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Decision-makers, managers and communities in low-lying coastal regions face many challenges in planning for and adapting to escalating coastal hazard risk, given uncertainty about sea-level rise and complex and contested environmental and socio-economic futures. Collaborative and participatory approaches can help to address such challenges and enable proactive adaptation. However, there is limited empirical evidence of such approaches yielding outcomes that can genuinely be described as shifting business as usual, and fewer still that have informed institutional change. This paper provides such evidence based on an assessment of a novel collaboration between local government, Māori, stakeholders, community members, consultants and researchers in the formulation of a 100-year coastal hazard management strategy in Aotearoa New Zealand. Thematic analysis of interviews, surveys and workshop materials was used to distil lessons learned by participants involved in formulating this anticipatory long-term strategy. Results indicated the importance of deliberative, flexible and transparent governance processes that can enable collaboration amongst Māori, local and region-wide stakeholders, in a process consistent with and supported by the national governmental frameworks, and regulatory and non-regulatory measures. The importance of aligning scientific, local and Indigenous knowledges is highlighted. Furthermore, novel tools and methodologies were used in the strategy formulation process, hitherto not applied in a real-life coastal decision-making process, to address changing risk over time and uncertainties. This enabled the tailoring of strategic planning and decision processes to reflect local contexts and governance interactions. Adaptive pathways were developed to enable short-term actions to be taken while leaving open long-term options and alternative pathways available for future adjustment as the hazards and impacts intensify. The lessons learned from the development of the coastal management strategy offer insights to support future collaborative decision-making processes in climate change adaptation. They advance scholarly understanding about how sea-level rise risks can be addressed in a long-term strategic formulation process in a dynamic and 'fit-for-purpose' manner. [Display omitted] • We thematically analysed the formulation of a 100-year coastal hazards strategy. • Key themes emerged to reveal lessons learned from the process. • Collaborative and flexible governance processes contributed to building trust. • Proactive, tailored decision tools enabled development of adaptation pathways. • Scientific, technical, local and Indigenous knowledges were incorporated. [ABSTRACT FROM AUTHOR]

Determining effects of climate change on landscapes involves numerous uncertainties. This paper presents and illustrates a protocol for climate attribution of landscape responses. The major steps are ascertaining potential climate-related responses, establishing plausibility for a climatic influence, identifying alternative or additional causes, testing possible climate and non-climate causes, and interpreting the role of climate and climate change in the landscape response. The protocol is based on existing practice in the historical and interpretive branches of Earth and ecological sciences, and explicitly considers negative (non-confirmatory) results for climate and other factors. The protocol is applied to the conversion of brackish marsh to open water in the upper Neuse River estuary, North Carolina. Conversion since at least the mid twentieth century can be attributed to relative sea-level rise, driven primarily by general climate warming, with no supporting evidence for any additional or alternative drivers. The only other factor with supporting evidence is human modification in the form of ditches, around which conversion was concentrated, though marsh loss also occurred in unditched portions. Rapid recent marsh loss is attributable to Hurricane Florence (2018), particularly the storm surge. Weak positive inferential support exists for a role of climate change in the storm, but aspects of the storm's impact not linked to climate are more important for the marsh conversions. Overall, the landscape response can be linked to climate, exacerbated by direct human impacts of marsh ditching, and strongly influenced by local place factors and the specific storm track. Recent and ongoing climate change is a significant factor, but not paramount, in determining the landscape response. The Neuse River case study is not unusual—and is probably typical—in identifying a combination of climate and other factors strongly influencing landscape response. [Display omitted] • Attributing landscape responses to climate change presents numerous complexities. • Landscape response attribution protocol based on traditional geomorphic approaches • LRA protocol applied to recent conversion of estuarine marsh to open water • Marsh loss due to sea-level rise & major storm, but non-climate factors important • LRA protocol useful to identify & evaluate climate & non-climate drivers of change [ABSTRACT FROM AUTHOR]

This paper describes a probabilistic approach for mapping of coastal flood hazards associated with sea-level rise and storm intensification toward the end of the 21st century. Under the Representative Concentration Pathway (RCP) 8.5, the Coupled Model Intercomparison Project Phase 5 (CMIP5) predicts a 0.6-m ensemble mean of sea-level rise for the Central Pacific from the 1986–2005 to 2081–2100 epochs. Fifty downscaling simulations of the 2080–2099 period from the CMIP5 NCAR-CCSM4 model produce 2492 hurricanes around the Hawaiian Islands. In comparison with a control dataset for the 1980–1999 period, the simulated future hurricanes show a slight increase in number and a northward shift of the tracks toward the Hawaiian Islands. There are 627 hurricanes in the 2080–2099 dataset with potential impact on Oahu, and the top 24 storms selected by wind speed at the urban Honolulu coast define a scenario set for inundation mapping. A suite of spectral wave, circulation, and Boussinesq models in a nested grid system describes generation and propagation of surge and waves across the ocean as well as wave setup and runup at the coast. The interoperable package includes phase-averaged and phase-resolving processes to determine the coastal flood hazards over a range of spatial and temporal scales during a hurricane event. Since the simulated dataset corresponds to a quasi 1000-year period, barring the tail end of the distribution, the suite of inundation scenarios enables definition of flood hazard maps with return periods of up to 500 years or annual exceedance probabilities of 0.2% or greater for climate change adaptation. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines adaptation to current storm surge flood risk as one indicator of anticipatory adaptation to climate change impacts. Focusing on community businesses, a web-based survey obtained information on hurricane preparedness and risk perceptions in Sarasota County, Florida. A model of current precautionary action that utilized previously identified business characteristics predictive of business preparedness and post-disaster recovery, a spatial variable indicating storm surge exposure, and items measuring the risk perception and information-seeking behavior of business owners explained a majority of the variance in current levels of preparedness. Use of online risk information sources and the geographic distribution of customers and were the strongest predictors of preparedness. Results indicate that the adaptive capacity of businesses may vary significantly with types of businesses, locations, and socio-cognitive characteristics of business owners. To encourage overall community resilience, risk communication efforts should be targeted based on specific elements that predict business preparedness. [Copyright &y& Elsevier]

Abstract: This paper describes the impacts of sea surface temperature (SST) rise and sea-level rise (SLR) on cyclonic storm surge flooding in western Bangladesh. A calibrated numerical hydrodynamic model was used to simulate surge wave propagation through the rivers and overland flooding. The model was calibrated with base condition (present climate), and then eight flooding scenarios of plausible future conditions were assessed by considering increased surge heights. Flooded area, flooding depth and surge intrusion length were computed by superimposing the predicted maximum water level information on a digital elevation model (DEM). This analysis showed that for a storm surge under 2°C SST rise and 0.3m SLR, flood risk area would be 15.3% greater than the present risk area and depth of flooding would increase by as much as 22.7% within 20km from the coastline. Within the risk area, the study identified 5690km2 land (22% of exposed coast) as a high-risk zone (HRZ) where flooding of depth 1m or more might occur, and people should move to nearby cyclone shelters during extreme cyclonic events. Predicted area of HRZ is 1.26 times the currently demarcated HRZ. It was estimated that 320 additional shelters are required to accommodate people in the newly identified HRZ. This information would be of value to policy and decision makers for future shelter planning and designing shelter heights. [Copyright &y& Elsevier]