This session will focus on the physical forcing factors, development conditions, anthropogenic contributions, and natural variability defining evolution and severity of storm surges. Forcing parameters include meteorological factors with possible contribution from waves, currents, tides, sea level rise and sea ice on storm surge severity. Temporal variability of physical forcing on a range of scales will be addressed with particular emphasis on differentiating between short-term variability in storm frequency and severity and longer term cycles or trends which are increasingly influenced by global climate change.

Geomorphological factors affecting storm surges may incorporate bathymetry and topography features, seabed or land surface properties and how they vary both spatially and temporally due to sediment transport or human activities on shore and offshore.

Subsidence due to extraction of water or hydrocarbons potentially coupled with natural subsidence due to tectonic of isostatic effects affects many coastal communities and will also act in concert with rising sea level and other factors to increase the severity of storm surges. The session will highlight the importance of the human activities and how they interact with the meteorological, oceanographic, and geological parameters in controlling storm surge severity.

Key themes
- Does climate change matter?
- How does surge hazard vary globally?
- Why are so many coastal cities sinking?

Papers in this theme might address:
- Climate and climate change
- Variable storminess
- Sea level rise
- Geological processes
- Water works and coastal defence
- Oil, gas and groundwater extraction – anthropogenic subsidence
- Urbanisation, demographic change in coastal areas and deltas