Low-elevation coastal cities Coasts have long provided attractive urban locations, particularly in trading economies, but many coastal areas are periodically threatened by storms and flooding. Climate change is expected to result in sea level rise, more extreme tropical cyclones and more intense episodes of precipitation (Alley et al., 2007; Nicholls and Cazenave, 2010). This will increase longstanding coastal hazards and undermine protective measures designed around historical weather patterns. Local specificities will play a major role in determining the risks people face, but generally those living near the coast at a low elevation will be likely to bear the brunt of these increasing coastal hazards. In 2000, about 630 million people lived in the Low Elevation Coastal Zone (< 10 meters elevation contiguous to the coast), of which about 360 million were urban (McGranahan, Balk, and Anderson, 2007). The average population density in this zone was about five times the world average, and the urban share was about 60 per cent, compared to a world average of less than 50 per cent. While low- and lower-middle income countries generally had less urbanized coastal zones than upper-middle and high-income countries, the share of their urban populations in the zone were actually higher. Most of the countries with large populations in the zone were large countries with heavily populated delta regions, predominantly in Asia, and almost two thirds of the cities with populations over 5 million were located at least partly in the zone. In a more detailed look at the hazards faced by port cities of over 1 million, a study by Nicholls and colleagues for the Organisation for Economic Co-operation and Development (OECD) (2008) estimated that, in 2005, about 40 million inhabitants (about a tenth of the total population in these port cities) were exposed to one-in100 year coastal flood events. They estimated that, by 2070, climate change, subsidence, population growth and urbanization would increase this figure to about 150 million. In 2005, the top 10 cities, in terms of exposed population, were almost evenly split between “developed” and “developing” countries, with most of the latter in Asia. They estimated that, by 2070, nine of the top 10 cities would be in Asia, largely because of rapid urban growth. They also looked at the exposure of assets and found, not surprisingly, that asset exposure was considerably higher in wealthier countries. For any given exposure, however, risks were generally found to be lower for port cities in wealthier countries, as these had more protection. This was not always the case: Shanghai, for example, was found to have a higher level of protection than New York. With coastal risks on the increase and ocean shipping in relative decline, this might seem like a good time to shift urban development away from exposed coastal locations. Indeed, this might seem like a priority, given that some have suggested on the basis of the estimates of low-elevation coastal population summarized above that in the foreseeable future hundreds of millions of people will be forced to migrate from their coastal homes anyway (Brown, 2010). However, while there is good reason to be concerned, such deductions are unfounded and potentially pernicious, in part for the reasons given in the previous section and also because they deflect attention from the adaptive measures that are needed in coastal areas. As of yet, there is little sign of any movement of population away from coastal settlements, except temporarily in the wake of disasters, and there is insufficient evidence to Fai r A n d E ffe ct i ve R e s po n s e s to U rban i zat i o n A n d C li m at e Ch a nge : Tap pi ng Sy n e rgi e s an d Avo i d i ng E xc lus i o nary P o li c i e s
Demography and Climate Change-text.indd 29
29
1/25/13 1:59 PM