Future storm surge impacts on insurable losses for the North Sea region

T F Stocker,C C Raible,A Schwerzmann,L Gaslikova

doi:10.5194/nhess-11-1205-2011

Abstract

Abstract. The influence of climate change on storm surges including increased mean sea level change and the associated insurable losses are assessed for the North Sea basin. In doing so, the newly developed approach couples a dynamical storm surge model with a loss model. The key element of the approach is the generation of a probabilistic storm surge event set. Together with parametrizations of the inland propagation and the coastal protection failure probability this enables the estimation of annual expected losses. The sensitivity to the parametrizations is rather weak except when the assumption of high level of increased mean sea level change is made. Applying this approach to future scenarios shows a substantial increase of insurable losses with respect to the present day. Superimposing different mean sea level changes shows a nonlinear behavior at the country level, as the future storm surge changes are higher for Germany and Denmark. Thus, the study exhibits the necessity to assess the socio-economic impacts of coastal floods by combining the expected sea level rise with storm surge projections.

Highlights

Coastal areas are historically highly populated and extensively utilized
Event sets were built for the hindcast representing the 1958–2002 period, for the control (Ctl) data set interpreted as present day climate conditions, as well as for SRES emission A2 and between calibrated A2 (B2) scenarios representing future climate
To show the method’s ability, the climate change influence on insurable losses is assessed for the North Sea basin

Summary

Introduction

Coastal areas are historically highly populated and extensively utilized. In Europe, about 200 million people live in coastal zones and the population density of the North Sea coasts has currently reached 250 inhabitants per km (Eurostat Regio database, 2009). The authors pointed out that the rate of change varies significantly depending on the analyzed period They found that the number and intensity of surge extremes has remained nearly constant during the last years of the 20th century. ScTholeswigstorm surge model setups, global and regional sea level rise get a firHsotlsitmeinp(rGeesnseiroalnplaonfKtuhsetenesxchteutnz)sion of the coastal areas at estimates and future development scenarios. Of England found by Lowe et al (2001) could be only par- BelgiuFmigure 1Agsehncoywfosr tMhaeriatirmeeaasndagCgoarsetaglaSteervdicbesy, Fplaonsdtearsl code units and tially confirmed by Debernard and Røed (2008) and was not UK potentiaElnlvyiropnrmoennet Atogeflncoyoding in the absence of coastal protecdetected by Woth (2005a) Given these changes, the quantification of associated risks tion, i.e. with the average land elevation less than 10 m and located closer than 50 km to the present day coastline.

Storm surge data and sea level rise scenarios

Building the storm surge event set

Defining the probabilistic event set insurable loss estimates for portfolio

Calibration of scenario data

Inland penetration

Coastal protection failure probability

Findings

Discussion and summary