Exploring storm tides projections and their return levels around the Baltic Sea

Extreme sea levels are a global concern, as they can lead to substantial economic losses and pose risks to human communities in coastal regions. Accurate projections of extreme sea levels are essential for effective coastal management and planning. While relative sea level rise, driven by ongoing climate change, is a major factor influencing future extremes, changes in storm surges due to shifts in storm climatology may also have critical impacts.
In this study, a random forest machine learning approach is employed to project daily maximum storm tides (storm surge and tides) for 59 stations across the Baltic Sea. The model uses atmospheric variables, including wind speed, wind direction, and surface pressure derived from climate datasets. Projections for the period 2070–2099 are compared to pre-industrial conditions from 1850–1879 to assess changes in 50-year storm tide return levels.
The results indicate sub-regional variation in projected changes. Increases of up to 10 cm are projected along Sweden’s west coast and the northern Baltic Sea, while decreases down to 6 cm are anticipated along the southern Swedish coast, the Gulf of Riga, and the Gulf of Finland. Other areas are projected to experience negligible change. These spatially varying trends highlight the importance of local analysis for future sea level risk assessments. However, the variability in atmospheric drivers across climate models contributes to significant uncertainty, underscoring the need for further research to refine projections and reduce uncertainties in future climate storm tides projections.