Increasing risks of extreme salt intrusion events across European estuaries in a warming climate

Over the last decade, many estuaries worldwide have faced increased salt intrusion as a result of human activities and a changing climate. Despite its socio-economic importance, our current projections on the statistics of future salt intrusion are limited to case studies in certain regions. Here, we show that, compared to present-day conditions, river discharge in the summer months is projected to be reduced by 10–60% in 17 out of 22 investigated major European river basins at the end of the 21st century under the high CO2 emission scenario (Shared Socioeconomic Pathways, SSP 3-7.0). We find that the reduced future river discharge in the summer months, in turn, increases salt intrusion lengths by 10–30% in 9 representative European estuaries at low and mid latitudes. Our analysis further indicates that the European estuaries are projected to experience more than five times more frequent extreme salt intrusion events.

Jiyong Lee, Bouke Biemond, Huib de Swart, Henk A. Dijkstra