Future sea level rise is considered to be one of the most serious and tangible consequences of climate change. Coastal flood damages are expected to increase significantly during the twenty-first century as sea levels rise and socio-economic development increases the number of people and value of assets in the coastal floodplain [1].

The population worldwide exposed to a 1-in-100-year coastal flood is projected to increase from about 270 million in 2010 to 350 million in 2050 due to socioeconomic development alone [2]. For 136 coastal cities above 1 million inhabitants, the number of people exposed to a 1-in-100-year extreme sea level is expected to increase from 39 million in 2005 to 59 million by 2070 as a consequence of a 0.5 m increase in global mean sea level alone, and to 148 million if socioeconomic development is also considered [3].

A recent study estimated costs of up to €25 billion per year by 2080 for European countries alone from sea level rise [4], while for countries such as Bangladesh, Vietnam and small island states in the Western Pacific, the potential consequences are likely to be even more severe and profound.

The Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) [5] concludes that protecting against coastal flooding and erosion is considered economically rational for most developed coastlines in many countries under all socioeconomic and sea level rise scenarios.However, a crucial element of successful coastal adaptation decisions is a robust and reliable projection of sea level rise.

References
[1] Hinkel, J., et al., Coastal flood damage and adaptation costs under 21st century sea-level rise. Proceedings of the National Academy of Sciences of the United States of America, 2014. 111(9): p. 3292-3297.
[2] Jongman, B., P.J.Ward, and J.C.J.H.Aerts, 2012: Global exposure to river and coastal flooding: long term trends and changes. Global Environmental Change: Human and Policy Dimensions, 22(4), 823-835.
[3] Hanson, S., R. Nicholls, N. Ranger, S. Hallegatte, J. Dorfee-Morlot, C. Herweijer, and J. Chateau, 2011: A global ranking of port cities with high exposure to climate extremes. Climatic Change, 104(1), 89-111.
[4] Brown, S., et al., The impacts and economic costs of sea-level rise in Europe and the costs and benefits of adaptation. Summary of results from the EC RTD ClimateCost Project, in 1. The ClimateCost Project. Final Report. Volume 1: Europe, P.e. Watkiss, Editor. 2011. p. 44.
[5] Wong, P.P., I.J. Losada, J.-P. Gattuso, J. Hinkel, A. Khattabi, K.L. McInnes, Y. Saito, and A. Sallenger, 2014: Coastal systems and low-lying areas. In: Climate Change 2014: Impacts,Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L.White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 361-409.