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The expansion of irrigated agriculture has increased global crop production but resulted in widespread stress to freshwater resources. Ensuring that increases in irrigated production only occur in places where water is relatively abundant is a key objective of sustainable agriculture, and knowledge of how irrigated land has evolved is important for measuring progress towards water sustainability. Yet a spatially detailed understanding of the evolution of global area equipped for irrigation (AEI) is missing. Here we utilize the latest sub-national irrigation statistics (covering 17298 administrative units) from various official sources to develop a gridded (5 arc-min resolution) global product of AEI for the years 2000, 2005, 2010, and 2015. We find that AEI increased by 11% from 2000 (297 Mha) to 2015 (330 Mha) with locations of both substantial expansion such as northwest India and northeast China and decline, such as Russia. Combining these outputs with information on green (i.e., rainfall) and blue (i.e., surface and ground) water stress, we also examine to what extent irrigation has expanded unsustainably in places already experiencing water stress. We find that more than half (52%) of irrigation expansion has taken place in areas that were already water stressed in year 2000, with India alone accounting for 36% of global unsustainable expansion. These findings provide new insights into the evolving patterns of global irrigation with important implications for global water sustainability and food security.

The response of China's rice yield to climate change is crucial for ensuring food security for China and the globe. However, previous studies have focused on the impact of climate change on a specific rice type or rice as a whole. For the first time, this study combines a new set of the early, middle, and late rice production data and daily weather data at the county level to comprehensively estimate the heterogeneous yield response to extreme temperatures in China. Along with the projections of future temperature and precipitation, we also forecast the potential yield losses when exposed to higher future warming trends. The results show that holding current growing regions and calendars fixed, the yield of popular middle and late rice types will drop by 5.7% ± 1.5% and 11% ± 4.5% under the most extreme scenario compared to no climate change scenarios by the end of this century (2070-2090 average). These results imply that recent structural changes in favor of producing these popular types of rice may satisfy the demand for high-quality rice but may also increase the risks of climate change to the food supply in China. Therefore, more efforts should be concentrated on incorporating this type of heterogeneity in climatic impacts into national and regional plans for the agricultural adaptation.