Download Storm surges – the case of Hamburg, Germany

Storm surges – the case of
Hamburg, Germany
Hans von Storch
Institute for Coastal Research
GKSS Research Center, Geesthacht
Parallel 26: Global environmental change, natural disasters, and their
implications for human security in coastal areas, 11. November 2006
Historically, the coast was
a place of danger (and
some opportunities) for
humans.
The first priority was to
defend against storm
surges. Life was adapted
to this risk.
Nowadays, people
consider themselves safe
from the dangers of the
sea, and are concerned
about the health and the
opportunities related to
the coastal seas.
Hamburg – storm surges
In the early 90s, the specter of Global Warming
entered the perception of people. Storm got worse.
2
1
Proxy for storm activity in the North Sea region
(after Alexandersson, SMHI, 2003)
0
-1
1880
1900
1920
1940
1960
1980
2000
•Scientists related worsening of storm climate to GHG emissions
(warmer world > more water vapor > more energy for storms > situation
will continue to worsening).
•Insurance companies supported the claims.
•Media took up the message, which is consistent with cultural preconception of humans changing climate to become worse.
•Nowadays widely accepted among media and lay-people that storms are
getting worse. However, the claim is false.
2
Proxy for storm activity in the North Sea region
(after Alexandersson, SMHI, 2003)
1
0
-1
1880
1900
1920
1940
1960
Bärring, 2005; blue - Lund; red – Stockholm
1980
2000
Where does the enhanced storm
surge levels Hamburg come from?
• Sea level rise – a few centimeters
• Intensification of storm activity 19601995
• What else has happened in the
coastal/estuarine environment?
Difference in storm surge heights – mouth
of Elbe estuary and Hamburg, 1900- 2005
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).
• Thus, so far, global warming had no
discernible impact on the storm surge
risk in Hamburg.
• Will it have an effect?
Regional and lcoal effect of
expected anthropogenic
climate change (A2 and B2)
Model of
North Sea hydrodynamics
Katja Woth
Global scenario
Dynamical Downscaling
Tide gauge St. Pauli
Joint work with regional authorities.
Empirical “localization”
Only the effect of anthropogenic
climate change (A2, B2)
- No effect of water works.
Scenarios
2030, 2085
Conclusions
• For storm surge risk in Hamburg, modifications of the
estuary are presently more important than
anthropogenic climate change; in the distant future
they may be of comparable significance.
• Public perception is changing to: Storm surge risk is
mostly related to GHG emissions. Thus storm surge
risk can be controlled by regulating these emissions.
• Vulnerability enhanced by framing storm surge risk as
GHG problem and not as natural hazard exaggerated
by regional modifications.
• Sloppy talking about Global Warming has detrimental
effect on better adaptation.
• The same true for Hurricane hazard?