This is one reason why populations are concentrated along the coastline, with a rate of urbanization slightly higher than the interiors. As a result, many capitals and major towns are coastal.
Along the northwest coast of Africa average rates of coastal retreat are between one and two meters per year.
However, more serious rates of up to hundreds of metres per year have been observed locally, especially when the process has been created by human activities.
Coastal erosion has devastating effects, inducing the loss of infrastructure such as roads.
It also threatens populations, who can no longer live close to the coastline, and the worry is it is expected to increase due to climate change and sea level rise.
This will bring other problems such as salinisation of water and soils, degradation of ecosystems and flooding. Such predictions were reiterated in the fourth Intergovernmental Panel on Climate Change (IPCC) report.
Moreover, recent studies indicate that sea level observations are already higher than the maximum limit of IPCC projections. This means that we can expect more than the one-meter sea level rise projected for 2100, a fact that the rapid melting of the Greenland ice sheet, as well as strong indications that the western part of the Antarctic ice sheet is also melting, strongly support.
Whatever the dispute about the rates and amounts of sea level rise, it is evident that coastal populations and ecosystems will need to adapt to these changes.
For human beings only three options are available to combat coastal erosion: retreat, accommodate or protect.
A very limited number of studies – conducted mainly during preparation of the Initial National Communications from Parties not included in Annex I of the United Nations Framework Convention on Climate Change (UNFCCC) – indicate that the costs of adaptation are likely to be lower than the impacts costs of doing nothing.
However, the cost of adaptation is already considered to represent between 5 and 10 per cent of the GDP of affected countries, which is a significant sum, especially for the economies of the least developed countries.
This debate is by no means over, since all the elements that could allow a significant cost-benefit analysis are not yet available. A limited number of adaptation options (mainly sea walls) were evaluated but indirect costs (expertise, manpower, technical help) have not been considered. Even the retreat option would have a cost – both economically and socially.
The Intergovernmental Oceanographic Commission of UNESCO is implementing the project Adaptation to Climate Change in Coastal zones of West Africa (ACCC) which is a tentative response to the problem of coastal erosion.
It operates on a sub-regional level and involves five countries: Mauritania, Senegal, Gambia, Guinea Bissau and Cape Verde. National components are developing pilot activities in selected sites – one per country – with the aim of reducing the threat of coastal erosion, while increasing biodiversity and strengthening the adaptive capacities of local communities and ecosystems.
Guest Editorial