Sea-level rise: coastal impacts and responses

In the 1990s it was estimated that 21 and 37 per cent of the global population lived within 30 km and 100 km, respectively, of the coast (Cohen et al. 1997; Gommes et al. 1997). Population densities in coastal areas are three times the global mean, and it is estimated that 50% of the world’s population will live within 100 km of the coast by 2030 (Small and Nicholls, 2003). Human settlements, including many large cities, are also concentrated near or on coastlines, and a large proportion of global economic productivity derives from coastal areas (Turner et al., 1996). Trends towards urbanisation are likely to increase population densities in low-lying coastal areas; the population living within 30 km of the coast is estimated to be growing at twice the global average reflecting coastward migration, and GDP growth in coastal areas exceeds the national average in many countries (Bijlsma et al., 1996). Coastal zones are therefore of great importance as zones of settlement and play a vital role in the economic well-being of many nations.