Climate risk indicates the factors which are associated with the potential consequences of climate change. According to the Intergovernmental Panel on Climate Change (IPCC), it results from the interaction of hazard, exposure and vulnerability (IPCC, 2014a).

• Hazard refers to the potential occurrence of physical impact from changes in long-term climate trends or extreme weather events. For instance, if a country is projected to experience an increased frequency of intense climate-related events, the level of hazard will increase.
• Exposure indicates the presence of assets, services, resources and infrastructure that could be adversely affected. For instance, if a power system has most of its grids located in a coastal area, it can be considered more exposed to climate risks of sea-level rise or coastal flooding than a system located further inland.
• Vulnerability is the propensity or predisposition to be adversely affected. It includes sensitivity to climate change impacts and lack of adaptive capacity which refers to the ability of a system to anticipate, prepare for and plan effectively for climate change. (DFID, 2011). If a power system is well equipped with a robust data system and capable human resources to anticipate and adapt to climate change impacts, the system can be considered less vulnerable.

A risk assessment of a power system can help governments and utilities understand the potential hazardous events; identify the assets and resources exposed to the hazards; and reduce vulnerability to a changing climate. Based on the understanding of climate-related risks, effective measures to enhance resilience to these risks can be identified to mitigate the potential impacts of climate change.

Africa is one of the regions most susceptible to the impacts of climate change. The continent is already seeing increased anomalies in climate patterns, and it is projected to experience more climate hazards during the rest of this century.

According to the IPCC Fifth Assessment Report (IPCC, 2014b), the mean annual temperature of Africa has steadily increased over the past century and is likely to rise faster than the global land average. Under a scenario which assumes a high GHG Representative Concentration Pathway (RCP 8.5), the mean annual temperature of Africa is likely to exceed 4°C above the 1986‑2005 average by the end of the century, which is higher than the projected level of global warming (3.7°C) (IPCC, 2014c). Indeed, the majority of African countries are likely to see an increase in hot days. Some parts of southern Africa already experienced a warmer temperature in 2019 which was more than 1°C above the average temperature of 1981‑2010 (WMO, 2020). The long-term changes in the mean annual temperature of Africa can increase evaporation losses from reservoirs, leading to a decrease in hydropower generation.

Changing precipitation patterns can also aggravate climate impacts on the continent. Southern Africa, where hydropower accounts for over 20% of the electricity of the regional power pool, is projected to experience electricity shortages due to a persistent occurrence of droughts in the forthcoming decades (Kuo, 2016). Indeed, last year, some southern African countries received lower than normal amounts of precipitation (WMO, 2020). On the other hand, in East Africa, a wetter climate with more frequent heavy precipitation (IPCC, 2014c) is projected to pose a challenge to the management of hydropower systems. It is likely to result in increasing inter-annual variability and uncertainty in hydropower generation in East Africa. These regional variations in precipitation patterns will exacerbate the existing gap in water availability among African countries (IPCC, 2014a). They will require tailored measures for each country to cope with these potential changes.

The increasing likelihood of extreme weather events could also raise the level of climate risk on African hydropower. Last year tropical cyclone Idai hit the east coast of Africa, resulting in strong winds, landfalls, storm surges and flooding in Mozambique, Malawi and Zimbabwe (WMO, 2020). Due to the flooding and excessive debris at the power stations, two major hydropower plants in Malawi went off line, reducing Malawi’s hydropower capacity from 320 MW to 50 MW (Centre for Disaster Philanthropy, 2019; The Watchers, 2019). It caused widespread disruptions to electricity access for several days (ReliefWeb, 2019). 

Hydropower is particularly susceptible to the adverse impacts of climate change because it is directly affected by changing patterns in rainfall and temperatures. For instance, hydropower generation output can fluctuate due to variations in the mean annual streamflow, shifts of seasonal flows, and increased evaporation from reservoirs (IPCC, 2014a). Therefore, an increasing reliance on hydropower could mean a higher probability of exposure to climate hazards.

Hydropower currently plays a significant role in Africa, accounting for 17% of electricity generation on average (IEA, 2019a). In countries such as the Democratic Republic of Congo, Ethiopia, Malawi, Mozambique, Uganda and Zambia, hydropower’s share in electricity generation exceeds 80% (IEA, 2019b; International Hydropower & Dams, 2019). The share of hydro in Africa’s electricity generation is likely to increase to more than 23% by 2040 thanks to its low-carbon nature and cost-effectiveness. The expansion of the share of hydropower will also contribute to ongoing efforts towards the mitigation and adaptation goals of the Paris Agreement, as well as the Sustainable Development Goals (SDGs) (IEA, 2019a).

Some African countries have already initiated large hydropower projects tapping into their enormous hydropower potential. Africa holds considerable technical potential for hydropower, with only 11% of this potential utilised (IHA, 2019). The maximum of the technically feasible hydropower potential of the continent is over 12 times today’s hydropower generation. About two-thirds of the technical potential is likely to be economically feasible (Gernaat et al., 2017; International Hydropower & Dams, 2019). The Democratic Republic of Congo and Ethiopia have the greatest hydropower potential, followed by other countries such as Egypt, Zambia, Mozambique, Tanzania and Sudan (International Hydropower & Dams, 2019).

In 2018, 1 009 MW of installed capacity was added in Africa, bringing the region’s total installed capacity to 36.3 GW (IHA, 2019). Two new hydropower stations in Uganda are projected to double Uganda’s total installed hydropower capacity from 764 MW to 1 552 MW (IHA, 2019). One of the two new hydropower stations, the Isimba Dam, was already commissioned in March 2019, and the other one, Karuma Dam, is scheduled to be commissioned in 2020. These dams will contribute to meeting the increasing electricity demand in Uganda and advancing the electricity access rate, currently at less than 30%.

However, tapping into this hydropower potential without considering exposure to climate hazards may increase risk. Indeed, past hydropower projects in Africa rarely took into account the future increase in exposure to climate hazards. Few studies assessed risks and impacts of climate change on hydropower resources in Africa (IPCC, 2014a). Most projects relied on past meteorological and hydrological records to assess climate risks due to a low human capacity and limited information on climate projections (CDKN, 2015; Trace, 2019).

However, the long lifespan of hydropower assets, which generally ranges from 50 to 100 years, mandates that new hydropower projects consider the long-term implications of climate change (Trace, 2019). During the lifespan, most African hydropower plants are likely to be increasingly exposed to climate impacts. Given the growing role of hydropower in the continent, the issue of increasing exposure needs to be taken into account from the initial planning to the overall management of hydropower.

Some recent attempts have been made to incorporate future climate conditions into the design and operations of hydropower projects in Africa. For instance, the World Bank conducted a climate risk assessment for hydropower generation in five river basins of Cameroon (World Bank, 2014). Based on the findings from this assessment, the Bank has implemented the Nachtigal Hydropower Project since 2018. The project is expected to step up climate resilience against erratic precipitation in dry seasons by ensuring all-season flow on the Sanaga river basin with a new regulating dam and main reservoir upstream (World Bank, 2019).

In addition to climate hazards and the level of exposure, vulnerability must be considered to manage climate risks. Vulnerability stems from the sensitivity and limited adaptive capacity of a power system and the stakeholders involved in the system. Sensitivity is the extent to which a system is impacted by a sector or a source that could be negatively affected by climate hazards. Adaptive capacity refers to the ability of a system and stakeholders to anticipate, prepare for and plan in advance to cope with potential climate impacts.

African hydropower is particularly vulnerable to climate change due to its sensitivity to water availability which is often restricted. Africa has less than 9% of the world’s renewable freshwater resources, half of which are concentrated in just six African countries (UNESCO, 2019). Some cities in Mozambique, Zimbabwe and Ghana already experienced water shortages in 2019 (IEA, 2019a). Water scarcity means that electricity generation using hydro often needs to compete with other uses of water. Competition for water between energy, residential and productive uses are expected to be accentuated in some locations, given the increased risk of water stress due to changing and erratic precipitation patterns.

Moreover, public officials and utilities in the majority of African countries, particularly those in rural areas, have low levels of adaptive capacity; some of them are already experiencing difficulties in coping with the current level of climate variability (IPCC, 2014a). For example, an expert mission of the World Meteorological Organization (WMO) to Mozambique after cyclone Idai identified the limited capacities of key central and local government authorities to respond to emergencies as one of its major weaknesses (WMO, 2019a). Managing the adverse impacts of climate change may become more challenging with the increasing variability of climate patterns and more frequent extreme weather events. A lack of appropriate regulatory regimes, low levels of planning and the absence of disaster risk reduction strategies could exacerbate vulnerability to climate impacts in African countries (IPCC, 2014a). Several studies point to the importance of improving access to quality climate data, analysis and knowledge to reduce vulnerability (IPCC, 2012; WMO, 2019b).