**1. Introduction**

It is now clear that the world is experiencing climate change and the Sahel of Africa is no exception to this [1–7]. In the past thirty years the Sahel has witnessed temperatures in the range of between 0.2–2.0° C [8]. 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 [9]; (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 [10–12], with the region likely projected to potentially experience about 250 million tons of food deficits by 2020 [12–14]; (iii) enhanced

occurrence of malaria and diarrheal diseases, [15–17]; (iv) with more frequent water shortages also documented [18]. These impacts, in turn, are believed to have increased the number of climate refugees in the Sahel [19–22]. Climate change may also present opportunities, including increasing food production through better water management, irrigation, rainwater harvesting [3], and potential increase in crop productivity due to increased aerial fertilization by carbon dioxide [23].

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 [24–31]. 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) [34] 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 [35]. 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 [40–42] 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.
