Future water availability for global food production: The potential of green water for increasing resilience to global change

TLDR

The paper argues that green water dominates food production and must be integrated with blue water management, especially under future climate change and population growth scenarios. The authors use a spatially disaggregated green‑blue water analysis with the LPJmL dynamic vegetation and water balance model to show that many water‑short countries can meet food demand when green water is accounted for and managed. The 2050 scenario projects blue‑water shortages for 59 % of the global population and combined green‑blue shortages for 36 %, yet resilience can be built without expanding cropland by managing local green water to mitigate dry spells and droughts.

Abstract

While past strategies for agricultural water management have focused on irrigation (use of blue water), this paper demonstrates the dominance of green water in food production. A global, yet spatially disaggregated, green‐blue analysis of water availability and requirement, using the LPJmL dynamic vegetation and water balance model, indicates that many countries currently assessed as severely water short are able to produce enough food for their populations if green water is considered and is managed well. The need to integrate green and blue water management is highlighted in a future scenario of water availability under climate change and population growth (HadCM2 A2). For 2050, the scenario indicates that 59% of the world population will face blue water shortage, and 36% will face green and blue water shortage. Even under climate change, good options to build water resilience exist without further expansion of cropland, particularly through management of local green water resources that reduces risks for dry spells and agricultural droughts.