Abstract
The world’s coastal areas are increasingly at risk of coastal flooding due to sea-level rise (SLR). We present a novel global dataset of extreme sea levels, the Coastal Dataset for the Evaluation of Climate Impact (CoDEC), which can be used to accurately map the impact of climate change on coastal regions around the world. The third generation Global Tide and Surge Model (GTSM), with a coastal resolution of 2.5 km (1.25 km in Europe), was used to simulate extreme sea levels for the ERA5 climate reanalysis from 1979 to 2017, as well as for future climate scenarios from 2040 to 2100. The validation against observed sea levels demonstrated a good performance, and the annual maxima had a mean bias (MB) of -0.04 m, which is 50% lower than the MB of the previous GTSR dataset. By the end of the century (2071–2100), it is projected that the 1 in 10-year water levels will have increased 0.34 m on average for RCP4.5, while some locations may experience increases of up to 0.5 m. The change in return levels is largely driven by SLR, although at some locations changes in storms surges and interaction with tides amplify the impact of SLR with changes up to 0.2 m. By presenting an application of the CoDEC dataset to the city of Copenhagen, we demonstrate how climate impact indicators derived from simulation can contribute to an understanding of climate impact on a local scale. Moreover, the CoDEC output locations are designed to be used as boundary conditions for regional models, and we envisage that they will be used for dynamic downscaling.
Highlights
The world’s coastal areas are increasingly at risk of coastal flooding due to sea-level rise (SLR)
Aiming to contribute to the accurate global mapping of the impact of climate change on coastal regions, we have presented a novel global dataset of extreme sea levels, the CoDEC
This dataset is based on the generation GTSMv3.0, which has a coastal resolution of 2.5 km (1.25 km in Europe)
Summary
The world’s coastal areas are increasingly at risk of coastal flooding due to sea-level rise (SLR). By 2100, global mean sea-levels are projected to be 30–60 cm higher than today, even with a sharp reduction of greenhouse gas emissions (Church et al, 2013; Oppenheimer et al, 2019). The expected economic annual losses due to flooding may come close to 10% of the global gross domestic product (Hinkel et al, 2014). Raising flood defenses is critical in densely populated and economically important coastal areas, and is cost effective for 13% of the global coastline (Lincke and Hinkel, 2018). The stabilization of global temperatures to 1.5◦C, as agreed upon in the Paris Agreement, will lead to a strong reduction of the economic impact of SLR (Nicholls et al, 2018)
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