The economically optimal mix and timing of coastal adaptation in Europe to 2150

Coastal adaptation to sea level rise involves combining and sequencing adaptation options into adaptation pathways that include adaptation tipping points - moments requiring a switch between options, often due to economic limits. While local case studies show costs depend on the economically optimal timing of actions and adaptation tipping points, this remains unexplored on global and continental scales. We present economically optimal adaptation pathways for 41,327 coastal floodplains along Europe's coastline through 2150. For 99% of floodplains requiring adaptation, the optimal timing for initial actions is immediate due to current economic under-adaption. Adaptation tipping points, primarily driven by sea level rise, predominantly occur along the Mediterranean coastline, necessitating a switch from accommodation to either protection or retreat. Their timing depends on climate change, occurring 30 years earlier under higher climate change scenarios compared to lower ones. In contrast, socioeconomic parameters have minimal impact on the timing of adaptation tipping points.