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- Title
Changing Climate Threatens Irrigation Benefits of Maize Gross Primary Productivity in China.
- Authors
Liao, Dehai; Niu, Jun; Ciais, Philippe; Du, Taisheng; Zhang, Baozhong; Kang, Shaozhong
- Abstract
Intensive irrigation has been proven to profoundly impact climate through the surface energy budget. However, the impacts of irrigation and climate interactions on gross primary productivity (GPP) in maize cultivated areas remain uncertain. Here we quantified the irrigation effects on maize GPP (∆GPP) across China by combining a land surface model and a light‐use efficiency model and using satellite‐based irrigation water use. We show that irrigation significantly contributed to an increase in maize GPP by an average of 430 gC · m−2 · yr−1, equivalent to 28% of the irrigated maize GPP in China. These benefits (∆GPP) were attributed to irrigation effects (water supply, surface cooling) and climate interactions based on a machine learning framework (eXtreme Gradient Boosting model‐SHapley Additive exPlanations). Irrigation water supply and surface cooling explained 54% ± 19% and 23% ± 20% of ∆GPP respectively, the rest being due to strong climate interactions with irrigation through water and energy balance. Assuming business‐as‐usual irrigation levels, changing climate both increases and decreases ΔGPP over different regions, driven primarily by temperature changes. The irrigation benefits in those areas under heat stress are greatly threatened due to changing climate. The roles of climate change on ∆GPP are reversed from beneficial to detrimental in the North China Plain, dominated by different warming levels of future scenarios. Our analysis provides new insights into assessing irrigation potential with the climate interactions and future irrigation priority regions. Plain Language Summary: Irrigation is the most important water use sector accounting for about 70% of the global freshwater withdrawals and contributing 75% of China's total grain production. Application of irrigation water significantly alters agroecosystem water cycle, energy cycle and carbon cycle. The magnitudes of irrigation impact are also influenced by climate variability. In this study, we simulated irrigation benefits for maize gross primary productivity (GPP) using land surface models and satellite observations. The effects of climate interactions on the irrigation benefits were untangled using an explainable machine learning framework (eXtreme Gradient Boosting model‐SHapley Additive exPlanations). We found that alterations in water cycle (water supply) and energy cycle (surface cooling) accounted for 54% ± 19% and 23% ± 20% of the irrigation benefits variability respectively, the rest being due to temperature‐dominated climate interactions. With the climate change driven by persist warming, the irrigation benefits will be substantially reduced for those regions under ongoing heat stress, such as North China Plain. Future maize productivity will be greatly threatened by changing climate, considering the prevailing negative trends for the irrigation benefits throughout the nation. Reinforcing anthropogenic activities such as irrigation water management and planting structure adjustment are strongly required to improve crop resilience to climate variability. Key Points: Irrigation contribution to the maize gross primary productivity across 15 agricultural regions is quantified in ChinaThe irrigation benefits explained by water supply and cooling are identified, and the rest being due to climate interactionsChanging climate both increases and decreases irrigation benefits for maize over different regions, contingent on heat conditions
- Subjects
CHINA; IRRIGATION; IRRIGATION water; IRRIGATION management; WATER management; CARBON cycle
- Publication
Earth's Future, 2024, Vol 12, Issue 1, p1
- ISSN
2328-4277
- Publication type
Article
- DOI
10.1029/2022EF003474