The Energy-Water Nexus: The Linkage of Big Ag, Water Use, and Carbon Emissions

July 20, 2015 Jenna Bieller

{This is the Second blog in a series on the intersection and interdependence of energy and water. Read blog 1, here.}

In our first post on the intersection of water and energy, we introduced how renewable energy generation not only reduces carbon emissions, but how it can also be used as a tool to save water.

In recent years, big ag has come under scrutiny for practices like GMO use and factory farming, primarily required to meet the food needs of a seven billion person planet.  Big ag is also a major consumer of both water and energy – and a major polluter as well.

Modern farming practices like irrigation, fertilization, and livestock cultivation have a detrimental impact on the environment.  Food production has been transformed from the family farm to an industry reliant on fossil fuels and water.  Depletion of groundwater and contamination of both inland and coastal waters from big ag have had devastating effects, particularly in areas like California where agriculture is booming but water supplies are stressed.

Big Ag’s Water Draw

As global food demands rise, conventional farmers have turned to practices that allow for the mass production of highly demanded crops. Among these practices, flood irrigation, monoculture cropping, and growing non-native crops have had implications on water supplies and quality, resulting in loss of water and contamination of waterways. Agriculture today accounts for 70% of total global freshwater withdrawals.

When a crop is flood irrigated with groundwater supplies, about half the water used evaporates or is flushed into the nearest stream or river as runoff. These wasteful watering practices also require large amounts of energy to treat, transport, and pump the excessive amount of water needed. Solutions like drip irrigation not only decrease the amount of water necessary to keep a plant alive, thus decreasing the energy required to prepare the water, but also slow the process of salinization of cropland due to high evaporation.

The Impact of Fertilizers on Water & the Climate

Worldwide, agriculture is a major contributor to conditions that foster climate change, including deforestation, soil erosion, and emissions from fossil fuel production and livestock.  Agriculture aloneaccounts for 9% of US greenhouse gas emissions annually.

Conventional farming uses large quantities of petroleum-based fertilizers and pesticides to ensure the highest crop yield possible. Manufactured fertilizers require natural gas inputs to produce in addition to the mining of necessary nutrients like phosphorous.  This mining produces additional carbon emissions, degrades land, and disrupts natural habitats. The natural gas used in fertilizers must be acquired through hydraulic fracturing (or fracking), a process that requires enormous volumes of water, and that pollutes groundwater while simultaneously releasing abundant volumes of the greenhouse gas (GHG) methane, a short-term GHG that is more than 20x more damaging to the atmosphere than carbon dioxide.

In addition to their energy intensity, common synthetic fertilizers and pesticides used on crops are carried away from farms as runoff into waterways, which inevitably reach the ocean. Not only can these chemicals seep into the groundwater and contaminate drinking supplies, but the nutrients found in fertilizers (primarily phosphate and nitrate) have been responsible for widespread eutrophication of lakes, rivers, and coastal waters. The process of eutrophication involves man-made nutrient saturation of waters, which spurs algae and phytoplankton blooms at the surface. Large algal blooms lead to deoxygenation of the water which kills off desirable fish species and shifts the biodiversity of nearby aquatic plant life. Besides having negative economic impact on fishing industries, fertilization of surface waters also leads to degradation of local water supplies and loss of recreational value due to overgrown weeds and algae odor.

The Role of Livestock

Modern agriculture has also put an emphasis on profit; a pound of beef can sell for a lot more than a pound of corn. Likewise, a pound of beef takes a lot more water to produce than corn does. According to a study from the Institution of Mechanical Engineers (IME), the production of one pound of beef takesover 1,800 gallons of water compared to the 147 gallons of water necessary to produce the same amount of corn.

Aside from the water that it takes to produce the beef we eat, a study from the US Food and Agriculture Organization (FAO) reveals that the production of meat results in more greenhouse gases than both transportation and industry! The study notes that total global livestock emissions account for 14.5% of all anthropogenic greenhouse gases, and the life cycle to produce 1kg of beef emits a total of 300kg CO2 equivalent into the atmosphere. While emissions coming from power plants are nothing to downplay, the emissions that result from livestock cultivation could be an even larger obstacle to overcome to fight global warming—compounded by the clear cutting often required for grazing land.

Adopting sustainable farming practices is beneficial for water supplies, water quality, and carbon emissions.  As consumers, we can support these efforts by choosing organic produce, buying from small, local farms, and shifting more of our meals to meatless.

To continue to blog 3 in the series, click here.


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