New research proposes solutions for reducing environmental costs of feeding Earth’s 7.6-billion human population

Researchers at Oxford University in the UK and Agroscope, a Swiss agricultural research institute, have compiled an extensive database on food production around the world in order to determine the best means of reducing the environmental impacts of what we eat.

There are more than 570 million farms producing food in almost all of the climates and soils found on our planet. To pinpoint possible solutions for reducing the impact of food production on terrestrial and aquatic ecosystems and the global climate that would be effective for the large and diverse range of food producers across the globe, the researchers compiled a database covering five different indicators of the environmental impacts (including greenhouse gas emissions, water and land use, eutrophication, and terrestrial acidification) of 38,700 farms and 1,600 processors, packaging types, and retailers.

They found that environmental impacts can vary widely — by as much as 50-fold — even among producers of the same food product. These discrepancies in the environmental tolls exacted by the same foods when grown in different geographies and under different production practices present a number of opportunities to mitigate those impacts, the researchers write in a paper summarizing the results of their analysis in the journal Science last month.

“Two things that look the same in the shops can have very different impacts on the planet,” lead author Joseph Poore, a researcher with the Department of Zoology and the School of Geography and Environment at the University of Oxford, said in a statement. “We currently don’t know this when we make choices about what to eat. Further, this variability isn’t fully recognised in strategies and policy aimed at reducing the impacts of farmers.”

Feeding Earth’s 7.6 billion humans takes a significant environmental toll on the planet. According to Poore and his co-author, Agroscope’s Tomas Nemecek, the global food supply chain is responsible for about 13.7 billion metric tons of carbon dioxide equivalents (CO2eq), more than a quarter of manmade greenhouse gas emissions. Food production also creates about 32 percent of global terrestrial acidification — also known as acid rain, which is the result of nitrogen and sulfur building up in the atmosphere — and 78 percent of eutrophication — the excessive accumulation of nutrients in bodies of water, which can lead to harmful algal blooms, dead zones, and fish kills.

Of course, feeding the growing human population requires an ever-expanding amount of land and resources, as well. The researchers note in the study that as much as two-thirds of freshwater withdrawals are for irrigating crops, and that our agricultural system covers more than 40 percent of Earth’s land areas that aren’t desert or covered in ice. About 87 percent of that agricultural land is used for food production, while the other 13 percent is used to grow biofuels, textile crops, or non-food products like wool and leather.

“Immediately apparent in our results is the high variation in impact among both products and producers,” Poore and Nemecek write in Science. For instance, they found that the top greenhouse-gas-emitting beef producers are responsible for 105 kilograms of CO2eq and use 370 square-meters-per-year for every 100 grams of protein they produce. That’s 12 and 50 times the emissions and land use, respectively, of the lowest-impact beef production. “High variation within and between protein-rich products is also manifest in acidification, eutrophication, and water use,” the authors note.

Among major crops like wheat, maize, and rice, the highest-impact products are responsible for more than three times the environmental impacts for all five indicators Poore and Nemecek studied.

The researchers discovered that a relatively small number of producers are creating the majority of environmental impacts. “For many products, impacts are skewed by producers with particularly high impacts,” the researchers write in the study. “This creates opportunities for targeted mitigation, making an immense problem more manageable.”

For example, they found that, when it comes to beef, the 25 percent of producers with the highest impacts represent a whopping 56 percent of the global beef herd’s greenhouse gas emissions and 61 percent of land use — an estimated 1.3 billion metric tons of CO2eq and 950 million hectares of land, primarily pasture. “Across all products, 25% of producers contribute on average 53% of each product’s environmental impact,” they add. “For scarcity-weighted freshwater withdrawals, the skew is particularly pronounced: Producing just 5% of the world’s food calories creates ~40% of the environmental burden.”

Poore and Nemecek argue in the paper that these results demonstrate the need for “far-reaching changes in how food’s environmental impacts are managed and communicated.”

“Food production creates immense environmental burdens, but these are not a necessary consequence of our needs. They can be significantly reduced by changing how we produce and what we consume,” Poore said. But, he cautioned, “An approach to reduce environmental impacts or enhance productivity that is effective for one producer can be ineffective or create trade-offs for another. This is a sector where we require many different solutions delivered to many millions of different producers.”

Among the solutions identified by Poore and Nemecek are new technologies that would allow farmers to better monitor their agricultural operations by tracking data on inputs, outputs, climate, and soil on their mobile devices. These technologies could then quantify the environmental impacts of food production practices and recommend ways to both reduce impacts and increase productivity.

But there’s only so much producers can actually do to lower environmental impacts, the researchers found. For instance, they discovered that, despite the variability in production practices around the world, there isn’t currently a way to shift the production of animal products so that they produce lower impacts than vegetable-based equivalents. As an example, they say that even a litre of the lowest-impact cow’s milk requires twice as much land and creates almost double the emissions as an average litre of soy milk.

“Today, and probably into the future, dietary change can deliver environmental benefits on a scale not achievable by producers,” the researchers conclude in the study. “Moving from current diets to a diet that excludes animal products has transformative potential,” reducing food’s land use by 76 percent (or 3.1 billion hectares) and greenhouse gas emissions by 49 percent (6.6 billion metric tons of CO2eq).

But getting the whole world to forego meat altogether probably isn’t going to happen, so Poore and Nemecek cite another potential solution: We could use the variable environmental impacts of food production to our advantage by simply avoiding the highest-impact producers. That would reduce consumption of animal products by 50 percent and still allow us to net 73 percent of the emission reductions a shift to an all-plant-based diet would achieve.

This scenario would require greater communication with consumers about environmental impacts by producer, as opposed to by product, however. Poore and Nemecek say this could be achieved through environmental labels in combination with taxes and subsidies.

“We need to find ways to slightly change the conditions so it’s better for producers and consumers to act in favour of the environment,” Poore said. “Environmental labels and financial incentives would support more sustainable consumption, while creating a positive loop: Farmers would need to monitor their impacts, encouraging better decision making; and communicate their impacts to suppliers, encouraging better sourcing.”

CITATION

• Poore, J. & Nemecek, T. (2018). Reducing food’s environmental impacts through producers and consumers. Science, 360(6392), 987-992. doi:10.1126/science.aaq0216