Irrigation of biomass plantations may globally increase water stress more than climate change

Abstract Bioenergy with carbon capture and storage (BECCS) is considered an important negative emissions (NEs) technology, but might involve substantial irrigation on biomass plantations. Potential water stress resulting from the additional withdrawals for irrigation warrants evaluation against the avoided climate change impact. Here we quantitatively assess potential side effects of BECCS with respect to water stress by disentangling the associated drivers (irrigated bioenergy, climate, land use patterns) using comprehensive global model simulations. By considering a widespread use of irrigated BECCS to limit global warming to 1.5°C, our results suggest that both the global area and population living under severe water stress will double by the end of the 21st century, which could even exceed the impact of climate change avoided by the NEs (3°C warming). Such side-effects of achieving substantial NEs would come as an extra pressure in an already water-stressed world and could only be avoided if sustainable water management would be implemented globally.