An ensemble study of extreme storm surge related water levels in the North Sea in a changing climate

[摘要] The height of storm surges is extremely important for a low-lyingcountry like The Netherlands. By law, part of the coastal defencesystem has to withstand a water level that on average occurs only onceevery 10 000 years. The question then arises whether and how climatechange affects the heights of extreme storm surges. Published researchpoints to only small changes. However, due to the limited amount ofdata available results are usually limited to relatively frequentextremes like the annual 99%-ile. We here report on results from a17-member ensemble of North Sea water levels spaning the period1950–2100. It was created by forcing a surge model of the North Seawith meteorological output from a state-of-the-art global climatemodel which has been driven by greenhouse gas emissions following theSRES A1b scenario. The large ensemble size enables us to calculate10 000 year return water levels with a low statistical uncertainty.In the one model used in this study, we find no statisticallysignificant change in the 10 000 year return values of surge heightsalong the Dutch during the 21st century. Also a higher sea levelresulting from global warming does not impact the height of the stormsurges. As a side effect of our simulations we also obtain results onthe interplay between surge and tide.

[学科分类] 海洋学与技术