Category: Ethiopia

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.