Rainfall extremes are intensifying across Ethiopia’s Lower and Upper Dega highland agroecosystems, according to a new study in Scientific Reports, with projections pointing to further increases in heavy rain, heat and dry spells by mid-century — trends the authors warn could threaten potato farming, a staple crop across the region.
Researchers including Asrat Ayalew, Mezegebu Getnet and Shegaw Getu of the University of Gondar examined the Debark, Dabat and Wogera districts, using observed data from 1989 to 2018 alongside MIROC6 climate model projections for 2019–2048 and 2049–2078. Observed data already show annual wet-day rainfall rising by about 168mm per decade in Upper Dega and 66.6mm per decade in Lower Dega, alongside more frequent warm extremes and fewer frost days, with Lower Dega warming faster.
Under a high-emission scenario (SSP5-8.5), the study projects total wet-day rainfall, extremely wet days and very heavy precipitation days to rise by roughly 13–16%, 20–35% and 45–58% respectively by mid-century, with the sharpest increases in Upper Dega. The warmest day and night temperatures are projected to rise by up to 1.95°C, while consecutive dry days could increase by as much as 40% in Lower Dega over the same period.
A crop caught between extremes
The study’s authors set out specific risks for potato growers in its “implications for potato farming” section. Heavier rain can waterlog root zones, promoting tuber and root rot, leaching nutrients and disrupting field operations, with Upper Dega most exposed given its sharper projected rainfall increases. Rising heat threatens tuber initiation and bulking — the stages at which potato plants form and fill their tubers — and the study cites existing evidence of heat-related yield losses in the crop. Longer dry spells add a further threat during early tuber development, when the plant is most sensitive to drought.
The authors also note that shifting day-night temperature ranges may favour the spread of late blight, a fungal disease that has historically devastated potato harvests worldwide.
Adapting on both fronts
The study suggests several responses: breeding or adopting heat- and drought-tolerant potato varieties, improving field drainage to cope with heavier rain, building more flexible planting calendars that can shift with rainfall timing, and improving irrigation management to buffer longer dry spells.
The authors caution that their analysis relies on gridded ENACTS rainfall data rather than station records, which may miss local microclimate effects, and that climate model and emission-scenario uncertainties also affect the projections for 2019–2078.
