Ranking on factors including greenhouse gas emissions and water pollution, scientists have for the first time mapped the environmental footprint from the production of all foods—whether produced on land or in oceans.
The new research, published in the journal Nature Sustainability, aims to identify the true environmental impact of the complex food system and how producers and growers can best improve their systems. It’s also aiming to help policymakers look at how best to address the global food supply and the changing needs of the changing planet.
‘Everyone eats food’
As the global population grows and climate change’s impact on our food supplies increases, food is top of mind for governments and consumers around the world.
“Everyone eats food, and more and more people are paying attention to the planetary consequences of what they eat,” said Ben Halpern executive director at NCEAS and a professor at UCSB’s Bren School of Environmental Science & Management, who led the research.
“The individual choice of eight billion people adds up,” he said, “and we need to know the overall impact of total food production—not just per pound—especially when setting food policy.”
According to the findings, almost half of all environmental pressures from food production come from just five countries: India, China, the United States, Brazil, and Pakistan.
“The environmental efficiency of producing a particular food type varies spatially, such that rankings of foods by efficiency differ sharply among countries, and this matters for guiding which foods we eat and from where,” said Halley Froehlich, assistant professor in environmental studies at UCSB and a coauthor of the study.
The researchers looked at 2017 data on greenhouse gas emissions, freshwater use, habitat disturbance, and nutrient pollution (e.g., fertilizer runoff) generated by 99 percent of the total reported production of aquatic and land-based foods. The team mapped the impacts at high resolution, which they say paints a more nuanced picture of the pressures of the global food supply.
Food’s footprint, by type and by pound
The results narrow in on the impact of food by pound (or kilogram). They also identified the environmental efficiency of food by its type, which allowed for differences by country. For example, the U.S., which leads the world in soy production, is more than twice as efficient at growing and producing it than India, the fifth largest producer.
Cumulative pressures of food production are “more concentrated than previously believed,” says Melanie Frazier, a research scientist at NCEAS and coauthor of the paper. She says the vast majority—92 percent of pressures from land-based food production—are concentrated on just ten percent of the Earth’s surface.
Specifically, the space required for dairy and beef farming accounts for about a quarter of the cumulative footprint of all food production, the researchers note.
Raising cattle requires the most grazing land of any animal, but the researchers say the cumulative pressures of pig farming, “which produces a lot of pollution and uses more water than cattle farming,” are slightly greater than that of cows.
For the first time, the research was also able to look at the ocean footprint of land-based factory-farmed animals including pigs and chickens. The researchers say they have an ocean footprint because fish including sardines, anchovies, and herrings are often used in their feed. The issue goes the other way, too; crop-fed fish farms put pressure on land, the researchers noted. Aquatic systems are problematic in other ways, according to the findings; they produce only 1.1 percent of food but 9.9 percent of the global footprint.
Measured by cumulative pressures, the researchers identified the top five offenders as pigs, cows, rice, wheat, and oil crops.
“We need this comprehensive information to make more accurate decisions about what we eat,” Halpern said.
In some cases, the researchers say “major shifts” are needed to the current food system, such as improvements to farming and reductions in animal production. In other cases, consumers may simply need to make more sustainable choices at home.
Scientists have been sounding the alarm about food’s impact on the planet for years. Recent research from Impossible Foods founder Pat Brown, professor emeritus in the department of biochemistry at Stanford University, found that a shift away from animal agriculture over the next 15 years is a critical key to reversing climate change.
“Everybody knows that methane is a problem. Everybody knows that livestock contribute to global warming in some way,” Michael Eisen, professor of molecular and cell biology at the University of California, Berkeley, who co-authored the study along with Brown, said in a statement accompanying the research. “But animal ag contributes to global warming in two ways: It contributes via emissions and contributes because that land would otherwise be holding carbon. Most analyses only look at one of those things.”