Climate Change Projections

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Please cite page as: Africa Groundwater Atlas. 2023. Climate Change Projections. British Geological Survey. Accessed [date you accessed the information]. https://earthwise.bgs.ac.uk/index.php/Climate_Change_Projections.

Climate Change Projections

Of all the continents, Africa is among the lowest contributors of historical greenhouse gas (GHG) emissions and currently has the lowest per capita GHG emissions of all regions. However, Africa has already experienced, and is projected to experience further widespread impacts from human-induced climate change (IPCC Chapter 9).

With increased global GHG emissions, mean temperature is projected to rise over the whole continent of Africa and temperature extremes are projected to increase. At lower latitudes, large increases in frequency of daily temperature extremes (hotter than 99.9% of historical records) are projected for early in the 21st century compared to nations at higher latitudes Harrington et al, 2016. Previous assessments have shown that hot days and nights have become more frequent in Africa and heatwaves have become longer and more frequent. Drying is projected, particularly for West and southwestern Africa (IPCC 2019).

Based on projections by the IPCC (2023), global warming of 1.5°C with an initial overshoot to 2°C will likely cause an intensification of the global water cycle, with impacts on precipitation including increased variability and seasonality, more frequent and intense heavy precipitation events and droughts.

Projections for precipitation at the regional scale by the IPCC (2023)

• North-East and Central Africa as well as the Ethiopian Highlands are projected to see increased mean annual precipitation.

• Central Sahel and East Africa are projected to see longer and wetter wet seasons.

• In Coastal West, Northern and Southern Africa decreased mean annual precipitation is projected.

• The frequency and intensity of heavy precipitation is projected to increase across most of the continent, except northern and southwestern Africa.

Summary of climate change impacts on Africa

With 1.5°C - 2°C global warming, the impacts in Africa are projected to become widespread and severe. These impacts include:

• Reduced food production
  • Many African regions are vulnerable to food insecurity due to low adaptive capacity (Evariste et al, 2018).
  • Agricultural activities are mainly rainfed. It’s projected that future climate warming will have an adverse impact on food security in Africa as it coincides with low adaptive capacity and climate change exacerbates other anthropogenic stressors (Adams, L., 2018).

• Reduced economic growth
  • GDP per capita is on average 13.6% lower for African countries (although there is substantial variation across countries) than if human-caused global warming since 1991 had not occurred (Diffenbaugh, N. S. and M. Burke, 2019).
  • Abidoye and Odusola estimated that a 1°C increase in 20 year average temperature reduced GDP growth by 0.67 percentage points, with Central African Republic, DRC and Zimbabwe worst affected.

• Increased inequality and poverty
  • In urban areas, climate risk and poverty will increasingly coincide. Particularly affected will be fast-growing informal settlements in more exposed, flood-prone areas with limited services (Hallegatte et al., 2016, 2017).

• Biodiversity loss
  • Increasing temperatures might have contributed to the declining abundance and range in size of South African birds (Milne et al, 2015).
  • An increase in woody cover has led to a decrease in occurrence of bird, reptile and mammal species that require a grassy habitat (McCleery et al, 2018).
  • Warming of water temperature in several lakes from 0.2°C to 3.2°C, over 1927-2014, has been attributed to human-caused climate change (Ogutu-Ohwayo et al., 2016). This, along with changes in rainfall and reduced windspeed, caused changes in the physical and chemical properties of inland water bodies, reducing water quality, affecting the productivity of algae, invertebrates and fish (Ndebele-Murisa, 2014).

• Increased human morbidity and mortality.
  • Climate change is already affecting health outcomes in Africa with increases in temperature-related mortality. Young children, the elderly, pregnant women and people living in poverty are among the most vulnerable to increasing risks to health outcomes (IPCC 2023). Bishop-Williams et al., 2018 showed that emergency department visits and hospital admissions increase at moderate to high temperatures in Uganda. At 2°C global warming projected rates of heat-related mortality in the Middle East and North Africa, in the >65 years age bracket to increase 8-20 fold in the years 2070-2099 compared with 1951-2005 (Ahmadalipour, A. and H. Moradkhani, 2018).
  • Increase in vector-borne diseases. There has been an expansion of the Anopheles vector (of malaria) in higher altitudes in east Africa (Gone et al, 2014) and increasing incidence of infection with higher temperatures (Alemu et al, 2014). In southern Africa, malaria transmission is increasing due to changes in temperature and rainfall (Abiodun et al, 2018. In east and southern Africa, malaria vector hotspots and prevalence are projected to increase under 1.5°C-1.7°C global warming (Semakula et al, 2017).

Impacts on water supply

Impacts on water supply At a global scale. It’s projected that extreme daily precipitation events will intensify by approximately 7% for every 1°C of global warming (IPCC 2021). Flood risk will potentially double between 1.5°C and 3°C of warming. Flooding poses direct risks to water and sanitation infrastructure and amplifies risk of water contamination and disease. Populations in rural, low-income areas with limited/no sanitation or safe water are most exposed to health risks, as heavy rains can flood latrines, spreading faecal matter into unprotected/poorly protected water sources (Calow et al., 2017).

It is likely that large areas of North Africa will become drier over the coming decades (IPCC Interactive Atlas, 2021). With warmer climate intensifying both wet and dry weather, drought risks are projected to increase over much larger areas (IPCC, 2021). With long-term decline in rainfall or increased drought risk comes a threat to the safe and continuous supply of drinking water. Even short interruptions or reversion to unprotected sources has been shown to increase risks to health (Hunter et al., 2009). More basic water supply systems (e.g. shallow dug wells and rooftop rainwater harvesting) are most at risk from reduced rainfall. These problems exist beyond low income, rural areas. For instance, between 2015 and 2018, Cape Town has experienced a severe drought where the city’s water supply is dependent on streamflow from a relatively small area, made up of several mountainous catchments. As dam levels dropped to less than 20% of their capacity, authorities were forced to plan for Day Zero when taps would run dry (Simpson, et al., 2019). This highlighted issues with over-reliance on one water source and the importance of groundwater storage as a buffer against drought and longer-term aridity.

Adaptations to climate change involving groundwater

Groundwater storage can provide resilient drinking water supplies even under drying conditions and severe drought with storage replenished by intense rainfall events. A study by Cuthbert et al showed that there is medium confidence that increased precipitation intensity enhances groundwater recharge. Groundwater studies in Sub-Saharan Africa over the last decade (MacDonald et al., 2019); (MacAllister et al., 2020) have shown that provided systems are built and maintained to a reasonable standard, groundwater-based services are resilient. However, in the context of increased abstraction of water for irrigation and consumptive uses, these pressures could deplete groundwater storage (Scanlon et al., 2023).

MacAllister et al, 2020 conducted an analysis of performance data from over 5000 water points collected during the 2015-16 El Niño drought in Ethiopia. Their findings showed that problems were largely confined to areas dependent on unprotected rivers, streams and ponds, relying on hand dug wells and springs or deep motorised boreholes that broke or ran out of fuel due to increasing demand. Boreholes equipped with simple handpumps were much more resilient, provided they were maintained. The Paris Agreement , UNISDR Sendai Framework and 2030 Sustainable Development Goals are among other treaties and agreements with the goal of addressing and mitigating the effects of climate change on a global scale. SDG6 focusses on water access, management, and sanitation.