What did irrigation modernization in China bring to the evolution of water-energy-greenhouse gas emissions?

Irrigation modernization impacts irrigation energy consumption and greenhouse gas (GHG) emissions, enhancing irrigation water efficiency. To systematically examine the impact of irrigation system modernization on China's irrigation energy consumption and GHG emissions, a scenario-decomposition-based calculation method of irrigation energy consumption and GHG emissions at national and provincial scales based on the physical processes of irrigation energy consumption was proposed. The relationship between irrigation water consumption, energy consumption, and GHG emissions during the rapid development period (2005–2015) of water-saving irrigation technology in China was clarified. The data demonstrate that the irrigation water volume and energy consumption increased by 7.9% and 22.3%, respectively, from 2005 to 2015, and the national equivalent of GHG reached 42.5 Mt CO2e in 2015. Water-energy consumption across the country was extremely divergent. The irrigation energy consumption per unit volume of water and per unit area is 3.74 and 2.88 times more in the northern provinces than in the southern provinces. Promoting water-saving irrigation technology can effectively improve China's irrigation water-energy-GHG emissions structure, which can help improve irrigation efficiency while ensuring no dramatic increase in irrigation energy consumption. Water-saving irrigation technologies should be promoted following the local conditions throughout the country. The relationship between irrigation water-energy-GHG emissions in northern provinces should be considered significantly.