Climate change vulnerability assessment (CCVA) can inform adaptation policy and help in incorporating climate futures in planning. The literature on CCVA stems from a number of research paradigms (e.g., risk assessment, natural disaster management, and urban planning), therefore making it difficult to extract major directions and methodologies from this body of work. A large number of assessments are based, partly or totally, on indicators which bring up specific methodological problems and constraints. In this study, first, we discuss the most important methodological challenges facing indicator-based vulnerability assessment (IBVA) based on a set of key conceptual papers in the field. Second, we conduct a meta-analysis of a representative sample of peer-reviewed IBVA studies, to identify how current research on IBVA is engaging with these challenges. We attempt to elicit major thematic and methodological trends in this corpus with specific focus on issues related to geographical and temporal scales, aggregation, and nonlinearity. We find that health of ecosystems and biodiversity (28%), freshwater quantity and quality (12%), and public health (10%) have attracted the highest number of studies. Less than a third of the papers in our sample give some consideration to uncertainty and nonlinearity. Assessments typically use aggregation methods that are based on the Multiple Attribute Utility Theory despite the fact that IBVA rarely satisfies the theoretical requirements of this approach. A small percentage of IBVA studies critically scrutinize prevalent assessment methodologies or attempt to develop new ones, despite the raised questions in key theoretical papers about its methodological aspects.

a b s t r a c tClimate change vulnerability assessment is a complex form of risk assessment which accounts for both geophysical and socio-economic components of risk. In indicator-based vulnerability assessment (IBVA), indicators are used to rank the vulnerabilities of socio-ecological systems (SESs). The predominant aggregation approach in the literature, sometimes based on multi-attribute utility theory (MAUT), typically builds a global-scale, utility function based on weighted summation, to generate rankings. However, the corresponding requirement for additive independence and complete knowledge of system interactions by analyst are rarely if ever satisfied in IBVA.We build an analogy between the structures of Multi-Criteria Decision Analysis (MCDA) and IBVA problems and show that a set of techniques called Outranking Methods, developed in MCDA to deal with criteria incommensurability, data uncertainty and preference imprecision, offer IBVA a sound alternative to additive or multiplicative aggregation. We reformulate IBVA problems within an outranking framework, define thresholds of difference and use an outranking method, ELECTRE III, to assess the relative vulnerability to heat stress of 15 local government areas in metropolitan Sydney. We find that the ranking outcomes are robust and argue that an outranking approach is better suited for assessments characterized by a mix of qualitative, semi-quantitative and quantitative indicators, threshold effects and uncertainties about the exact relationships between indicators and vulnerability.

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Australia's coastline is exposed to climate change and sea-level rise impacts from erosion, inundation, and changes to storm tracks and intensity. It accommodates about 80% of the population. Around 250 local councils are responsible for coastal management, with very different capacities to undertake adaptation. A decision support framework was developed to support coastal managers seeking to understand present-day and future climate change, its impacts and possible response options. Extensive engagement was undertaken with practitioners before commencing the design and at all stages of the build, in order to ensure usefulness and usability. The resulting framework, CoastAdapt (coastadapt.com.au), provides comprehensive guidance and support, including understanding of climate change science, expected impacts, and adaptation options. It contains datasets on historical flooding; present-day coastal sensitivity to erosion; and future climate extremes, sea-level rise, and inundation for each coastal council. A risk management framework supports users through the six stages of adaptation from identifying the challenges through to monitoring and evaluation. The performance of CoastAdapt has been evaluated through 11 6-week test cases with coastal managers in the public and private sectors. In future, if CoastAdapt is to remain a useful resource, it must be seen by practitioners as dynamic, relevant, and current, and on-going resources will be needed to achieve this. Climatic Change (2019) 153:491-507 https://doi.

A decision support and information delivery framework, CoastAdapt, has been built to support the coastal adaptation community in Australia to take action to address climate change and sea-level rise. For such frameworks to be useful, used and long-lived, their development requires collaboration between creators and potential users. Therefore, we undertook extensive consultation throughout the design, build and evaluation. In this paper, we explore those aspects of the consultation that focused on understanding and addressing user needs and how CoastAdapt could best provide support to effectively carry out adaptation planning and action. The first step was to identify, through an online survey and workshops, the knowledge gaps and barriers that could be addressed by CoastAdapt. The responses fed into the design and build, together with additional feedback from users on the layout and content. Following release of the beta version, further comments from users were collected and scrutinised to identify modifications that could increase relevance and utility. Finally, test cases were carried out to understand whether CoastAdapt is truly fit for purpose in addressing 'real-world' adaptation situations. The end result is a supportive framework for coastal adaptation that will require constant monitoring and updating to ensure it remains fit for purpose given Australia's rapidly evolving adaptation landscape.Climatic Change