Doctor of Philosophy / Department of Environmental Design and Planning Program / Lee R. Skabelund / Despite the growing number of urban adaptation planning initiatives to climate change hazards, there exist significant barriers related to implementation uncertainties that hinder translation of adaptation plans into actions, resulting in a widely recognized ‘planning-implementation gap’ across scales and regions. Bridging the planning-implementation gap will require overcoming implementation uncertainties by better understanding the relationships between the primary factors driving adaptation planning initiatives and emerging adaptation options across spatial scales. The modified Driver-Pressure-State-Impact-Response model published by Rounsevell, Dawson, and Harrison in 2010 provided a robust framework for identifying the primary factors driving adaptation planning initiatives and the emerging adaptation options related to risk of changing climate and flooding events in the urban context. Drawing on evidence from the systematic review of 121 adaptation planning case studies across North America, this research derived qualitative and quantitative data, which was subsequently analyzed using binary logistic regression to generate objective and generalizable findings. The findings of binary logistic regression models suggest that the choice of specific adaptation options (namely enhancing adaptive capacity; management and conservation; and improving urban infrastructure, planning, and development) may be predicted based on the assessment of primary factors driving adaptation planning initiatives (namely, anticipation of economic benefits; perceived threats to management and conservation of urban natural resources; support of human and social systems; and improvement of policy and regulations) in relation to the risk of changing climate and urban flooding events. This does not imply that other primary factors (namely information and knowledge; perceived funding and economic opportunities; evidence of climate change effects; and general concerns) have no or insignificant relationships with the selection of adaptation options, only that the review did not find evidence to support such claims. These study findings may offer useful guidance to the design and further development of planning and decision support tools that could be used for assessment of adaptation plans and selection of robust adaptation options that take account of uncertainties surrounding implementation of effective climate adaptation actions. Study findings can also inform evidence-based policy and investment decision making, especially in regions where urban adaptation plans are weak or absent.

Climate resilience is increasingly an attribute of competitive global cities. Cities that are most responsive to change will continue to prosper. To achieve this, governance structures and decision-making approaches that promote flexible and/or robust adaptation action are required. This thesis introduces a framework for urban adaptation planning that links medium-term risk management with the development and appraisal of long-term adaptation pathways. A long-term plan informed by the appraisal of a range of plausible pathways provides the opportunity to retain the flexibility to respond to future uncertainties, whilst also demonstrating how a city could manage future climate risk. This provides stakeholders with confidence that long-term risk is adequately considered, even if there is not a need to act immediately. To demonstrate how adaptation pathways can support adaptation decision-making in an urban system, the approach and methods developed as part of this thesis are applied in London. Adaptation pathways in response to water scarcity, surface water flood and heat risk were developed, and their appraisal presented as pathways diagrams. These diagrams provide a visual representation of the sequencing of decision points and plausible adaptation actions that may be implemented in the future. Pathways diagrams present climate risk and adaptation information for decision-makers in a salient and actionable manner. The pathways responding to individual risks in London are then brought together to demonstrate how an integrated assessment framework may be used to appraise city-scale adaptation pathways that respond to multiple climate risks. The growing emphasis within adaptation planning on approaches that can react flexibly to change increases the need to better understand the dynamics of climate risk and embed learning about the effectiveness of adaptation actions. To complement the pathways and adaptation decision-making research presented in this thesis, a framework that links adaptation monitoring and evaluation (M&E), risk assessment and decision-making is presented and explored to highlight the potential benefits of, and mechanisms for, adaptation M&E to inform and strengthen iterative risk-based adaptation planning. Demonstrated for the Thames Estuary, where concepts of adaptation planning have been pioneered but the opportunities of linking to monitoring and evaluation have not been extensively explored, we show how the framework can highlight actions and factors that are contributing to improving adaptation outcomes and those that require strengthening. This thesis contributes to the literature on urban climate change adaptation planning under conditions of uncertainty. This thesis also contributes to the evidence base needed to justify long-term planning and realise the benefits of climate risk reduction through the implementation of flexible, long-term integrated urban adaptation plans.

As the effects of climate change become increasingly damaging and costly, a public and political consensus is building for planning that will protect private property and public infrastructure. Climate-related planning has primarily focused on mitigation, assessing vulnerability, and building adaptive capacity. Adaptation has not gained substantial ground in the area of implementation. The uncertainty associated with climate change projection and variability has emerged as a dominant barrier to adaptation. However, as knowledge accrues, the global and national science communities have been developing more detailed, fine-scale climate projections. Regional climate assessments are available for the sub-national climate regions in the U.S., and have been created based on the measurement of many components of climate, often referred to as indicators. This thesis evaluates the use of those and other indicators as adaptation decision support tools. Findings suggest that indicators can be effectively integrated into a step-wise, risk-based adaptation planning process to overcome barriers to adaptation, many of which contain concern over climate change uncertainty at their core. The combination of climate science data and information about the local experience of climate change are found to be key to the effective use of indicators in adaptation, as is the direct integration of indicators into the policy-making process. Ideally, these indicators can be used to inform trigger points for phases in a flexible adaptation approach, but more work is needed to develop methods for managing the risks and costs associated with adaptation.