A comprehensive review of climate adaptation in the United States: more than before, but less than needed

We reviewed existing and planned adaptation activities of federal, tribal, state, and local governments and the private sector in the United States (U.S.) to understand what types of adaptation activities are underway across different sectors and scales throughout the country. Primary sources of review included material officially submitted for consideration in the upcoming 2013 U.S. National Climate Assessment and supplemental peer-reviewed and grey literature. Although substantial adaptation planning is occurring in various sectors, levels of government, and the private sector, few measures have been implemented and even fewer have been evaluated. Most adaptation actions to date appear to be incremental changes, not the transformational changes that may be needed in certain cases to adapt to significant changes in climate. While there appear to be no one-size-fits-all adaptations, there are similarities in approaches across scales and sectors, including mainstreaming climate considerations into existing policies and plans, and pursuing no- and low-regrets strategies. Despite the positive momentum in recent years, barriers to implementation still impede action in all sectors and across scales. The most significant barriers include lack of funding, policy and institutional constraints, and difficulty in anticipating climate change given the current state of information on change. However, the practice of adaptation can advance through learning by doing, stakeholder engagements (including “listening sessions”), and sharing of best practices. Efforts to advance adaptation across the U.S. and globally will necessitate the reduction or elimination of barriers, the enhancement of information and best practice sharing mechanisms, and the creation of comprehensive adaptation evaluation metrics.

Developed Guiding Principles for federal adaptation efforts and policy goals and recommended actions for the federal government. Guides interagency adaptation planning efforts.
The October 2010 Progress Report of the ICCATF laid out eight principles for federal adaptation efforts and made five key recommendations, including the development of agency adaptation plans and strategies to address key cross-cutting issues such as water management, natural resource management, and the integrating of adaptation actions into existing planning processes.

ICCATF Water Resources Adaptation workgroup
Developed and is leading implementation of the National Action Plan: Priorities for Managing Freshwater Resources in a Changing Climate.
The National Action Plan was released in October 2011, and is designed to ensure adequate water supplies and protect water quality, human health, property, and aquatic ecosystems. The workgroup is chaired by the Department of the Interior's (DOI's) U.S. Geological Survey (USGS) and the Environmental Protection Agency (EPA) and coordinated by CEQ.

ICCATF Agency Adaptation Planning Workgroup
Established and coordinates the federal agency adaptation community of practice.
The community of practice provides information and support to federal agencies working to reduce their climate change-related risks and a forum for collaboration and coordination across agencies. Coordinated by EPA.
Steering Committee of the National Fish, Wildlife, and Plants Climate Adaptation Strategy Developed the National Fish, Wildlife, and Plants Climate Adaptation Strategy.
Requested by Congress and the ICCATF, this strategy is a collaborative effort of federal, state, and tribal partners to provide a unified approach for reducing the negative impacts of climate change on these resources. The steering committee is chaired by DOI's Fish and Wildlife Service (FWS), NOAA, and the New York Division of Fish, Wildlife, and Identifying critical science information and decision support needs and capabilities in support of adaptation.
Formerly an ICCATF Adaptation Science Workgroup, the Adaptation Science Workgroup was transferred to USGCRP in 2010 as a new program element to improve the federal government's capacity to provide science in support of adaptation decisions at all scales for a diversity of users.
Material provided in Table is derived from Agency websites  Supports research teams such as Regional Integrated Sciences and Assessments (RISAs) to inform resource management, planning, and policy. Established six regional climate centers (RCCs) to better assess and deliver regionally focused climate science and services. Developed the Digital Coast partnership.

Department of Energy (DOE)
Develops higher spatial and temporal scales of climate projections, and is working to integrate adaptation and climate Develops community-based, highresolution (temporal and spatial) models for climate projections and integrated assessment models that increasingly reflect multi-sectoral

States
States have become important actors in national climate-related policy efforts, often through the creation of policies and programs that incentivize or inhibit adaptation at other governance scales (Morsch and Bartlett 2011); through the application of pressure on Federal and private entities (Goulder and Stavins 2011); and by serving as laboratories for climate innovation (Feldman and Kahan 2007;Moser 2009). Although many of these actions are not specifically designed to address climate change, they often include climate adaptation components. Many of the climate-specific adaptation actions at the state level focus on planning. As of early 2012, at least 13 U.S. states have completed climate adaptation plans; one state is in the process of writing its plan; and eight states have made recommendations to create statewide adaptation plans (C2ES 2012b). In addition to formal adaptation plans, numerous states have created sectorspecific plans that consider long-term climate change. For example, at least 16 states have biodiversity conservation plans that focus on preparing for long-term changes in climate (AFWA 2011), and states such as North Carolina and South Carolina are actively working to revise their state wildlife strategies to incorporate climate adaptation (Lackstrom et al. 2012). Strategies identified in state-level adaptation plans generally fall into one of four categories (Feldman and Kahan 2007;Morsch and Bartlett 2011;Moser 2009;NRC 2010a): (1) research and education; (2) promotion and facilitation of existing policies or programs that improve resilience; (3) integration of adaptive measures into current policies or planning processes; and (4) development of new policies or practices that reduce vulnerability (Feldman and Kahan 2007;Morsch and Bartlett 2011;Moser 2009;NRC 2010a).
In addition to planning, some states have created legislation and/or programs that are either directly or indirectly targeted at reducing state-relevant vulnerabilities (Table 3). The Maine Sand Dune Rules require that structures greater than 2,500 square feet be set back at a distance that is calculated based on the future shoreline position and considers two feet of sea level rise over the next 100 years (Grannis 2011). Maryland (MD) Passed Living Shorelines Act to reduce hardened shorelines throughout the state (Feifel 2010); passed "Building Resilience to Climate Change" policy, which establishes practices and procedures related to facility siting and design, new land investments, habitat restoration, government operations, research and monitoring, resource planning, and advocacy. Montana (MT) Maintains a statewide climate change website to help stakeholders access relevant and timely climate information, tools, and resources. New Mexico (NM) The Active Water Resource Management program allows for temporary water use changes in real time in case of drought (Propst 2012). Pennsylvania (PA) Enacted polices to encourage the use of green infrastructure and ecosystem-based approaches for managing stormwater and flooding

Local/regional and tribal governments
Most adaptation efforts to date have occurred at local and regional levels (Anguelovski and Carmin 2011;Gregg et al. 2011;Rabe 2009;Wallis 2011;Wheeler 2008). Primary mechanisms that local governments are using to prepare for climate change include land use planning; provisions to protect infrastructure and ecosystems; regulations related to the design and construction of buildings, roads, and bridges; and emergency preparation, response, and recovery (Dierwechter 2010;Grannis 2011;Kahn 2009;Selin and VanDeveer 2007;Solecki and Rosenzweig 2012). According to a recent survey of 298 U.S. local governments, 59 % indicated they are engaged in some form of adaptation planning (Carmin et al. 2012). Local adaptation planning and actions are unfolding in municipalities of varying sizes and in diverse geographical areas. Communities such as Keene, New Hampshire; New York City, New York; King County, Washington; and Chicago, Illinois are vanguards in the creation of climate adaptation strategies (Binder et al. 2010;Solecki and Rosenzweig 2012). These communities are now implementing their strategies-such as stormwater pipe replacement in Keene, green infrastructure installations in New York City, and green roofs in Chicago (Carter and Fowler 2008;Cruce 2009;Hamin and Gurran 2009;Kessler 2011;Rosenzweig et al. 2011a;Sussman 2009 Tribal governments have also been active in assessing and preparing for the impacts of climate change. For example, adaptation planning in Point Hope, Alaska considered climate impacts and potential actions for issues such as community health (Brubaker et al. 2010). Their plan also noted that while many effects of climate change are negative, there could be positive effects as well, including new food resources and a longer season for securing potable water (ibid). In Newtok, Alaska, the village council is leading a land-acquisition and planning effort to relocate the community, because climate-induced coastal erosion has destroyed essential infrastructure, making the current village site unsafe (Bronen 2011). The Swinomish Indian Tribal Community in Washington State used video storytelling, the tribal newsletter, and alliances built with local organizations to identify and address locally relevant climate concerns (Lamb and Davis 2011;Swinomish Indian Tribal 2010;University of Oregon and USDA 2010). These efforts led to the integration of climate change into decision-making in major sectors of the Swinomish Community, such as education, fisheries, social services, and human health (Lamb and Davis 2011).
Additional examples of local and regional adaptation efforts are listed in Table 4. There is no one-size-fits-all adaptation solution to the challenges of adapting to the impacts of climate change as solutions will differ depending on context and scale, as well as on the local culture and internal capacity (National Climate Adaptation Summit Committee 2010; Solecki and Rosenzweig 2012).

Nongovernmental and private sector
Many nongovernmental entities have been significant actors in the national effort to prepare for climate change by providing assistance that includes planning guidance, implementation tools, contextualized climate information, best practice exchange, and help with bridging the science-policy divide to a wide array of stakeholders (Agrawal 2008;Guston et al. 2000;van Aalst et al. 2008). The Nature Conservancy, for example, established the Canyonlands Research Center in Monticello, Utah to conduct research and develop conservation applications for resource issues in the Colorado Plateau region, focusing on forest-climate Table 4 Examples of U.S. local/regional and tribal-level adaptation activities Local/regional government Adaptation action Satellite Beach, FL Collaboration with the Indian River Lagoon National Estuary Program led to the incorporation of sea level rise projections and policies into the city's comprehensive growth management plan (Gregg et al. 2011).
Portland, OR Updated the city code to require on-site stormwater management for new development and re-development, and provides a downspout disconnection program to help promote on-site stormwater management (EPA 2010b).

Lewes, DE
In partnership with Delaware Sea Grant, ICLEI-Local Governments for Sustainability, the University of Delaware, and state and regional partners, the City of Lewes undertook a stakeholder-driven process to understand how climate adaptation could be integrated into the hazard mitigation planning process. Recommendations for integration and operational changes were adopted by the City Council and are currently being implemented (City of Lewes 2011).
Point Hope, AK The village of Point Hope, AK created a plan that summarized the effect of climate change on several issues and identified observed changes, health concerns, projected changes, and potential adaptation actions to address each issue (Brubaker et al. 2010).
Groton, CT Partnered with Federal, state, regional, local, nongovernmental, and academic partners through the EPA's Climate Ready Estuaries program to assess vulnerability to, and devise solutions for, sea level rise (Stults and Pagach 2011).
San Diego Bay, CA Five municipalities partnered with the port, the airport, and more than 30 organizations with direct interests in the future of the Bay to develop the San Diego Bay Sea Level Rise Adaptation Strategy. The strategy identified key vulnerabilities for the Bay and adaptation actions that can be taken by individual agencies, as well as through regional collaboration .
Chicago, IL Through a number of development projects, the city has added 55 acres of permeable surfaces since 2008 and has more than four million square feet of green roofs planned or completed (City of Chicago 2010).

Tulalip Tribes
The Tulalip Tribes in Washington State are using traditional knowledge gleaned from elders, stories, and songs and combining this knowledge with downscaled climate data to inform decision-making (Simmonds 2011 (English et al. 2007;NRDC 2012). Table 5 provides examples of the broad types of adaptation efforts and services that nongovernmental actors are providing. With regard to the private sector, evidence from organizations such as the Carbon Disclosure Project (CDP) and the Securities and Exchange Commission's Climate Change 10-K Disclosure indicate that a growing number of companies are beginning to actively address risks from climate change (CDP 2011). The World Business Council for Sustainable Development and the Center for Climate and Energy Solutions (C2ES) have identified three types of risks driving private sector adaptation efforts, including risks to: core operations, the value chain, and broader changes in the economy and infrastructure (  Philadelphia, PA In 2006, the Philadelphia Water Department began a program to develop a green stormwater infrastructure intended to convert more than one-third of the city's impervious land cover to "Greened Acres": green facilities, green streets, green open spaces, green homes, etc., along with stream corridor restoration and preservation (ORNL 2012b). Table 5 Examples of U.S. nongovernmental adaptation efforts and services Types of adaptation efforts and services Examples of organizations providing services* Adaptation planning assistance, including creation of guides, tools, and templates 2011 CDP, and suggests that companies are concerned about how changes in climate will impact issues such as feedstock, water supply and quality, infrastructure, core operations, supply chain, and customers' ability to use (and their need for) services (CDP 2011). To address these risks, some companies are working to proactively avoid risk by minimizing the magnitude of impacts, diversifying the sources of risks, and spreading the burden of any future impact through a variety of strategies, including reallocation of financial risks such as through insurance and reinsurance (Table 6) (CDP 2011). For example, the insurance industry has started integrating climate considerations into their rate programs (Ojima et al. 2012) and requiring the insured to adapt to projected changes (McGraw-Hill Construction 2011), although efforts to date have been piecemeal (Culver et al. 2012;GAO 2007). Some companies are taking action to not only avoid risk, but to explore potential opportunities embodied in a changing climate, such as developing new products and services; developing or expanding existing consulting services; expanding into new operational territories; extending growing seasons and hours of operation; and responding to the potential for increased demand for existing products and services (Agrawala et al. 2011;CDP 2011;Dell and Pasteris 2010;Oxfam America 2009;PWC 2010).
It is difficult to assess the degree to which the private sector is adapting, and whether such adaptations are sufficient to prepare for and minimize future risks from climate change. Many actions that may be spurred by climate change may not be correctly attributed either partially or wholly to climate change. Thus many actions that can be considered to be climate change adaptations by the private sector, such as supply chain diversification, may not be reported as such. Indeed, this may also be true of many public sector actions. Conversely, it is possible that companies (and governments) can claim they are making changes out of a professed concern for the environment or to prepare for climate change when other factors, particularly the cutting of costs or increasing of revenues, are the primary drivers of action.  Coca-Cola is working around the world to replenish the water used in finished beverages by participating in locally relevant water projects that support communities and nature. Since 2005, the Coca-Cola system has engaged in more than 320 projects in 86 countries. The range of community projects includes watershed protection; expanding community drinking water and sanitation access; water for productive use, such as agricultural water efficiency; and education and awareness programs. (http://www. thecoca-colacompany.com/citizenship/ conservation_partnership.html) ConAgra Foods, Inc.

Consumer Staples
Company experienced weatherrelated sourcing challenges, such as delayed tomato harvesting due to unseasonably cool weather and difficulty sourcing other vegetables due to above-normal precipitation.
As part of its business continuity planning, ConAgra Foods has analyzed its supply risk to develop strategic partnerships with suppliers, minimize sole-sourced ingredients, and identify alternate suppliers and contract manufacturers to minimize production disruptions in case of an unexpected disruption in supply. PG&E's adaptation strategies for potential increased electricity demand include expanded customer energy efficiency and demand response programs and improvements to its electric grid. PG&E is proactively tracking and evaluating the potential impacts of reductions to Sierra Nevada snowpack on its hydroelectric system, and has developed adaptation

Adaptation process
General patterns in adaptation processes are only beginning to emerge, with similarities discernible across sectors, systems, and scales (Anguelovski and Carmin 2011;Dell and Pasteris 2010;Means et al. 2010). Figure 2 depicts a generalized and iterative adaptation Spectra Energy uses a corporate-wide risk analysis framework to ensure the oversight and management of its four major risk categories: financial, strategic, operational, and legal. Physical risks posed by climate change fall within these categories, and the company uses risk management committees to ensure that all material risks are identified, evaluated, and managed prior to financial approvals of major projects. (http://www.spectraenergy.com/ Sustainability/) process. This is not a step-wise or linear process, as various stages of the adaptation process can occur simultaneously or in an order different from that presented; some steps can be omitted completely. More detail about each phase in this process is provided below.

Identifying and understanding risk, vulnerabilities, and opportunities
Most adaptation actions are currently in the initial phase, with many actors focusing on identifying the relevant climate risks and conducting current and future risk and vulnerability assessments of their assets and resources (Carmin et al. 2012;Glick et al. 2011;Ingram et al. 2012;Lackstrom et al. 2012;NRC 2010a;Rowland et al. 2011;USGS 2012;West et al. 2009). In 2011, out of 298 U.S. municipalities surveyed, only 13% had completed vulnerability or risk assessments-but 42% expected to complete an assessment in the future (Carmin et al. 2012). At least 21 state fish and wildlife agencies are undertaking climate vulnerability assessments, or have recently completed an assessment of a particular species, habitat, or both (AFWA 2011). Multiple qualitative and quantitative methods are used to understand climate vulnerability, including case studies and analogue analyses, scenario analyses, sensitivity analyses, peer information sharing, monitoring of key species, and information sharing among peers (Barrett et al. 2011;EPA 2011;Ford et al. 2010;Fussel 2007;Hulme and Dessai 2008;NPS 2010). Participatory research and "on the ground" efforts in places such as New York City, Boston, Flagstaff, Interior Alaska, and in the Swinomish Tribe demonstrate the importance of starting with the identification of existing vulnerabilities (City of Flagstaff 2012; Lamb and Davis 2011;McNeeley and Shulski 2011;Rosenzweig et al. 2011b). Relevant historical and future climate data are often then used to conduct a risk and/or vulnerability analysis; such efforts have been used in the water utility (Berry et al. 2011), land and ecosystems management (Glick et al. 2011;Heller and Zavaleta 2009;NPS 2010;USGS 2012), and government sectors (Pahl-Wostl et al. 2011;Wheeler 2008).
3.2 Planning, assessing, and selecting options Once risks and vulnerabilities are understood, the next stage typically involves identifying, evaluating, and selecting options for response to existing and future changes in climate (NPS 2010). Decision support planning methods and associated tools help to identify flexible and context-relevant adaptation activities for implementation (Means et al. 2010;NRC 2010a). Participatory approaches enable the design of adaptation processes with context-specific information (Fazey et al. 2010;Few et al. 2007;Preston et al. 2011;Smit and Wandel 2006), often by having community stakeholders and governing institutions work collectively to define the problem and identify adaptation strategies that are robust, while incorporating stakeholder values (Brunner 2005;Preston et al. 2011;Stern and Fineberg 1996;World Bank 2008). Moreover, regional collaboration has emerged in places such as San Francisco Bay, San Diego Bay, Southeast Florida, Chesapeake Bay, and the Intermountain West, where stakeholders are coming together to address issues of regional concern (e.g., sea level rise, water distribution, transportation systems). In this way they are defining common strategies to reduce potential threats, identifying metrics for tracking purposes, and often creating governance structures to help navigate political challenges (ICLEI 2012; Moser and Ekstrom 2010;Pyke et al. 2011;Southeast Florida Compact Counties 2011). Common approaches to adaptation planning include "mainstreaming" or integrating climate adaptation into existing environmental, climate, or sustainability frameworks or sector-based plans (e.g., hazard mitigation, ecosystem conservation, water management, risk contingency planning, public health, environmental management, energy and national security) or developing standalone adaptation plans ( The selection of options appropriate for building resilience to climate impacts depends on the socio-political and environmental context in which these decisions are made. Uncertainty about the timing and magnitude of climate change poses challenges to making such choices (NRC 2008), and many frameworks, tools, and approaches have emerged to help decisionmakers make decisions in the face of this uncertainty (Kareiva 2008). Many of these, however, are specific to particular localities or resources, are not easy to use, and require sophisticated knowledge of climate change (Federspiel 2012;Hammill and Tanner 2011). In general, these approaches seek options that allow reversibility, preserve future options, can resist a variety of impacts, and are flexible, such that mid-course adjustments are possible (OTA 1993;Wilby and Vaughan 2011). Among these approaches are Robust Decision Making (RDM), Iterative Risk Management (IRM), Adaptive Management or Co-Management, Portfolio Management, and Scenario Planning (Gregg et al. 2011;Groves and Lempert 2006;Kareiva 2008;Lee 1993;Lempert et al. 2006;Moore et al. 2012;Moser 2012;NPS 2010;NRC 2004;Williams and Brown 2012).

Implementation
Because adaptation activities in the United States are relatively new, there is little peer-reviewed literature on adaptation actions or evaluation of their successes and failures (Ford et al. 2011;Ingram et al. 2012;Moser 2009;NRC 2010a). Much of the documentation that does exist is in "grey" literature, such as government reports and planning documents; agency "white" or background papers; and "expressions of interest" reports officially submitted as part of the upcoming NCA process. These documents indicate that adaptation actions are being implemented for a variety of reasons-often with an aim toward reducing current vulnerabilities to hazards or extreme weather events. For example, forest thinning and fuel treatments can reduce fire risks in national forests. Similarly, diversifying material sourcing in the private sector can reduce the risk of supply chain disruption (CDP 2011;Vose et al. 2012). Additionally, an increasing movement toward mainstreaming climate adaptation concerns into existing processes means that discerning unique climate adaptation activities will be a challenge (Dovers and Hezri 2010;Lackstrom et al. 2012). An example of local adaptation implementation is Seattle Public Utilities' RainWatch-an early warning precipitation forecasting tool used for drainage operations (CEQ 2011a) (more examples can be found in Fig. 3).

Monitoring and evaluation
There is little literature evaluating the effectiveness of adaptation actions (Means et al. 2010;Preston et al. 2011;Solecki and Rosenzweig 2012;Vose et al. 2012). Evaluation and monitoring efforts to date have focused on the creation of process-based rather than  (Jacob, et al. 2010).
In addition, a number of efforts are underway to create indicators related to climate adaptation (USCGRP, 2012). The National Climate Assessment Development Advisory Committee (NCADAC) Indicators Working Group is currently working to develop indicators that will aid in identifying effective climate adaptation and mitigation activities . EPA is also working to develop indicators of resilience, specifically in the urban setting (EPA 2010a; Federspiel 2012). Both of these efforts anticipate the pilot testing of draft indicators in mid-2013.

Revise strategies/processes and information sharing
Uncertainty about the future climate, as well as about population growth, economic development, response strategies, and other social and demographic issues, can stymie climate adaptation activity (McCollum et al. 2011;Moore et al. 2012;USGS 2012). Through iterative processes, however, stakeholders can regularly evaluate the appropriateness of planned and implemented activities and revise them as new information becomes available (EPA 2011;NPS 2010;NRC, 2010a). Additionally, the sharing of best practices and lessons learned is crucial in advancing understanding and uptake of climate adaptation activity (Lackstrom et al. 2012;Preston et al. 2011).
Established information-sharing networks such as the World Business Council on Sustainable Development, ICLEI-Local Governments for Sustainability, WUCA, and regional climate initiatives are the types of networks that have supported stakeholder adaptation activity to date (Means et al. 2010;WBCSD 2009). Facilitating and encouraging networking will be instrumental in ensuring that lessons learned and best practices are shared in a manner that will foster the scaling up of climate adaptation activity.
The following map and table highlight some adaptation activities taking place in different geographical regions and scales in the United States (Fig. 3). The map is not intended to be a comprehensive compilation of adaptation activities throughout the country, but is illustrative of the types of activities taking place. 14. Tulsa, OK has a three-pronged approach to reducing flooding and managing stormwater: (1) prevent new problems by looking ahead and avoiding future downstream problems from new development (e.g., requiring on-site stormwater detention); (2) correct existing problems and learn from disasters to reduce future disasters (e.g., through watershed management and the acquisition and relocation of buildings in flood-prone areas); and (3)   Despite emerging recognition of the necessity of climate change adaptation, many barriers still impede efforts to build local, regional, and national-level resilience. Barriers are obstacles that can delay, divert, or temporarily block the adaptation process (Ekstrom et al. 2011), and include difficulties in using climate change projections for decision-making; lack of resources to begin and sustain adaptation efforts; fragmentation of decision-making; institutional constraints; lack of leadership; and divergent risk perceptions/cultures and values (Table 7). Additionally, an array of barriers, such as uncertainty about future costs and benefits, high costs of action, and institutional constraints, are impeding transformational adaptations, which may be necessary for long-term adaptation (Kates et al. 2012). The barriers described here are distinguished from physical or ecological limits to adaptation, such as physiological tolerance of species to changing climatic conditions that cannot be overcome (except with technology or some other physical intervention) Gregg et al. 2011;McIlgorm et al. 2010; USGS 2012).   Verweij et al. 2006;Kahan et al. 2007;Kahan et al. 2011;Adger et al. 2009;Renn 2011;van Aalst et al. 2008;Doria et al. 2009;Renn et al. 2011;Lackstrom et al. 2012;Leiserowitz 2006;McNeeley 2012;Simmonds 2011;NRC 2009;Ding et al. 2011;Gifford 2011;Weber and Stern 2011 Little integration of local knowledge, context, and needs with traditional scientific information

Cultural taboos and conflict with cultural beliefs
Resistance to change due to issues such as risk perception help to inform decision-making, but currently do not exist or are difficult to obtain or assemble, include: & Projections: Regular and updated projections of climate change and impacts at appropriate spatial and temporal scales to inform planning horizons (Barsugli et al. 2012); & Options: Portfolios of adaptation options that can help to build adaptive capacity and resilience despite remaining uncertainties (Kareiva 2008); & Cost, Benefit, and Effectiveness Analysis: Detail on the relative costs, benefits, and effectiveness of sustainable adaptation options-including, in some cases, no action; & Adaptive Capacity: Information on how enhancing adaptive capacity can address multiple other stresses, such as pollution and habitat fragmentation (IPCC 2007;NRC National Research Council 2007;OTA 1993;USGCRP 2009); & Adaptation-Mitigation Interface: Information on how choices for adaptation options may interact with mitigation actions; & Limits: Limits to adaptation ); and & Metrics of Success: An evaluation framework with supporting metrics to gauge adaptation success or failure (Culver et al. 2012;Horton et al. 2012;McCollum et al. 2011;USCGRP, 2012;USGS 2012;Vose et al. 2012;Winkler et al. 2012).
An important aspect of the first item (projections) is the lack of knowledge among stakeholders about where to find scientifically sound information that can be translated into understandable and useful formats to support communication and policy-making (Brunner and Nordgren 2012;Hauser and Jadin 2012;Lackstrom et al. 2012;Lebow et al. 2012;Lemos and Rood 2010;McNie 2007;Mitchell 2010;Needham et al. 2012).
The inability to access information and apply it in the right context can also be a significant hurdle (National Climate Adaptation Summit Committee 2010; Needham et al. 2012;NRC, 2010b). The complex nature of the climate system, combined with uncertainty about future climate impacts, is often a stumbling block to effective communication of climate risks, adaptation needs, and decision-making on climate change adaptation (Fowler and Wilby 2007;Kerr 2011;Larsen et al. 2011;White-Newsome et al. 2011). Many professionals working in public health, engineering, planning, and natural resource management are not formally trained on climate change, which limits their ability to communicate about and use climate information in decision-making (ASTHO 2012;Carmin et al. 2012;Marra et al. 2012;National Climate Adaptation Summit Committee 2010;NRC, 2010b;Schramm 2012). Similarly, many scientists do not conduct research to answer questions posed by users of climate information (Dilling and Lemos 2011;McNie 2007). Decisionmakers and scientists must collaborate to ensure that timely answers can be found to key adaptation questions.

Lack of resources to begin and sustain adaptation efforts
Many stakeholders lack the financial resources and staff to successfully identify, implement, monitor, and maintain adaptation efforts (Brugger and Crimmins 2011;Carmin et al. 2012;Marra et al. 2012;Needham et al. 2012;Schramm 2012;Simmonds 2011). Very few resource managers, municipalities, states, and regional councils of governments have dedicated funds for adaptation; the funding that is available is often a one-time influx of capital rather than a sustained source of revenue (e.g., the American Recovery and Reinvestment Act and the Partnership for Sustainable Communities program administered jointly by HUD, DOT, and EPA) (Carmin et al. 2012;Ingram et al. 2012;Lackstrom et al. 2012).
The lack of comprehensive, coordinated, and sustained multi-year funding continues to impede stakeholders' ability to advance climate adaptation planning, implementation, and evaluation (Brunner and Nordgren 2012; Garfin et al. 2012;Mittal 2009). Without additional funding, current budgetary constraints and competing priorities will continue to be significant barriers to adaptation activity (Gregg et al. 2011;Needham et al. 2012;USGS 2012).

Fragmentation of decision-making
Many government agencies and businesses may have some responsibility for a given resource, with different regulations and incentives motivating its management and use. Adaptations to climate change are being inhibited by fragmentation of responsibilities; a lack of coordination at the federal, private, and nongovernmental levels; and the proliferation of often duplicative and sometimes contradictory adaptation data, tools, and resources Lebow et al. 2012;National Climate Adaptation Summit Committee 2010;Simmonds 2011;Winkler et al. 2012). Fragmentation of jurisdictional control is also a critical barrier to building the resilience of systems that cross jurisdictional boundaries (e.g., transportation systems, ecosystems) (NRC 2009;OTA 1993;USGS 2012).
Beyond the policy environment, fragmentation among research efforts and data production from the physical and social sciences (Clark and Levin 2010) has led to many stakeholders feeling overwhelmed by the amount and complexity of available information ).

Institutional constraints
Preparing for climate change requires flexible systems and approaches, such as adaptive management, (Folke 2006;Lee 1993;Nelson et al. 2007;NRC 2004). However, many existing institutional structures, such as accepted rules for water infrastructure planning, inherently lack the flexibility to allow for effective responses to a dynamic and changing climate Garfin et al. 2012;McNeeley 2012). Existing regulations and laws often have rigid structures, or are based on principles of a non-changing climate (stationarity) that can inhibit the use of flexible strategies needed to prepare for climate change (Brugger and Crimmins 2011;Garfin et al. 2012;Simmonds 2011;USGS 2012). This includes the lack of clear, legal mandates to consider climate conditions and impacts when making decisions (Gregg et al. 2011;Marra et al. 2012;NRC, 2010a). Restrictive management procedures in systems such as biodiversity conservation and emergency management can also prevent the advancement of adaptation activity (USGS 2012). Other barriers to current adaptation efforts stem from past decisions, institutions, or infrastructure (Carpenter and Brock 2008;Moser and Ekstrom 2012).
A lack of influence, legal or management authority, or operational control over systems and sectors likely to be vulnerable to climate change can also impede action and inhibit responsiveness (CDP 2011;Craig 2008;Vose et al. 2012). For example, a frequently flooded road within a municipality may be under state or federal control, which limits the local community's ability to implement adaptation actions. This is also the case when a river or stream is under state authority, but cuts through private, tribal, or Federal lands.

Lack of leadership or champions
Strong political leadership and the creation of champions for adaptation are frequently noted as a reason that many adaptation efforts have been successful (Moser and Ekstrom 2012;Smith et al. 2009). A lack of political leadership and entrenched political structures, however, can be barriers to advancing resilience-building approaches (Brugger and Crimmins 2011;Schramm 2012). Adaptation processes and policies adopted through Executive Order by one Administration but not incorporated into legislation can be reversed by successors . Moreover, even as the scientific evidence for climate change becomes more robust and certain, evidence from public polls on climate change indicate political polarization (Ding et al. 2011;Leiserowitz et al. 2012).

Divergent risk perceptions, cultures, and values
Because of different and sometimes conflicting individual and group cultures, values, and experiences, there are many divergent perceptions about the risk of climate change impacts Leiserowitz 2006;Verweij et al. 2006). This can lead to polarization and gridlock surrounding decisions about how to prepare for long-term climate variability and change. Some think climate adaptation and mitigation are top priorities, and others do not Kahan et al. 2011;Renn 2011). It is critical to move beyond this gridlock and create collaborative and inclusive processes for implementing climate adaptation (Doria et al. 2009;Renn et al. 2011;van Aalst et al. 2008;Verweij et al. 2006). Currently, a dearth of experience integrating local knowledge and needs with traditional scientific information has impeded adaptation activity and capacity building in many parts of the nation (Lackstrom et al. 2012;McNeeley 2012). Cultural taboos, resistance to change, and psychological barriers are also be impediments to climate action (Ding et al. 2011;Gifford 2011;NRC 2009;Simmonds 2011;Weber and Stern 2011).

Overcoming barriers
A number of actors across sectors and regions are organizing to collectively overcome barriers and adapt to climate change. This section profiles four examples of adaptation in the Colorado River Basin, in the Northwoods of Wisconsin, on Cape Cod Massachusetts, and through the National Integrated Drought Information System (NIDIS). These examples were selected because of their explicit attempts to lessen or overcome the barriers presented in the previous section and their ability to bridge multiple spatial and temporal scales.

Illustrative case one: adaptive governance in the Colorado River Basin
The Colorado River supplies water and valuable ecosystem services to 33 million people, and is highly vulnerable to climate change because of decreases in mountain snowpack and water availability, increased competition among water users, fires, drought, invasive species, and extended extreme heat events, among other threats (Cayan et al. 2010;Christensen and Lettenmaier 2007;Garfin et al. 2012;Hidalgo et al. 2009;Pierce et al. 2008;Seager and Vecchi 2010). The 1922 Colorado River Compact, which allocates water among seven U.S. states and Mexico, was agreed upon in a particularly wet time period (Gray et al. 2011;Woodhouse et al. 2006); thus the river water is already over-allocated for current conditions. Given the likelihood of having less water because of climate change, resource managers and government leaders are increasingly recognizing that water must be managed with flexibility to respond to the projected impacts and the range of possible future climates (Brown 2010;Garfin et al. 2012). Multiple actors across all scales of governance (i.e., tribal, local, state, federal), nongovernmental organizations, and the private sector are organizing and working together to address these concerns and the relation between climate and other stresses in the basin.
The Western Governors' Association (WGA) spearheaded adaptation efforts to enable Federal, state, tribal, local, and private sector partners to address a range of issues, including climate change (WGA 2006;. For example, the Western Federal Agency Support Team (WestFAST), which was established in 2008, created a partnership between the Western States Water Council (WSWC) and 11 Federal agencies with water management responsibilities in the western United States. The agencies created a work plan in 2011 to address three key areas: (1) climate change; (2) water availability, water use, and water reuse; and (3) water quality. To date they have produced the WestFAST Water-Climate Change Program Inventory, the Federal Agency Summary, and a Water Availability Studies Inventory (http://www.westgov.org/wswc/WestFAST.htm).
The WSWC and the USACE produced the Western States Watershed Study (WSWS), which demonstrated how Federal agencies could work collaboratively with western states on planning activities (USACE 2009). In 2009, the WGA also adopted a policy resolution titled "Supporting the Integration of Climate Change Adaptation Science in the West" that created a Climate Adaptation Work Group composed of western state experts in air quality, forest management, water resources, and wildlife management. Other important adaptation actions were the SECURE Water Act in 2009, the Reclamation Colorado River Basin water supply and demand study, and the creation of NIDIS to support stakeholders in coping with drought (Hayes and Pulwarty 2012 [in press]; Reclamation 2011a, b).

Illustrative case two: climate change adaptation in forests
Northern Wisconsin's climate has warmed over the past 50 years, and windstorms, wildfires, insect outbreaks, and floods are projected to become more frequent in this century (Swanston et al. 2011). The resulting impacts on forests, combined with fragmented and complex forest ownership, create management challenges that extend across ownership boundaries, creating the need for a multi-stakeholder planning process (Joyce et al. 2009;Miles 2010;WDNR 2009;. To address these concerns, the Northern Institute of Applied Climate Science, the USDA's Forest Service, and many other partners initiated the Climate Change Response Framework to incorporate scientific research on climate change impacts into on-the-ground management. Originally developed as a pilot project for all-lands conservation in northern Wisconsin, it has expanded to cover three ecological regions [Northwoods (Fig. 4), Central Hardwoods, and Central Appalachians] across eight states in the Midwest and Northeast. The Framework uses a collaborative and iterative approach to provide information and resources to forest owners and managers across a variety of private and public organizations. Several products were developed through the Framework in northern Wisconsin: 1. Vulnerability and mitigation assessments summarized the observed and projected changes in the northern Wisconsin climate; projected changes in forest composition and carbon stocks across a range of potential climates; and assessed related vulnerabilities of forest ecosystems in northern Wisconsin (Swanston et al. 2011). 2. Forest Adaptation Resources: Climate Change Tools and Approaches for Land Managers (Swanston and Janowiak 2012) was developed to help managers identify management tactics that facilitate adaptation. A "menu" of adaptation strategies and approaches for planning, implementing, and monitoring adaptation activities was synthesized into an adaptation workbook from a broad set of literature, and refined based on feedback from regional scientists and managers (Butler et al. 2011;Janowiak et al. 2012).
3. A series of adaptation demonstrations was initiated to showcase ground-level implementation. The Framework and adaptation workbook provide a common process shared by diverse landowners, and a formal network that supports cross-boundary discussion about different management objectives, ecosystems, and associated adaptation tactics.
From the beginning, the Framework has taken an adaptive management approach in its adaptation planning and projects. Lessons learned include: The Framework brings scientists and land managers together to assess the vulnerability of ecosystems based on scientific information and experience in order to plan adaptation actions that meet management goals. On-the-ground implementation has just begun, and an increased focus on demonstrations, monitoring, and evaluation will inform future adaptation efforts.
5.3 Illustrative case three: transportation, land use, and climate change: integrating climate adaptation and mitigation in Cape Cod, Massachusetts Cape Cod, Massachusetts, a region of scenic beauty and environmental significance, is currently affected by sea level rise, coastal erosion, and localized flooding-impacts that are likely to be exacerbated by climate change (Volpe National Transportation Systems 2011a; Fig. 4 Northwoods climate change response framework region b). To address these concerns and help meet the state's greenhouse gas (GHG) reduction target (25% reduction based on 1990 levels by 2020), the DOT's Volpe Center worked with Federal, regional, state, and local stakeholders to integrate climate change into existing and future transportation, land use, coastal zone, and hazard mitigation planning through an initiative called the Transportation, Land Use, and Climate Change Pilot Project (Commonwealth of Massachusetts 2004; Volpe National Transportation Systems Center 2011a).
The process was initiated through an expert elicitation held in mid-2010 to identify areas on Cape Cod that are or could potentially be vulnerable to sea level rise, flooding, and erosion. The Volpe Center then used a geographic information system (GIS) software tool to develop and evaluate a series of transportation and land use scenarios for the Cape under future development projections (Esri 2011; Volpe National Transportation Systems Center 2011b). All scenarios were evaluated against a series of criteria that included: (1) reduction in vehicle miles traveled (VMT); (2) reduced GHG emissions; (3) reduction in transportation energy use; (4) preservation of natural/existing ecosystems; (5) reduction in percentage of new population in areas identified as vulnerable to climate change impacts; and (6) increased regional accessibility to transportation (Volpe National Transportation Systems 2011a).
Once the preliminary scenarios were developed, a workshop was convened in which community and transportation planners, environmental managers, and Cape Cod National Seashore stakeholders selected areas for new development and transit improvements to accommodate new growth, while meeting the goals of reduced GHG emissions, increased resilience to climate change, and the conservation of natural systems (Volpe National Transportation Systems 2011b). Through interactive visualization tools, participants were able to see, in real time, the impacts of their siting decisions, allowing them to evaluate synergies and potential tradeoffs of their choices and to highlight areas where conflict could or already does exist, such as density enhancement in areas already or likely to be vulnerable to climate change (APA 2011). As a result, the stakeholders developed a refined transportation and land use scenario that will support the region's long-range transportation planning, as well as other local, regional, and state plans.
This updated scenario identifies strategies that have climate adaptation and mitigation value, helping to ensure that the region simultaneously reduces its GHG footprint while building resilience to existing and future changes in climate (Volpe National Transportation Systems 2011a; b). The overall success of the pilot project stemmed from the intensive stakeholder interaction at each phase of the project (design, implementation, and evaluation). ), is a Federally created entity that improves the nation's capacity to proactively manage drought-related risks across sectors, regions, and jurisdictions. It was created by Congress to "enable the Nation to move from a reactive to a more proactive approach to managing drought risks and impacts." NIDIS has successfully brought together government partners and research organizations to advance a warning system for drought-sensitive areas.
The creation of NIDIS involved many years of development and coordination among federal, state, local, regional, and tribal partners, with the help of Governors' associations and Senate and congressional leaders. NIDIS provides: (1) drought early warning information systems with regional detail concerning onset and severity; (2) a web-based portal (www.drought.gov); (3) coordination of federal research in support of and use of these systems; and (4) leveraging of existing partnerships and of forecasting and assessment programs. NIDIS currently supports work on water supply and demand, wildfire risk assessment and management, and agriculture. Regional drought early warning system pilot projects have been established to illustrate the benefits of improved knowledge management, improved use of existing and new information products, and coordination and capacity development for early warning systems. These prototype systems are in the Upper Colorado Basin, the Apalachicola-Chattahoochee-Flint River Basin in the Southeast, the Four Corners region in the Southwest, and the State of California. The NIDIS Outlook in the Upper Colorado Basin early warning system, for example, is conducted weekly, and now draws in a variety of users from Federal agencies, water resource management, and the recreation industry.
The Western Governors' Association, the U.S. Congress, and others formally acknowledge that NIDIS provides a successful example of achieving effective Federal-state partnerships by engaging both leadership and the public, and by establishing an authoritative basis for integrating monitoring and research to support risk management. Some of NIDIS' keys to success include: & Usable Technology and Information for Decision Support: The U.S. Drought Monitor map, which integrates multiple indicators and indices from many data sources, was developed before NIDIS was established and has become a useful visual decision support tool for monitoring and characterizing drought onset, severity, and persistence. NIDIS has engaged regional and local experts in refining the regional details of this national product and in "ground truthing" maps via email discussions and webinars. & Financial Assistance: Federal funding was NOAA-allocated specifically for NIDIS, but leveraged in kind by other agencies and partners. & Institutional/Partnerships: Effective collaborations, partnerships, and coordination with NOAA, WGA, USDA, DOI, and USGS, as well as local, regional, state, and tribal partners and with the National Drought Mitigation Center at the University of Nebraska-Lincoln, have led to multi-institutional interest. & Institutional/Policy: The NIDIS Act was oriented toward the improvement of coordination across Federal agencies and with regional organizations, universities, and states. It focused on the application of technology, including the Internet, and on impact assessments for decision support. A key aspect of NIDIS is the development of ongoing regional outlook forums based on the above information to build awareness of the drought hazard and to embed information in planning and practice (in partnership with the National Drought Mitigation Center, the Regional Integrated Sciences and Assessments (RISAs), and other research-based boundary organizations) to reduce risks and impacts associated with drought (see Fig. 5). & Leadership and Champions: There was leadership at all levels over more than two decades (1990s and 2000s) to establish the NIDIS Act, including political (WGA, Southern Governors' Association, National Governors Association, U.S. Senators, and congressmen); scientific (Wilhite, Pulwarty, Verdin); and federal agency leadership (NOAA, USDA, DOI). & Risk Perceptions: Whereas drought had been considered primarily a western issue in previous decades, drought is now regularly impacting the southern, southeastern, and northeastern parts of the country, and response strategies are needed. Because of the 2012 drought, more than 63 % of the area in the contiguous U.S. was classified by the end of July as experiencing moderate to exceptional drought, and more than 3,200 heat records were broken in June 2012 alone (NOAA 2012;Schwalm et al. 2012).

Research and development needs in support of adaptation
Adaptation to climate change is in an emerging stage and will therefore benefit from more research. This section draws on the information gleaned from our analysis, but it is not meant to be a comprehensive research agenda on adaptation. It does not identify the many research needs that are specific to individual sectors and regions, such as development of heat-and drought-resistant varieties of crops, appropriate management of reservoirs under increased uncertainty about future conditions, strategies for managing coastal resources, the effectiveness of corridors for species migration, and ecosystem-based adaptation. Some of these sector-and region-specific adaptation needs are mentioned in the sector-specific chapters of the upcoming 2013 NCA. The focus of this section is instead on some high-level actions that the federal government can enable.
6.1 Research on the policy-making process (i.e., governance and institutions) As noted above, a key barrier to climate adaptation and to resource management in general is the fragmentation at different levels of government (federal, state, and local); at geographic boundaries (e.g., ecosystems or watersheds crossing international borders, borders between states, and borders between municipalities); and in various sectors (e.g., different departments and agencies within the same government having overlapping or competing authorities) (Craig 2008;Kates et al. 2012). Research is needed on how to reduce this barrier by, for example, fostering coordination and better communication and sharing of knowledge among fragmented governing structures and stakeholders. Understanding the dynamics of governance and institutional structures (including the influences of multiple and sometimes conflicting risk perceptions, cultures, values, and ideas about how to govern the economy and environment) is critical to adaptation concerning complex environmental resource problems such as climate change (Lemos and Agrawal 2006;Verweij et al. 2006). Ongoing research that supports, sustains, and identifies criteria for best practices for building governance and institutional capacity to anticipate and respond to climate change is imperative (Bierbaum et al. 2007;Kareiva 2008). It should focus on identifying climate-sensitive laws, policies, and regulations that support climate-related activities (Lackstrom et al. 2012;Moser and Ekstrom 2012).
One important consideration of the policy-making process is that rigid laws, regulations, and institutions can sometimes encourage maladaptive behaviors in particular locations (Carpenter and Brock 2008;Easterling et al. 2004;Kates et al. 2012). Because adaptation is inherently place-and time-specific, a detailed understanding of institutional interworkings and dynamics is critical to moving adaptation strategies forward. Information gathered from areas outside of the traditional climate studies can be researched for relevance to various adaptation processes (Dovers and Hezri 2010;Skaggs et al. 2012).
Research is also needed to better understand how certain underrepresented and highly vulnerable groups (e.g., tribes, inner city poor, rural communities) can be supported in reducing vulnerability and building adaptive capacity (Dow et al. 2006;Intertribal Climate Change Working Group 2009;Kates et al. 2006;Thomas and Twyman 2006). Research on policy processes, governance, and institutions in the United States to date has been understudied and underappreciated (Eakin and Patt 2011).

Research on organizing and delivering usable climate change information
One of the challenges to adaptation often cited by decision-makers is the lack of clear information about the rate and magnitude of climate change. Research investigating the types of information users want and the creation of appropriate delivery mechanisms are needed. To be usable, scientific information must be relevant to users (Lemos and Rood 2010). To best understand the needs and context of decisionmakers, researchers will need to involve and engage decision-makers in clarifying how decision-making processes unfold and how scientific and other information to support, enable, and empower decision-making is used in these proceses (Hulme and Dessai 2008). The participation and engagement of stakeholders in the development of questions for research agendas and project implementation are important, as this creates a two-way conversation about what is needed and possible.
The research could examine, for example, how to make relevant monitoring data and climate change information accessible, as well as how to update it regularly, in a federally supported clearinghouse. It will be important to create a "translational" capacity-i.e., to enable users to combine data sets to evaluate how climate change, in concert with other multiple stresses, may change desired options. Having the further capability of linking local users to regional and federal tools to support adaptation decision-making, evaluation, and monitoring would advance the collection of best practices. A map of existing federal science, capabilities, and services in support of adaptation could begin to provide a useful information system for users (CEQ 2010;2011b; National Climate Adaptation Summit Committee 2010; USGS 2012).
One of the challenges for adaptation is the complexity of information on climate change. Some decision-makers find that climate model projections are too coarse and look too far into the future and that they address average conditions rather than variability, and may be about variables that are not useful (Lemos and Rood 2010). General Circulation Model (GCM) output, for example, is often considered to have too coarse a resolution, and different GCMs can yield very different projections. Climate model output can be used to project changing growing season average temperatures, but this may be less useful than dates of first and last frost, or the timing and extent of extreme rainfall events. The matter is further complicated by the lack of a single institution providing climate change information.
Research should address the types of information that need to be made available, as well as the methods for transmitting such information in a way that can best support understanding of climate change risks and opportunities and facilitate decision-making.

Research on decision-making in light of uncertainty
Climate change adaptation involves making decisions about an uncertain future climate, as well as other future conditions, that can extend for many decades (Moore et al. 2012). Even if information on projected trends were accessible and clearly understood, there would remain uncertainty about exactly how much the climate will change, where it will change, how key variables such as precipitation will change, and how society will react to these changes. This is added to the uncertainty about important future socioeconomic conditions, such as population, income, settlement patterns, global competition, changing human preferences, and technology and innovation (Lemos and Rood 2010). There is research on decision-making approaches that account for uncertainty (Lempert and Groves 2010;Means et al. 2010), which is useful for making decisions in light of complexity and changing conditions (Moore et al. 2012;NRC 2004;Renn 2008). Additional research is needed, however, on the role and efficacy of inclusive and iterative risk management approaches in climate change adaptation, including how various risk perceptions influence behavior in these decision-making processes (Aven and Renn 2009;Aven et al. 2011;Jones and Preston 2011;Kahan et al. 2011;NRC 2010a;Renn 2011;Renn et al. 2011;van Aalst et al. 2008).

Research on methods to incorporate adaptation
Adapting to climate change requires altering the planning for, and management of, our natural and built systems (ORNL 2012b;USGS 2012). Research on how measures that promote adaptation to climate change can be built into existing institutions, networks, and agencies, rather than creating a brand new set of institutions, is needed. Our regulations, laws, and agency missions should be reevaluated with climate change in mind. For example, flood plain maps could be required to take projected climate change (e.g., sea level, storm surge, rainfall intensity, and flood volumes) into account. Building codes may need to be updated to handle more extreme weather impacts, and multi-hazard mitigation planning may need to be revised to allow future climate projections, not historical climate conditions, to inform decision-making.
Climate change is occurring within the context of other environmental and socioeconomic stresses. Given that the adaptation options chosen will have both short-and long-term consequences, and may affect sectors and regions differently, it is important to develop evaluation criteria to measure outcomes and learn to characterize successful adaptation. As the adaptation process itself must be adaptive, continued evaluation and revision of adaptive strategies will be needed (National Climate Adaptation Summit Committee 2010; PCAST President's Council of Advisors on Science and Technology 2011).

Other research and development needs
In addition to the aforementioned research and development needs, a series of needs that cross across sector, scale, and geography emerged during analysis. Many of these crosscutting needs include: & Costs and Benefits of Adaptation. There is uncertainty about the costs of different adaptation options, as well as the costs of inaction (i.e., benefits of adaptation). This includes analysis of the costs of traditional grey adaptation (i.e., for hard infrastructure) versus green approaches to adaptation (Ingram et al. 2012;Lebow et al. 2012;Sussman et al. 2012;USGS 2012;Winkler et al. 2012). & Best Adaptation Practices. Research could define and apply criteria that are useful to decision-makers to evaluate adaptation options. The research could involve a comprehensive assessment of adaptation options that are effective under changing climate conditions and are affordable and feasible. It should also examine conditions that affect relative costs and benefits (Doria et al. 2009;Sussman et al. 2012;Ackerman et al. 2009). & Adaptation and Mitigation Interface. Many mitigation measures affect adaptation, and many adaptation measures have consequences for mitigation. The literature on this topic, however, is limited. Among the topics to be explored through research are the growing and competing demands for land, water, and energy, and how mitigation actions could affect adaptation options, and vice versa Ingram et al. 2012;ORNL 2012a;Skaggs et al. 2012). & Climate Adaptation Science. While major advancements have taken place, there remains a need for basic and applied research on climate adaptation science to help inform decision-making. & Critical Thresholds. Research is needed to identify critical thresholds beyond which social and/or ecological systems are unable to adapt to climate change. This should include analyzing historical and geological records to develop models of "breakpoints" (NAST 2000; National Climate Adaptation Summit Committee 2010). & Extreme Events. Research is needed on preparedness for and response to extreme events, such as droughts, floods, intense storms, and heat waves, to protect people, ecosystems, and infrastructure. Increased attention must be paid to how the "tails" of the distribution may change as climate change proceeds, and how that affects adaptation actions (IPCC 2012; Kates et al. 2012).

Conclusions
Our main conclusions are: 1. Substantial adaptation planning is occurring in public and private sectors and at all levels of government, however, few measures have been implemented and those that have appear to be incremental changes. 2. Barriers to implementation of adaptation action include lack of funding, policy and legal impediments, and difficulty in anticipating climate-related changes at local scales. 3. There is no one-size fits all adaptation, but there are similarities in approaches across regions and sectors. Sharing best practices, learning by doing, and iterative and collaborative processes including stakeholder involvement, can help support progress.
4. Climate change adaptation actions often fulfill other societal goals, such as sustainable development, disaster risk reduction, or improvements in quality of life, and can therefore be readily incorporated into existing decision-making processes. 5. Vulnerability to climate change is exacerbated by other stresses such as pollution and habitat fragmentation. Adaptation to multiple stresses requires assessment of the composite threats as well as tradeoffs amongst costs, benefits, and risks of available options. 6. The effectiveness of climate change adaptation has seldom been evaluated, because actions have only recently been initiated, and comprehensive evaluation metrics do not yet exist.
Adaptation to climate change is in a nascent stage, but is happening at all levels of government, as well as in the private and non-profit sectors. Yet there is a long way to go. Adaptation will require not only the protection of existing livelihoods and land and water uses, but in some cases the enabling of changes in livelihoods and land and water uses. The federal government is beginning to develop the institutions and practices necessary to address adaptation. A number of states have developed adaptation plans, but most have not. Many local governments have developed adaptation plans or engaged in adaptation activities, but many others have not. Among the important barriers to adaptation that governments must address are lack of financial and staff resources, lack of access to useful information about climate change, difficulty in making decisions under uncertainty, and fragmentation of policies, authorities, and information.
A key federal role in adaptation is enhancing the adaptive capacity of regions and sectors. This could include reviewing existing laws and regulations to ensure that they enable proactive as well as efficient reactive adaptation to climate change; funding pilot projects; providing usable information, including disseminating best practices; and helping to develop tools to evaluate successful adaptation.
Protecting people, infrastructure, and ecosystems in a changing climate will require the updating of current best practices for adaptation and disaster preparedness and response. A streamlined national clearinghouse for current best practices is needed, and existing small networks of scientists and stakeholders could be linked (National Climate Adaptation Summit Committee 2010; NRC, 2010b). Building blocks could include the existing USDA Extension Services, the Sea Grant Programs, the NOAA Regional Climate Centers (RCCs) and RISAs, the DOI Landscape Conservation Cooperatives (LCCs), and new regional Climate Science Centers (CSCs).
The authority to undertake necessary changes varies among levels of government, but the need to identify and implement these changes at the appropriate scale is nationwide. The federal government owns 30% of U.S. land, and state governments own large tracts of land. Land-use planning, however, is generally carried out at the local government level. The challenge is to ensure that existing institutions, agencies, and networks identify the potential threats posed by climate change, and move forward with appropriate transparent and collaborative processes to develop and implement effective adaptation plans and measures. The Federal government can help facilitate this systematically and thoughtfully, and with adequate provision of relevant information, resources, and funding.
Key information gaps remain. Decision support tools need to be further developed and evaluated for usefulness and usability. For example, rules for managing Great Lakes levels, reservoir levels, and dam dredging times will need revision; surveillance for disease outbreaks and extreme events such as floods, droughts, and heat waves needs to be heightened; and new tools to characterize "breakpoints" in management and infrastructure must be developed and shared.
As identified in the research section, basic and applied research is needed on climate adaptation science (e.g., management of the resources of an acidifying ocean, the effectiveness of migration corridors in preserving ecosystem integrity and services) and how to effectively manage transformations of social or natural systems. Similarly, regional analyses of climate change impacts need to be conducted and refined. No one lives in the "global average temperature," and climate change impacts will occur in concert with existing regional conditions; thus continually updating and sustaining regional assessments will be important. Stakeholders must be included from the outset to define the key questions to be answered and to identify feasible options for coping with climate change that address regionally specific needs. Regional vulnerability mapping and regional listening forums will be key to determining which impacts are of greatest concern for different regions and in ensuring the development of effective response strategies. A short-and long-term research agenda must also be developed that will provide timely answers for decision-makers. New research foci on adaptation, decision support, and education and outreach will be important in providing useful, usable, and understandable information in a timely fashion.
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