Human population growth and landscape alteration

Anthropogenic impacts on coastal wetlands include landscape alteration and reclamation of tidal wetlands, accelerated climate warming and sea level rise, spread of alien plant and animal species, construction of dams, draining of tidal wetlands and discharge of pollutants – deliberately or accidentally. Coastal wetlands are particularly vulnerable to the impacts of sea level rise (Cahoon et al., 2006). In the Stern Review of the Economics of Climate Change (Stern, 2007), the costs of future coastal flooding are projected as around US$7.5 to $11 billion per decade for Europe and North America, respectively. Syvitski et al. (2009) have shown that 17 of the world’s largest deltas (Table 5.1) are critically vulnerable to being flooding and converted to open ocean. In the past decade, 85% of these deltas experienced severe flooding, with a total area of 260 000 km2 being temporarily submerged. The Syvitski team estimate that the area vulnerable to flooding could increase by 50% under projected values for twentieth-century sea level rise. In contrast, other models predict that increased storminess will transport more sediment into coastal wetlands and enable salt marshes to keep pace with sea level rise (Schuerch et al., 2013).