Global Investment Costs for Coastal Defence Through the 21st Century
Sea-level rise threatens low-lying areas around the world’s coasts with increased coastal flooding during extreme sea level events during storms. One response to this challenge is to build or upgrade coastal flood defences as exemplified by the Netherlands, New Orleans or much of the Chinese coast. In this paper the authors examine the potential investment costs of such an adaptation strategy applied globally over the 21st Century for sea-level rise scenarios consistent with the RCP2.6 and RCP8.5 emissions and the SSP2 socio-economic scenarios. Results are reported at the scale of World Bank Regions and the globe. This considers several contrasting scenarios of protection strategies as defined below. The DIVA model framework for coastal analysis is used to perform the analysis.
The results provide improved estimates of the protection costs given sea-level rise compared to earlier estimates. Considering the Constant Protection Level Strategy from 2015 to 2100, the total accumulated defence costs are US$2.7 to US$7.6 trillion and US$3.4 to US$9.6 trillion for the RCP2.6 and RCP8.5 scenarios, respectively. These new defence costs are higher than earlier estimates, reflecting several improvements.
Future analyses could useful focus on benefit-cost analysis as well as more investigation of protection costs, including empirical data collection. Linking these types of analyses to more detailed datasets and also a wider range of adaptation types would be useful.