Virtual water trade makes the relationship between food and water very complicated.
Virtual Water in Food Products
Virtual water is the water “hidden” in the products, services and processes people buy and use every day. While it is unseen by the end-user of the product or service, that water has been consumed throughout the creation of products like mobile phones or services like electricity generation.
The prime example of virtual water is agriculture and food production because it takes a lot of virtual water to bring food from the farm to your plate.
Crops receive rain and irrigation water, thirsty animals get a drink, food of all types gets processed, packaged and transported to markets, and all of it requires water at each step of the production chain — in many cases, a lot of it. When water from each step is added up, the amount of virtual water becomes sizable.
Virtual water can be considered a predecessor to the water footprint, which highlights the relationship between water-related dependencies on societies and economies, and impacts on resources.
In the United States, for instance, irrigation accounted for 42 percent of the nation’s freshwater withdrawals in 2015 and the majority went to agriculture. In addition, agriculture in the US accounts for approximately 80 to 90 percent of the nation’s consumptive water use.
In effect, producing food can mean taking water resources out of a watershed. Most of the water is consumed in irrigation and processing. In addition, water is taken out of the local water supply through evaporation, so that water is not returned, or pollution, where additional water is required to dilute it.
In water rich areas, this is not usually a problem. In areas where water is scarce or in short supply, it can be problematic, because different water users — agricultural, industrial and residential — are often in conflict with each other, and often there is not enough to meet all needs.
Virtual Water Flows Move Water From Water-Rich to Water-Poor Places
Virtual water was invented by geographer and Stockholm Water Prize winner, Dr. Tony Allan, to chart the global trade of products and the water embodied in them. The Water Footprint Network has written about virtual water flows and how they can help us understand how water resources are moved between countries, often to support water-scarce countries or higher-income countries that consume a lot of water-intensive foods, household goods and services.
As the Water Footprint Network explains:
“The global trade in goods has allowed countries with limited water resources to rely on the water resources in other countries to meet the needs of their inhabitants. As food and other products are traded internationally, their water footprint follows them in the form of virtual water. This allows us to link the water footprint of production to the water footprint of consumption, wherever they occur.
“…A country may aim to be self-sufficient by relying primarily on goods that can be produced within its borders. Or a country may choose to reduce the burden on the natural resources within its borders by importing water intensive products.
“A country may select energy security by using its natural resources to produce electricity in exchange for food security by importing food…Virtual water helps us understand the dependencies our economies have on others’ resources.
An examination of virtual water trade helps water resource managers understand the dependencies between regions and where water scarcity risks – or potential scarcity risks – exist. These dependencies become especially important when imbalances between water, food and energy systems create civil and political instability.”
For a deep dive into the evolution of virtual water trade and trade policies, read, “Global virtual water trade and the hydrological cycle: patterns, drivers, and socio-environmental impacts.”
Virtual Water Trade in the United States
Virtual water trade happens on a regional or watershed level as well, including between states. For example, the United States has large agricultural regions that dominate in production of certain crops (wheat, corn, soy, cotton, livestock, etc.) based on “similar types of farms and similar physiographic, soil, and climate traits.” Each of those regions engages in import and export of all kinds of food products, regardless of the dominant crops grown in those regions, thereby moving water around the country through food products.
The United States has one of the highest water footprints of consumption related to agricultural products. A 2008 study of virtual water flows in the United States, by Mubako and Lant, quantified “…water footprints and internal virtual water flows for the forty-eight contiguous states…by examining the water requirements of eighteen primary water-intensive crops and livestock.”
In general, researchers found “An overall pattern where virtual water is transferred from sparsely populated states mostly in the Midwest, where the country’s most fertile agricultural land is located, to the relatively dry Western states, and to the densely populated, but relatively wet coastal regions in the East of the country.”
They authors concluded that “Virtual water flows in the United States are large compared to total water withdrawals, evapotranspiration from rainfed crops, or total water footprint in nearly every state, with several Eastern states importing roughly half their water footprint and some Midwestern states exporting more virtual water than they withdraw or consume domestically [through municipal- or well-supplied sources].”
Changing climate and socioeconomic factors will have a significant impact on the direction of those flows as states grapple with shortages.
Virtual Water Trading in the Future
Virtual water flows have real-world implications as the planet moves into a period of rapidly changing extreme weather patterns, like the extreme and widespread drought the country is currently experiencing in the western United States. The most recent Intergovernmental Panel on Climate Change (IPCC) report now links increasing extreme weather events to increasing carbon emissions.Climate change is altering how, when and where precipitation falls. In addition, it is causing more intense droughts and storms, all of which heavily impact agricultural productivity.
Modeling estimates that incorporate population dynamics and climate-induced water stress into the relationships between energy, water, land and human activities reveal that the volume of water embedded in internationally traded agricultural goods will at least triple current values by the end of the century.
Any examination by water managers of potential water scarcity would be incomplete without an examination of how virtual water — or water embedded — in food products is moved into and out of a region.
Image: Virtual water balance per country and direction of gross virtual water flows related to trade in agricultural and industrial products over the period 1996–2005. Only the biggest gross flows (>15 Gm3∕y) are shown. From Hoekstra and Mekonnen, (2011).