Climate change enhances interannual variability of the Nile river flow

Nile basin countries are expected to double their population by 2050. Observations and climate model projections now suggest water resources may be additionally stretched by a 50% (±35%) increase in interannual Nile flow variability in the twenty-first century. The human population living in the Nile basin countries is projected to double by 2050, approaching one billion1. The increase in water demand associated with this burgeoning population will put significant stress on the available water resources. Potential changes in the flow of the Nile River as a result of climate change may further strain this critical situation2,3. Here, we present empirical evidence from observations and consistent projections from climate model simulations suggesting that the standard deviation describing interannual variability of total Nile flow could increase by 50% (±35%) (multi-model ensemble mean ± 1 standard deviation) in the twenty-first century compared to the twentieth century. We attribute the relatively large change in interannual variability of the Nile flow to projected increases in future occurrences of El Nino and La Nina events4,5 and to observed teleconnection between the El Nino–Southern Oscillation and Nile River flow6,7. Adequacy of current water storage capacity and plans for additional storage capacity in the basin will need to be re-evaluated given the projected enhancement of interannual variability in the future flow of the Nile river.