Assessment of Global Drought Characteristics and Associated Impacts on Agricultural Water Use in Future Climate Scenarios

Drought is the most widespread and most influential natural disaster in the world, especially a threat to agricultural production. In future climate scenarios, regional meteorological elements such as precipitation and temperature will change, affecting the distribution and characteristics of future global drought. Reformulated standardized precipitation evapotranspiration index (SPEI) based on Penman-Monteith equation was calculated with 9 General Circulation Models (GCMs) to evaluate global drought propensity in three future climate scenarios (RCP2.6, RCP4.5 and RCP8.5). Mann-Kendall (MK) non-parametric test and empirical orthogonal function (EOF) analysis were used to assess the spatial-temporal distribution and evolution characteristics of the future global drought. Taking reference evapotranspiration (ET₀) of crops as the indicator, potential effects of global drought on agricultural water use were assessed. The results showed that in three climate scenarios, the trend of severe drought was detected in Africa, North America, South America and Oceania. Spatial distribution of SPEI was consistent and intensified drought was detected in southern, northern and northeast of Africa in all scenarios in three decades (2030s, 2050s, 2080s). EOF analysis showed that there were more positive time coefficients in RCP8.5 than other scenarios, then parts of South America and Africa would face intensified drought in all climate scenarios. Future global drought would pose a threat on global water use for agricultural production. The annual average ET₀ in three decades in major grain producing countries would be on the rise compared to the baseline (1976-2005), among which RCP8.5 was most obvious. Large increase of ET₀ would occur in Ukraine, Turkey, Russia and Canada in the 2080s in three scenarios. In the future, major grain producing countries would face serious threats of drought, which would pose a great challenge to regional agricultural water use. The study will provide forward-looking information to alleviate the adverse effects of drought on agricultural water use.