GeoJournal 17, 3, — Rowntree, K. South African Geographical Journal 71, 74—80 Schlesinger, W. Soil Science Sow, N. Africa Pixel 2, 69—96 Tolba, M. Desertification: financial support for the biosphere. Hodder and Stoughton, London Trucker, C. Science , — Warren, A. A Report for Greenpeace International, 90 pp. Download references. You can also search for this author in PubMed Google Scholar.
Reprints and Permissions. Desertification as a Global environmental issue. GeoJournal 31, 11—14 Download citation. Issue Date : September Anyone you share the following link with will be able to read this content:.
Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. References Agnew, C. Journal of Climatology 9, — Google Scholar Ahlcrona, Eva: The impact of climate and man on land transformation in central Sudan. Google Scholar Blaikie, P. Practically speaking, the consequences of this are less available land for grazing, and less productive soils.
Ecosystems start to look different as more drought tolerant shrubs invade what used to be grasslands and more bare soil is exposed. Examples are many countries in East Africa — especially Somalia, Kenya and Ethiopia — where over half of the population are pastoralists relying on healthy grazing lands for their livelihoods. The UNCCD estimates that around 12m hectares of productive land are lost to desertification and drought each year. This is an area that could produce 20m tonnes of grain annually.
This has a considerable financial impact. Loss of livestock, reduced crop yields and declining food security are very visible human impacts of desertification, says Stringer:. Another impact of desertification is an increase in sand and dust storms. Dust storms can have a huge impact on human health, contributing to respiratory disorders such as asthma and pneumonia, cardiovascular issues and skin irritations, as well as polluting open water sources.
They can also play havoc with infrastructure, reducing the effectiveness of solar panels and wind turbines by covering them in dust, and causing disruption to roads, railways and airports.
Adding dust and sand into the atmosphere is also one of the ways that desertification itself can affect the climate, says Kimutai. Dust particles in the atmosphere can scatter incoming radiation from the sun, reducing warming locally at the surface, but increasing it in the air above.
They can also affect the formation and lifetimes of clouds, potentially making rainfall less likely and thus reducing moisture in an already dry area. Soils are a very important store of carbon. This process also makes nutrients in the soil available for plants to use as they grow. Soil erosion in Kenya. And typically, respiration declines with decreasing soil moisture to a point where microbial activity effectively stops.
While this reduces the CO2 the microbes release, it also inhibits plant growth, which means the vegetation is taking up less CO2 from the atmosphere through photosynthesis. Overall, dry soils are more likely to be net emitters of CO2. So as soils become more arid, they will tend to be less able to sequester carbon from the atmosphere, and thus will contribute to climate change. Other forms of degradation also generally release CO2 into the atmosphere, such as deforestation , overgrazing — by stripping the land of vegetation — and wildfires.
But coming up with a robust global estimate for desertification is not straightforward, explains Kimutai:. The multiplicity and complexity of the processes of desertification make its quantification even more difficult. Studies have used different methods based on different definitions. And identifying desertification is made harder because it tends to emerge relatively slowly, adds Michaelides:.
By the time it is detected, it may be hard to halt or reverse. Status of desertification in arid regions of the world.
Taken from Dregne, H. The GLASOD project was itself based on expert judgement, with more than soil and environmental scientists contributing to regional assessments that fed into its global map, which it published in It categorised the degradation into chemical red shading , wind yellow , physical purple or water blue. Shading indicates type of degradation: chemical red , wind yellow , physical purple and water blue , with darker shading showing higher levels of degradation.
Source: Oldeman, L. As the report puts it:. A single global map of land degradation cannot satisfy all views or needs. The parts of the world with the most potential issues shown by orange and red shading — such as India, Pakistan, Zimbabwe and Mexico — are thus identified as particularly at risk from degradation. Shading indicates the number of coincident risks. The areas with the fewest are shown in blue, which then increase through green, yellow, orange and the most in red.
Credit: Publication Office of the European Union. As desertification cannot be characterised by a single metric, it is also tricky to make projections for how rates of degradation could change in the future. In addition, there are numerous socio-economic drivers that will contribute. For example, the number of people directly affected by desertification is likely to increase purely because of population growth. The impact of climate change on aridity is also complicated.
A warmer climate is generally more able to evaporate moisture from the land surface — potentially increasing dryness in combination with hotter temperatures. These policies include a shift to low-carbon energy technologies and the deployment of carbon capture and storage. In RCP4. The UN conference defined a plan of action to stop desertification which, after 15 years, was acknowledged as a complete failure.
UNEP has argued that the plan failed because it applied technical solutions to socio-economic and socio-political problems, did not include local populations in drawing up solutions and failed to integrate these programmes into other development programmes. Desert-stricken countries, primarily from Africa, negotiated with Northern countries to support the Desertification Convention in exchange for African governments' support for a forests convention.
The Desertification Convention was opened for signing in October when 87 governments signed. Desertification is a significant threat to the arid, semiarid and dry sub-humid areas of the globe - the 'susceptible drylands' which cover 40 per cent of the Earth's land surface.
Soil degradation in the drylands affects or puts at risk the livelihoods of more than 1, million people who are directly dependent on the land for their habitat and source of livelihood. Some 1, million hectares, or 20 per cent of the world's susceptible drylands, are affected by human-induced soil degradation.
Of this total, 45 per cent is affected by water erosion, 42 per cent by wind erosion, 10 per cent by chemical deterioration and 3 per cent by physical deterioration of the soil structure. Water erosion is the dominant form of degradation in semi-arid areas 51 per cent of total degradation and dry sub-humid regions also 51 per cent , and wind erosion is dominant in the arid zone 60 per cent. More than a billion hectares of arid lands are already degraded worldwide, an area the size of China.
Hundreds of millions of people suffer the consequences, forced migration and economic ruin. Globally every year an additional , square kilometres - an area larger than Senegal - are reduced by desertification to the point of yielding nothing.
The process is accelerating: some 3. The annual cost of preventative, corrective and rehabilitation measures combined are between Nearly two-thirds of African land is arid or semi-arid. The continent is the most seriously affected by desertification which threatens more than one-third of Africa's land area, particularly in Mediterranean Africa, the Sudano-Sahelian region and Southern Africa.
In Northern Africa alone, more than million hectares 57 per cent of total land are threatened by desertification. Although overgrazing has long been considered the primary cause of desertification in Africa, it is now thought that rainfall variability and long-term droughts are more important determinants. Attempts at reforestation in Spain, Italy and Greece would certainly have been more successful had the opposite shores of the Mediterranean still been covered with a wide belt of fertile land, as they once were.
But the desert has already reached the shore of the Mediterranean on a wide front and sends out its drying winds to the European countries. Although approximately countries are affected by desertification, the process is most serious in sub-Saharan Africa particularly the Sudano-Sahelian zone , northwestern Asia, and the Middle East.
By , one country, Tunisia, was beyond the "water barrier" -- less that the bare minimum cubic metres of water per person per year.
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