Hamburg is raising its 103 km public flood protection line by 2050 at a cost of EUR 20–30 million a year. The design water level, published in 2013, allows for sea-level rise only to 2050, and the construction programme is due to finish that year. BUKEA, the city's environment authority, says further raising will be needed if current sea-level projections hold.
What the projections say
The German Weather Service's 2021 climate report for Hamburg cites global projections of 43 cm median sea-level rise by 2100 under a low-emission scenario and 84 cm under a high-emission one, against 1986–2005. The likely range under high emissions reaches 110 cm. The report notes that no regional sea-level study for Hamburg was available and assumes the German Bight and the Elbe will rise by a similar amount.
The Elbe is already changing
At Cuxhaven, at the mouth of the Elbe, the measured sea level rose by 2.37 cm a decade between 1843 and 2019, about 40 cm in all. Upstream at Hamburg St. Pauli, the tidal range doubled from under 2 m to 3.8 m, mainly because low water fell. Hamburg's dikes stood about 5.70 m above mean sea level in 1962 and have since been raised by about 2.50 m on average.
Longer high water, harder drainage
The climate report finds that a higher sea level makes storm-surge peaks arrive earlier and last longer. It also shortens the time windows in which low-lying areas behind the dikes can drain into the Elbe without pumping. BUKEA notes that storm surges since 1962 have exceeded that year's peak level without serious damage to the main dike line.
How exposed Hamburg's water system is to heavy rain and summer drought, what the 2025 adaptation strategy prioritises, and where investment is planned are covered in the full report. The full report, Climate Resilience: Drought and Flood Risk in Hamburg, is available for USD 249.