Global spatiotemporal multi-criteria analysis of coastal risk: current and future hot spots and clusters

Coastal zones are among the environments most threatened by climate change. Although various efforts for global mapping and classification of coastal social and ecological systems have been undertaken, the ability to analyse and describe the spatial heterogeneity and multidimensionality of these phenomena remains limited. In the current study, we developed a methodological framework for assessing risk from extreme sea levels and examined its application at the global level. A multi-criteria analysis method was applied to the current scenario and to two future combinations of shared socioeconomic (SSP2 and 5) and representative concentration pathways (RCP4.5 and 8.5), accounting for risk attitudes. Risk maps derived from multi-criteria analysis aggregation of spatial indicators of hazard, vulnerability, and exposure enabled the identification of global hot spots, comprising large areas facing high levels of risk, mostly located in Northern Europe, South-East Asia and Southern USA. Spatial clusters with common risk features were identified and mapped using multivariate analysis. The results contribute to improving the state of the art by providing a synoptic view of global coastal risks. Given the high spatial resolution (1 km), the proposed methods may also be helpful for improving adaptation strategies at the regional and national scales and for facilitating the sharing of solutions between areas with similar situations identified by cluster mapping.