EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

High-resolution climate ensemble reveals low confidence in projected changes in storm surges for the mid-century

Sanne Muis1,2, Jeroen C.J.H. Aerts1,2, José A. Á. Antolínez3, Dewi Le Bars4, Job C. Dullaart1, Trang Minh Duong5,2,7, Li Erikson6, Rein Haarsma4, Maialen Irazoqui Apecechea2,9, Andrea O'Neill6, Roshanka Ranasinghe2,5,7, Malcolm Roberts8, Kun Yan2, Martin Verlaan2,3, and Philip J. Ward1
Sanne Muis et al.
  • 1Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
  • 2Deltares, Delft, The Netherlands
  • 3Technical University Delft, Delft, The Netherlands
  • 4KNMI, de Bilt, The Netherlands
  • 5IHE Delft Institute for Water Education, Delft, The Netherlands
  • 6USGS, Santa Cruz, USA
  • 7University of Twente, Enschede, The Netherlands
  • 8Met Office Hadley Centre, Exeter, UK
  • 9Mercator Ocean, Toulouse, France

In the coming decades, regions across the globe will be faced with increases in coastal flooding due to sea-level rise and changes in climate extremes. In a collective effort, we have produced new extreme sea level projections derived from an ensemble of high-resolution climate models. Our approach is based on the Global Tide and Surge Model forced with model outputs from the HighResMIP experiments. The HighResMIP models have a much higher spatial resolution than the previous generation of climate models, and can better resolve storms, including tropical cyclones. The dataset has global coverage and spans the period 1950-2050. The dataset provides: 1) timeseries of storm surges, astronomical tides, and total still water levels; and 2) water level statistics for different time slices, including percentiles and return periods.

In this contribution we focus on storm surges and have a first look at model performance for present-day climate conditions and at projected changes. Comparison of the 1 in 10-year surge levels against the ERA5 reanalysis reveals a large spatial bias for some of the HighResMIP models, highlighting the need for multi-model ensembles and bias correction. Comparison of the 1 in 10-year surge levels between the 1951-1980 and 2021-2050 period, shows that some regions, such as Northwest Europe, Alaska, China, and Patagonia, may be faced with an increase in storm surges (>0.1 m), while other regions, such as the Mediterranean and South Australia may see a decrease in storm surges. Overall, the projected changes are characterized by large intermodel variability due the uncertainties that arise from the climate models, internal variability, and extreme value statistics. Future research should aim to better constrain the uncertainties, which can be achieved by a more in-depth exploration of the changes in the meteorological conditions, enlarging the model ensemble, and the implementation of bias correction methods.

The full datasets will soon become openly available at the C3S Climate Data Store and can be used to inform climate impact assessments.

How to cite: Muis, S., Aerts, J. C. J. H., A. Á. Antolínez, J., Le Bars, D., Dullaart, J. C., Minh Duong, T., Erikson, L., Haarsma, R., Irazoqui Apecechea, M., O'Neill, A., Ranasinghe, R., Roberts, M., Yan, K., Verlaan, M., and Ward, P. J.: High-resolution climate ensemble reveals low confidence in projected changes in storm surges for the mid-century, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4414,, 2022.