Projections of global-scale extreme sea levels and resulting episodic coastal flooding over the 21st Century

TLDR

Global tide, surge, and wave models project episodic coastal flooding for the 21st century. The models were rigorously validated with tide gauge data and uncertainties were quantified. The study identifies north‑western Europe and Asia as hotspots of increased episodic flooding, and under an RCP8.5 scenario with no adaptation, 48 % of land area, 52 % of the global population, and 46 % of assets will be at risk by 2100, with 68 % of flooding caused by tide and storm events and 32 % by projected sea‑level rise.

Abstract

Abstract Global models of tide, storm surge, and wave setup are used to obtain projections of episodic coastal flooding over the coming century. The models are extensively validated against tide gauge data and the impact of uncertainties and assumptions on projections estimated in detail. Global “hotspots” where there is projected to be a significant change in episodic flooding by the end of the century are identified and found to be mostly concentrated in north western Europe and Asia. Results show that for the case of, no coastal protection or adaptation, and a mean RCP8.5 scenario, there will be an increase of 48% of the world’s land area, 52% of the global population and 46% of global assets at risk of flooding by 2100. A total of 68% of the global coastal area flooded will be caused by tide and storm events with 32% due to projected regional sea level rise.