The Great Green Wall is a climate change initiative involving 11 African nations to halt the spread of the Sahara Desert. It originally envisioned a line of trees across Africa but now focuses on sustainable land use. The project aims to reduce desertification, support communities, and increase resilience to climate change through practices like assisted tree regeneration. While early efforts in Senegal show promise, some question if top-down tree planting can succeed at the needed scale or whether natural regeneration is better.

1. The Great Green Wall

2. The Concept
●
The Great Green Wall is a major climate change mitigation initiative aimed at
addressing the social, economic and environmental impacts of land degradation and
desertification in northern Africa, specifically the Saharan and Sahel regions.
●
It involves the eleven nations that cross African from the Atlantic coast to the Red
Sea:
○
Burkina Faso, Chad, Djibouti, Eritrea, Ethiopia, Mali, Mauritania, Niger, Nigeria,
Senegal and Sudan

3. The Concept
● The initial idea of a line of trees crossing Africa
originated in the 1980s and reemerged in the early
2000s
● It was finally approved in 2007 with the first trees being
planted in 2008.
● Subsequently the vision of a Great Green Wall has
evolved into that of a mosaic of interventions addressing
the challenges facing the people of this region

4. The Sahel Region: Geography and Climate
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●
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The Sahel is the ecoclimatic and
biogeographic zone of transition in Africa,
between the Sahara desert in the north
and the Sudanian Savanna in the south.
The Sahel covers parts of (from west to
east), The Gambia, Senegal, southern
Mauritania, central Mali, Burkina Faso,
southern Algeria and Niger northern
Nigeria and Cameroon, central Chad
southern Sudan, northern South Sudan
and Eritrea.
The Sahelian climate is a tropical semiarid climate with the dry season mainly
(but not exclusively) during the cooler
months.

5. The Sahel Region: Geography and Climate
●
●
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The mean monthly temperature of these
months is around 18°C.
The Sahel is mostly covered in grassland
and savanna, with areas of woodland and
shrubland.
Grass cover is fairly continuous across the
region and is the source of grazing for
both livestock and native wildlife’
Over grazing of livestock is an important
contributor
to
the
problem
of
desertification of the region.

6. Desertification and Climate Change
●
Desertification is a form of land degradation whereby land in dry regions becomes increasingly
arid, meaning that it can no longer be used for agriculture.
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This can come about from a variety of factors including deforestation, overgrazing and other
human activities as well as climate change.

7. Desertification: Feedback Loops
●
There are feedback loops between desertification and climate change.
○
Vegetation that is removed by human activity means that there are fewer plants in the
region to hold moisture.
○
This moisture would normally evaporate in the warm climate and subsequently condense
to form rain clouds which typically produce rain the afternoons.
○
Decreased rainfall dries the soil which can then be easily blown away creating desert.
○
As land turns to desert, carbon stored in the drying land vegetation and soil is released to
the atmosphere.
○
Because of its geography, many regions in Africa can expect to have decreased rainfall as
a result of climate change.

8. Desertification: Rainfall
●
Since 1970 countries in this region have experience
significant variation in expected rainfall.
○
Burkina Faso there has been around 50 mm
less rainfall on average
○
In Nigeria there has been an increase of
around 250 mm on average. In addition
temperatures in the region have risen by 2°C
on average over the same time period [9].
○
In Senegal the rainy season typically started
in July or august but now starts in September
and the capital city of Dakar, which is over a
thousand miles from the Sahara desert, is
more frequently subjected to sand storms
[10].
○
In Chad, Lake Chad which is a principal
source of water and also the source of this
land locked nation’s fishing industry had been
drying significantly in this time period as can
be seen in the photo below [11].

9. Objectives of the Great Green Wall
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●
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The planting of trees is expected to provide a
barrier against desert winds and will help to
hold moisture in the air and soil.
This will allow agriculture to be sustained
which will enhance regional food security and
provide
job
opportunities
in
local
communities.
It is also expected that the Wall will reduce
erosion, enhance biodiversity and improve
countries’ resilience to climate change.
Additional the project should provide local
communities with knowledge to change
current practices which lead to land
degradation

10. Objectives of the Great Green Wall
●
●
The project also has major
symbolic significance given that it
represents a multinational initiative
to mitigate the consequences of
climate change.
For instance the Global Economic
Facility (GEF), which is a major
funder of the project, sees it as "a
visual concept symbolizing the
collective work we all have to do in
order to combat environmental
degradation".

11. Early Progress - Senegal
●
●
Senegal seems to be the nation most
enthusiastically embracing the project
and bearing the early successes.
Trees have to be planted during the
short rainy season and so far 50,000
acres of trees have been planted.
One example of success is a tree
planting project in the village of Widou
which has resulted in the creation of
market gardens which provide an
additional food and income source for
the villagers.

12. Early Progress - Senegal
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Villagers are taught how to plant
vegetable crops and use drip irrigation
by connecting a small elevated water
tank to perforated pipes that deliver
small amounts of water to each plant .
When the trees are more fully
developed it is expected that they will
also provide nutrients for the goats that
the villagers tend as well as help
stabilize the water plane.
The choice of trees matches those in
the local area and the communities
have been involved in the decision
making process.

13. Skepticism - Timberwatch
●
●
Timberwatch points to the failure of a similar project which was undertaken in
China which resulted in worsening the environmental situation
Whilst they acknowledge that the Widou project has utilized trees that fit local
environments, Timberwatch has a concern that this will not be the case across the
region and that too often consultation will actually take the form of misleading local
communities.

14. Skepticism - United States Geological Survey
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The United States Geological Survey
believes that natural regeneration is
much more likely to succeed than
planting trees.
They point to Niger where historically
farmers habitually removed any trees or
bushes as they sprouted their fields.
This practice changed after the
devastating drought in the 1980s.
Farmers decided to allow the natural
vegetation to grow and planted food
crops around it.
The result was a surplus of food and 12
million acres of trees.

15. References
● Slide 1: http://www.elrst.com/tag/great-green-wall/
● Slide 2-3: Great Green Wall http://en.wikipedia.org/wiki/Great_Green_Wall,
Don Leiber. The Great Green Wall
of Africa - A 4,000 Mile Defense Against Climate. Planet Save. 21 April 2013 http://planetsave.
com/2013/04/21/the-great-green-wall-of-africa-a-4000-mile-defense-against-climate-change/ The African Wall http:
//www.fao.org/docrep/016/ap603e/ap603e.pdf
● Slide 4-5: Sahel http://en.wikipedia.org/wiki/Sahel
● Slide 6: The African Wall http://www.fao.org/docrep/016/ap603e/ap603e.pdf Desertification http://en.wikipedia.
org/wiki/Desertification Deserticiation in the Saheel http://oceanworld.tamu.edu/resources/oceanographybook/desertificationinsahel.html
● Slide
7:
Desertification
and
Climate
Change.
Learning
Zone.
BBC.
http://www.bbc.co.
uk/learningzone/clips/desertification-and-climate-change/1501.html
Desertification.
World
Preservation
Foundation.
http://www.worldpreservationfoundation.org/topic.php?cat=climateChange&vid=23#.UfPXwI20cQM
Climate
Change
and
Desertification.
World
Meteorological
Organization.
http://www.wmo.
int/pages/prog/wcp/agm/publications/documents/wmo_cc_desertif_foldout_en.pdf

16. References
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Slide 8 Tierney Smith. Climate change, desertification and migration: Connecting the dots. Responding to
Climate Change. 14 August 2012. Bobby Bascombe. Senegal begins planting the Great Green Wall against
Climate Change. The Guardian. 13 July 2012.http://www.guardian.co.uk/environment/2012/jul/12/senegal-greatgreen-wall
Shrinking Lake Chad. http://en.wikipedia.org/wiki/File:ShrinkingLakeChad-1973-1997-EO.jpg
Slide 9: African nations strive to stem desertification with a ‘Great Green Wall’. UN News Centre. http://www.un.
org/apps/news/story.asp?NewsID=44671#.UfPJ3420cQM
Slide 10: Daniel Ajegbo. The Great Green Wall? Think Africa Press. 5 September 2011. http://www.
thinkafricapress.com/senegal/great-green-wall
Slide 11: Bobby Bascombe. Senegal begins planting the Great Green Wall against Climate Change. The
Guardian. 13 July 2012. http://www.guardian.co.uk/environment/2012/jul/12/senegal-great-green-wall
Slide 12: SENEGAL: Prospects and pitfalls along a Great Green Wall. IRIN. http://www.irinnews.org/printreport.
aspx?reportid=94322 Africa’s “Great Green Wall” Bears Fruit For Families In Senegal. World Food Programme.
11 April 2013. http://www.wfp.org/stories/africas-great-green-wall-bears-fruit-village-senegal
Slide 13 - 14
AFRICA: Opposition building to Great Green Wall. IRIN. http://www.irinnews.
org/report/92422/africa-opposition-building-to-great-green-wall Daniel Ajegbo. The Great Green Wall? Think
Africa Press. 5 September 2011. http://www.thinkafricapress.com/senegal/great-green-wall Bobby Bascombe.
Senegal begins planting the Great Green Wall against Climate Change. The Guardian. 13 July 2012.http://www.
guardian.co.uk/environment/2012/jul/12/senegal-great-green-wall