Climate Change and Africa: Potential impacts of sea-level rise on populations and agriculture

Abstract: The paper discusses some issues related to the potential impacts of sea-level rise (SLR) on coastal populations and agriculture. This is a study mostly based on global data at the countrywide (national) scale. Indirect effects of SLR, as well as the potential impact of extreme events, may be more significant than direct effects in the future. In the absence of an accepted methodology for building long-term scenarios, two approaches are explored: an analysis of a large database of extreme events that have occurred over the last 100 years, and an analysis of population statistics in relation to a national vulnerability index based on physiographic features and population density. Recent historical data are examined with a view to identifying trends that could be extrapolated into the 21st century. Despite the limitations of the data sets, some trends do emerge, but they do not necessarily point in the direction of greater property and population losses in the future owing to sea-caused disasters. Rather, they seem to indicate that difficulties − independent of the global changes − will be relatively larger on land than along the coasts, and that the major component of life and property losses is associated with levels of economic development. The “national vulnerability index” confirms that vulnerability − if considered at the scale of the globe − varies considerably, over several orders of magnitude. In addition, the index exhibits a marked positive skew. Combined with changes in population concentrations and the positive skew of many climatological elements (such as wind and rainfall), as well as of SLR itself, this indicates that relatively greater disasters are likely. The paper stresses the fact that both the impacted system (population and coastal agriculture) and the extreme physical factors have their own dynamics, and that those dynamics are