Impact of climate change on reference evapotranspiration in Egypt

•Climate change has prompted significant ETo change in Egypt since the 1980s.•Statistically significant differences of ETo due to climate change has occurred.•Southeastern areas in Egypt are the most sensitive parts for climate change.•Changes in temporal trends of ETo has occurred in various agricultural regions.•Significant monthly spatial differences have occurred during the summer season. Egypt is a country that is vulnerable to many of the sustainability challenges and climate change effects to which all countries around the world are struggling to respond, and the United Nations is warning that Egypt could run out of the water by the year 2025. Reference evapotranspiration is the first step in estimating crop water requirements and irrigation water management. A better understanding of trends in reference evapotranspiration is crucial for scientific management of water resources in arid and semi-arid regions. The aim of this study is to identify the spatiotemporal of annual and monthly reference evapotranspiration changes in Egypt, as evidenced by spatial distribution and temporal trends. The results showed that significant changes in spatial distribution of reference evapotranspiration have occurred in the last 35 years beginning in the 1980s. The southeastern regions, the older agricultural lands in the Nile Delta and valley, as well as the northwestern regions were most affected regions. However, the western desert showed the lowest impact from climate change. The winter season from November to February showed the lowest impact from climate change, while during the summer season, the highest significant differences occurred, especially from June to October. The last five years (2013–2017) showed a significant decrease from the previous 5 years (2008–2012) but still show a significant increase from previous periods of time (1983–2007). Hence, the western desert is more suitable for agricultural expansion. Furthermore, agricultural and irrigation activities during the summer season have to change respond to the impact of climate change on water resources management.