Responses to coastal climate change: Innovative Strategies for high End Scenarios – Adaptation and Mitigation
RISES -AM- assessed the impacts of future sea-level rise and the effectiveness of a wide range of adaptation options and strategies. RISES -AM- also considered the barriers to implementing adaptation at local, regional and global scales, across a range of representative concentration pathways (RCPs) and shared socio-economic pathways (SSPs), including exploring high-end scenarios not included in IPCC reports.
High-end scenarios may refer to climate change drivers of coastal impacts (such as e.g. sea level rise) or to socio-economic drivers affecting exposure and vulnerabilities (e.g. assets or population affected). RISES -AM- has considered such high-end scenarios from short (months) to long (decades) time scales. The analysis includes a new high-end sea-level rise scenario developed within RISES -AM-. High-end scenarios are particularly important for the management of situations of high exposure and risk aversion, which is generally the case for many densely populated coastal zones.
RISES -AM- assessed impacts both under present adaptation practice (business as usual) as well as under “additional” adaptation that will be required due to the expected acceleration of climate change during this century. For the latter the possible adaptation interventions have been sequentially structured into adaptation pathways that prevent decisions conflicting with longer term limits or requirements. The emphasis has been on vulnerable coastal systems such as deltas or low-lying coastal areas with large population.
The project RISES -AM- is funded by the European Commission’s Seventh Framework Programme (2007 – 2013), under the grant agreement number 603396.
RISES -AM- analysed technological, economic, financial and social conflicts and barriers to coastal adaptation under high-end sea-level rise in a range of case studies at different scales. Across all cases, adaptation was found to be technologically possible. Generally, in the cases considered adaptation is costly but pays off in pure monetary terms for densely populated urban regions. We found very high benefit-cost ratios for protecting cities as well as for nourishing beaches used for tourism, which suggests that these two measures will be wide-spread in the future. In rural and poorer areas, however, protection measures generally have benefit-cost ratios smaller than one, which suggests that it will be difficult to mobilise the required resources for protection if those regions don’t receive money from elsewhere.
|Adaptation goal||Options considered||
|Liverpool/Mersey||Reduce flood risk in situ||Tidal barrage, tidal lagoons||no||yes||no||yes|
|Danube delta||Maintain wetlands||Planting reeds, artificial reefs||no||some||yes||yes|
|Catalan coast||Maintain beaches and tourism||Beach nourishment||no||no||no||no|
|Reduce erosion damage to land||Beach nourishment, artificial dunes, protection structures, managed retreat||no||yes||yes||yes|
|Reduce sea-level rise damage to ports||Break waters, covered with vegetation||no||no||yes||yes|
|Ebro delta||Maintain rice production||Dikes, land raising, segmentation of drainage and irrigation networks||no||yes||yes||some|
|Hamburg||Reduce flood risk in situ||Dikes, sea-walls, retention areas||no||n/a||no||yes|
|Hulhumalé (Maldives)||Reduce flood risk in situ||Flood warning system, beach nourishment, sea-walls, pumps & drainage, land raising||no||no||no||yes|
|Ho Chi Min City||Reduce flood risk in situ||Dike rings, land raising and flood-proofing buildings||no||no||yes||yes|
|Croatia||Reduce flood risk||Dikes, set-back zones||no||some||yes||yes|
|Aveiro coast (Portugal)||Maintain land threatened by erosion||Nourishment||no||no||yes||no|
|Holland coast (The Netherlands)||Maintain land threatened by erosion||Nourishment||no||no||no||no|
|Global flood risk||Reduce flood risk||Dikes, managed retreat||no||no||some||yes|
|Mediterranean||Reduce flood risk||Dikes, set-back zones, flood-proofing buildings||no||no||some||yes|
|European Union flood risk||Reduce flood risk||Dikes||no||no||some||yes|
But even when coastal protection is attractive in monetary terms, mobilising financial resources may be difficult due to high up-front investments paired with long-term stochastic returns on investment. Irrespective of the technological, economic and financing situation, it was also found that most coastal adaptation options involve significant social conflicts due to diverse coastal stakeholders, interests, activities and policy goals (e.g., flood security, tourism, nature protection, shipping and ports). We conclude that integrating financial, equity and social conflict issues will be a key for advancing coastal adaptation.
The main findings of RISES -AM- are summarised in a global policy brief.
Hinkel, J., D. Lincke, A. T. Vafeidis, M. Perrette, R. J. Nicholls, R. S. J. Tol, B. Marzeion, X. Fettweis, C. Ionescu, and A. Levermann (2014). Coastal flood damage and adaptation cost under 21st century sea-level rise. In: Proceedings of the National Academy of Sciences. Published ahead of print February 3, 2014. Press release