Annual Sea Dike Costs

Key messages:

  • Adaptation needs to consider long-term conditions, as sea-levels continue to rise
  • While dikes can reduce damages, other forms of defence are also available
  • To remain effective dikes require maintenance which can be costly

Why is the content of this map important?

Sea-levels take many decades to respond to warming temperatures, so the effects of warming today will be felt a long time in the future. Coastal protection measures have long design lives, so future conditions need to be considered. These maps provide indicative costs of building sea dikes in the 2080s using SSP2 (see background information).

Which sectors are affected by this result?

These costs are helpful for coastal managers, either at European or national levels who require the estimated costs of protection to strategically and financially plan for the future. Specific sectors such planning could encompass include: infrastructure, transport and local communities.

What is shown on the maps?

These maps illustrate the annual sea dike costs under a +2°C and +3°C (special map) global warming scenario (assuming a median level of ice melt) in the 2080s in EU countries, with a 0.31 m and 0.42 m rise in global mean sea-levels respectively (data projections from the HadGEM2-ES climate model). Costs under a +3°C global warming is shown in the special map. The low-lying nations surrounding the North Sea have the greatest costs. Europe’s smallest economies benefit most from climate change mitigation, as shown in the difference in costs between the two maps.

Details and further information:

Sea dikes must also be maintained in order to remain effective. Projecting maintenance costs at 1% of capital dike costs indicates that under a +2°C global warming in the 2080s, annual maintenance costs are projected to be 5.9 billion per year. Under a +3°C global warming, these maintenance costs could increase up to 6.1 billion per year (see Figure below). Alternative adaptation measures, such as sand nourishment, managed realignment or elevating houses can also reduce flood risk.


Annual costs of maintaining sea dikes per annum in EU countries under a SSP2 scenario for sea-level rise projections under HadGEM2-ES

Additional information:

For many impact studies, raising the global mean surface temperature by 2°C will produce an impact that may be apparent within hours to a few years. The situation is not as simple for the sea level rise as oceans can take many decades to respond to warming surface temperatures and ice sheets can continue to melt for hundreds of years, even if temperatures stabilize. Thus, in the project the impact of sea-level rise has been analyzed at a range of temperature projections, focusing on the benefits of climate mitigation e.g. 2080s.

To investigate this, the Dynamic Interactive Vulnerability Assessment (DIVA) modelling framework was used. DIVA was driven by sea-level rise projections and socio-economic scenarios. Information on sea-level rise was taken from one model (HadGEM2-ES) and two emission scenarios. For a +2°C global warming sea-level rise is represented by the RCP2.6 simulation and is 0.31m.  For a +3°C global warming sea-level rise is represented by the RCP4.5simulation and is 0.42m.

The socio-economic scenarios of the variables land-use class, coastal population growth and gross domestic product (GDP) growth correspond to the SSP2 Scenario.


Sea-level scenarios were extracted from:

Hinkel, J., Lincke, D., Vafeidis, A.T. Perrette, M., Nicholls, R.J., Tol, R.S.J., Marezion, B., Fettweis, X., Ionescu, C. & Levermann, A., 2014. Impact of future sea-level rise on global risk of coastal floods. doi: 10.1073/pnas.1222469111.

The costs were generated from the Dynamic Interactive Vulnerability Assessment (DIVA) modelling framework. Further information about DIVA may be found at www.diva-model.net and the following references:

Hinkel, J., 2005. DIVA: an iterative method for building modular integrated models. Advances in Geosciences, 4, 45-50.

Hinkel, J. & Klein, R.J.T., 2009. Integrating knowledge to assess coastal vulnerability to sea-level rise: The development of the DIVA tool. Global Environmental Change 19(3): 384–395.

Vafeidis, A.T., Nicholls, R.J., McFadden, L., Tol, R.S.J., Hinkel, J., Spencer, T., Grashoff, P.S., Boot, G. & Klein, R.J.T., 2008. A new global coastal database for impact and vulnerability analysis to sea-level rise. Journal of Coastal Research, 24, 917-924.

Hinkel, J., Nicholls, R.J., Tol, R.S.J., Wang, Z.B., Hamilton, J.M., Boot, G., Vafeidis, A.T., McFadden, L., Ganopolski, A. & Klein, R.J., 2013. A Global Analysis of Coastal Erosion of Beaches due to Sea-level Rise: An Application of DIVA. Global and Planetary Change 111, 150–158.


Sally Brown, Robert J Nicholls

University of Southampton (SOTON), United Kingdom

Daniel Lincke, Jochen Hinkel

Global Climate Forum, Germany