Impacts of precipitation variations on agricultural water scarcity under historical and future climate change

Both blue water and green water contribute to agricultural water scarcity, which is subjected to impacts of precipitation variations in the context of climate change. However, an explicit quantification of the possible effects of precipitation variations on agricultural water scarcity index (AWSI) under historical and future climate is absent. In this study, we applied an integrated AWSI, which incorporates blue water and green water, to es-timate agricultural water scarcity in China and to determine the association of AWSI with precipitation variations over the historical (1971-2010) and future (2031-2070) periods. Precipitation variations have substantial effects on changes in AWSI. Especially during extremely dry years with precipitation anomaly lower than-2 standard deviation, changes of AWSI from the multi-year average could be as high as 31%. Future climate change would further intensify AWSI and amplify the effects of precipitation variations, particularly in Inner Mongolia with changes of AWSI over 200%. Southwestern China could also experience expanding agricultural water scarcity under future climate scenarios. Improving irrigation efficiency has potential to alleviate water scarcity by up to 30%. This study provides valuable information for scientists and policy decision makers to cope with the impacts of precipitation variations on AWSI.