Livelihood Security: Climate change, conflict and migration in - UNEP

account for 31.4 per cent of GDP, while imported
goods and services are equal to 54.9 per cent. 29
2.2 Environmental and climatic
conditions
With an area of 7.4 million km², the study region
is comprised of the transitional zone between the
arid Sahara and the tropical forest that borders
the maritime coast. Desert and semi-desert in the
northern parts of the region gradually give way to tall
grass savannah, followed by savannah woodland,
while the southernmost and coastal parts of the
region are dominated by a semi-humid and humid
tropical climate with equatorial and tropical-zone
rainforest. 30 Although the landscape is relatively
flat, mountains in the northern reaches of the Sahel,
including in Mali, Mauritania, Niger and Chad,
reach upwards to 3,400 m in elevation. 31
The main water basins in the region are Lake Chad
and the Niger, Senegal and Gambia Rivers. The
Niger River basin is Africa’s third largest after the
Nile and Congo, and is shared by no less than 11
countries. Major lakes in the region include Lake
Faguibine in Mali, Kainji Lake in Nigeria, Lake Volta in
Ghana and Lake Chad, which borders Chad, Nigeria,
Niger and Cameroon. Groundwater resources
range from shallow aquifers that are refilled seasonally
to ancient sedimentary water basins, which are
non-renewable and difficult to access, reaching
depths of up to 2,000 m. 32
Both surface and groundwater are highly dependent
on seasonal rainfall, which is characterized by
strong variability and irregularity across the region.
With the majority falling in only three months of the
year, between July and September, rainfall can
vary by more than 1,000 millimetres (mm) over a
north-south distance of 750 km, from the arid zones
in the north to the humid and sub-humid zones on
the coast. 33,34 The desert-like climate in the far north
receives an average of only 200 mm 35 per year,
while the more humid climate in the southern part
of the Sahelian semi-arid belt receives an annual
average of some 600 mm. Halfway between these
values – at approximately 350 mm – is the limit
at which rain-fed agriculture can be practiced, 36
which has shifted southward in recent years. 37 In
addition, a variation of more than 30 per cent in
the length of the rainy season can be experienced
18
from one year to the next. 38 This cycle of dry years
and wet years is a typical feature of this climate.
Desertification and sand intrusion, finally, are a
threat in the arid northern regions, where sand
encroachment compromises the growth of seeds
and renders some production areas sterile. 39 Sand
intrusion from desertification also threatens major
water courses in the region, such as the Niger
River, as well as roads and other development
infrastructure.
2.3 Livelihoods: Farmers,
herders and fishermen
Despite significant seasonal fluctuations in rainfall,
erratic crop yields, poor soil, and depleted fish
stocks, farming, herding and fishing remain the
dominant livelihoods in the region. In 2008, 46
per cent of the land area of the countries covered
by this study was categorized as agricultural
land – defined as arable lands under permanent
crops and pastures – by the Food and Agriculture
Organization (FAO). 40 Farming accounts for more
than 50 per cent of the part of GDP that is derived
from agricultural practices, 41 closely followed by
pastoralism, which accounts for approximately 40
per cent. 42
Rain-fed agriculture is the dominant method used
by both farmers and herders at the subsistence
level, with few mechanical inputs to enhance
production, and low monetary income. 43 However,
rain-fed agriculture can only be practiced
in the region up to the 350 mm rain belt, which
varies between 14 and 17 degrees latitude, from
east to west (see Map 7). 44 North of this fluctuating
line, farming gives way to pastoralism as the main
livelihood.
Only a small proportion of arable land in the
region 45 – an estimated 5 per cent of the total land
area – is irrigated. 46 The Markala dam, along the
Niger River in Mali, and Senegal’s Manantali and
Diama dams, at the mouth of the Senegal River,
facilitate large-scale irrigation. 47,48 In addition, flood
recession agriculture occurs along some rivers and
lakes, allowing farmers to grow crops in the soil
moistened by the inundations of the rainy season.
Livelihood Security: Climate Change, Migration and Conflict in the Sahel