Adaptation actions in the Sahel in order of importance.
Climate change adaptation continues to be central on the agenda of most African countries. Current understanding of the state of adaptation is limited in Africa. The Sahel is selected because of persistent declines in precipitation and rising temperatures. Here, we examine the status of adaptation actions across the Sahel by reviewing the primary peer review literature. A total of 70 peer review papers that document 414 discrete adaptations provide a snapshot of adaptations developed between 1975 and 2020. From a country-to-country perspective, Kenya has the highest number of reported adaptation actions (75 or 18.1%). From a regional standpoint, West Africa recorded about 261 or 18.1% of all adaptation actions reported. Income diversification of livelihoods, and water harnessing were reported as the most used adaptation actions in the Sahel. Based on categories, technically based adaptation actions are the most used options. The period 2008–2016 registered 65.2% of all adaptations. 98% of adaptation actions are reported to be driven by climate while non-climatic drivers account for 95% of adaptation actions. The findings presented here are proxies of climate change adaptation; some relevant information might be found in gray literature which not used because gray literature is less standardized because it is not subject to peer review.
- Climate change
- West Africa
- Income diversification
- Technical adaptation
It is now clear that the world is experiencing climate change and the Sahel of Africa is no exception to this [1, 2, 3, 4, 5, 6, 7]. In the past thirty years the Sahel has witnessed temperatures in the range of between 0.2–2.0° C . At the same time, the precipitation gradient has witnessed a decline from the south to the north of the Sahel. The effects of the above precipitation and temperature nexus in the Sahel have been declining crop yield, water resources and degradation of forest species. Specifically, they include: (i) increase mortality and dieback of various tree species in parts of the Sahel such as Mauritania, Chad, Mali, Burkina Faso, Senegal, and Niger, as seen in observations of the last quarter of the 20th century ; (ii) enhanced stress on food systems, with about 50% of the 60 million people living in the Sahel believed to be facing food insecurity linked to climate change [10, 11, 12], with the region likely projected to potentially experience about 250 million tons of food deficits by 2020 [12, 13, 14]; (iii) enhanced occurrence of malaria and diarrheal diseases, [15, 16, 17]; (iv) with more frequent water shortages also documented . These impacts, in turn, are believed to have increased the number of climate refugees in the Sahel [19, 20, 21, 22]. Climate change may also present opportunities, including increasing food production through better water management, irrigation, rainwater harvesting , and potential increase in crop productivity due to increased aerial fertilization by carbon dioxide .
Climate change Adaptation is important as it reduces the damages caused by climate change and takes advantage of new opportunities in-light of the rapid climate change already occurring and expected future impacts [24, 25, 26, 27, 28, 29, 30, 31]. Governments, indigenous people, farmers, non-governmental organizations, donor organizations, the African Development Bank, the World Bank, and United Nations Environment Program have been active making suggestions through several policies, programs, and adaptations. For example, actions include those of the United Nations Reductions of Emissions from Deforestation and Forest Degradations (REDD+) which supports reforestation efforts in the Sahel [32, 33], and adaptation funding programs established under the United Nations Framework Convention on Climate Change (UNFCCC)  and at the regional level, the African Development Bank (AfDB) is now masterminding the African Climate Change Fund which has as objective to increase access of African countries to international climate finance . Despite the importance of climate change and adaptations in the Sahel, a lot remains unknown with respect to how adaptation actions have occurred over time in various part of the Sahel. This knowledge gap reduces the ability to characterize key gaps in adaptations. Furthermore, this underscore the necessity is create adaptation metrices across Africa that can assist in evaluating progress and monitoring the status of adaptation.
This chapter provides a better understanding of the status of climate change adaptation actions across various Sahel regions and countries, showing how adaptations have changed over time as well as the relative contributions of climatic and non-climatic drivers. This is based on what has been recorded in the scientific peer review literature, underscoring a general and baseline overview of adaptation in the region. This work contributes to an important gap in the literature, with most studies examining the state of adaptation focusing on developed nations e.g., [31, 36, 37], or focused on other regions of Africa e.g., [38, 39]. This chapter is vital because there are currently insufficient studies that adopt the holistic approach fostered by this chapter. Prior to this study, the peer review data on climate change adaptation in the Sahel was found in several scattered publications which evidently did not provide a holistic approach. Furthermore, this chapter is vital because the Sahel remains a territory witnessing persistent shocks that need to be better addressed [40, 41, 42] that calls for urgent adaptation actions to enhance resilience. Therefore, a holistic picture on where the peer review literature has so far focused goes a long way in improving our understanding on where the emphasis is and where attention needs to be given.
2. The Sahel: geography, livelihood and overview of climate change
The Sahel is the semiarid strip of land located between the tropical rainforest in the south and the arid north of Africa and covers an area of about 3.053 × 103 km2 and has about 60 million inhabitants . The Sahel is located between latitude 10° and 20° north and extends from about 5000 km around northern Senegal around the west towards southern Mauritania, central Mali, northern Burkina Faso, south-western Niger, northern Nigeria, central Chad, north of Cameroon, Central African Republic, central Sudan and southern Sudan, northern Eritrea, extreme north of Ethiopia, to Somalia in the east and south east of the Sahel into Kenya (Figure 1).
In the Sahel, the vegetal landscape is covered by open Acacia shrubs and grassland. The Sahel represents a transition between the humid savanna in the south and the desert in the north [44, 45]. In terms of rainfall, the Sahel experiences declining rainfall with increasing latitude. At the southern border of the Sahel, about 450–500 mm of rainfall are recorded yearly while towards the higher latitudes less than 200 mm of rainfall are recorded yearly [46, 47]. Between 1930 and 1965 and 1966 and 2000, the Sahel recorded about 100 mm of rainfall per year . The rainfall pattern in the Sahel is tied to the migration of the Inter-tropical Convergence Zone (ITCZ) [44, 46, 47, 49]. In the Sahel, a rainfall gradient of between 250 and 300 mm between the southern and northern spheres of the region is recorded. At 17° latitude north less than 200 mm of rainfall are recorded annually while southwards at about 15° latitude north (southern boundary of the Sahel), more rainfall of about 450–500 mm is recorded annually [44, 46, 47].
3. Countries and regions where adaptations are occurring in the Sahel?
In the Sahel, climate change adaptation actions can be categorized into four main categories (Figure 2). These include technically based, economically based, indigenous based and socially based (Figure 2). A total of 414 adaptation actions were reported in 70 peer review journal articles. An analysis of the articles illustrates that Kenya had recorded the highest number of adaptation actions of about 75 or 18.1% during the period 1975 and 2015. This was followed by Senegal with 65 or 15.7% of all recorded adaptations (Figure 3). Even though these countries recorded the highest rates of adaptation actions, it is worth noting that the overall picture in term of adaptation actions in the Sahel appears to be generally low (Figure 1).
Regionally, with a frequency and percentage of about 261 or 63%, West African Sahel witnessed the highest adaptation actions as reported by the peer review literature. East Africa recorded 127 or 30.6% and therefore is the second most adapted region in the Sahel (Figure 4). Furthermore, it can be said that when a region has more adaptation actions, the same is said of its adaptive capacity (Figure 1).
4. Actual adaptation actions in the Sahel
Based on this systematic review, income diversification adaptation actions recorded the highest frequencies in the scientific peer review literature. This is seen as they stood at a frequency of 53 or 12.8% and tailed closely by water harnessing actions which recorded a frequency of 48 or 11.5%. Adaptation actions like soil conservation, farm inputs, and planting high yielding varieties recorded 6.5%, 6.2% and 5.5% respectively (Figure 5, Table 1). From these results, we note that emphasis is placed on employment diversification actions or on providing water harnessing options. While Kenya and Senegal recorded the highest cumulate amounts of adaptation actions with income diversification actions appearing to record the highest frequencies.
|Off farm employment||Fleuret ; Mertz et al. ; Elmqvist and Olsson ; Morand et al. |
|Working for development projects||Nielsen and Reenberg ; Moretimore |
|Small-scale commerce||Nielsen and Reenberg |
|Non-farm income||Mertz et al. ; Reardon et al. ; Burnham and Ma |
|Selling of personal belongings||Schaer ; Brockhaus et al. ; Opondo |
|Supplemental occupation||Epule et al. ; Opiyo et al. |
|Hunting||Mosberg and Eriksen |
|Rainwater harvesting||Bryan et al. ; Zampaligré et al. ; Barbier et al. |
|Irrigation||Bryan et al. ; Deressa et al. ; Fleuret |
|Water management||Rockström ; Douxchamps et al. ; Burnham and Ma |
|Boreholes||Mbow et al. |
|Construction of dams and drainage systems||Magistro and Medou |
|Use of water pumps||Schaer |
|Use of green and blue water||Recha et al. |
|Mulching||Burnham and Ma |
|Change in tillage and rotation||Bryan et al. |
|Half-moon and stone dykes||Zampaligré et al. |
|Planting shade trees||Burnham and Ma ; Deressa et al. ; Bryant et al. |
|Fallowing||Gebrehiwot and Van der Veen ; Nyong et al. |
|Soil erosion control/stabilization dunes||Okoye ; Brockhaus et al. ; Burnham and Ma |
|Manure||Mertz et al. ; Marenya and Barrett ; Wood et al. |
|Fertilizers||Mertz et al. ; Mertz et al. ; Croppenstedt et al. |
|Inorganic fertilizers||Marenya and Barrett ; Wubeneh and Sander |
|Adoption of compost||Somda et al. |
|Organic fertilizers||Epule et al. |
|High yielding crop varieties||Bryan et al. ; Deressa et al. ; Fleuret |
|Improved varieties of potatoes||Thuo et al. ; Burnham and Ma ; Abebe et al. |
|Improved varieties of sorghum||Adesina and Baidu-Forson |
|Improved varieties of maize||De Groote et al. |
|High biomass variety of maize||De Groote et al. |
|Improved animal husbandry||Zander et al. |
5. Categorization of actual adaptation actions in the Sahel
In terms of broad adaptation categories, four key categories of broad adaptation actions were identified. All other actions fall within any of these four categories, these include: (i) technically based actions; (ii) indigenous problem-solving based; actions; (iii) socially based actions and (iv) economics-based actions (Figure 5).
Technically based adaptation actions recorded the highest number of adaptation actions with a frequency of 206 or 49%. The other broad-based categories in order of importance are: Indigenous problem-solving based options with a frequency of 173 or 41.7% (Table 2), socially related based actions with a frequency of 21 or 5% and economics-based actions with frequencies of 14 or 3.3%. Though the technically based actions are leading, Kenya has the highest number of total adaptation actions. The indigenous problem-solving based actions recorded 39 or 9.4%. Similarly, in Senegal, indigenous problem-solving adaptation recorded a frequency of 34 or 8.2%. When all the categories are put together, the frequencies for the latter category, does not outbid the former (Figure 5). Regionally, the West African Sahel recorded the highest number of adaptation actions and tallied highest in the context of technically based adaptation actions with a frequency of 133 or 32.1%. In terms of other regions, East Africa records the second highest frequency as technically based adaptation actions recorded 64 or 15.4% (Figure 6).
|Water Harnessing||Zampaligré et al. ; Barbier et al. ; Recha et al. |
|Soil conservation||Burnham and Ma ; Deressa et al. ; Bryan et al. |
|Climate monitoring||Boyd et al. ; Huq et al. ; Reenberg |
|Early harvesting||Tambo and Abdoulaye ; Burnham and Ma ; Deressa et al. |
|Mixed farming||Moretimore |
|Income diversification||Schaer ; Brockhaus et al. ; Opondo |
|Migration/relocation||Zampaligré et al. ; Scheffran et al. ; Burnham and Ma |
|Farm inputs||Marenya and Barrett ; Wubeneh and Sanders |
|Pasture management||Brockhaus et al. ; Burnham and Ma ; Mertz et al. |
|Buying food/gov’t relief||Epule et al. ; Oluoko-Odingo |
|Help from kin/social organizations||Mortimore ; Epule et al. ; Oluoko-Odingo ; Fleuret |
|Spiritual/prayers/religion||Fleuret ; Mertz et al. ; Burnham and Ma |
|Partnership between local people and development project||Nielsen et al. |
|Creating local committees for natural resources management||Brockhaus et al. |
|Investing in education of kids||Opondo |
|Market gardening||Mertz et al. ; Mertz et al. ; Nielsen et al.  and Reenberg |
|Selling of personal belongings||Schaer |
|Access to credits||Ebi et al. |
6. Temporal variations in adaptation actions and drivers of adaptation in the Sahel
The decade 2008–2016 recorded a total of 270 or 65.2% adaptation actions which represent the highest number of adaptation actions in the Sahel. The subsequent decades witnessed adaptation actions as follows: 1997–2007: (n = 58, 14%); 1986–1996: (n = 29, 7%); 1975–1985: (n = 57, 13.7%). In summary, we end up having a total of 414 adaptation actions which is like the total number of adaptation actions (Figure 7a). It can be observed that there has been an increase in the number of adaptation actions over the decades. A review of the drivers shows that most of the adaptation actions are anchored on climatic factors. The climatic drivers recorded 406, or 98% while the non-climatic drivers recorded 395 or 95% (Figure 7b). Though the climatic drivers are dominant, an interesting observation is the increase prominence of non-climatic drivers. Some potential climatic drivers include increase precipitation, decreasing precipitation, temperature increase, temperature decline, sea surface temperature changes, trade winds, El Niño, increase solar radiation, atmospheric circulation, and the prevalence of winds/sandstorms like the equatorial westerlies. Non-climatic drivers of adaptation cited in the literature encompass agriculture, population growth, settlements, poor urban planning, pastoralism, and cattle rearing, over exploitation of resources, grazing of animals, deforestation and land degradation, wildfires, insects, economic fluctuations and socio-political.
In the Sahel, some adaptation actions have gained prominence over time. Income diversification which is the highest used adaptation action recorded a frequency of 21 during the decade 1985–1996. Th decade 2008–2016; also recorded 18 adaptation actions. Here also, water harnessing actions were dominant during the decade 1985–1996 in which they recorded a frequency of 27. The decade 2008–2016, witnessed 15 adaptation actions. On the other hand, soil conservation related actions recorded their highest frequency during the decade 1985–1996. Migration had a frequency of 8 and this was during the decade 2008–2016. High yielding varieties also recorded a frequency of 13 adaptation actions during the decade 2008–2016. Generally, during the decade1975–1985, two adaptation actions were most frequently used. These included
Climate change adaptation is currently receiving a lot of global attention as governments, NGOs, International organizations, civil society groups inter alia are now placing climate change adaptation as a priority on their political and environmental agenda [94, 95]. Even though we have agreed that climate change adaptation is vital in establishing resilience in the Sahel, stakeholders are still in disagreement with respect to what approach climate change adaptation actions represent [96, 97]. This chapter attempts at improving our understanding of the regional and country level adaptation actions in the Sahel as well as their drivers and evolution through several decades. The approach used in this study is similar to those used by Ford et al. [30, 98]. Systematic reviews enhance the ability to compare how adaptation is taking place across the Sahel [30, 98, 99]. The results from this study should therefore be considered as proxies for the level of adaptation in the Sahel as they are based on what exist in the scientific literature and therefore provide a baseline.
These findings can be weakened by the fact that several adaptation actions in the Sahel might be beyond the scope covered by this current study. For example, this work does not consider the gray literature and studies beyond 2020. However, the fact that this study covers a time frame that goes beyond 40 years makes these results valid. The decade 1975–1985 recorded the highest number of adaptation actions while the decade 1985–1996 recorded fewer adaptation actions. The surge in adaptation actions recorded during the decade 1975–1985 can be attributed to the surge in climate change shocks in the form of droughts that dominated this decade [43, 48]. These shocks triggered a lot of actions from governments, international and non-governmental organizations to enhance adaptations [7, 46]. From 1985, the droughts that affected the Sahel had reduced and so did the number of adaptation actions due to ‘adaptation fatigue’ of the previous decade. The adaptation actions of the 1970s and 1980s have already produced positive results in the Sahel. Recent studies show that the Sahel has become greener with a parallel increase in precipitation. Normalized difference vegetation index (NDVI) and precipitation across the Sahel show a strong correlation between NDVI and greening [3, 53, 100, 101]. Prince et al.  has argued that the increase precipitation and greening recorded in the Sahel can be attributed to rising aerial fertilization effect of carbon dioxide. The decades 1997–2007 and 2008–2016 recorded 14% and 65.2% adaptations, respectively. These decades are consistent with an increase in the number of adaptation initiatives over time. It is difficult to argue that the climate change adaptations reported in this study are mainly driven by the adaptation initiatives presented in the peer review literature. In addition, with a total of 414 discrete adaptation actions reported in this study, it remains clear that the level of adaptation is still relatively low in the Sahel. Regionally, West African Sahel dominates in terms of adaptation actions. However, in term of countries, Kenya in East Africa records the highest frequency of 18.1%. According to Ford et al. , during the period 2006–2012, Kenya recorded a total of 34 adaptation actions and thus was the highest in terms of adaptation actions from a set of African and Asian countries. The fact that West African Sahel has a higher adaptation rate from a regional perspective can be linked to the “Great Green Wall of the Sahara and the Sahel initiative” (GGWSSI) .
In terms of policy, it has become evident that income diversification and water harnessing actions have gained prominence over time. This provides an opportunity to further leverage these actions and to investigate how other actions can be further enhanced to improve adaptations. The fact that technically based adaptation actions are more frequently reported shows that policies that enhance both technically based adaptations and others that are less cited should be leveraged in other to enhance the level of adaptation actions in the Sahel. It is important to emphasize the fact that no single adaptation action can single handedly revamp the adaptation landscape in the Sahel because several actions indeed work together better. Those that have been ignored this far need to be researched into to verify what the indigenous people think about them before concrete suggestions are made.
Most of the studies presented here showed that most of the adaptations are driven by climatic variables. However, we also observe an increase attribution of the drivers to non-climatic drivers. Non-climatic drivers are becoming increasingly vital as there are many cases when adaptations are not just taken to adapt to climate change but also in response to other issues such as health, poverty, literacy, and socio-cultural disparities that affect adaptive capacities [95, 96]. The evidence across Africa and the Sahel shows that the problems that Africa and the Sahel are facing ranging from food crisis, deforestation, water scarcity, pandemics and epidemics are mainly caused by non-climatic variables such as deforestation, population movements, wars, and land degradation inter alia with climate change only playing a reinforcing role [1, 3, 4, 5].
These results tend to be similar and different from some previous studies based on results and methodology. A study by Ford et al.  researched into the status of climate change adaptation in Africa and Asia based on a systematic approach and showed that Kenya had the highest number of adaptation actions. When compared with other vulnerable regions, as the Arctic, there are more reports of adaptation actions in the Sahel. Also, another study by, Ford et al. , reported about 157 adaptation actions between 2003 and 2013 while this current study reports 414 adaptation actions for the Sahel for the period 1975–2020. The major areas of differences are that the Ford et al.  study focused on both peer review and gray literature while this chapter is based on peer review literature. The Ford et al. study is based on Africa and Asia and covers studies published from 2006 while this current study is based on the Sahel and covers studies from 1975 to 2020. Also, Berrang-Ford et al.  used the systematic approach and focused on the peer review literature only, an approach like that adopted by this current study. The results from the latter are also consistent with this in that they report that considerable research has been done with a greater focus on intentions than groundwork. Also, non-climatic drivers are increasingly being presented as the drivers of climate change adaptation .
In this chapter, we investigated the state of climate change adaptation in the Sahel. The findings show that Kenya recorded the most adaptation actions while regionally, West Africa reported the highest. The approach used in this study provides a proxy-based perspective and baseline from which climate change can be monitored and tracked over time. It is important that various stakeholders come together using this information to further enhance climate change adaptation in the Sahel. This is important as the results from this study show that at country level adaptations to climate change are still at infancy judged by the low frequencies and percentages recorded at the country level.
Due to the existence of a lot that is unknown about climate change adaptation across the Sahel, it becomes important that moving forward attention is given to evidence-based research. It is suggested that more systematic reviews that cover most other regions of Africa be considered. Additionally, gray literature and a wider time scale should be considered. Advancing more research into other regions will go a long way in providing a bigger picture of the status of climate change adaptation across the continent of Africa. Looking at the gray literature will help in brining to the lamplight other potential options not found in the peer review literature. Finally, it is also important to better understand the climatic and non-climatic shocks that are driving adaptation actions in the Sahel and Africa in general. This will enhance the policy process aimed at triggering better adaptation options based on the actual drivers of change.
We would like to thank all the authors whose works we consulted. Special thanks to UM6P for providing the funding for this research.
Conflict of interest
The authors declare no conflict of interest.