RESPONSES, CHAPTER 1 Introduction The Changing Northwest AUTHORS Amy K. Snover, Patty Glick, Susan M. Capalbo Human influences on climate, already apparent at the global and continental scales (IPCC 2007), are projected to alter the climate, ecology and economy of the Northwest (NW). Despite large natural variations, changes in regional temperature, snowpack, snowmelt timing, and river flows have already been observed that are consistent with expected human-caused trends (Mote 2006; Pierce et al. 2008; Stewart et al. 2005; Hidalgo et al. 2009; Luce and Holden 2009). With 21st century rates of global and regional warming projected to be at least double those observed in the 20th century (IPCC 2007; Mote and Salathé 2010; see Chapter 2 ), these changes are expected to continue even as new changes emerge. Climate change is projected to alter environmental conditions across the region, affecting the Northwest's natural resource base and changing habitat conditions for fish and wildlife. The regional consequences of climate change will pose new risks to health, safety, and personal property, alter the reliability of transportation interconnections, and drive changes in local and regional economies. More fundamentally, these changes mean that many of the climatic assumptions inherent in decisions, infrastructure, and policies across the Northwest—from where to build, to what to grow where, to how to manage variable water resources to meet multiple needs—will become increasingly incorrect. Many of the changes set in motion are unavoidable, caused by greenhouse gases already emitted (Solomon et al. 2009), though they may be temporarily obscured by the Northwest's highly variable climate (Hawkins and Sutton 2009; Deser et al. 2012). What risks will a changing climate bring for the region as a whole and for specific sectors and locations? What strategies are emerging for evaluating and altering management of regional water and energy supplies, infrastructure, transportation, health, and ecological and agricultural systems to address these risks? To what extent is the region preparing? This report synthesizes currently available information to provide answers to these questions. It focuses on impacts that matter for the region as a whole, chosen with an eye toward the likely major drivers of regional change and consequences of highest regional and local importance. It is an assessment of existing knowledge that builds on and augments previous assessments (e.g., Climate Impacts Group 2009, Oregon Climate Change Research Institute 2010) and draws on a wealth of resources from local government and state agency reports to academic peer-reviewed journal articles. It is intended to be a resource for preparing the Northwest for climate change. While we can do our best to discern the most likely consequences of climate change for NW ecosystems and communities, the ultimate consequences of the changes now in motion remain partially contingent o