Ethiopia: Agriculture

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.

Figure 10: Projections of crop land area exposed to drought at least once a year for Ethiopia for different GHG emissions scenarios.

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.

Figure 11: Projections of crop yield changes for major staple crops in Ethiopia for different GHG emissions scenarios assuming constant land use and agricultural management, relative to the year 2000.

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.

Ghana: Agriculture

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.

Figure 11: Projections of at least once per year exposure of crop land area to drought for Ghana for different GHG emissions scenarios.

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.

Figure 12: Projections of crop yield changes for major staple crops in Ghana for different GHG emissions scenarios assuming constant land use and agricultural management, relative to the year 2000.

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