Global Warming and Frequency Amplification of Extreme Sea Levels

Extreme sea level (ESL), a major driver of coastal flooding, is widely used as a benchmark for coastal engineering design, coastal zone management, and risk assessment. With global warming, ESL events are projected to become more frequent and intense along most of the world’s coastline. Tebaldi et al. (2021) estimated the minimum global warming level (GWL) and timing at which the present-day 100-year ESL becomes an annual event along the global ice-free coastline. Comparable information for other return periods—such as 10-, 20-, 50-, 100-, and 200-year events—relevant to broader applications remains unavailable. Here, we present global datasets describing the minimum GWL and timing at which multiple present-day ESL return levels transition to annual occurrence. The datasets are derived using a multimethod framework consistent with Tebaldi et al. (2021), combining multiple global datasets of present-day ESL and projections of relative sea level change, while accounting for uncertainties. The resulting datasets provide a consistent global reference for assessing how the frequency of ESLs changes across return periods and GWLs, supporting applications in large-scale coastal impact assessment, planning, and risk analysis.