Transcript Desertification - s3.amazonaws.com

Desertification
Causes and consequences.
At the end of this lesson I will
be able to:
1.
2.
3.
4.
5.
State what desertification is?
Name a place that is experiencing
desertification.
Write two points (containing 3 bullet points
each) on the causes of desertification.
Examine 3 consequences of
desesrtification.
Describe 3 solutions to desertification.
Desertification is
 The gradual spread of the desert
into agricultural land.
The Sahel experiences
desertification.
 It borders on the
Sahara Desert.
Causes of desertification.
1. Drought

This is insufficient precipitation.
 There is also high evaporation due to
high temperatures and trade winds.
 Scientists believe droughts are
becoming more severe due to climate
change.
2. Human Activity
 Increased populations has seen increased
demand for food leading land to be
overworked and overgrazed.
 The destruction of the roots of plants by
grazing animals and cutting down of shrubs
and trees for firewood leaves soil exposed.
 Soil erosion occurs once the soil is exposed.
i.e it blows away.
 Goats, sheep and cattle overgrazing
fragile pasture, Bakino Fasa in the
Sahel.
Goats grazing fragile pasture
in Chad
 The Sahel is the name given to a 1,000-
kilometre band of savannah in Africa
south of the Sahara, stretching from
Mauretania in the west to Eritrea on the
Red Sea coast.
 The four driest periods in this relatively
arid region were in 1913, 1972, 1983 and
1984. Three of these dry spells followed
an eruption of Katmai in Alaska in 1912
and of El Chichon in Mexico in 1982.
 The extended drought between 1970 and
1990 in the Sahel region claimed 250,000
lives and created 10 million refugees: it was
one of the world’s biggest humanitarian
disasters.
 All kinds of causes were evoked, including
overgrazing, natural variability and industrial
exhausts, but Professor Haywood and his
colleagues think that volcanic eruptions also
strongly influence the sea temperatures in the
Atlantic, which are associated with Sahelian
drought.
 They simulated the impact of continued
global warming into the future and found
that only 11 of the 50 years between
2020 and 2070 would have negative
Sahelian precipitation anomalies.
A new analysis of Africa's past and future climate
shows that the Sahel region, which
experienced catastrophic drought for decades
until rains returned in the 1990s, could
experience wetter monsoons for decades to
come. However, drought across southern
Africa is projected to intensify further.
Scientists have linked this to changes in temperatures
of the atlantic ocean( cooling ) indian ocean
(warming)
What were our causes again?
1. Drought



2. Human Activity



Population growth
Evaporation
Insufficient rain
Climate change
Drought
Cutting down trees
overgrazing
Human Activity
Soil become bare
and exposed and blows
away
Desertification
Population growth
Evaporation
Insufficient rain
Climate change
Drought
Cutting down trees
overgrazing
Human Activity
Soil become bare
and exposed and blows
away
Desertification
At the end of this lesson I will
be able to:
1.
2.
3.
4.
5.
State what desertification is?
Name a place that is experiencing
desertification.
Write two points (containing 3 bullet points
each) on the causes of desertification.
Examine 3 consequences of
desesrtification.
Describe 3 solutions to desertification.
What is a consequence?
 Something that happens as a result of
something.
What is a consequence of
desertification?
1. Loss of agricultural land.
 Millions of hectares of land has turned
into desert.
 People don’t have any land to work.
 Livelihoods of millions is threatened.
2. Famine
 Loss of agricultural land means less
food is produced.
 Less food when the population is
growing has led to famine.
 Famin results in death E.g in Ethiopia.
3. Migration
 People leave the areas of
desertification,
 Population rises in other areas.
 Overgrazing etc. occurs here causing
desertification.
At the end of this lesson I will
be able to:
1.
2.
3.
4.
5.
State what desertification is?
Name a place that is experiencing
desertification.
Write two points (containing 3 bullet points
each) on the causes of desertification.
Examine 3 consequences of
desesrtification.
Describe 3 solutions to desertification.
Desertification
Migration
No land to farm
Famine
Solution
 Irrigation
 Restrict grazing
 Drought resistant shrubs and plants
Solution to Desertification
http://www.icrisat.org/news
room/latest-
1. Irrigation
 This means bringing water from one
area to places that don’t have any
water.
 This allows previously unusable land to
be used for agriculture.
 Solar powered pumps are now being
used for irriagtion in the Sahel
2. Restricted Grazing
 Limits on the number of animals grazing
and the types of animals grazing help
preserve roots of plants.
 Plant keep the soil together.
 Soil less likely to be eroded.
3. Drought resistant plants
 Sorghum – drought and heat tolerant.
 Grass/grain crop for food, fodder,
biofuel and alcohol.
 Easier to grow than grass for grazing
and soil isn’t eroded.
http://vimeo.com/20850064
What is desertification?
What causes it?
 Drought
 Human Activity
What are the consequences?
 No land
 Famine
 Migration
Solution
 Irrigation
 Less grazing
 Drought tolerant crops.
Regreening the Sahel
At the end of this lesson I will
be able to:
1.
2.
3.
4.
5.
State what desertification is?
Name a place that is experiencing
desertification.
Write two points (containing 3 bullet points
each) on the causes of desertification.
Examine 3 consequences of
desesrtification.
Describe 3 solutions to desertification.