Researchers from the University of East Anglia’s Water Security Research Centre have calculated the carbon footprint of the world’s second largest irrigator; the researchers found China’s groundwater irrigation system is responsible for polluting the atmosphere with more than 30 million tonnes of CO2 per year.

Researchers from UEA, working together the Tyndall Centre for Climate Change Research, the Centre for Chinese Agricultural Policy, the Chinese Academy of Agricultural Sciences and Cranfield University, found the country’s pumping systems, which support China’s immense irrigation network produce 33.1MtCO2e (33.1 mega tonnes of carbon dioxide equivalent ) each year. Their results were published today in the journal Environmental Research Letters.  

 image expired

The pollution measures by the UEA researchers is caused by the huge amount of energy needed to pump water from underground, from an average depth of 70 meters in some areas. The UEA researchers said theirs is the first to calculate how much pollution is being created by this process.

The research team used extensive survey data collected from 366 villages in 11 provinces. They then up-scaled these results to calculate the emissions created by groundwater pumping across China’s remaining 20 provinces. The results account for more than 0.5 per cent of China’s total CO2 emissions, or the total amount of CO2 emissions produced by New Zealand in a year.

The research was undertaken as a growing population in China, climate change and socio-economic transition in the country mean the problem is likely to worsen unless action is taken to improve China’s water management policies and drive abstraction in a more sustainable direction.

Professor Declan Conway, from UEA’s school of international Development and the Tyndall Centre commented on the project, “Generally, there is a surprising gap in research knowledge about the energy required for water use. Irrigation is fundamental to food security in China as it is the world’s second largest irrigator. It is vital that we understand the sources of greenhouse gas emissions in agricultural water use to design and implement sustainable policies for the future.”

 
However, Professor Jinxia Wang of the Centre for Chinese Agricultural Policy said that regulatory measures may prove difficult, as the nature of groundwater pumping in China means implementing new measures to small-scale abstractors will be a complex process. He explained, “Improved access to pumping technology, cheap energy and the ability to directly control water availability has led to a massive expansion of groundwater pumping across large parts of Asia, particularly in China and India. The small scale of pump operations makes regulation and control of use extremely difficult.”

Remedial actions

Sabrina Rothausen of UEA explained some of the measures that could be implemented to improve water management in China, where irrigation efficiency is relatively poor. She told Farming Online that, “By improving efficiency through irrigation scheduling and sprinkler or drip irrigation, less water is needed which will reduce the energy use.”

Ms Rothausen, a research fellow at the Tyndall centre, continued, “Another remedy is to expand and improve the local storage facilities for surface water, for example for rainwater harvest. This will enable the farmers to be able to better control the timing of irrigation, compared to traditional surface water flood irrigation, and minimize the energy use for pumping. Our research also showed that improving pump efficiency through proper fitting and maintenance will decrease energy use for groundwater pumping substantially.”

However, she acknowledged that assessing the actual effects of water savings is a complex procedure, and so speculating what effect these measures would have on the overall carbon footprint of China’s irrigation system would be difficult.  She explained, “Despite introducing water pricing, taxes, monitoring, quotas and investments in water-saving technologies in China, the nature of the supply, the agricultural and cultural traditions and subsidies on energy make it difficult to control water use.”

Implications for EU agriculture

In the EU, rather than increasing pressure on the environment through an over reliance on groundwater and river flows, which due to forecasts for increasingly dry summers may see farmers and other abstractors increasing the amount of water taken from rivers, threatening wildlife and local ecosystems, Defra and the Environment Agency have urged farmers to focus on developing water storage and increasing efficiency.

In Britain, the national Farmers’ Union has called for more government investment into on-farm water storage capacity and urged the government to reinstate the tax relief for the cost of farm reservoirs in next week’s Budget to add extra incentive for farmers, increasing uptake of water storage measures.

Ms Rothausen explained the relevance of the UEA team’s research to agriculturalists in the EU, “Irrigation is likely to become more necessary with hotter and drier springs and summers in Europe and with this the necessity of pumping water from rivers and aquifers, maybe from further distances. Improved irrigation efficiency and rain water harvesting will most likely become increasingly relevant in the EU to avoid an increase in the carbon footprint of agricultural water use.”

Tweet