Hamburg – storm surges Hans von Storch

Bärring, 2005; blue - Lund; red – Stockholm Plausible cause: more or more violent storms?

Gaussian low-pass filtered (21 yr) curves for annual 99%tiles of daily geostrophic wind speeds. The heavy curve is made up by Kremsmünster, Vienna and Prague-Klementinum while the heavy dashed curve by Kremsmünster, Vienna and Prague-Karlov. (note that tails are based on less data then the rest) Matulla, C., W. Schöner, H. Alexandersson, H. von Storch, and X.L. Wang, 2007: European Storminess: Late 19th Century to Present, accepted for publication by Climate Dynamics

Where does the enhanced storm surge levels Hamburg come from? Sea level rise – a few centimeters Intensification of storm activity What else has happened in the coastal/estuarine environment?

The tidal change is due to coastal protection measures and modifications of the tributaries, and to the deepening of the shipping channel. These measure also had an effect on the heights of severe storm surges – estimates are 45 cm caused by measures of coastal defense and 15 cm by deepening the shipping channel (Haake, 2004: 27). Difference in storm surge heights – mouth of Elbe estuary and Hamburg,

Thus, so far, global warming had no discernible impact on the storm surge risk in Hamburg. Will it have an effect? - yes, but we may be able to do something about it.

Scenarios 2030, 2085 Only the effect of anthropogenic climate change (A2, B2) - No effect of water works. Grossmann, I., K. Woth and H. von Storch, 2007: Localization of global climate change: Storm surge scenarios for Hamburg in 2030 and Die Küste 71,

Conclusions In the past 40 years, storm surge heights in St. Pauli have been increased by about 60 cm due to coastal defense and shipping channel deepening measures Scenarios indicate an intensification of about 60 cm for the end of the 21 st century due to global warming. “Tide-Elbe” Project, prepared by Hamburg Port Authority, plans for a deceleration of the tidal dynamics – primarily for slowing down sedimentation – but also for reducing storm surge risk. It may be possible to “pay” for the future risk by rectifying the effect of past river bed modifications.