Climatic Change Impacts on Growing Degree Days and Climatologically Suitable Cropping Areas in the Eastern Nile Basin

Abstract

Agriculture is the dominant livelihood generation in the eastern Nile region (Egypt, Ethiopia, Sudan, and South Sudan). Adverse climate change would thus have detrimental impacts on agriculture. The regional climate change impact studies have biased to hydrological aspects with very limited ones on the agricultural impacts which were even carried out either within a larger scale or a country-based one. This study made the use of the daily temperature outputs of two regional climate models (RCMs), namely the CCCma-CanESM2 and the CSIRO-MK3, for estimating changes in the growing degree days (GDDs) under the worst climate change scenario (RCP 8.5) for the period 2040–2050. The baseline datasets (1960–1990) were obtained from the Climate Research Unit. The analysis was being carried out in R and QGIS software. Results showed that changes in the minimum temperature (3.0 °C) exceed that of the maximum temperature (2.65 °C) relative to the baseline. The performance of RCMs in reproducing the regional variability in temperature is a seasonal dependent, with a slightly better performance of the SCIRO-Mk3 compared to the CCCma-CanESM2. The GDDS of winter wheat (November–April) and sorghum (May–October) were increased by 9% and 35%, respectively, due to global warming. Also, the regional climatological suitable areas of winter wheat showed decreasing and increasing trends, depending on the RCM, contrasting the pure decreasing trend in the areas of sorghum of -8.5%. Consequently, the region experiences delays in sowing dates and shortened season lengths. The central region of Sudan is found to be the most sensitive area to climate change, whereas the rainfed wheat in Ethiopia is the most sensitive crop. A regional center with a mandate of adapting shorter and longer crop varieties is direly needed to cope with changes in GDDs due to global warming.