Revision Booklet

Extreme Climates

  • Physical characteristics of the Sahel Region
  • Adaptations of Flora (plants) and Fauna (animals) semi-arid areas
  • Adaptations by people in semi-arid areas
  • Problems facing people insemi-arid areas
  • Sustainable management of the Sahel Region

Physical characteristics of the Sahel Region

Places with extreme climates have a low carrying capacity. This means that the number of people they can support without the aid of technology is lower than in other places where temperatures and rainfall are less extreme.

On the borders of deserts are semi-arid areas where rainfall is low, often between 250mm – 500mm per year. The Sahel is a semi-arid area that borders the south of the SaharaDesert. It includes parts of countries such as Sudan, Chad, Burkina Faso and Niger.

Adaptations of Flora (plants) and Fauna (animals) in semi-arid areas

Flora (plants) adapt to the hot dry environment of the Sahel in 3 ways:

  1. Succulence
  2. Drought tolerance
  3. Drought avoidance

1. Succulent plants (cactus)

  • Have very thick leaves that are able to absorb a large amount of water very quickly from their shallow root system. They are able to store the water they collect in their leaves for a long period of time.
  • The roots are shallow as the rainfall never infiltrates the soil very deeply.
  • Their stems and leaves are waxy and their stomata can close during drought periods, this stops their growth but helps preserve their water by stopping transpiration.
  • They are attractive to animals, because of the amount of water stored in their leaves, so they

have developed spines or are toxic to put off

animals from eating them.

2. Drought Tolerance

  • During droughts (long periods without rainfall) some plants have adapted so that their leaves fall off. This stops water being lost from the plants through the stomata on the leaves.
  • Some plants have developed really deep roots which are able to get water from deep underground.

3. Drought Avoidance

  • These are annual plants (plants that only flower once).
  • After flowering they die, but leave behind their seeds, which can survive for years before growing into plants when it rains again.

Fauna (animals) adapt to survive in the Sahel Region, for example some beetles let early morning mist condense as water droplets on their bodies which then runs into their mouths.

However extreme droughts, desertification or changes to the climate due to man-made climate change can lead to all species of plants and animals becoming vulnerable.

Adaptations by people in semi-arid areas

People living in the Sahel Region have adapted to a certain way of life that allows them to cope with the extreme conditions. Many of the people are migratory (meaning they move around) allowing them to move to the areas with the best water supply. This also allows their animals to move to new grassland areas when the area they are using starts to run out of grass.

Adaptations to life in semi-arid regions
Buildings / Flat roofs collect rain water and walls are painted white to reflect sunlight to keep buildings cool. In poorer areas, windows are small to reduce light and keep temperatures inside low. Walls are often thick to help maintain the cool temperature inside. In richer areas air conditioning is used.
Clothing / Middle Eastern tribes of Bedouin people wear loose-fitting clothing, often white to reflect sunlight. Heads and faces are often covered to protect the wearer from sunburn and also from the wind and sand.
Transport / Camels were used as the main form of transport in many North African and Middle Eastern countries, due to their ability to travel so far without needing water. However, in richer areas 4x4 cars are now the preferred choice of transport through desert terrain.

Problems facing people of the Sahel Region

The problem of desertification is one of the biggest issues for the people who live in the Sahel. Desertification is when wind erodes away the top layer of soil that contains the nutrients which plants need to grow. This is a form of land degradation, which results in plants not being able to grow and the area becoming a desert.

Desertification is caused by both human and natural factors. A lack of rainfall can cause desertification as the plant life dies and the soil becomes more easily eroded by the wind as the plant roots are no longer able to hold the soil together.

However human actions can also cause desertification by:

Human Action / Process of Desertification
Over population / An increase in population leads to more intensive farming methods to get more food from the land. This leads to a loss of nutrients from the soil that eventually leads to the soil becoming infertile, so no plants will grow and the soil can become eroded by the wind leading to the land turning to desert.
Overgrazing / With desertification spreading the people of the Sahel are forced to farm on less and less land. This can lead to their cattle overgrazing the available grasslands, which can lead to the plants dying and desertification taking place.
Deforestation / With a growth in population there is a greater demand for firewood. This leads to more trees being cut down. The soil then becomes exposed to the wind and is more easily eroded, leading to desertification.

Climate Change can also make desertification worse. A change in rainfall patterns due to climate change can lead to desertification in two ways:

  1. If the rains don’t arrive, the grasslands of the Sahel die. This leaves the soil exposed and can then be easily eroded by the wind.
  2. When the rains then do arrive, the exposed soil is easily washed away by the heavy rain.

Sustainable Management of the Sahel Region

Local Scale: Case study Bunding in Burkina Faso

Oxfam heard about a local method of putting lines of stones across a slope to stop rain water running away and also stopping the wind from eroding the topsoil. This is called Bunding (intermediate technology, “simple”, cheap and easy to use technology. Suitable to the needs of the people).

Training people in this simple method of building lines of stones has improved the soil quality and slowed down the loss of water. It allows water the time to infiltrate into the top soil. As a result farming has improved on existing fields and land that could not previously be used is now being farmed on. This has increased the production of food in the area.

The project has now been in operation for 12 years and parts of Burkina Fasoare criss-crossed with lines of stones. Oxfam has taught local people how to cultivate trees and other plants because of the improved soil conditions. These locals have then gone on to train other members of the community so that the skills are passed on around the region

Global Scale: Case Study Kyoto and Copenhagen Agreements

Climate change is a major cause of desertification, so stopping climate change should help stop desertification.

Global agreements such as Kyoto and Copenhagen, when governments from all over the world agree to reduce carbon dioxide emmissions, are the world’s way of responding to the global problem of climate change.

By encouraging the use of renewable energy instead of fossil fuels, it is hoped that climate change will not be as extreme and areas of the world such as the Sahel will not suffer from unpredictable rainfall.

(see climate change revision guide re Copenhagen and Kyoto)