PrintOther than energy, it is through food that most of us most frequently directly interact with sustainability. Humans cannot survive without food, and most (and probably all) of you reading this eat multiple meals each day. The food industry has immense sustainability implications, including soil health and conservation, water use, forest clear-cutting, environmental and social justice, economics and equity, and much more. The following provides some insight into a few of these issues.
Water Use
You probably recall from a previous lesson that irrigation is the single biggest user of freshwater in the United States. You may also recall the large water footprint of some common foods. The following are footprints of common main dishes, according to the Water Footprint Network (see Water Footprint report). (Note that these are global averages. Also, 1 litre/kg equals about 0.12 gal/lb.):
- beef: 15,400 litre/kg (1,848 gal/lb)
- sheep: 10,400 litre/kg (1,248 gal/lb)
- pig: 6,000 litre/kg (720 gal/lb)
- chicken: 4,325 litre/kg (519 gal/lb)
- tofu: 2,517 litre/lb (302 gal/lb)
- rice: 2,497 litre/kg (300 gal/lb)
- pasta: 1,849 litre/kg (222 gal/lb)
If you are interested, the Huffington Post does a nice job of comparing the water footprint of common foods. (They use Water Footprint Network data.)
Almost all of the water used in producing meat is the result of irrigating the crops that are used to feed the animals, and some irrigation methods are more efficient than others. (Oregon State University Cooperative Extension provides a good analysis of various irrigation techniques if you are interested in learning more.)
Dead Zones
One sustainability impact that happens on more of a macro scale is something called a "dead zone." The National Oceanic and Atmospheric Administration (NOAA) explains dead zones thus:
Less oxygen dissolved in the water is often referred to as a “dead zone” because most marine life either dies, or, if they are mobile such as fish, leave the area. Habitats that would normally be teeming with life become, essentially, biological deserts.
Hypoxic zones can occur naturally, but scientists are concerned about the areas created or enhanced by human activity. There are many physical, chemical, and biological factors that combine to create dead zones, but nutrient pollution is the primary cause of those zones created by humans. Excess nutrients that run off land or are piped as wastewater into rivers and coasts can stimulate an overgrowth of algae, which then sinks and decomposes in the water. The decomposition process consumes oxygen and depletes the supply available to healthy marine life.
Dead zones occur in many areas of the country, particularly along the East Coast, the Gulf of Mexico, and the Great Lakes, but there is no part of the country or the world that is immune. The second largest dead zone in the world is located in the U.S., in the northern Gulf of Mexico.
Dead zones happen all over the world and are in fact a natural occurrence. However, humans have significantly increased the incidence of dead zones, including the one in the Gulf of Mexico, which grows to about the size of New Jersey every summer, as you will see in the video below. These dead zones are caused by eutrophication, which is when a body of water has an excessive amount of nutrients (primarily nitrogen and phosphorous) that lead to unusually high plant/algae growth. (Note that eutrophication just refers to excess nutrients, but this often results in a dead zone.) When eutrophic streams and rivers empty into ponds, lakes, or other open bodies of water (such as the Gulf of Mexico), it causes excessive algae growth and ultimately leads to anoxic ("oxygen-less") conditions near the bottom of these bodies of water. NOAA does a good job of explaining eutrophication in the video below.
What is eutrophication? It’s a problem that should matter to you, whether you live near the ocean or not. That’s because it begins wherever people live and ends with damage to resources we all use and enjoy. It all starts when nutrients get into lakes and oceans. Remember, what’s waste to humans can be food to plants and other creatures. Nutrients feed algae like they do other plants. Algae grows and blocks sunlight. Plants die without sunlight. Eventually, the algae die too. Bacteria digest the dead plants, using up remaining oxygen, and giving off carbon dioxide. If they can’t swim away, fish and other wildlife become unhealthy or die without oxygen. But it doesn’t have to be this way. Protecting marine resources starts with sound agricultural and waste management practices.
Eutrophication has a few anthropogenic causes, but the primary one is the use of artificial fertilizers on farms. Fertilizers feed plants, but if they get into bodies of water they feed algae. The video below from NOAA provides a good explanation of this. Please note that the explanation at the end of the video of what causes the dead zone is incomplete: waste from organisms that eat the phytoplankton plays a role in the dead zone, but (as described in the video above) the main cause of dead zones is when bacteria eat the dead phytoplankton after they sink to the bottom.
Did you know that half of the oxygen that we breathe comes from tiny organisms that live in the ocean? It's true! These microscopic marine organisms, called phytoplankton, produce oxygen just like land plants. But phytoplankton are not plants, they are Protists, single celled organisms. They are so small that thousands of them can fit in a single drop of water. In order to study phytoplankton, scientists often use microscopes... or satellites.
From space we see Earth like this. But some satellites see Earth like this… a dance of rainbow colors. In this case, the colors represent the concentration of phytoplankton in the ocean: red is high concentration; blue is low concentration.
Phytoplankton depend on nutrients and proper temperature and light conditions to grow and reproduce. Coastal areas are extremely rich in nutrients, which have been washed off the land by rivers. Areas such as the open ocean have lower concentrations of phytoplankton because of the limited amount of nutrients there.
The mouth of the Mississippi River is a perfect example of how nutrient run-off creates plankton blooms. 41% of the United States drains into the Mississippi River and then out to the Gulf of Mexico. That's a total of 3.2 million square kilometers of land or about 600 million football fields. About 12 million people live in urban areas that border the Mississippi, and this area constantly discharges treated sewage into rivers. However, the majority of the land in the Mississippi Watershed is farmland. Each spring as farmers fertilize their lands preparing for crop season, rain washes fertilizer off the land and into streams and rivers. All of the urban and farm discharges include nutrients such as nitrogen and phosphorus that are very important for the growth of phytoplankton. Incredibly, about 1.7 million tons of these nutrients are dumped into the Gulf of Mexico every year.
Once the Gulf of Mexico receives this huge influx of nutrients, massive phytoplankton blooms occur. These blooms result in an area called the dead zone with such low oxygen concentrations that few organisms can survive there.
But if phytoplankton blooms produce oxygen, then why does a Dead Zone occur? For animals, such as microscopic zooplankton and fish, phytoplankton blooms are like an all-you-can-eat buffet. Small animals eat the phytoplankton, and are, in turn, eaten by bigger fish. All along, these animals are releasing waste, which falls to the bottom of the gulf. There lurk bacteria that decompose the waste, and in the process use up the oxygen, creating hypoxic conditions. The different densities of freshwater from the Mississippi and saltwater from the Gulf create barriers that prevent mixing between the surface and deep waters. Soon there is not enough oxygen for other organisms to use. The Dead Zone has arrived. But as summer turns to fall, winds helps stir up the water, allowing the layers to mix and replenish oxygen throughout the water. Eventually, the Gulf and its fish populations return to normal. Until next year...
Food Deserts
Over the past 10 - 15 years, food deserts have (slowly) become a more prominent issue. The following is a summary from the U.S. Centers for Disease Control (emphasis added):
Food Desert
Food deserts are areas that lack access to affordable fruits, vegetables, whole grains, low-fat milk, and other foods that make up a full and healthy diet (1). Many Americans living in rural, minority, or low-income areas are subjected to food deserts and may be unable to access affordable, healthy foods, leaving their diets lacking essential nutrients.What's the Problem?
Rural, minority, and low income areas are often the sites of food deserts because they lack large, retail food markets and have a higher number of convenience stores, where healthy foods are less available (2). Studies have shown that food deserts can negatively affect health outcomes but more research must be done to show how that influence occurs. There appears to be a link between access to affordable nutritious foods and the eating of these foods, meaning less access may lead to less incorporation of healthy foods into the populations’ diets.Who's at Risk?
Because there is no standard definition of a food desert, estimates of how much of the population is affected vary by quite a bit. However, it’s safe to say that many Americans have limited access to affordable nutritious foods because they do not live near a supermarket or large grocery store. Transportation is specifically part of the USDA food desert definition. Only common theme among food desert definitions is that there is limited access.Can It Be Prevented?
Food deserts can be improved through several different types of efforts. Establishing a community garden where participants share in the maintenance and products of the garden and organizing local farmers markets are two efforts that community members themselves can do (3, 4). Local governments can improve local transportation like buses and metros to allow for easier access to established markets (5). They can also change zoning codes and offer economic or tax incentives to attract retailers with healthier food offerings to the area (6).The Bottom Line
Food deserts are a big problem for many Americans that may limit their ability to eat healthy and nutritious foods on a regular basis. However, there are a variety of ways that local governments and community members can both improve food access in their neighborhoods.Case Example
Maria is a 60-year-old woman living in a low-income area of St. Louis. As she’s gotten older, she hasn’t been able to get around as well and doesn’t have a car. She usually eats a lot of unhealthy and microwavable foods because the closest store to her apartment is the local convenience store around the corner. She wishes that she could eat better and begins talking to some of her neighbors and other families in the building to get their input. Maria and her next-door neighbor Sylvia organize all the residents in their building to establish a community garden on the roof of the building so that they will all have fresh fruits and vegetables to share.
As indicated above, there is no one definition of a food desert, but it is meant to indicate a lack of access to fresh foods. The U.S. Department of Agriculture (USDA) considers three ways to define a food desert. (The number of people in the U.S. in each category as of 2017 are in parentheses.):
- "Low-income census tracts where a significant number (at least 500 people) or share (at least 33 percent) of the population is greater than ½ mile from the nearest supermarket, supercenter, or large grocery store for an urban area or greater than 10 miles for a rural area." (54.4 million, 17.7% of the population)
- "Low-income census tracts where a significant number (at least 500 people) or share (at least 33 percent) of the population is greater than 1.0 mile from the nearest supermarket, supercenter, or large grocery store for an urban area or greater than 10 miles for a rural area." (19 million, 6.2% of the population)
- "Low-income census tracts where a significant number (at least 500 people) or share (at least 33 percent) of the population is greater than 1.0 mile from the nearest supermarket, supercenter, or large grocery store for an urban area or greater than 20 miles for a rural area." (17.3 million, 5.6% of the population)
The USDA has created a Food Access Research Atlas (available here), where you can explore food deserts across the U.S. Feel free to tool around with it. (You will have to explore it for this week's quiz.)
Food Insecurity
A topic closely related to food deserts is food insecurity. The USDA defines food insecurity and very low food security as follows:
- Food insecurity: "Food-insecure households (those with low and very low food security) had difficulty at some time during the year providing enough food for all their members due to a lack of resources."
- Very low food security: "In this more severe range of food insecurity, the food intake of some household members was reduced and normal eating patterns were disrupted at times during the year due to limited resources."
The USDA provides an annual report and analysis on food insecurity in the U.S. through its Economic Research Service. Highlights (okay, lowlights) from the "Household Food Security in the United States 2017" report summary (full Household Food Security report available here) include:
- "An estimated 11.8 percent of U.S. households were food insecure in 2017, down from 2016 and continuing a decline from a high of 14.9 percent in 2011, while still above the pre-recession (2007) level of 11.1 percent"
- 11.8% of U.S. households were food insecure, which equates to 15.0 million households!
- 4.5% had very low food security, which equates to 5.8 million households.
- 2.9 million households with children (7.7% of all households) were food insecure.
- 250,000 households with children (0.7% of all households) had very low food security.
- "Rates of food insecurity were higher than the national average for the following groups: households with incomes near or below the Federal poverty line, all households with children and particularly households with children headed by single women or single men, women and men living alone, Black and Hispanic-headed households, and households in principal cities and nonmetropolitan areas."