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Coastal flood damage and adaptation costs under 21st century sea-level rise

  1. Anders Levermannc,i
  1. aGlobal Climate Forum, 10829 Berlin, Germany;
  2. bInstitute of Geography, Christian Albrechts University Kiel, 24098 Kiel, Germany;
  3. cPotsdam Institute for Climate Impact Research, 24098 Potsdam, Germany;
  4. dSchool of Civil and Environmental Engineering and Tyndall Centre for Climate Change Research, University of Southampton, Southampton SO17 1BJ, United Kingdom;
  5. eDepartment of Economics, University of Sussex, Falmer BN1 9SL, United Kingdom;
  6. fInstitute for Environmental Studies and Department of Spatial Economics, Vrije Universiteit, 1081 HV, Amsterdam, The Netherlands;
  7. gInstitute of Meteorology and Geophysics, University of Innsbruck, 6020 Innsbruck, Austria;
  8. hDepartment of Geography, University of Liège, 4000 Liege, Belgium; and
  9. iPhysics Institute, University of Potsdam, 14476 Potsdam, Germany

  1. Edited by Hans Joachim Schellnhuber, Potsdam Institute for Climate Impact Research, Potsdam, Germany, and accepted by the Editorial Board December 20, 2013 (received for review January 31, 2013)

Significance

Coastal flood damages are expected to increase significantly during the 21st century as sea levels rise and socioeconomic development increases the number of people and value of assets in the coastal floodplain. Estimates of future damages and adaptation costs are essential for supporting efforts to reduce emissions driving sea-level rise as well as for designing strategies to adapt to increasing coastal flood risk. This paper presents such estimates derived by taking into account a wide range of uncertainties in socioeconomic development, sea-level rise, continental topography data, population data, and adaptation strategies.

Abstract

Coastal flood damage and adaptation costs under 21st century sea-level rise are assessed on a global scale taking into account a wide range of uncertainties in continental topography data, population data, protection strategies, socioeconomic development and sea-level rise. Uncertainty in global mean and regional sea level was derived from four different climate models from the Coupled Model Intercomparison Project Phase 5, each combined with three land-ice scenarios based on the published range of contributions from ice sheets and glaciers. Without adaptation, 0.2–4.6% of global population is expected to be flooded annually in 2100 under 25–123 cm of global mean sea-level rise, with expected annual losses of 0.3–9.3% of global gross domestic product. Damages of this magnitude are very unlikely to be tolerated by society and adaptation will be widespread. The global costs of protecting the coast with dikes are significant with annual investment and maintenance costs of US$ 12–71 billion in 2100, but much smaller than the global cost of avoided damages even without accounting for indirect costs of damage to regional production supply. Flood damages by the end of this century are much more sensitive to the applied protection strategy than to variations in climate and socioeconomic scenarios as well as in physical data sources (topography and climate model). Our results emphasize the central role of long-term coastal adaptation strategies. These should also take into account that protecting large parts of the developed coast increases the risk of catastrophic consequences in the case of defense failure.

Footnotes

  • ↵1To whom correspondence should be addressed. E-mail: hinkel{at}globalclimateforum.org.

  • Author contributions: J.H., A.T.V., R.J.N., R.S.J.T., and A.L. designed research; J.H., D.L., A.T.V., M.P., R.J.N., R.S.J.T., B.M., X.F., and A.L. performed research; C.I. contributed new reagents/analytic tools; J.H., D.L., A.T.V., M.P., R.J.N., B.M., and X.F. analyzed data; and J.H., D.L., A.T.V., M.P., R.J.N., R.S.J.T., and A.L. wrote the paper.

  • The authors declare no conflict of interest.

  • This article is a PNAS Direct Submission. P.K. is a guest editor invited by the Editorial Board.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1222469111/-/DCSupplemental.

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