New sea level scenarios for the Netherlands

We present the framework used to develop a new set of sea level scenarios for the Dutch coast published by KNMI in October 2023, to help the Netherlands adapt to sea level rise. Based on interactions with stakeholders, the development of the scenarios focused on two main areas: the connection between observations and projections and the development of low-likelihood high-impact scenarios up to 2300. We developed a local sea level budget for the period 1993-2021 to better understand past observations and to constrain the scenarios. In particular, the contribution of Ocean Dynamic Sea Level was important in the benchmark period 1993-2021, and observational evidence was used to select CMIP6 models that were close to the observations. For the low-likelihood high-impact scenarios three lines of evidence were used: structured expert judgement, a numerical model including Marine Ice Cliff Instability, and a physical evidence discussion. We also discuss some practical applications of these scenarios.