How one item in your shopping cart could deplete ground water

One suggestion to help consumers make more sustainable choices about their food, is that producers should consider adding water labels that make these impacts clear. Urmi A. Goswami reports

You may be a hypercon scious consumer, only buying foodstuff that is organic and fair trade, or you may be one of those who embraced vegetarianism because it is good for the environment.But for all this effort to do the right thing for the planet, it is more than likely that more than one food item in your shopping cart is responsible for depleting groundwater in parts of the world faster than it can be replenished.Growing food consumption across the globe and efforts by governments to boost agricultural trade in order to improve incomes of farmers has put increasing pressure on groundwater sources. Much of increased food trade is in items such as rice, wheat, maize and sugarcane, all of which rely on irrigation. Higher production has led to greater demand on groundwater, since the amount of water required is much greater than the global supply of water from rivers and lakes. Groundwater accounts for 43 per cent of the water used for irrigation globally. Rising food production has meant that farmers draw groundwater deemed as non-renewable because the rate at which it is being extracted outstrips the rate at which the aquifer is recharged and replenished.

A new study by researchers from the University College London, International Institute for Applied Systems Analysis, Columbia University‘s Climate Research Centre and NASA’s Goddard Institute of Space Studies has found that the use of non-renewable groundwater has increased exponentially. In 2000, non-renewable groundwater accounted for 20 per cent of the world’s irrigation. In the next ten years, ground water depletion increased 22 per cent. This quantum jump in use of non-renewable groundwater in the first decade of the 21st century was powered by China, which registered a 102 per cent increase in groundwater depletion, along with the United States (31 per cent) and India (23 per cent).

Some 11 per cent of global non-renewable groundwater drawn up for irrigation is used to produce crops that are traded on the international market. Two-thirds of the exported crop that uses non-renewable groundwater is produced in three countries ­ Pakistan (29 per cent), United States (27 per cent) and India (12 per cent). The crops that contribute the most to trade of nonrenewable groundwater are rice (29 per cent), wheat (12 per cent), cotton (11 per cent), maize (4 per cent) and soybeans (3 per cent).

“It’s not just individual countries that experience groundwater depletion, but also their trade partners,“ said Carole Dalin of the University College London, the lead author of the study.

The continued high rate of depletion of the world’s stock of underground fresh water stock threatens food production, water availability and food security. The environmental degradation resulting from the depletion of aquifers is significant ­ the researchers point to land subsidence and sea water intrusion.

“People are rightfully food shopping with the environment in mind more than ever before ­ but it is not just about meat versus vegetables, organic or fair trade. Where and how the products are grown is crucial, and basic foods like rice and bread could have a damaging impact on global water supplies,“ said Dalin.

Using data from the United Nations and OECD-FAO projections of food demand and water availability, the study suggests that groundwater depletion will continue to increase in the absence of targeted measures.The current pace of groundwater extraction is leading to rapid depletion of aquifers in the major breadbaskets and population centres of the planet ­ USA, Mexico, Middle East and North Africa, India, Pakistan and China. However, addressing this situation will require countries, both exporters and end-consumers, to make changes to the way food is produced and consumed.

Thomas Kastner, senior scientist at the Senckenberg Biodiversity and Climate Research Centre, Germany and co-author of the study said, “The use of non-renewable water in one place can put food supply in distant regions at risk. This study can help us identify entry points for a more sustainable global water resources management.“

The study suggests that solutions to minimise groundwater depletion could include water-saving strategies such as improving irrigation efficiency and growing more droughtresistant crops, together with targeted measures such as metering and regulation of groundwater pumping.It calls for supporting these policy efforts with local analysis that takes into account socio-economic, cultural and environmental aspects, and identifying importing countries.

To promote consumption driven changes in the use of groundwater, Yoshihide Wada, a co-author and deputy director of the IIASA Water Program suggested the idea of including water labels on products.“The products that consumers buy at a supermarket may have very different environmental impacts depending on where they are produced and how they are irrigated. In order to help consumers make more sustainable choices about their food, producers should consider adding water labels that make these impacts clear,“ he said.