Category: Impacts

Climate change threatens the health and sanitation sector through more frequent incidences of heatwaves, floods, droughts and storms [30]. Among the key health challenges in Ethiopia are morbidity and mortality through temperature extremes, vectorborne diseases, such as malaria, non-vector borne diseases related to extreme weather events (e.g. flooding and droughts) such as diarrhoea and cholera, respiratory diseases, injury and mortality through extreme weather events as well as climate impacts on food and water supply, which can increase the risk of malnutrition and hunger [31]. Many of these challenges are expected to become more severe under climate change. The Ethiopian Ministry of Health estimates that already today, around 68 % of the population is at risk of contracting malaria [32]. Climate change is likely to lengthen transmission periods and alter the geographic range of vector-borne diseases, for instance, due to rising temperatures. Malaria could expand from lowland areas in Somali and Afar to highland areas in Tigray or Amhara [33].

Heatwave exposure and mortality

Rising temperatures will result in more frequent heatwaves in Ethiopia, leading to increased heat-related mortality. Under RCP6.0, the population affected by at least one heatwave per year is projected to increase from 0.3 % in 2000 to 2.1 % in 2080 (Figure 17).

Furthermore, under RCP6.0, heat-related mortality will likely increase from about 2 to about 6 deaths per 100 000 people per year, which translates to an increase by a factor of more than three towards the end of the century compared to year 2000 levels, provided that no adaptation to hotter conditions will take place (Figure 18). Under RCP2.6, heat-related mortality is projected to increase to about 4 deaths per 100 000 people per year in 2080.

References

[30] B. Simane, H. Beyene, W. Deressa, A. Kumie, K. Berhane, and J. Samet, “Review of Climate Change and Health in Ethiopia: Status and Gap Analysis,” Ethiop. J. Heal. Dev., vol. 30, no. 1, pp. 28–41, 2016.
[31] Environmental Protection Authority of Ethiopia, “CRGE Vision: Ethiopia’s Vision for a Climate Resilient Green Economy.”
[32] Ministry of Health of Ethiopia, “Malaria Prevention & Control Program,” 2013. [Online]. Available: http://www.moh.gov.et/ejcc/en/malaria-prevention-control-program. [Accessed: 07-Oct-2019].
[33] Ministry of Water of Ethiopia, “Climate Change National Adaptation Programme of Action (NAPA) of Ethiopia,” Addis Ababa, 2007.

Climate change is expected to have a significant influence on the ecology and distribution of tropical ecosystems, even though the magnitude, rate and direction of these changes are uncertain [28]. Under rising temperatures, increased frequency and intensity of droughts and shorter growing periods, wetlands and riverine systems are increasingly at risk of being converted to other ecosystems with plant populations being succeeded and animals losing habitats. Increased temperatures and droughts can also influence succession in forest systems while concurrently increasing the risk of invasive species, all of which affect ecosystems. In addition to these climate drivers, reduced agricultural productivity and population growth might motivate further agricultural expansion resulting in increased deforestation, land degradation and forest fires, all of which will impact animal and plant biodiversity.

Species richness

Model projections of species richness (including amphibians, birds and mammals) and tree cover for Ethiopia are shown in Figure 15 and 16, respectively. The models applied for this analysis show particularly strong agreement on the development of animal species richness under RCP6.0: Northern Ethiopia is expected to gain up to 40 % in the number of animal species due to climate change, while eastern Ethiopia is expected to lose around 20 %.

Tree cover

With regard to tree cover, model results are less certain. For RCP2.6, no reliable estimates can be made. However, under RCP6.0, tree cover is projected to start changing around 2050 with more significant and certain changes towards the end of the century: Median model projections agree on an increase of tree cover by more than 10 % in the eastern part of the country (Figure 16).

Although these results paint an overall positive picture for climate change impacts on ecosystems and biodiversity, it is important to keep in mind that the model projections exclude any impacts on biodiversity loss from human activities such as land use, which have been responsible for significant losses of global biodiversity in the past, and which are expected to remain its main driver in the future [29].

References

[28] T. M. Shanahan et al., “CO2 and fire influence tropical ecosystem stability in response to climate change,” Nat. Publ. Gr., no. July, pp. 1–8, 2016.
[29] IPBES, “Report of the Plenary of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on the work of its seventh session,” 2019.

Climate change is expected to significantly affect Ethiopian infrastructure through extreme weather events, such as floods and droughts. High precipitation amounts can lead to flooding of transport infrastructure including roads, railroads and airports, while high temperatures can cause roads, bridges and protective structures to develop cracks and degrade more quickly. This will require earlier replacement and lead to higher maintenance and replacement costs [23]. Transport infrastructure is vulnerable to extreme weather events, yet essential for agricultural livelihoods. Roads serve communities to trade goods and access healthcare, education, credit and other services. Especially in rural areas, roads are the backbone of Ethiopia’s transportation network with more than 90 % of exports and imports transported by road [24]. Investments will have to be made into building climate-resilient road networks [25].

Extreme weather events will also have devastating effects on human settlements and economic production sites, especially in urban areas with high population densities like Addis Ababa, Dire Dawa or Mekelle. Informal settlements are particularly vulnerable to extreme weather events: Makeshift homes are often built in unstable geographical locations including steep slopes or river banks, where flooding can lead to loss of housing, contamination of water, injury or death. Dwellers usually have low adaptive capacity to respond to such events due to high levels of poverty and lack of risk-reducing infrastructures. For example, heavy rains in May and June 2019 have caused flooding in 38 districts across seven regions of Ethiopia, displacing 42306 families and causing livestock death and property damage [26]. Flooding and droughts will also affect hydropower generation: Ethiopia is planning to increase its hydropower capacity from 3.7 gigawatts in 2015 to a volume of 19.5 gigawatts in 2030, however, variability in precipitation and climatic conditions could severely disrupt hydropower generation [27].

Despite the risk of infrastructure damage being likely to increase due to climate change, precise predictions on specific location and extent of exposure are difficult to make. For example, projections of river flood events are subject to substantial modelling uncertainty, largely due to the uncertainty of future projections of precipitation amounts and their spatial distribution, affecting flood occurrence (see also Figure 4). Among the models applied for this analysis, two models project only a slight increase and one model projects a stronger increase in the exposure of major roads to river floods at least once a year. The very likely range of model results indicates that road exposure to floods may increase by 70 % by 2080 (from 1.3 % of the national road network exposed in 2000 to 2.1 % in 2080). However, projections are characterised by high modelling uncertainty with median projections for RCP6.0 showing only a 0.2 % change from 2000 to 2080 (Figure 12). Hence, no reliable estimations on future occurrence of river floods can be made. Also, urban land area exposed to floods at least once a year is projected to increase (Figure 13), with a very likely range of 0.1–1.1 % by 2080 under RCP6.0.

With the exposure of the GDP to heatwaves projected to increase from around 0.3 % in 2000 to 1.4 % (RCP2.6) and 2.8 % (RCP6.0) by the end of the century, economic policy planners are advised to start identifying heat-sensitive production sites and activities, and integrating climate adaptation strategies such as improved solar-powered cooling systems or switching the operating hours from day to night.

References

[23] Ministry of Transport of Ethiopia, “Ethiopia’s Climate Resilient Transport Sector Strategy,” Addis Ababa.
[24] EPCC, “First Assessment Report – Summary of Reports for Policy Makers,” Addis Ababa, 2015.
[25] T. Gebre and F. Nigussa, “Greenhouse Gas Emission Reduction Measures in the Urban Road Transport Sector of Ethiopia,” Environ. Prog. Sustain. Energy, vol. 38, no. 5, pp. 1–8, 2019.
[26] OCHA, “Ethiopia: Situation Report No. 23,” 2019.
[27] D. Conway, P. Curran, and K. E. Gannon, “Policy brief: Climate risks to hydropower supply in eastern and southern Africa,” no. August, 2018.

Agriculture is amongst the sectors most exposed to climate change. Smallholder farmers in Ethiopia are increasingly challenged by the uncertainty and variability of weather that climate change causes. Since crops are predominantly rainfed (only 5 % of the national crop area is irrigated), crop yields depend on water availability and are prone to drought [4]. Climate change will have a negative impact on maize, which is the most important staple crop in terms of caloric intake, number of farmers growing it and production volume in Ethiopia [21]. Millet will also suffer from climate change impacts (Figure 11). However, actual yields for both crops will depend on the site and year as well as aggregate, regional and local drivers of crop production. Nonbiophysical factors such as access to markets will also influence production levels. Six zones are projected to experience yield losses under climate change, which are Western Tigray, South Omo, North Shewa (Amhara), Metekel, Illubabor and Gamo [22]. It should be noted that teff is another major staple crop in Ethiopia; however, due to lack of modelling data, we were unable to include it as part of our analysis.

Cropland exposure to droughts

Currently, the high uncertainty of projections regarding water availability (Figure 9) translates into high uncertainty in drought projections (Figure 10). According to the median over all models employed for this analysis, the national crop land area exposed to at least one drought per year will hardly change in response to global warming. However, there are models that project an increase in drought exposure. Under RCP6.0, the likely range of drought exposure of the national crop land area per year widens from 0.04–1.4 % in 2000 to 0.04–3.9 % in 2080. The very likely range widens from 0.01–2.3 % in 2000 to 0.01–7.1 % in 2080. This means that some models project a tripling of drought exposure over this time period, while others project no change.

Crop yield projections

In terms of yield projections, model results indicate a negative yield trend for maize and millet under RCP6.0. Compared to the year 2000, yields are projected to decline by 3.8 % for maize and 4.9 % for millet by 2080 under RCP6.0. Under RCP2.6, maize yields are projected to decrease only slightly and millet yields do not change. Yields of field peas, on the other hand, are projected to significantly gain from climate change. Under RCP6.0, yields are projected to increase by 17 % by 2080 relative to the year 2000. A possible explanation for the positive results under RCP6.0 is that field peas are so-called C3 plants, which follow a different metabolic pathway than maize and millet (which are C4 plants), and thus benefit more from the CO2 fertilisation effect under higher concentration pathways. Wheat is projected to slightly decrease under both RCP2.6 and RCP6.0. Although there appears to be almost no change in national-level wheat yields, it is likely that crop yields will increase more strongly in some areas and, conversely, decrease more strongly in other areas as a result of climate change impacts.

A complimentary climate risk study for Ethiopia provides indepth information on climate impacts and selected adaptation strategies in the agricultural sector.

Overall, adaptation strategies such as switching to improved varieties in climate change sensitive crops need to be considered, yet should be carefully weighed against adverse outcomes, such as a resulting decline of agro-biodiversity and loss of local crop types.

References

[4] P. Woldemariam and Y. Gecho, “Determinants of Small-Scale Irrigation Use: The Case of Boloso Sore District, Wolaita Zone, Southern.
Ethiopia,” Am. J. Agric. For., vol. 5, no. 3, p. 49, 2017.
[21] T. Abate et al., “Factors that transformed maize productivity in Ethiopia,” Food Secur., 2015.
[22] L. Murken et al., “Climate Risk Analysis for Identifying and Weighing Adaptation Strategies in Ghana,” 2019.

Ethiopia is known as the “water tower of Africa”, having twelve river basins, 22 major lakes and a groundwater potential of about 2.6 billion m3 [19]. However, rapid population growth and future variability of water resources can affect the economy through a growing energy and water demand in different sectors including agriculture, infrastructure, ecosystems and health. Precipitation strongly depends on elevation: It currently ranges from 1900 mm per year in the highlands to around 100 mm per year in low-lying areas [15]. Agricultural production follows these precipitation patterns. However, areas with high agricultural production also coincide with high population density and pressure on land, especially in the weyna dega (warm to cool climate) and dega (cool climate) zones that are best suited for the production of major staple crops in Ethiopia [20].

Per capita water availability

Current projections for water availability in Ethiopia display high uncertainty under both GHG emissions scenarios. Assuming a constant population level, multi-model median projections suggest no change in per capita water availability over Ethiopia by the end of the century under RCP2.6 and only a slight increase under RCP6.0 (Figure 8A). Yet, when accounting for population growth according to SSP2 projections⁶, per capita water availability for Ethiopia is projected to decline by 65 % by 2080 relative to the year 2000 under both scenarios (Figure 8B). While this decline is driven primarily by population growth, rather than climate change, it highlights the urgency to invest in water saving measures and technologies for future water consumption.

Spatial distribution of water availability

Projections of future water availability from precipitation vary depending on the region and scenario (Figure 9). Under RCP2.6, water availability will decrease by up to 30 % in southern Ethiopia and increase by up to 35 % in eastern Ethiopia by 2080. All models agree on this trend, making water saving measures in these regions particularly important after 2050. However, the picture is different for RCP6.0, where projections for the south and east of Ethiopia are less certain and the projected difference in water availability is smaller, which is why a clear trend cannot be identified.

6 Shared Socio-economic Pathways (SSPs) outline a narrative of potential global futures, including estimates of broad characteristics such as country-level population, GDP or rate of urbanisation. Five different SSPs outline future realities according to a combination of high and low future socio-economic challenges for mitigation and adaptation. SSP2 represents the “middle of the road”-pathway.

References

[19] D. Mulugeta, D. Weijun, and J. H. Zhao, “Hydropower for sustainable water and energy development in Ethiopia,” Sustain. Water Resour. Manag., vol. 1, no. 4, pp. 305–314, 2015.
[20] J. Chamberlin and E. Schmidt, “2 Ethiopian Agriculture: A Dynamic Geographic Perspective,” in Food and Agriculture in Ethiopia, 2014.

Temperature

In response to increasing greenhouse gas (GHG) concentrations, air temperature over Ethiopia is projected to rise by 1.6 to 3.7 °C (very likely range) by 2080 relative to the year 1876, depending on the future GHG emissions scenario (Figure 2). Compared to pre-industrial levels, median climate model temperature increases over Ethiopia amount to approximately 1.5 °C in 2030, 1.8 °C in 2050 and 1.8 °C in 2080 under the low emissions scenario RCP2.6. Under the medium / high emissions scenario RCP6.0, median climate model temperature increases amount to 1.5 °C in 2030, 1.8 °C in 2050 and 2.4 °C in 2080.

Very hot days

In line with rising mean annual temperatures, the annual number of very hot days (days with daily maximum temperature above 35 °C) is projected to rise substantially and with high certainty, in particular over eastern Ethiopia (Figure 3). Under the medium / high emissions scenario RCP6.0, on average over all Ethiopia, the multi-model median projects 18 more very hot days per year in 2030 than in 2000, 26 more in 2050 and 50 more in 2080. In some parts, especially in eastern Ethiopia, this amounts to about 200 days per year by 2080.

Precipitation

Future projections of precipitation are less certain than projections of temperature change due to high natural year-to-year variability (Figure 4). Out of the three climate models underlying this analysis, one model projects almost no change in mean annual precipitation over Ethiopia, while the other two models project an increase. Median model projections for RCP2.6 show almost no change in total precipitation per year until 2080, while median model projections for RCP6.0 show a precipitation increase of 85 mm / year by 2080 compared to year 2000.

Heavy precipitation events

In response to global warming, extreme precipitation events are expected to become more intense in many parts of the world due to the increased water vapour holding capacity of a warmer atmosphere. At the same time, the number of days with heavy precipitation events is expected to increase. This tendency is also found in climate projections for Ethiopia (Figure 5), with climate models projecting a slight increase in the number of days with heavy precipitation events, from 7 days / year in 2000 to 8 days / year in 2080 under RCP2.6 and 9 days / year under RCP6.0 by 2080.

Soil moisture

Soil moisture is an important indicator for drought conditions. In addition to soil parameters, it depends on both precipitation and evapotranspiration and therefore also on temperature as higher temperatures translate to higher potential evapotranspiration. Annual mean top 1-m soil moisture projections for Ethiopia show almost no change to a slight decrease for RCP2.6, while under RCP6.0, soil moisture is projected to slightly increase approaching a 1 % change by 2080 compared to the year 2000 (Figure 6). However, looking at the different models underlying this analysis, there is large year-to-year variability and modelling uncertainty, which makes it difficult to identify a clear trend.

Potential evapotranspiration

Potential evapotranspiration is the amount of water that would be evaporated and transpired if sufficient water were available at and below land surface. Since warmer air can hold more water vapour, it is expected that global warming will increase potential evapotranspiration in most regions of the world. In line with this expectation, hydrology projections for Ethiopia indicate a stronger and more continuous rise of potential evapotranspiration under RCP6.0 than under RCP2.6 (Figure 7). Under RCP6.0, potential evapotranspiration is projected to increase by 2.0 % in 2030, 2.7 % in 2050 and 4.4 % in 2080 compared to year 2000 levels.

5 Changes are expressed relative to year 1876 temperature levels using the multi-model median temperature change from 1876 to 2000 as a proxy for the observed historical warming over that time period.

Climate change threatens the health and sanitation sector through more frequent incidences of heatwaves, floods, droughts and dry winds [32]. Climate change impacts on health can be direct, e.g. via increasing exposure to heatwaves or floods, or indirect, e.g. via more frequent incidences of vector-borne diseases, such as malaria, as well as via increasing food insecurity or malnutrition.

Heatwave exposure and mortality

Rising temperatures will result in more frequent heatwaves in Ghana, which will increase heat-related mortality. Under RCP6.0, the population affected by at least one heatwave per year is projected to rise from 5 % in 2000 to 19 % in 2080 (Figure 17). Furthermore, under RCP6.0, heat-related mortality will likely increase from about 1 to about 5 deaths per 100 000 people per year, which translates to an increase by a factor of more than five towards the end of the century compared to year 2000 levels, provided that no adaptation to hotter conditions will take place (Figure 18). Under RCP2.6, heat-related mortality is projected to increase to about 2 deaths per 100 000 people per year.

Among the key health challenges in Ghana are also communicable diseases, such as malaria, tuberculosis, and HIV, maternal and children’s health as well as malnutrition, many of which are expected to become increasingly severe under climate change. Studies show that Malaria, diarrhea, and Cerebro Spinal Meningitis are being aggravated by impacts of climate change in Ghana [33].

References

[32] A. Haines, R. S. Kovats, D. Campbell-Lendrum, and C. Corvalan, “Climate change and human health: Impacts, vulnerability and public health,” Public Health, vol. 120, no. 7, pp. 585–596, Jul. 2006.
[33] D. B. K. Dovie, M. Dzodzomenyo, and O. A. Ogunseitan, “Sensitivity of health sector indicators’ response to climate change in Ghana,” Sci. Total Environ., vol. 574, pp. 837–846, Jan. 2017.

Climate change is anticipated to have a significant influence on the ecology and distribution of tropical ecosystems, though the magnitude, rate and direction of these changes are uncertain [29]. Under rising temperatures, increased frequency and intensity of droughts and shorter growing periods, wetlands and riverine systems become at risk of being converted to other ecosystems with plants being succeeded and animals losing habitats. Increased temperatures and droughts can also affect succession in forest systems while concurrently increasing the risk of invasive species, all of which affect the ecosystems. In addition to these climate drivers, reduced agricultural productivity and population growth might motivate further agricultural expansion resulting in increased deforestation, forest degradation and in return in increased forest fires, all of which will impact animal and plant biodiversity [30]. While ecosystems in the northern areas of Ghana are expected to be particularly affected given the higher expected temperature increase and mounting pressure from human land use, the challenges are prevalent throughout the entire country.

Species richness

Model projections of species richness (including amphibians, birds, and mammals) and tree cover for Ghana are shown in Figure 16 and 17, respectively. The volatility in species richness between 2030 and 2050 under RCP6.0 suggest a high sensitivity of species survival and population recovery to natural climate variability. Overall, however, model results indicate a slightly positive long-term impact of climate change on species richness under both RCPs (Figure 15), with the majority of models (at least 75 %) agreeing on this trend.

Tree cover

With regards to tree cover shifts, model results are highly uncertain. Until mid-century, tree cover is projected to not change significantly in most parts of Ghana. Towards the end of the century, the average model projects slight decreases of tree cover under RCP2.6 and slight increases under RCP6.0, yet model agreement about these trends is low in most parts of the country (Figure 16).

Although these results paint an overall positive picture for climate change impacts on ecosystems and biodiversity, it is important to keep in mind that the model projections exclude any impacts on biodiversity loss from human activities such as land use, which have been responsible for significant losses of global biodiversity in the past, and are expected to remain the main driver of biodiversity loss in the future [31].

[28] T. M. Shanahan et al., “CO2 and fire influence tropical ecosystem stability in response to climate change,” Sci. Rep., vol. 6, no. 1, p. 29587, Jul. 2016.
[29] S. Agyemang, M. Muller, and V. R. Barnes, “Fire in Ghana’s dry forest: Causes, frequency, effects and management interventions,” in Proceedings of the large wildland fires conference, 2014, pp. 15–21.
[30] IPBES, “Global Assessment Report on Biodiversity and Ecosystem Services,” Bonn, 2019.

Extreme weather events have been the cause of major damage to the infrastructure sector in Ghana in the past. A study by Twerefou et al. [25] from 2014, for example, states that within one year, 1016 km of roads were destroyed, 13 bridges collapsed and 442 sewers damaged in the northern region of Ghana in 2007 alone through climate-related events. In general, high temperature can cause roads to develop cracks, while high precipitation rates may create potholes or deepen existing ones. [26]. Transport infrastructure is very vulnerable to extreme weather events and yet very important for social, economic and agricultural livelihoods. Roads allow communities to trade their goods and access healthcare, education, credit, as well as other services, especially in rural and remote areas of Ghana.

Storms, extreme rainfall and floods can also have devastating effects on economic production sites as well as settlements, especially in areas where large populations reside, such as Accra, Kumasi and Tamale. Informal settlements are particularly vulnerable to these events, as structures are generally weak and dwellers have low adaptive capacity to respond to disruptive events. Hydropower generation plants are affected by both droughts and floods, whereas sea level rise is already beginning to erode coastal roads [27]. Overall, climate change will make the life span of infrastructure shorter than planned while maintenance costs will increase significantly to keep them functioning [27], [28].

Under climate change, extreme weather events are likely to become more frequent, and temperatures are projected to rise. Accordingly, the risk for infrastructure damage in the country is likely to increase. However, precise predictions of the location and extent of exposure are difficult to make. For example, projections of river flood events are subject to substantial modelling uncertainty, largely due to the uncertainty of future projections of precipitation amounts and their spatial distribution, affecting affecting flood occurrence (see also Figure 5). According to this analysis, flood projections show a decrease in exposure for one climate model, no change for another, a slight increase for the third and a strong increase for the fourth. Thus, no reliable estimates on river flood occurrence in the future can be made. While median model trends suggest an approximate doubling of road exposure to floods under RCP6.0 (Figure 13) from 2000 to 2080, the very likely range of model results indicates a possibility of up to a fivefold increase in road exposure to floods by 2080 (from 0.2 % of the national road network exposed in 2000 to 1.1 % in 2080). Also urban land area exposed to floods is projected to increase (Figure 14), with a very likely range of 0–0.6 % of the urban area exposed by 2080 under RCP 6.0.

Twerefou et al. [27] estimate that the future (2020-2100) cost of climate change-related damage on road infrastructure will amount to USD 473 million if no adaptation actions are taken, and USD 678.47 million if pricing in the costs for adaptation efforts in designing and constructing new road infrastructure. They estimate that the highest adaptation costs will incur in the northern region and the lowest in the greater Accra region.

With the impact to GDP from heatwaves projected to increase from around 5 % in 2000 to 15 % (RCP2.6) and 20 % (RCP6.0) by the end of the century, it is recommended that policy planners start identifying heat-sensitive economic production sites and activities, and integrating climate adaptation options, such as improved, solar-powered cooling systems or switching of operation times from day to night.

References

[25] D. Twerefou, K. Adjei-Mantey, and N. Strzepek, “The economic impact of climate change on road infrastructure in sub-Saharan Africa countries: evidence from Ghana,” 2014.
[26] M. Taylor and M. Philp, “Adapting to climate change-implications for transport infrastructure, transport systems and travel behaviour,” Road Transp. Res., vol. 19, no. 4, 2011.
[27] D. Twerefou, K. Adjei-Mantey, and N. Strzepek, “The economic impact of climate change on road infrastructure in sub-Saharan Africa countries: evidence from Ghana,” World Institute for Development Economics Research. Helsinki, Finland, 2014.

Agriculture is amongst the sectors most exposed to climate change. Smallholder farmers in Ghana are increasingly challenged by the uncertainty and variability of weather that climate change causes, particularly in the northern regions of Ghana. Since crops are predominantly rainfed (as less than 1 % of the national crop area is irrigated), crop yields depend on water availability and are susceptible to drought. The impacts of climate change on the agricultural sector will be crop-specific and also site-specific with major negative impacts expected for maize in the central to northern parts of the country [24]. Yet, the high uncertainty of water availability projections (Figure 10) translates to high uncertainty in drought projections (Figure 11). According to the median over all models employed for this analysis, the national crop land area exposed to at least one drought per year will hardly change in response to global warming. However, there are models that project an increase in drought exposure. Under RCP6.0, the likely range of drought exposure of the national crop land area per year widens from 0.3–8.8 % in 2000 to 0.5–21.0 % in 2080. The very likely range widens from 0.1–25.0 % in 2000 to 0.1–53.0 % in 2080. This means that some models project more than a doubling of drought exposure over this time period, while others project no change.

In terms of yield projections, model results indicate a clear negative yield trend for maize and millet under both RCP2.6 and RCP6.0. As a best estimate, compared to year 2000, yields averaged over the whole country are projected to decline by 9% for maize and 10% for millet by 2080 under RCP6.0, and by 4% and 5% under RCP2.6, respectively. Yields of cassava, groundnuts and field peas, on the other hand, are projected to significantly gain from climate change. Under RCP6.0, yield increases by 2080 relative to year 2000 are projected to amount to 33% for cassava, 14% for field peas, and 3% for groundnuts. A possible explanation for the positive results under RCP6.0 is that cassava, groundnuts and field peas are so-called C3 plants, which follow a different metabolic pathway than maize and millet (which are C4), and thus benefit more from the CO2 fertilization effect under higher concentration pathways. Cassava and groundnuts are also more tolerant to both low and high rainfall extremes.

[24] L. Murken et al., “Climate Risk Analysis for Identifying and Weighing Adaptation Strategies in Ghana,” 2019.