Knowing what to eat to minimize impact on the planet can feel like an impossible task: Eat locally? Skip meat? Opt for organic, free range, humanely raised?
But each of those choices, however Earth-friendly they may sound, come with environmental impact. And they can reverberate in unexpected ways, according to a recent study out of the National Center for Ecological Analysis and Synthesis, affecting not just the climate but water and wildlife habitats around the globe.
Consider the environmental footprints of some common dietary staples, including meat, fish, dairy and eggs and crops.
See how some of the more than 50 foods the researchers analyzed compare along four key metrics: contribution to global warming, water use, nutrient pollution and disturbances to wildlife habitats.
Some foods score poorly — or comparatively well — on all four tests, but in most cases the results are mixed.
Compare two foods of your choice
Overall impact
Greenhouse gas emissions
Water use
Nutrient pollution
Habitat disturbance
2.5x higher for beef
Note: All comparisons are on a per-calorie basis. Charts use a logarithmic scale
The data provides a more holistic way to evaluate how our meals shape the planet, said Ben Halpern, a professor at the University of California at Santa Barbara and the study’s lead author.
“When you do pay attention to these multiple pressures, things you thought weren’t bad get worse,” Halpern said. “Others you thought were bad aren’t as bad.”
Halpern already abstains from eating pork and beef to limit his personal environmental footprint. But the data also showed that some fish, for example, had greater consequences than he realized, while chicken scored “way better than I thought.”
The research also emphasizes how food production that may seem to have relatively low impacts still cause significant environmental shocks around the world.
Nuts such as almonds, for example, are a resource-intensive crop but aren’t produced on as large a scale as wheat, exacting less environmental damage. Wheat is cultivated across hundreds of millions of acres globally, causing a massive ecological footprint despite a relatively low per-calorie impact.
Crops like sugar cane and corn have similarly vast effects, mostly because of their ubiquity.
Impact per calorie and production
Meat Fish Dairy, eggs Crops
*Farmed **Wild caught
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Note: Chart uses a logarithmic scale.
The data helps us understand how food can be produced more efficiently, while maximizing the nutrition it offers, said Jim Leape, a professor at Stanford University and co-director of its Center for Ocean Solutions. The study showed that while about 1 percent of food production comes from oceans and other waterways, it accounts for close to 10 percent of the total global environmental impact.
“There are a lot of opportunities here to meet the challenges of building a food system that offers both healthy diet and a lower footprint,” Leape said.