**Abstract**

In Africa, the Sahel is increasingly susceptible to climate shocks such as droughts, sandstorms (winds), and floods. Through a systematic review this work tracks the frequency with which these shocks are reported in the literature during the period 1975–2020. This work examines trends to identify which shocks are most reported, documenting their spatial distribution and evaluating the impacts of climatic and non-climatic drivers. In general, 388 shocks were reported in 164 relevant peer review papers. Southern Niger recorded 15.97% of all the shocks while Ethiopia and Senegal recorded 11.85% and 10.85% respectively. Also, West African Sahel saw about 49.97% of all shocks followed by East African Sahel with 29.89% and Central African Sahel with 12.11%. Generally, droughts (n = 219), appear to be the most frequently reported shocks followed by floods (n = 123) and winds (n = 46). The 1975–1985 decade recorded the most shocks (n = 207), followed by the 1997–2007 decade which saw (n = 80) shocks while between 1986 and 1996 a total of 52 shocks were recorded. 52% of the shocks are driven by climatic factors while 47% are driven by non-climatic drivers.

**Keywords:** Climate change, Shocks, Droughts, Floods, Winds, Climatic, Non-climatic, Regional, Country-level, Sahel

### **1. Introduction**

Global environmental changes cannot be excluded from the debates on development and environmental protection in Africa. The latter is true because ecosystems respond to climate change and climate change also determines the pace of global development in general and African development in particular [1, 2]. The influence of climate change in sub-Saharan Africa is even more evident as in the last three and a half decades the region has witnessed temperatures increasing in the range of 0.2–2.0° C amidst declining precipitation [3]. The projections of future temperatures right up to 2100 shows that it will cumulatively exceed the range of 0.2–2.0° C that was observed in the last three and a half decades. The fifth assessment report (AR5) of the IPCC further supports this assertion by observing that mean temperatures will potentially increase on a decade basis by 1.8° C in 2020, by 1.9° C in 2030, by 1.8° C in 2040, by 1.7° C by 2050 and by 1.2° C by 2100 [4]. The impacts of the above observations are enhanced vulnerability of cropping systems and amplified poverty, low adaptive capacity, and more frequent climate shocks [5, 6]. Despite the importance of climate factor in the region, non-climatic drivers such as agricultural expansion, deforestation, occasioned by rapid population growth have tilted the debate on which of climatic and non-climatic factors drives the shocks more [7].

Three main climate shocks (droughts, floods, and sandstorms (winds)) are dominant across Africa and the Sahel [8–15]. The Sahel is well known for its droughts and as a result, the region is one of the most susceptible to droughts globally [16–18]. The causes of these droughts are either human related (human induced climate change) or climatically driven (sea surface temperature, effects of vegetation, CO2 emissions and land degradation, and dust feed backs) [11]. It has been reported that hydrological droughts are becoming frequent in the Sahel due to observations of enhanced discharge in rivers. Since the 1970s, river Niger for example has witnessed increase discharge of its tributaries. It is indeed surprising that while temperatures are observed to be rising in the Sahel and projections of the same are pessimistic, some rivers in the region are witnessing increase discharge in what has been termed the "Sahel paradox" [19–23]. Furthermore, the Sahel is increasingly impacted by airborne dust or sandstorms which are also impacting the climate of the region [3]. Satellite sensors have shown that Sahelian dust are not only regionally restricted but also globally distributed [14, 24]. In fact, reports hold that most of the dust outbreaks around the world are linked to the Sahel [25–27].

Climate change stakeholders in the Sahel have been active seeking ways and means of addressing these climate shocks. In this context, adaptations actions, policies and programs have been designed to help address the surge [28–30]. For example, the United Nations Reductions of Emissions from Deforestation and Forest Degradation (REDD+); has been designed to support reforestation project across the world [12, 31–37]. We also have the United Nations Framework Convention on Climate Change (UNFCCC) [38] which enhances research and adaptive capacity in developing countries. The African Development Bank (AfDB) has created the African Climate Fund which focuses on enhancing increase to climate finance in Africa [39]. Additionally, the Pan African Agency for the "Great Green Wall (GGW)" has been involved in planting trees across the Sahel [40].

Even though there is an increase in the proliferation of studies on climate shocks in the Sahel, there is still a shortage of studies that provide updated and holistic information on the dominant shocks, their distribution, across the Sahel and their drivers. In fact, it is still unclear which climate shocks are most reported in the scientific literature over time. This enhances the ability to monitor existing gaps in the scientific scholarship and to pave the way for the future. In addition, it provides a holistic picture of the regional and country level variations in the dominant shocks impacting the Sahel and further provides and opportunity to leverage our understanding in shaping adaptation actions.
