Hydroelectric production from Brazil's São Francisco River could cease due to climate change and inter-annual variability

Highlights: • Annual rainfall in the São Francisco (SF) basin has been below its long-term average every year bar one since 1992. • From 2015 to 2017 the SF's streamflow was at least 60% below its long-term average. • Streamflow and hydroelectricity in semi-arid regions are susceptible to climate change. • Rainfall reduction projected for 2100 in the SF basin could actually eventuate before 2050. • In the 2030s hydroelectric production from the SF River could virtually cease during drought years. By the end of this century higher temperatures and significantly reduced rainfall are projected for the Brazilian North and Northeast (NE) regions due to Global Warming. This study examines the impact of these long-term rainfall changes on the Brazilian Northeast's hydroelectric production. Various studies that use different IPCC models are examined in order to determine the average rainfall reduction by the year 2100 in comparison to baseline data from the end of the 20th century. It was found that average annual rainfall in the NE region could decrease by approximately 25–50% depending on the emissions scenario. Analysis of historical rainfall data in the São Francisco basin during the last 57 years already shows a decline of more than 25% from the 1961–90 long-term average. Moreover, average annual rainfall in the basin has been below its long-term average every year bar one since 1992. If this declining trend continues, rainfall reduction in the basin could be even more severe than the most pessimistic model projections. That is, the marked drop in average rainfall projected for 2100, based on the IPCC high emissions scenario, could actually eventuate before 2050. Due to the elasticity factor between rainfall and streamflow and because of increased amounts of irrigation in the São Francisco basin, the reduction in the NE's average hydroelectric production in the coming decades could be double the predicted decline in rainfall. Conversely, it is estimated that wind power potential in the Brazilian NE will increase substantially by 2100. Therefore both wind and solar power will need to be significantly exploited in order for the NE region to sustainably replace lost hydroelectric production.