Almost half of the terrestrial land surface, equal to 6.45 billion hectares,
is made up of drylands (47% according to the World Atlas of Desertification,
They are distributed among all the great regions of the planet.
One billion hectares is hyper-arid: these are real deserts such as the Sahara. 5.45 billion hectares are made up of arid, semi-arid and sub-humid areas. Desertification occurs in this part of the planet. These areas are inhabited by one fifth of the world’s population or 1.2 billion inhabitants in the year 2000. It is here— where the soils are especially fragile, vegetation is sparse and the climate particularly unforgiving— that desertification takes place. (Land degradation occurs everywhere, but can only be defined as ‘desertification’ when it occurs in the drylands). Some 70% of the 5.2 billion hectares of drylands used for agriculture around the world are already degraded.
Thus desertification now damages practically one quarter of the total land surface area of the world.
The world’s drylands are particularly affected by desertification.
On an environmental basis, these regions are defined by:
The drylands are comprised of arid, semi-arid and sub-humid areas, the difference being in their degree of aridity. Aridity is the result of the interaction between various climatic factors (rain, temperature, wind) and evapo-transpiration. These elements combine together to determine the growth of plants and the capacities of animals or humans to live fittingly in a harsh natural environment.
There are four main categories that are distinguished by their temperatures and rain cycles:
rainfall is less than 100 mm/year. Drought periods can last longer than a year. Biological productivity is low and the sole viable activity is nomadic pastoralism.
generally rainfall does not exceed 200 mm/year. These regions are characterized by farming (sedentary or nomadic) and irrigated agriculture.
These regions undergo the same processes of degradation as a result of natural resource over-exploitation and are all characterized by water shortages.
Locate your country and your region on the world map (See the poster).
Is your country located in a desertification zone?
Locate those countries that have arid zones and those that do not.
On the world map, colour the arid regions in yellow and write the names of the corresponding countries (or make and stick country flags on the map) in the desertification areas.
Colour the oceans in blue and the temperate zones
What do you notice?
On a ball or a sphere made of paper maché, draw the continents and their deserts with a felt tip pen while respecting their dimensions.
Decorate the colourful globe by painting the ball and glue sand for the desert areas.
You could also use an orange or any round fruit to achieve the same effect.
Select 10 words that symbolize the desert.
Write a poem using these 10 words.