Progress and gaps in climate change adaptation in coastal cities across the globe

In the context of climate change adaptation, coastal cities deserve special attention as they are faced with an abundance of climate impacts while also being engines of economic development, innovation, and culture with, in theory, high adaptation potential. While there is eclectic evidence for urban adaptation, we are lacking a global overview of the extent to which coastal cities are on track in adapting to climate risks. Building on the Global Adaptation Mapping Initiative (GAMI), this paper presents findings from a global review of empirical evidence for adaptation in coastal cities. We systematically analysed adaptation actions reported in the scientific literature for 199 coastal cities to provide the first stocktake of empirical evidence of coastal urban adaptation. The paper addresses four questions: (1) How is evidence for coastal urban adaptation spread across the globe? (2) Which hazards and trends of exposure and vulnerability are reported? (3) Which responses are reported and which actors are involved in their implementation? (4) What is the speed, scope, and depth of the reported adaptation? Using the World Bank’s income groups and city sizes as cross-cutting lines of analysis, our findings show among others that there is comparatively little published knowledge on coastal urban adaptation in low and middle-income economies. Reported adaptation measures are predominantly designed based on past and current, rather than future, patterns in hazards, exposure, and vulnerability and implementation actors differ depending on the income group. Overall, the assessed evidence mostly presents coastal urban adaptation that is rather slow, of narrow scope, and not transformative. These and further findings from this evidence mapping represent valuable insights for both, scientists and policy-makers as they provide a nuanced overview of the state of adaptation in coastal cities.