Climate variability, droughts, and temporal yield stability in Ethiopia

<p>Climate variability threatens food system stability, particularly among smallholders in developing countries who depend on rainfed agriculture. Drought and shifts in the onset of the rainy season are typical events in Ethiopia and there were at least three major droughts in the last decade.</p> <p>In this study, we aim to explore relationships between climate variability, agricultural diversity, and crop yield stability. The stability of food production is an important dimension of food security but less often studied than other dimensions due to the lack of multi-year microdata for households or individuals. Farm diversification could be a relevant adaptation strategy in this context as a greater number of species or a more even distribution of crops is postulated to have a stabilizing effect on farm output as compared to a homogeneous farm.</p> <p>We use agriculture-focused panel data from Ethiopia&#8217;s Socioeconomic Survey over four waves from 2011 to 2018, CRU TS v4.05 1901-2020 and CHIRPS 1981-2019 to derive measures of climate variability, drought frequency and crop yield stability. In a twofold analytical approach, we use mixed effects models to separately model i) farm richness and pastoralism prevalence with climate variability as predictors, and ii) crop yield stability with diversity, farm input, and climate characteristics as predictors.</p> <p>We find that temporal yield stability calculated from 23 crops commonly grown in Ethiopia is quite low at on average 2-3 kcal/ha, which means that the temporal mean yield is only 2-3 times the standard deviation over the same time. Long-term climate variability significantly affects the type of farming system, mixed or specialized with pastoralism more prevalent in the drier areas with larger rainfall variability. The frequency of past droughts had a positive effect on yield stability, although it was not a significant effect. Temperature variability, precipitation variability and the average temperature and rainfall in the wettest 3-months had a negative effect on yield stability, but it was not a significant effect either. Yield stability was most strongly and positively associated with farm diversity and the ratio of harvested to planted area which is a measure of crop failure. The effects were greater than from irrigation, fertilizer use and pesticide usage.</p> <p>Together, these findings suggest that shifts in typical ranges of climate variability could destabilize farm-level crop yield for smallholders by limiting diversification opportunities. Our findings highlight the need for researchers and policymakers to consider not only the direct effects of climate variability on crop yield, but also its indirect effects on yield stability caused by increasingly limited adaptation choices.</p>