Water is central to environmental, economic and social development. Water security is defined in the context of water quantity, quality and accessibility. It is the availability of, and access to sufficient and good quality water for human use and ecosystem functioning ( Nkiaka et al., 2021). Water quantity and quality affect ecosystem functions. There is variation in water availability regionally and within countries in the Horn of Africa; for example, the Ethiopian highlands are regarded as the water tower of the Horn of Africa and the greater region through its contribution to the Nile basin ( Müller-Mahn and Gebreyes, 2019). Though, water may be adequate in quantity and quality, its accessibility is influenced by socio-economic resources. For example, water insecurity in Ethiopia and Somalia is compounded by inadequate infrastructure and institutional capacity to exploit and manage both surface and groundwater resources ( Jemmali and Sullivan, 2014). In the Horn of Africa, water is the major contributor to the region’s food crisis as well as its recurrent famine and social instability ( Mohamed, 2014).

Increased surface water stress due to climate change will occur in countries facing politically and environmentally fragile situations like Somalia and Eritrea ( Olet et al., 2020). In Somalia, onsite sanitation systems, open defaecation and poor hygiene practices are a threat to groundwater sources ( Mourad, 2022). Djibouti has some of the lowest water resources in the world, with no perennial rivers, and thus most of its water sources are from groundwater aquifers which is threatened by over-exploitation leading to high salinity levels ( Mouhoumed et al., 2020) and risk of sea water intrusion in case of over-exploitation of coastal aquifers ( Razack et al., 2019).

Somalia relies heavily on water from the Juba and Shabelle rivers where 90% of the flows originate from Ethiopia ( Arcanjo, 2020). Therefore, any major water abstractions in Ethiopia jeopardize livelihoods in Somalia. Mohamed (2013) argued that the planned dam projects in the Juba and Shabelle rivers will have an economic and ecological impact in Somalia through reduction of water flows in the rivers. This will cause a collapse of existing irrigation schemes and planned irrigation developments and have a negative effect on the wetlands in the Shabelle depression areas and the Juba estuary at the mouth of the river causing seawater intrusions. Climatic events such as droughts and floods also impact the basin affecting both water supplies and crop production in the southern region of Somalia where irrigation is practiced. Groundwater is also an important source of water where boreholes have been sunk to a depth of 400 m in some areas and shallow wells with some less than 20 m deep ( Idowu and Lasisi, 2020).

The solution to addressing water insecurity in the region lies in the management of shared water resources. The countries in the region share a number of surface and groundwater sources. The major shared river basins and water bodies include Nile River basin (Burundi, Congo, Egypt, Ethiopia, Kenya, Rwanda, South Sudan, Sudan, Tanzania, Uganda), Juba River Basin (Ethiopia, Kenya and Somalia), Laag Dheere (Kenya and Somalia), Shabelle River (Ethiopia and Somalia), Omo River Basin (Ethiopia and Kenya), Awash River (Djibouti and Ethiopia), Tekeze or Atbara (Eritrea, Ethiopia and Sudan), Mereb River (Eritrea, Ethiopia and Sudan), Baro-Akobo (Ethiopia, South and Sudan), Sobata River (Ethiopia and Kenya), Lake Turkana (Ethiopia and Kenya), Merti Aquifer (Kenya and Somalia), and Shabelle Aquifer between Ethiopia and Somalia ( Mohamed, 2014). However, the countries in the region do not have regional policies on shared water resources and each state pursues unilateral legislations and frameworks ( Mohamed, 2014). These unilateral water policies and development plans are not only unsustainable but also a source of conflict in the region. The construction of the Grand Ethiopian Renaissance Dam (GERD) is one example of individual states pursuing their national projects on a shared water course, in this case the Nile basin, without adequate regional consensus on the effect on downstream riparian countries. The Nile basin is the largest project in the region comprising ten riparian countries with Ethiopia contributing a significant proportion of water through the Blue Nile. The shared rivers and water basins in the region instead of being a source of economic and political integration have become sources of tension and conflict due to declining water availability ( Mohamed, 2014). Co-operation among riparian states sharing transboundary river basins and aquifer systems is part of integrated water resources management (IWRM) as anchored in SDG 6.5 and therefore necessary for national and regional WEFE security ( Stephan et al., 2018). The degree of implementation of IWRM in the region is low with Ethiopia and Somalia at 41% and 22% respectively ( Table 1) while there was no data for Eritrea and Djibouti.

Energy security components are availability, affordability and reliability ( Awandu et al., 2022), which consequently affect access to energy options. It is the access to reliable and affordable energy for cooking, heating, lighting, communications and productive use ( Nkiaka et al., 2021). Access to affordable, reliable and modern energy services will transform the region’s development agenda by achieving SDG 7. Generally, energy infrastructure in the Horn of Africa has struggled to match the region’s growth and thus electricity grids remain unreliable rendering many countries dependent on costly fuel imports, and energy utilities are in financial stress ( IEA, 2022b).

Ethiopia suffers from acute electricity shortages due to a faster population growth than development in the energy sector and also due to over-reliance on hydro-electric power. This is affected by several factors such as trade-offs with domestic, industrial and agricultural water needs, droughts, dam siltation due to catchment degradation, and transboundary water conflicts ( Guta and Börner, 2017). There are three main sources of energy in Ethiopia: biomass, petroleum, and electricity, with supply accounting for 90%, 8.2% and 1.8% respectively in 2014 ( Benti et al., 2021). Electricity in the country is mainly supplied by hydro-power plants. Hydropower potential is 45,000 MW while geothermal sources have a potential of 1,070 MW ( Berta and Zerga, 2015). Traditional biomass energy is not sustainable due to environmental and social costs. Women and children spend hours trekking long distances to fetch firewood while urban dwellers spend a substantial amount of income on fuel ( Gebremeskel and Tesfaye, 2008). The country does not have a physical energy scarcity as it is endowed with sufficient potential renewable energy sources, but economic energy scarcity is the major challenge ( Tesfaye et al., 2021). Adoption of modern energy sources by rural households in Ethiopia is hindered by shortage of capital, lack of access to alternative energy sources, durability problems associated with renewable sources such as solar, and lack of awareness ( Tofu et al., 2022). The country aims to develop renewable sources of energy such as solar and wind, but its capability is limited by a lack of investment capital, an underdeveloped solar and wind supply chain, lack of a skilled workforce, unclear policy and strategies and regulatory uncertainties ( Gebreslassie, 2021). The recent political unrest in the country, which has triggered war in the northern region of Tigray, has slowed down access to electricity with destruction of electricity infrastructure ( IEA, 2022b). The completion of the 5,150 MW GERD hydropower plant (the largest in Africa) in addition to the Koysha (Gibe IV) hydropower plant (1,500 MW) will boost Ethiopia’s universal access to electricity ( IEA, 2022b) and consequently achieve the SDG 7 target.

Somalia is rich in renewable energy resources including solar, wind, hydropower, and vast geothermal energy but their exploitation is limited by political, financial, and institutional factors ( Warsame et al., 2022). It is worth noting that Somalia does not have state-owned energy utility and a national grid and most of the energy services are from private entities ( Aynte et al., 2022; IEA, 2022b). The government has tried to increase electricity access through provision of incentives to the private sector such as subsidies and tax exemptions ( IEA, 2022b). Most of the energy use in the country comes from generators running on imported diesel or from burning charcoal and other biomass ( Aynte et al., 2022). Despite the long-running civil war and low development, the country has the potential to achieve sustainable development and contribute to the reduction of greenhouse gases ( Warsame et al., 2022) through implementation of policies and encouraging investments in renewable and clean energy production such as solar, wind and hydroelectric power, and reduction in biomass energy (charcoal and firewood) use ( Warsame and Sarkodie, 2022). Somalia, through its updated nationally determined contribution, has identified the promotion of clean and fuel-efficient cooking as a pathway for reduced GHG emissions through adaptation actions such as increasing the production of non-forest fuel briquettes, including from agricultural residues and waste ( IEA, 2022b).

Eritrea initiated reforms in the energy sector in 2007, which revolved around four areas: expansion of the national grid to cover rural areas, adoption of renewable energy technologies, promotion of energy efficiency and saving techniques, and liberation of the energy market ( Habtetsion and Tsighe, 2007). However, the country has low hydropower potential and still relies on oil and gas imports to meet its energy demand ( Chandrasekharam et al., 2018). The grid is supplied only by electricity from fossil fuels ( Alam and Islam, 2019).

Improving energy security in the region requires integration through bodies such as the Intergovernmental Authority on Development (IGAD) where its energy sector strategy for 2050 envisages an interconnected system that harnesses the abundant renewable resources within its member states ( IEA, 2022b). Already, Ethiopia has an electricity interconnection arrangement with Djibouti which has boosted the latter’s electricity access ( Dabar et al., 2022). The regional efforts can be complemented by Africa-wide interventions through the African Union’s (AU) 2063 agenda which seeks expansion of renewable and clean energy sources to ensure energy security and reduction in carbon emissions ( IEA, 2022a).

Achievement of the SDG 7 in the region requires countries to expand the national grid and development of mini-grids and stand-alone (off-grid) systems ( IEA, 2022b). The Horn of Africa countries have high solar energy potential ( EIB, 2018) which can be used to power rural populations not covered by the national grid systems.

Countries in the Horn of Africa are facing serious food security challenges. In this context, food security is parameterized in terms of availability, accessibility and quality ( Awandu et al., 2022). Food security is attained when people have physical, social and economic access to enough, safe and nutritious food which meets their dietary needs and food preferences for an active and healthy life ( Nkiaka et al., 2021). Clapp et al. (2021) made a case for dimensionality of food security to include six components i.e. availability, access, utilization, stability, sustainability and agency with the last two being new concepts. Agency in this context refers to the sovereignty of individuals and groups in the food sector as a way of addressing widening inequities and power imbalances of actors within food systems ( Clapp et al., 2021). Sustainability in this context refers to food practices which adhere to the three elements of sustainable development i.e. social, economic and environmental. We are of the view that the expanded dimensions of food security will help its advancement in this era of climate change and other externalities in the food and agricultural sector.

Ecological systems are important in providing the material sources for food production and dietary diversity and thus relevant in ensuring nutritional quality and quantity ( Clapp et al., 2021) and therefore should be given special reference for holistic assessment of food sustainability. Therefore, sustainable agricultural practices need to be adopted to address food security challenges.

The Horn of Africa is considered one of the most food insecure regions in the world, which is exacerbated by persistent conflicts, climate shocks and economic instability ( Abebe, 2021). Eritrea is a low-income country with at least 70 percent of the population depending on traditional subsistence agriculture ( Ghebru et al., 2013), which is prone to climate change induced shocks. The country is highly food insecure and relies on imports which account for about 46% of food demand ( Chandrasekharam et al., 2018).

Food accessibility in Somalia is affected by poor transport infrastructure and distribution networks which limits price arbitrage between regions ( Hussein et al., 2021). The poor transport infrastructure and food distribution channels in Somalia can be attributed to a long period of armed conflict. Somalia’s food insecurity is compounded by climate variables such as droughts and floods, which have increased in frequency and intensity ( WFP, 2021). The unsustainable consumption pattern of traditional biomass (charcoal and firewood) has affected forest resources in the country, leading to desertification and loss of grazing and arable lands ( Warsame et al., 2022).

Ethiopia suffers from chronic and acute food insecurity partly due to climate variability and susceptibility to drought and poorly developed water resource infrastructure ( Gebreyes et al., 2020). Food security in Ethiopia is vulnerable to climate change and variability due to the fact that 80% of the population rely on rainfed agriculture coupled with low income which decreases their resilience ( Alemu and Mengistu, 2019). Use of firewood and charcoal as sources of energy has contributed to deforestation and consequently affected land productivity and ultimately contributed to food insecurity in Ethiopia ( Tofu et al., 2022). In the Tana basin, it was established that the continued use of biomass for energy purposes include deforestation and a depletion of soil organic matter and nutrients from agricultural soils and thus this is unsustainable in the long term ( Karlberg et al., 2015).

Human activities have played a pivotal role in enhancing the extreme effects of climate change impact on day-to-day life. Human beings are the perpetrators of the current and projected global warming of earth and are also the victims of the aftermath of the effects of extreme climate change ( Ofori et al., 2021). The global mean temperature ascertained in 2017 depicted an increase of 1°C higher than the pre-industrial values with a projected increase of 0.2°C/decade ( Bruhwiler et al., 2021). The temperature increase and warming of the continent of Africa is projected to be a higher value than the global average with anticipated temperature of 3–4°C over the 22 ^nd century ( Thompson et al., 2010; Zewdie, 2014). As a result, various regions within the African continent already experience unique extreme changes in precipitation patterns as discussed in Ofori et al. (2021).

Climate change, just like other anthropogenic activities such as changes in land use/cover, diversions, withdrawal of water from rivers and lakes etc., impacts freshwater ecosystems and contributes to their degradation. Climate change has led to a shift in precipitation patterns in the Horn of Africa thereby resulting in decreased precipitation and increased evaporation. For example, projections indicate that the Lake Tana Basin in Ethiopia will decrease in surface water discharge and seasonal run-off volumes ( Niang et al., 2014). The climate variability and trends in Ethiopia for instance show no consistent changes in the frequency or intensity of extreme events ( Tessema and Lamb, 2003; Seleshi and Camberlin, 2006), with extreme tendency towards lower rainfall during crop growing seasons. Historical flood disruption is an unheard of hazard in Ethiopia but recent years have recorded significant socio-economic disruption in Ethiopia due to flooding in 1997 and 2002 ( Jury, 2002). Similar trends of extreme droughts followed by extreme flooding that have led to deaths and destruction in the northeast of Kenya and parts of Somalia have been experienced frequently.

The Horn of Africa region continues to experience high water scarcity risks due to reduced streamflow and intensified water abstraction ( Hirpa et al., 2019). Water related conflicts are rampant in the region. The situation has been made worse by the impact of climate change which has exposed the vulnerability of the region through successive droughts, water shortages, floods, and desertification ( Burgess, 2008).

Hydropower production is heavily relied on by Ethiopia, Eritrea, Somalia and Djibouti. The man-made energy generation dams are susceptible to extreme climate change resultants such as floods, drought and cyclones ( ICPAC, 2007). Climate change influences the spatial and temporal rainfall distribution and intensity, which is an essential determinant of catchment hydrology. The increase in temperature coupled with decrease in rainfall are two hydrological processes that have profound influence on hydropower generation potential ( Bunyasi, 2012). Reduced river flows significantly affect hydropower generation due to inadequate reservoir levels. Due to extreme low rainfall in the vast Horn of Africa ASAL regions, the low flows have constantly resulted in power outages thus negatively affecting energy security in the region and encouraging overdependence on fossil fuels for running generators to provide power ( Awandu et al., 2022).

Mitigating the effects of climate change in the region requires adoption of mix of renewable energy options. For example, a study by Oyewo et al. (2021) found that it is least-cost to supply about 66% of electricity demand with solar PV, 14% with wind and 10% with hydropower in Ethiopia as a best policy scenario in 2050. However, Boke et al. (2022), noted that the stochastic nature of solar and wind energy sources threatens the stability of the electricity grid. Use of geothermal energy sources offers baseload power generation making it a great option to complement the intermittent power supply from solar and wind with Ethiopia planning to expand its geothermal power capacity to 10,000 MW by 2030 ( IEA, 2022b). Ethiopia has also developed energy policy and biofuels strategy with the aim of supporting energy diversification and development of renewable energy options and biofuel development as an energy security and climate change mitigation measure ( Motuma, 2017). Eritrea has huge potential for geothermal energy. Adoption of renewable energy options in Somalia is hindered by weak and fragmented independent electricity service providers facing financial challenges and limited support from federal and regional state governments ( Aynte et al., 2022).

Climate change events such as drought and floods have a negative impact on food security in Africa, particularly in the horn of Africa. Drought is a serious environmental problem in the Horn of Africa countries of Ethiopia, Somalia, Eritrea and Djibouti ( AghaKouchak, 2015). Agriculture is more affected than any other sector because it is susceptible to climate variability and change such as extreme weather events of droughts and floods, irregular rainfall patterns and increase in temperature. Drought decreases water availability for irrigation thus leading to a decrease in yield, which enhances food insecurity and also increases irrigation water demand. Water is required at various stages of food production and in the Horn of Africa rain-fed agriculture is heavily impacted by climate change.

Low-income countries such as those in the Horn of Africa largely depend on the agriculture sector as it contributes a significant proportion of their GDP. The high dependency on the agriculture sector and lack of climate change adaptation policies make developing countries more vulnerable ( Ghebrezgabher and Yang, 2018). Therefore, there is need for the development of policies and institutions for climate change adaptation and resilience building at regional or national levels.

Somalia faced drought in 2017 leading to the monetary loss of USD 71 million for the maize, sorghum, cowpeas and sesame industries; these are the four most important crops for the country ( World Bank and FAO, 2018). On the other hand, floods that occurred in 2019 claimed many lives and led to 412,000 individuals being displaced and substantial damage to crops ( FAO, 2020). A study on the climate change and crop production nexus in Somalia revealed that climate change is a significant determinant of Somalis’ crop production specifically rain fed crops as Somalia’s agricultural land totals about 3 million hectares ( World Bank and FAO, 2018).

El Nino led to a drought in the Horn of Africa in 2015 where Ethiopia faced severe hunger with 15 million people needing immediate food aid ( UNICEF, 2015). In 50 years, it is predicted that Ethiopia will experience erratic weather patterns, higher intensity rainfall and temperature rise ( Mcsweeney et al., 2010). This climate change could result in prolonged periods of drought and floods, which might lead to crop yield reduction and resource use conflicts ( Simane et al., 2012). However, using agroecology analysis with the Ricardian model, Solomon et al. (2021) established that climate change in Ethiopia will have marginal effects on crop yields as a result of changes in temperature and rainfall

Climate change in Eritrea is associated with environmental problems such as desertification, deforestation, soil erosion and overgrazing ( Nyssen et al., 2004). It has been established that climate change and drought are serious long term environmental problems due to the long-term trend in annual precipitation decrease and temperature increase ( Ghebrezgabher and Yang, 2018). Global warming is a great threat in Eritrea affecting crop production and increasing crop water requirements ( Alam, 2017).

Djibouti has limited arable land (0.1% by area), rainfall and groundwater reserves ( Ozer and Mahamoud, 2013). Vulnerability to natural hazards is enhanced by poor water resources management and by environmental degradation and/or contamination ( Wilby et al., 2010). In the past decades, Djibouti has experienced increased occurrence of climate change induced shocks especially droughts and floods which have decimated the country’s economic pillars of food security, water supply, public health systems and environment ( Yamin et al., 2005). Ozer and Mahamoud (2013) conducted a study which analyzed changes in extreme precipitation between 1980 and 2011 and found a strong decline in total precipitation −17.4% per decade.

The increasing threat of climate change coupled with urbanization, population and industrialization pressures require interventions aimed at improving water use in agriculture by improving crop water productivity in order to ensure sustainability of resources. Some of the techniques for improving crop water productivity include efficient irrigation systems and agronomic practices such as deficit irrigation and soil water conservation ( Kanda et al., 2021). Despite the importance of efficient irrigation systems and prudent agricultural water management, most countries in the Horn of Africa still use traditional methods of irrigation such as furrow and spate irrigation systems. For example, irrigation development in Ethiopia has failed to enhance food security in the country ( Kassa and Andualem, 2020) due to a myriad of challenges such as low technology adoption, lack of technical support given to smallholder farmers, lack of awareness of irrigation water management practices such as irrigation scheduling techniques, water saving irrigation technologies, operation and maintenance of irrigation facilities ( Haile, 2015).

The four pathways identified by the African Union (AU) for improving agricultural production is one of the holistic approaches for addressing water and food nexus challenges. These pathways are (1) improved water control and watershed management in rain-fed farming, (2) farmer-led irrigation development (FLID), (3) irrigation scheme development and modernization, and (4) unconventional water use for irrigation ( AU, 2020). These pathways are necessary for the Horn of Africa where climate change is a threat to water resources and consequently food production. The unconventional use of water in agriculture (pathway 4) requires consideration of food safety and improvement in sewerage and wastewater treatment infrastructure. This may be a challenge in the Horn of Africa where sanitation systems are poorly developed. According to Alemngus et al. (2017), wastewater is used for irrigation in Asmara, Eritrea though it could not qualify as wastewater re-use since there is no wastewater treatment facility. Use of untreated wastewater for irrigation presents food safety risks which can cause harm to human health.

Food production accounts for 30% of energy use in the world ( FAO, 2011). Energy inputs are required throughout the food production chain; from farm, storage, processing, handling, distribution and preparation for consumption ( Awandu et al., 2022). Poor access to energy sources is one of the main causes of post-harvest losses in the agricultural sector in Africa and thus a big contributor to chronic food insecurity and malnutrition ( Lynd et al., 2015).

Biomass energy is a classic example of a direct link between agriculture (food) and energy production ( Tashtoush et al., 2019). Therefore, reliance on biomass energy by households in Africa and specifically in the Horn of Africa exposes them to the risks of climate variability and change. Also, feedstocks used for biofuel production are mainly rainfed with few under irrigation. Therefore, climate change impacts on energy production from agricultural biomass cannot be ignored.

Bioenergy production requires land, and is thus inextricably linked with social development, agriculture, and environmental quality and if these links are not managed properly it can lead to undesirable consequences ( Lynd et al., 2015).

Production of biofuel from sugarcane mollases, Jatropha and castor beans in Ethiopia has improved social security by creating employment but increased the risk of food insecurity due to competition for land resources ( Gebremeskel and Tesfaye, 2008). Land grabbing for biofuel crop production has diminished the land for food crops. For example, Ethiopia has allocated 700,000 ha and 23 million ha to multinational companies for cultivation of sugarcane and Jatropha for biofuel production respectively ( Dobaa et al., 2014). The use of animal dung as bioenergy presents a direct competition from agriculture where it is used as manure and thus contributes to low agricultural productivity.

The pressure to feed an increasing population requires increasing food production from existing agricultural land or expanding the area under crop production. Since most areas in the Horn of Africa are ether arid or semi-arid, rainfed agriculture is vulnerable to climate change and variability and thus irrigation is necessary. Irrigation requires energy for pumping and distribution of water and thus expanding irrigation areas increases energy demand. For example, in Ethiopia electricity demand from large-scale irrigation schemes is increasing and is projected to reach about 13,000 GWh in 2030 ( Yalew, 2022). As discussed in the previous section, hydropower is vulnerable to climate variability and change and consequently irrigated agriculture is affected.

Adoption of climate-smart energy use and management practices can help in climate change adaptation and mitigation as described by Girmay and Gebreegziabher (2019) in the context of Ethiopia ( Table 2). These practices can apply to other Horn of Africa countries.