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desertification, and change

More than 30 per cent of the ’s are found in susceptible dry- Aridity zones land regions in North , the and the southern part of Africa.53 They cover almost 2 billion hectares in 25 countries, representing 65 per cent of the continental land mass. Over 400 million people live in the dry- lands of Africa and the majority of them are the rural poor. Moreover, the area registers an annual growth rate of 3 per cent.54

Dryland areas in Africa are under threat from , , nutrient , recurrent drought and , potentially result- ing in and , and aggravated . Sus- tainable agricultural innovations are key to limiting adverse impacts on the environment and on the livelihoods of rural .

Source: UNEP-GRID, 2007.

Drought is the silent killer—the natural catas- trophe that is only too easily forgotten. Hama Arba Diallo Former Executive Secretary of the Convention to Combat Desertification, 2005

AFRICA REPORT << 39 >> Percentage change in vegetation greenness in the The Sahel has been greening in recent years. Sahel, 1982-2003 Greening of the Sahel as observed from images is now well es- tablished, confirming that trends in rainfall are the main but not the only driver of change in vegetation cover. For the period 1982-2003, the over- 15˚W 10˚W 5˚W 0˚E 5˚E 10˚E 15˚E 20˚E 25˚E 30˚E all trend in monthly maximum Normalized Difference Vegetation Index (NDVI) is positive over a large portion of the Sahel region, reaching up to 15˚N 15˚N 50 per cent increase in parts of , Mauritania and Chad, and confirming previous findings at a regional scale.55

10˚N 10˚N Local conditions seem to have influenced the extent of 15˚W 10˚W 5˚W 0˚E 5˚E 10˚E 15˚E 20˚E 25˚E 30˚E vegetation recovery. 0 400 800 Kilometres NDVI change (%) –50 –20 –10 0 10 20 30 40 50 Some areas have greened more than what would be expected from rainfall recovery alone. In some regions (e.g., Delta of Mali; south-western Source: Herrmann, Anyamba and Tucker (2005). Mauritania), increases in vegetation can be explained by an expansion of Note: Overall trends in vegetation greenness throughout the period 1982-2003 based on irrigation. For other regions, such as the Central Plateau of , monthly Advanced Very High Resolution Radiometer, Normalized Difference Vegetation Index (AVHRR NDVI) time series. Percentages express changes in average NDVI between recovery of vegetation greenness beyond what would be expected from 1982 and 2003. the recovery of rainfall is thought to be the result of increased investment and improvements in soil and techniques. Some areas Changes in vegetation greenness not predicted by have registered less greening than expected from rainfall patterns. changes in rainfall

15˚W 10˚W 5˚W 0˚E 5˚E 10˚E 15˚E 20˚E 25˚E 30˚E

15˚N 15˚N

10˚N 10˚N

15˚W 10˚W 5˚W 0˚E 5˚E 10˚E 15˚E 20˚E 25˚E 0 400 800 Slope residuals (x102) Kilometres –10 –3 –2 0 2 3 10

Source: Herrmann, Anyamba and Tucker (2005). Note: Overall trends in the residual NDVI throughout the period 1982-2003 based on regression of vegetation greenness (AVHRR NDVI) on 3-monthly cumulative rainfall. Slopes of residual NDVI trend lines between 1982 and 2003 are expressed in units of NDVI x 104.

AFRICA REPORT << 40 >> The Niger has witnessed and population increase at the same time

Source: 1990 CILSS and others, 2005.

1984 2004 Source: CILSS and others, 2005. The Lama plateau in the Niger in 1984 (above) and 2004 (below). 2004

Better conservation and improved rainfall have led to at least 6 mil- An evaluation project under- newly tree-covered acres in the Niger, achieved largely without taken in three areas of the Ni- relying on large-scale planting of trees or other expensive methods ger in 2005 (Tahoua, Tillabéri often advocated for halting desertification. Moreover, these gains and Maradi) points to encour- have come at a time when the population of the Niger has grown aging results in the locations rapidly, confounding the conventional wisdom that population of projects initiated to fight growth leads to the loss of trees and accelerates land degradation. desertification with support from donors, compared to Kware village neighbourhood in 1975 areas where no such project (left) before interventions and in 2003 was implemented. Degraded (SPOT image). Black dots are trees. lands have been reclaimed Windbreaking lines consisting of trees and restored to crop produc- are clearly visible in 2003 (below). tion by local populations. Water tables have risen sig- nificantly, which has made the development of vegetable that have become significant produc- 1975 ers at the national level. In the three regions studied, Source: yields have increased both CILSS and others, 2005. for millet and sorghum. Side benefits of land regeneration 2003 have included reduced vul- nerability of women and re- duced emigration rates.56 AFRICA REPORT << 41 >> Mortality risks and economic loss from drought

Drought total economic loss Drought mortality Risk deciles Risk deciles st th 1st to 4th 1 to 4 th th 5th to 7th 5 to 7 th th 8th to 10th 8 to 10

Source: , 2005, Global Hotspots. Note: Deciles are based on all regions, not only Africa.

Africa is most vulnerable to extreme events. According to a global study undertaken by Columbia University and the World Bank, Africa is not stricken by more natural than other . However, impacts of such disasters tend to be particularly high in Africa, both in terms of number of people affected and in terms of mortality from and . A global study of losses from drought found that drought mortal- ity hot spots are concentrated exclusively in sub-Saharan Africa.57

While economic loss hot spots for drought tend to include more devel- oped regions, for example in southern and the Middle East, Mexico, north-east Brazil and north-east , a sizeable portion of African territory is also located in the top deciles for economic losses due to drought.58

AFRICA REPORT << 42 >> Composite time series of rainfall deviations from Variations in climatic conditions have been observed for a long long-term means for several Sahel stations time in Africa. Changes in rainfall patterns observed in the Sahel in the 1970s and have dramatically affected livelihoods in that region, which already had to cope with 1.75 highly irregular and unpredictable rainfall patterns. Decreases in rainfall have had 1.50 Annual Rainfall profound repercussions on the flows of the main rivers that provide an essen- 1.25 5-year moving average

1.00 tial source of livelihood for the population of areas. Declines in river flows

0.75 and runoff in those regions have typically been more pronounced than those in 59 0.50 rainfall. Decreased river flows have contributed to the shrinking of , 0.25 one of the largest lakes of Africa. Recent years have registered somewhat more 0.00 favorable conditions. However, events have also become -0.25 more common.60 -0.50 Annual Rainfall Index -0.75

-1.00

-1.25

-1.50

-1.75 1895 1900 1905 1910 1915 1920 1925 1930 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Source: Agrhymet, 2005.

Changes in the annual flow of the in Niamey, Niger

600

500

400

300

200

100

0

-100 Deviation (m3/s) -200

-300

-400

-500 1950 1954 1958 1962 1966 1970 1974 1978 1982 1986 1990 1994 1998 2002

Changes in annual flows: deviation from the mean

Source: CILSS, 2005. AFRICA REPORT << 43 >> Countries with highest projected share of population Current and projected zones of water tension affected by -level rise

Caspian Sea

Nigeria Mediterranean Sea

Togo

Gabon Tropic of Cancer Red Sea Tropic of Cancer Red Sea

Guinea Arabian Sea Arabian Sea 1-meter rise Mozambique

5-meter rise Gulf of Guinea Gulf of Guinea

Djibouti Equator Equator

Senegal

Atlantic 30° Benin

Liberia 20°

Tropic of Capricorn Mozambique Channel Mozambique Channel

Guinea-Bissau

Indian Ocean10°

Mauritania

Gambia Current zones of water tension (2000) Projected future zones of water tension in 2050 None None 0 5 10 15 20 25 Tense Tense Very tense Share of population affected (percentage) Very tense

Source: World Bank, 2007. Source: Le Blanc and Perez, 2008. Note: Tension in these maps is defined based on population densities conditional on Impacts from sea-level rise will be high for some African countries. average annual rainfall. Climate change is expected to translate into sea-level rise during the next century. The extent of the rise is still uncertain. According to World Bank es- Climate change, by modifying rainfall patterns, could exacerbate timates, less than a quarter of 1 per cent of sub-Saharan Africa’s GDP would water tensions on the . be impacted by a 1-metre sea-level rise. Only a very small percentage of the 61 On most of the continent, is going to impose additional region’s area and agricultural land would be affected. pressure on compared to the present situation, in particu- lar in the Sahel but also in Eastern Africa. However, changes in rainfall will However, some countries would be much more severely affected. The coun- modulate substantially the demographic impacts, and may have very dif- tries with greatest land area impact would be the Gambia and, to a lesser ferent implications in different subregions and at the country level. Many extent, Guinea-Bissau. Banjul, the capital of the Gambia, is particularly climate models project a wetter Sahel in the coming decades, as well as vulnerable to sea-level rise and the entire city could be lost with a 1-metre 62 drier conditions for Eastern Africa. If these trends materialize, pressure on rise in . A major ecological and economic consequence of sea- the water resources in the Sahel could be eased somewhat, although not level rise would be the destruction of and mangroves, which cur- to a sufficient extent to counterbalance the impact of population growth. rently provide livelihoods to coastal populations. Approximately 15 per cent 63 Eastern Africa is likely to see its situation worsen, because demographic of Benin’s wetlands would be impacted by a 1-metre sea-level rise. and climate impacts are predicted to work in the same direction towards increasing water stress.64

AFRICA REPORT << 44 >> Projected impact of climate change on agricultural yields by the 2080s with carbon fertilization

n.a <-25 -25 - -15 -15 - -5 -5 - 0 0 - 5 5 - 15 15 - 25 Impact of temperature rise on robusta in Uganda >25

Source: Cline, 2006.

Africa is the region where the impacts of climate change on agricul- ture are predicted to be the most severe. Increasing temperatures and changed rainfall patterns will affect African agricul- ture dramatically, by changing the geographical distribution of areas suited to the different crops. Keeping current crop mixes would result in decreased yields due to suboptimal climatic conditions compared to the current situation. As a result, countries will have to adjust the mix of crops they grow. Recent research focusing on the biophysical effects of climate change ( and temperature) sug- gests that Africa would be the continent most affected by climate change from the point of view of agricultural productivity, with almost all countries undergo- Source: UNEP-GRID, 2002. ing losses of productivity, even after crop adjustments and the positive effects of carbon fertilization are taken into account.65 At the country level, important adjustments in crop mix may be needed due to climate change. For some countries that are currently relying on a few crops, increases in tem- perature such as predicted by the main climate models will probably imply radical changes in the agricultural production system, because the crops in question will not be adapted to the agroclimatic conditions of the country any more. Whereas most parts of Uganda are currently suited for coffee cultiva- tion, one study estimates that a 2-degree Celsius temperature increase would render most of the country’s area unsuitable for coffee. AFRICA REPORT << 45 >>