Coevolution of extreme sea levels and sea-level rise
Abstract
Design of coastal defense structures like seawalls and breakwaters can no longer be grounded on stationarity assumption. An anticipated sea-level rise (SLR) in many locations around the world, will constitute historical return levels (e.g., 100-yr events) inappropriate for future coastal flood risk assessment since it will dramatically raise their probability of occurrence. Here, we first show that global extreme sea levels (ESLs) have been increasing in magnitude over the last decades partially due to a positive shift in mean sea level (MSL). Then, we apply non-stationary extreme value theory to model the extremal behavior of sea levels with MSL as a covariate and quantify the evolution of ESLs using probabilistic sea-level projections. We show that by year 2050 many locations will experience their present-day 100-yr return level as an event with return period less than 15 and 9 years under the moderate (RCP4.5) and high (RCP8.5) representative concentration pathways. Also, we find that by end of the century, almost all locations will encounter their current 100-yr return level on an annual basis, even under the RCP4.5. Our analysis accounts for uncertainty by incorporating ambiguities in both SLR projections and extreme value distribution parameters.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMGC23B..03M