A yearly maximum sea level simulator and its applications: A Stockholm case study

Magnus Hieronymus

doi:10.1007/s13280-021-01661-4

Magnus Hieronymus

Open Access

https://doi.org/10.1007/s13280-021-01661-4

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Abstract

A yearly maximum sea level simulator for Stockholm is presented. The simulator combines extreme sea level estimates and mean sea level rise projections into a joint probabilistic framework. The framework can be used, for example, to assess the risk that new structures placed at the current minimum allowed height above the sea level can become flooded in the future. Such assessments can be used to underpin future building free levels, which would be a great improvement over the much more arbitrary criteria in use today. Another strong point of the framework is that it can be used to quantify the influence of uncertainties in mean sea level projections, estimates of sea level extremes and future emission scenarios on the risk of flooding. For Stockholm mean sea level uncertainty is found to be much more important than extreme sea level uncertainty. The framework is also set-up to test adaptation measures. It is found that protections that are built once the mean sea level has risen above some given threshold can be very efficient. Lastly, the framework is embedded into a simple decision problem that can be used to calculate risk/reward ratios for land development as a function of height above today’s mean sea level.

Highlights

Infrastructure planning in many coastal areas around the world is complicated by rising mean sea levels (Hinkel et al 2018; Oppenheimer et al 2019)
Some key difficulties that must be tackled in coastal infrastructure plans, apart from the long time scales, are that: sea level rise is inhomogeneous in space, future sea level projections are highly uncertain and sea level projections depend on poorly constrained future emission, concentration or temperature pathways
Our results suggest that high percentile mean sea level rise should be given more thought in planning than high percentile extremes and that site specific recipes are likely needed

Summary

Introduction

Infrastructure planning in many coastal areas around the world is complicated by rising mean sea levels (Hinkel et al 2018; Oppenheimer et al 2019). Some key difficulties that must be tackled in coastal infrastructure plans, apart from the long time scales, are that: sea level rise is inhomogeneous in space, future sea level projections are highly uncertain and sea level projections depend on poorly constrained future emission, concentration or temperature pathways (van Vuuren et al 2011; Mitrovica et al 2018; Oppenheimer et al 2019). Plans must be made with regional or even local scales in mind. Planning for sea level rise with local scales in mind is, challenging and can be costly. Especially smaller, municipalities have limited expertise and lack adequate tools and data to make such plans (Schold et al 2020)

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