Climate change-induced northward shifts in double cropping system in China: Implications for crop production potential and water use

Climate change may shift double cropping system into new areas and increase cropping intensity in some regions, creating opportunities to boost crop production. However, these changes also reshape the land‒water‒food nexus, particularly by increasing irrigation demand and exacerbating tensions between crop production and water scarcity. In this study, we integrated multi-dimensional datasets during 1980−2019 to identify the traditional and potential expansion areas of double cropping system and empirically analyze how cropping intensity responds to climate change. We further assessed the resulting impacts on crop production and water use, and explored feasible strategies for promoting double cropping. Results reveal the potential northward expansion of the double cropping system driven by climate warming, covering 6.72×10 6 hm 2 of cropland. The multiple cropping index in traditional double cropping areas exhibited a pronounced response to climate warming, whereas potential expansion areas showed a weak and insignificant response. In the latter, the mean multiple cropping index was 0.99 during 2014–2019, indicating considerable untapped potential for more efficient use of climate and land resources. Using the winter wheat–summer maize system as a representative double cropping pattern, we found its expansion during the study period increased crop production by 39.18 Mt and irrigation demand by 15.17 × 10 9 m 3 in traditional double cropping areas, where the agricultural water resources stress index reached 3.47 in 2019. In potential expansion areas, under two hypothetical scenarios—converting spring maize to winter wheat–summer maize and fully utilizing idle arable land for the same rotation—national grain production could potentially increase by 2.16% and 0.88%, respectively, with irrigation demand rising by 10.85 × 10 9 m 3 and 4.52 × 10 9 m 3 . The agricultural water stress index would rise to 2.04 and 1.87 under the two scenarios, yet compared with traditional double cropping areas, water pressure in these regions would remain manageable. The study highlights the importance of fully leveraging emerging climatic resources to boost crop production in double cropping regions as a climate adaptation strategy. It also provides a comprehensive assessment of the trade-offs between increased food production and water use, offering valuable insights for promoting sustainable agricultural development in double cropping regions.