It’s Not Always Easy Being Green

You Are What You Eat

You’ve probably heard “you are what you eat” as it pertains to health, but have you considered the phrase as it pertains to sustainability? Your environmental impact is partly defined by the environmental impact of your eating habits. And those can carry a lot of weight, with global food production being a major source of fuel and water consumption, not to mention greenhouse gas emissions. On average, vegetable-based diets often have a much lower impact than meat-heavy diets. However, not all vegetables are created equal. Recent scientific results show that year-round demands for fresh produce can cause a substantial footprint as well.

A research team at the University of Manchester, led by Angelina Frankowska, collected and analyzed food sector data to determine how the consumption of vegetables in the UK affects the environment. The team conducted life cycle assessments on 19 different vegetables (fresh and processed) to determine which have the largest, and the smallest, environmental impacts.

What’s a Life Cycle Assessment?

 A life cycle assessment, or LCA, is a term that comes up a lot in the environmental and sustainability worlds. LCAs are evaluations that take something’s full “life” into account to determine its environmental impact. It’s not as simple as you might think. For example, to evaluate the carbon emissions saved with a hybrid car, it wouldn’t just be savings in gas by increased miles per gallon. An LCA would need to include emissions associated with manufacturing all the car parts, making replacement batteries, and properly disposing of the car (either into reusable parts or the environmental cost of landfill storage). So, what does this mean for vegetables? The research team divided all these factors into four life stages Farm Production, Storage, Processing, and Retail & Consumption. A map of all the different contributions, organized by life stage, is shown in Figure 1 and illustrates the level of detail the team included in their calculations. These details include: fertilizer and water needs in growing the vegetables, transportation, packaging, retail storage, home storage, waste management, etc. The researchers even took into account how each type of vegetables is cooked in the home, and the resulting energy and water use.

Figure 1. An organizational map of the sources of environmental impacts taken into account for each vegetable in the study’s life cycle assessment. “T” stands for transportation. Originally published by Frankowska et al. and reused under a Creative Commons Attribution License.

In order to manage so much data, the researchers ranked each vegetable in a variety of different categories that can negatively impact the environment, such as global warming potential, fossil fuel depletion, and marine ecotoxicity (the potential of related chemicals to affect marine ecosystems). The full range of categories, and the rankings of the vegetables (with 1 being the best for the environment and 21 being the worst) are given in Figure 2. Overall, Asparagus had the largest environmental impact per kilogram, while cabbage had the lowest.

Figure 2. Ranking of different vegetables in terms of different environmental impacts. Originally published by Frankowska et al. and reused under a Creative Commons Attribution License.
Location Matters

It’s important to note that all the information that these researchers collected, and the resulting rankings, are specific to vegetables being consumed in the UK. As you might expect, this location-dependence made it necessary for the researchers to learn a lot about vegetable consumption in the UK. For example, one of the big contributions to why asparagus has such a negative environmental impact is because a large fraction of the fresh asparagus consumed in the UK comes from Peru (which is over 15,000 miles away from the UK!). Consult the article (available for free!) for more tidbits.

The Big Takeaways

As mentioned above, this assessment was for the UK and exact findings are specific to that market. Different countries source vegetables from different places, produce them differently, and even consume them differently. However, there are a few concepts that can be broadly applied:

  1. Consider the source: Because of the resources required for transportation, Frankowska and coworkers found that air-freighted fresh vegetables can have a higher environmental footprint than processed vegetables. A good way to check if your produce was flown in—check the origin location that’s often printed on the produce labels, and buy local when you can.
  2. Shop seasonally: Without the help of heated greenhouses, many vegetables have specific growing seasons. Choosing vegetables that are in season reduces the need for artificial growing conditions and supplementation from other parts of the world. Here is a general guide to in-season produce.
  3. Excess packaging can lead to a lot of extra waste. Buying in bulk and using reusable shopping bags can help. In the event that you do accumulate a lot of plastic bags from grocery trips, return them to store drop-off bins for recycling.

While today’s global economy gives us many food options, some have more environmental consequences than others. Being conscious of the sustainability of your diet can go a long way toward reducing your personal environmental footprint. Thinking “Farm-to-table” doesn’t only apply at hip restaurants. While challenging yourself to eat more sustainably isn’t always easy… it could help you find some new favorite snacks!

 

Article Source: A. Frankowska, H. K. Jeswani, and A. Azapagic “Environmental impacts of vegetables consumption in the UK” Science of the Total Environment 682 (2019) p. 80-105. https://www.sciencedirect.com/science/article/pii/S0048969719319758

Cover Photo Source: https://pixabay.com/photos/vegetables-vegetarian-tomatoes-food-3386212/

 

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Mary Davis

I earned my PhD in Chemical Engineering from Princeton University in 2018, where my research focused on nanoscale polymer systems and how their properties change with geometry. I am now applying my background in polymers to environmental systems as a postdoctoral research associate at the U.S. EPA. This involves studying the breakdown of plastics and the generation of microplastics in the environment, as well as their interactions with other pollutants. When I’m not working in the lab, I enjoy crafting, cooking, and being outside.

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