How desert, and best friend water, could be our worst enemies
AFRICA could see climate change adaptation costs rise to $50 billion per year by 2050, even assuming international efforts keep global warming below 2°C this century, according to a recent United Nations Environment Programme (UNEP) report. That is a mind-freezing cost, but Africa can only ignore the underlying story it tells at its peril.
Within the next 1,000 years the face of the African continent is set to alter drastically through two processes – desertification and rises in sea levels.
Over the past century, the Global Mean Sea Level has risen by 10 to 20cm. If we are to crudely assume this rate will continue, even though there is evidence that due to increasing global temperatures, warmer oceans and melting ice sheets that it is accelerating, by 3015 we will see a rise of between 1-2 metres.
The effects will be devastating. Continental Africa comprises 48 countries of which 33 have coastlines and there are also seven adjacent island nations and territories. Today it is estimated that at least 25% of Africa’s population lives within 100km of a sea coast.
The continent’s coastal zone consists of a narrow, low-lying coastal belt composed of a variety of ecosystems, including barriers, lagoons, deltas, mountains, wetlands, mangroves, coral reefs, and shelf zones – all vulnerable to sea level rise and flooding.
Barring a major change in fortunes, low-lying islands of Seychelles, Mauritius, Sao Tome and Principe and Cape Verde could be submerged. A vast portion of Madagascar’s coastline would also disappear and the country would be severely affected by tropical storms which will increase flooding.
West Africa’s Atlantic coastline would take a severe beating. The coastal nations of west and central Africa – in particular Senegal, The Gambia, Sierra Leone, Nigeria, Cameroon, Gabon, Angola – have low-lying lagoonal coasts that are susceptible to erosion and hence are threatened by sea-level rise. Major cities such as Lagos, Banjul, Abidjan, Tabaou, Grand Bassam, Nouakchott, Sassandra, San Pedro, Banjul, and Port Harcourt – all situated at sea level – would be underwater.
The flooding would likely be most severe in Lagos because of its position at the southern end of the Gulf of Guinea where stronger tropical storms from the South Atlantic create storm surges.
Even where urban areas may escape actual flooding, the sea level rise would still challenge towns and cities by threatening the underground water with salination, from which millions of people across the region will be drawing their water.
The impact will reverberate through their economies. In Ghana, Benin, Togo, Sierra Leone and Nigeria, most of the economic activities that form the backbone of the national economies are located within the coastal zone. Coastal areas also form the food basket of the region.
In North Africa Egypt would be severely affected. A large portion of the 50km wide coastal strip lies below 2m and the sand belt which protects the coastal lakes and lagoons, is experiencing rapid erosion associated with the construction of the Aswan high dam. With a 1m rise in sea-level, the nation would experience an estimated loss of 28,000 km2 of agricultural land, 25,000 km2 of urban area and 24,000km2 of wetland loss.
Morocco would also experience heavy coastal damage, with a 2m sea-level rise, 24% of the eastern coastal area could be lost including urban (30%), agriculture & vegetation (29%), marshes (7%), and beaches (7%), most of them being the low-lying lands of the Moulouya delta and some parts of the coast where the natural coastal defences have been destroyed.
The coastal zone of east Africa also would be affected, although unlike west Africa’s Atlantic coast, this area experiences calm conditions through much of the year so would likely suffer less than the West side. However along the east coast of Africa, sea-level rise and climatic variation may decrease the attenuation of coral and patch reefs that have evolved along major sections of the continental shelf.
The lessening of this buffer effect increases the potential for erosion of the east coast. Mozambique, Kenya and Tanzania are of particular concern on the coast – losing major cities such as Mombasa, Dar es Salaam and Maputo to rising sea levels.
Another phenomenon that will significantly alter the continent’s landscape is desertification.
Desertification is caused by multiple direct and indirect factors. It occurs because drylands ecosystems are extremely vulnerable to over-exploitation and inappropriate land use. In Africa, because approximately two-thirds of the African continent is desert or drylands, a great proportion of the continent is at high risk.
A recent study estimated that desertification processes affect 46% of Africa, and 55% of that area is at high or very high risk. The worst affected areas are along desert margins and today in total about 485 million people are affected.
Today, the impact of desertification can be seen in the displaced communities from Lake Turkana, Darfur, around Lake Chad to the northern parts of Mali, Niger, Chad and the Central African Republic, who are migrating and increasingly displaced.
There is also evidence correlating desertification with increases in terror attacks as seen in the UN Convention to Combat Desertification charts above, showing the concentrations of past terrorist attacks, food riots and other conflicts in areas that are vulnerable to desertification.
Within imaginative and innovation pushback measures, the future looks particularly bleak. Unless there are clear economic and environmental actions that can prevent and/or reverse degradation, at the rate it’s swallowing villages today, desertification would consume vast swatches of Africa.
Data from UN, GRID-Arendal, PreventionWeb, UN Convention to Combat Desertification.