Global change caused by increasing greenhouse gas (GHG) emission has become a common concern of the international community. As the largest emitter of GHGs and the second largest irrigator in the world, a clear understanding of how much GHG is emitted from irrigation in China is of great importance. But no previous studies address this question. So based on Chinese official statistical data, this study estimates GHG emissions from agricultural irrigation in order to inform strategies for reasonable use of water resources and emission reduction. The study finds that in 2010 the total carbon dioxide (CO2) equivalent (CO2-e) emission from agricultural irrigation is 36.72~54.16 Mt. Emissions from energy activities in irrigation (including water pumping and conveyance) account for 50 % ~ 70 % of total emissions from energy activities in the agriculture sector. Ground water pumping is the biggest emission source, accounting for 60.97 % of total irrigation emissions. Given the extent of global ground water over exploitation, balancing conservation and exploitation of ground water resources is very important to both emission reduction and sustainable development. The GHG emission intensity of irrigation depends largely on water use efficiency, so improvement of water use efficiency (both technical and managerial) can be an effective way to reduce emissions. Enhanced overall management of water utilization, balanced exploitation of water resources to avoid excessive ground water consumption, and active promotion of water use efficiency can contribute to reducing GHG emissions and pressure on water resources and advance sustainable agricultural production.
