Engineering Adaptation Strategies and Infrastructure Design Requirements to Deal with Climate Uncertainty – Uncertainty, Certainty (and the Case of Coastal Defense) Hans von Storch Institute of Coastal Research Helmholtz Zentrum Geesthacht und Klimacampus Hamburg 6th International Conference on Water Resources and Environment Research (ICWRER) Koblenz, Germany, June 3–

Climate – Knowledge Uncertainty Detectability of change Characteristics of change: intensity, speed, signal-to-noise ratio (conditional upon time) Attributability of change (various drivers) Intensity and effectivity of claimsmaking by economic stakeholders and green ideology (post-normal science) Presence and emergence of other drivers

Certainties Risks exist and may change, some will. Climate (statistics of weather) is changing – as well as associated probabilities of hazardous situations – due to elevated GHG levels. A new “stationary” state will hardly be reached; statistics are getting instationary. The level of adaptation to change depends on the success of limiting the change (Klimaschutz) Scientific skeptic is needed. Overselling of claims-making is counterproductive on the long run.

Certainties- the time dimension Learning in time – in 10 years we know more than today, in 20 years more than in 10 years. Societal values change in time Technology changes – new, cheaper and more flexible answers to challenges will be available. Drivers of change will become more – some gradually, some abrupt and surprising. Success of limiting anthropogenic climate change gradually becomes a “known”

Consequences for today Maintenance and regular modernization should consider perspective of future change and flexibility in responding to such change. Decision needed as to when new adaptation measures should be implemented. Consideration of change of all drivers. Societal debate needed about options and timing. Check of societal claims-making reflecting special interests.

Research Needs Development of new or improved technology options for dealing with present and changing risk. Monitoring of environmental state, which allows detecting changing risks and attributing to causes.

Coastal Defense: Detection, Attribution 37 year trencs (2 x nodal tide) of regional sea level in the German Bight black, green: two reconstruction methods rot – Cuxhaven, Albrecht et al Difference of maximum heights in Hamburg and Cuxhaven Storm surges in Hamburg elevated because of modifying the river Elbe – both coastal defense and shipping channel deepening

Green ideology misleading the public Claimed flooding associated with a sea level rise of 1 (?) m. Area protected by contemporary coastal defense against “normal” high tide sea level.

Coastal Defense Analysis for Coastal Defense in Schleswig Holstein (Landtag, Kiel), in 2009 Fortification of dikes in Schleswig- Holstein Significant drivers of changing storm surge heights Recent changes Possible changes until 2030 Possible changes until 2100 Global mean sea level rise ca. 2 dmca. 1 – 2 dm ca. 2 – 8 dm Meteororological short term effects (storms) noneca. 0 – 1 dm ca. 1 – 3 dm Regional and local sea level change ca. 2 dmSo far unknown wavesnoneSo far unknown tidesRegionally very different So far unknown bathymetryRegionally very different So far unknown

Niemeyer & Kaiser 2008, NLWKN Currently overtopping tolerances:  3% of all – Lower Saxony  2 l/(m∙s) – Masterplan Schleswig-Holstein  0,1-1,0 l/(m∙s) – The Netherlands Results of overtopping test in Delfzijl/NL  No damage up to 50 l / (m ∙ s)  No severe damage at 50 l (m ∙ s)  after artificial damage still functioning Technology: Dyke overtopping tolerance

Overall conclusion: Time! When adapting to and talking about climate change three major, often overseen issues are -The issue is not new risk, but changing risk -Time is a key dimension – change occurs in time; development is instationary. -Knowledge, drivers and options for adaptation change in time.