Page 34 Desertification in the drylands – regions that don’t get much rain, and rainfall evaporates due to high temperatures.

Hot deserts

What is a desert? Deserts cover 25-30% of the Earth’s land surface. Key characteristic 1: aridity (dryness). Arid deserts: less than 250mm of rainfall a year. Semi-arid deserts (usually found on the edges of arid deserts): 250-500mm of rainfall a year.

Hot desert climates Low annual precipitation Unreliable Extreme high temperatures

The distribution of arid and semi arid areas The semi-arid areas are generally on the edges of the arid ones. They are on the western sides of continents and extend inland to varying degrees – this is most limited in South America and most extensive cross North Africa, across the Middle East into Asia. These areas are most extensive in North Africa, Asia and Australia These areas mainly occur between 30 degrees north and south of the Equator. With the exception of an area in east Africa, they are not found at the Equator.

Desertification: distribution of areas at risk, physical and human causes, impact on land, ecosystem and populations. Desertification occurs when there is an expansion of the deserts into areas on their margins. It is already affecting over one billion people!

AREAS AT RISK

Video: Desertification - A Visual Disaster (1.34m)-End: management Consequences: Video: Desertification - The Impact of Climate Change on Small Scale Farmers in Burkina Faso

Last homework! To what extent do you agree that the human causes of desertification are more important than the physical causes? (6 marks)

Last chance to improve grades…. Presentation/poster/video on Desertification Effects of desertification on people and the environment Find photos to show the effects (al least 6) Give a brief description of what each photo shows. Don’t forget to add name and class!

The fight against desertification

earthrise - The Great Green Wall Zai Planting Pits