Near-future changes in storm surges along the Atlantic Iberian coast

Decadal predictions bridge the gap between the short-term weather/seasonal forecasts and the long-term climate projections. They target the reproduction of large-scale weather patterns at multi-year time scales by both recognizing the long memory of some components of the climate system, and explicitly including the evolution of greenhouse gas concentrations as an external forcing. This study illustrates the use of decadal predictions to determine the near-future storminess at regional scales. Specifically, the evolution of extreme storm surges and sea levels along the Atlantic Iberian coast is assessed. Present (1980-2016) and near-future (2021-2024) storm surges are simulated over the northeast Atlantic, forced by atmospheric reanalyses (ERA-Interim) and decadal predictions (MiKlip), respectively. Results are then statistically analyzed to investigate the short-term effects of climate change and climate variability on extreme surges and extreme sea levels. Surges will increase mostly in early winter, while tides are largest in late winter. As a result, the impact of the increase in storminess on the extreme sea levels and coastal flooding will be modest, and the growth in extreme sea levels will be dominated by the contribution of mean sea level rise.