May 31, 2018

A blueprint to slash farming's staggering environmental toll

Cattle feedlot in Kansas. Credit: Mark Reinstein/Corbis via Getty Images

Producing food for the world's 7.6 billion people creates about 13.7 billion tons of carbon dioxide equivalent emissions per year, plus other major environmental effects. A new study published in Science attempts to take stock of the global food system's environmental footprint, and proposes how to reduce it.

Between the lines: The study makes the point that greater gains can be made by altering human dietary habits than by changing food production practices. If people were to switch to plant-based diets, we would reduce food's emissions by up to 70% and slash the amount of land devoted to agricultural use by about three-quarters.

"This says something new — it will always be better to consume vegetable proteins/milks, rather than trying to purchase sustainable animal products"
— study co-author Joseph Poore of the University of Oxford

"Cutting down on your flights or buying an electric car, while important, cannot achieve such large reductions on such a wide range of environmental issues," Poore said in an email.

The study: Researchers at Oxford University and the Swiss agricultural research institute, Agroscope, claim to provide the most comprehensive database ever assembled on how different production practices and locations affect the environmental footprint of more than two dozen foods. They show that as the world population continues to grow, there are ways to cut the environmental footprint from food production, while still providing everyone with sustenance.

The researchers included information on a staggering 38,700 farms, as well as 1,600 food processors, packagers, and retailers in 119 countries.

What they found:

  • The modern food supply chain causes 26% of all human-caused greenhouse gas emissions.
  • About 43% of land that is not covered by ice or located in a desert is used for food production.
  • An estimated two-thirds of freshwater withdrawals worldwide are used for irrigating crops.
  • When it comes to irrigation, producing just 5% of the world's calories creates about 40% of the "environmental burden," suggesting this water could be more equitably spent.
  • Freshwater aquaculture ponds can emit more greenhouse gases, including methane, than dairy cows per kilogram of liveweight.
  • The same food product's environmental impacts can vary by as much as 50 times, depending on a farm's land use practices, location and other factors, according to the study.
  • Even the highest-emitting plant protein producers still emit far fewer planet-warming greenhouse gases than dairy cow producers do.
Expand chart
Adapted from Poore, et. al., 2018, "Reducing food’s environmental impacts through producers and consumers", Science; Chart: Axios Visuals

The solutions: The authors acknowledge convincing everyone on Earth to become a vegetarian is likely to be impractical.

  • One possible solution is to provide consumers with information about the environmental effects of a food product's manufacturer or farmer, they write. That could start to put pressure on growers to cut their emissions and land use, in much the same way as calorie counts on restaurant menus have incentivized new consumption patterns.
  • On the production side, the researchers say new technology can help farmers decide what crops to plant and when, with the goal of limiting their environmental footprint.

Limitation: The researchers couldn't actually visit tens of thousands of farms and production plants. Instead, they used 570 published studies that calculated environmental impacts in different ways, along with other supplemental data sources.

According to Poore, they, "Went through an extensive process of harmonizing this data, eliminating as much methodological difference as possible, until the remaining differences between producers primarily reflect differences in geography and practice."

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