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Climate change is a massive challenge facing humanity–16 of the 17 most recent years have been the hottest on record. Sea levels have risen, and intense storm have become more frequent.  The extent of future climate instability depends on steps we take today.

Why should we care about what we eat?

Globally, food systems–what we eat, where and how we grow and process it– play a major role in determining our impact on the environment.  By considering our food choices, we can find “low hanging fruit” for reducing our carbon footprint.

But is it reasonable to think about shifts in diet for environmental reasons?

Yes!  First of all, diets are constantly shifting anyway. Over the last 50 years, in the United States we’ve seen a substantial increase in consumption of processed foods, fast food, sugar, and meat.  In fact, in countries across the globe, increases in demand for red meat and sugar has gone hand in with higher incomes.

It is generally acknowledged that these shifts have resulted in increased incidence of cardiovascular disease, type II diabetes, and some cancers.

It is also true that these shifts have resulted in a more resource-intensive global food system.  In fact, many researchers believe it will be almost impossible to meet the Paris climate targets if diet trajectories stay as they are.

Because healthier diets are generally more environmentally friendly, we get multiple benefits from some simple changes.

What are some general rules to follow for a planet-friendly diet?

  • Eat whole foods as much as possible. Highly processed foods have more steps in the production chain, and each step requires energy and transportation.  Thus, eating foods closer to their natural state is better for the environment.
  • Focus on plants as much as you can.  Foods higher on the food chain generally result in higher greenhouse gas emissions due to the production and transport of feed required to maintain the animals over their lifetime.
  • Try to minimize food waste.  In the U.S., we currently waste 40% of our food!  Imagine all of the resources that went into making and transporting all that wasted food!  Also, landfilling of food waste can lead to high global warming potential due to methane production.

Are some meats worse than others for the planet?

Yes.  Ruminant animals (cows, sheep, and goats) release methane, a very potent greenhouse gas, as part of their natural metabolism (whether raised on a pasture or feedlot).

Beef and lamb are the most resource-intensive meats, with production resulting in 26 and 23 kg CO2-eq per kg, respectively, for animals raised under typical conventional or organic conditions.  This includes methane emissions that occur during ruminant respiration along with the carbon footprint of the feed and maintenance of the animals.  In contrast, pork and poultry produce 7 and 5 kg CO2-eq per kg, respectively.  Eggs and nuts generate 4 and 2 kg CO2-eq per kg.

For comparison, beans produce just 0.8 kg CO2-eq per kg. (Data from Heller et al. Journal of Industrial Ecology, 2014, Supplemental Information).

Why do beans have such a low carbon footprint?

Well, first of all, eating plants directly is really efficient!  Think of all the energy saved by not having to grow more plants, on more land, with more resources, just to transport to animals as feed!  Also, beans are able to get their nitrogen from the atmosphere, due to the activity of microbes that live symbiotically with them.  Beans can deliver the protein people may otherwise get from meat, so shifting even some portion of meat in the diet to beans can have an enormous positive impact!

A personal note from the author:

I feel strongly that our food choices matter a lot–both to our health and to the world around us.  So, not only do our family meals need to be healthy for our bodies, they need to support a sustainable environment.  Through my research and teaching at UCLA, I have been calculating the carbon footprint and land use requirements of various dietary patterns.  I have applied these calculations to each recipe presented here, so you can see exactly how the meals stack up, ingredient by ingredient, with respect to greenhouse gas emissions next to comparable meals with less resource-efficient ingredients.

Also, as a busy mom,  I rely on meals that are very quick to put together, can be customized for picky eaters, and pack up well in thermoses for lunch the next day.

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Professional Bio of the author:

Jennifer Jay earned her B.S., M.S., and Ph.D. in Civil and Environmental Engineering at Massachusetts Institute of Technology.  For the last fifteen years, she has been a Professor in the Civil and Environmental Engineering Department at the University of California Los Angeles.  She specializes in the fate and transport of chemical and microbial contaminants in the environment.  Her research addresses a wide range of topics  including coastal water quality, arsenic in groundwater, and environmental proliferation of antibiotic resistance. She teaches classes in Aquatic Chemistry, Statistics, Chemical Fate and Transport, and Food: A Lens for Environment and Sustainability.  She was awarded the Presidential Early Career Award in Science and Engineering, and an engineering school-wide award for excellence in teaching.  In addition, she was the Pritzker Fellow for Environmental Sustainability and a Carnegie Fellow for Civic Engagement in Higher Education.  Jennifer also directs the Center for Environmental Research and Community Engagement (CERCE), a UCLA Center that addresses community-based environmental research questions in under-served communities in Los Angeles.

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