The carbon footprint of China's irrigation system

Water Online: China's groundwater irrigation system is responsible for polluting the atmosphere with more than 30 million tonnes of CO2 per year - according to research from the University of East Anglia. Groundwater used for crop irrigation in China has grown from 10 billion cubic metres in 1950 to more than 100 billion recently.

A research paper, published today in Environmental Research Letters, estimates that the pumping systems which support this immense irrigation network annually produce 33.1 MtCO2e (33.1 mega tonnes of carbon dioxide equivalent).

China is the largest greenhouse gas emitter in the world, with around 17 per cent of emissions coming from agriculture. Irrigated agriculture in China produces 70 per cent of the country's grain. But it takes some 500 litres of water to grow the wheat for one small loaf of bread.

Greenhouse gas pollution is caused by the huge amount of energy needed to pump water from underground – in some areas from an average depth of 70 meters. This research is the first to calculate how much pollution is being created.

...The results account for more than 0.5 per cent of China's total CO2 emissions. For comparison, this is similar to the total amount of CO2 that the whole of New Zealand emits in one year...

Mulanpo Irrigation System built in the 11th century (Song Dynasty) in Putian, Fujian province of China, shot by 湖畔老, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license.