Revealing the 'carbon hoofprint' of meat consumption for American cities

(Press-News.org) Depending on where you live in the United States, the meat you eat each year could be responsible for a level of greenhouse gas emissions that's similar to what's emitted to power your house.

That's according to new research from the University of Michigan and the University of Minnesota published in the journal Nature Climate Change. The study provides a first-of-its kind, systematic analysis that digs into the environmental impacts of the sprawling supply chains that the country relies on for its beef, pork and chicken.

Supported in part by the U.S. National Science Foundation, the team calculated and mapped those impacts, which they've dubbed meat's "carbon hoofprint," for every city in the contiguous U.S. While the study does underscore the size of America's urban carbon hoofprint—it's larger than the entire carbon footprint of Italy—it also provides city-specific information that residents and governments can use to make positive changes.

"This has huge implications for how we gauge the environmental impact of cities, measure those impacts and ultimately develop policies to reduce those impacts," said Benjamin Goldstein, a leader of the study and assistant professor at Michigan's School for Environment and Sustainability, or SEAS. 

For example, policymakers have rolled out campaigns and initiatives that help home owners reduce their carbon footprints by incentivizing and subsidizing things like installing solar panels and insulation, he said. These projects can still cost thousands, if not tens of thousands, of dollars.

"But if you just cut out half of your beef consumption and maybe switch to chicken, you can get similar amounts of greenhouse gas savings depending on where you live," Goldstein said. "If we can get people to use this type of study to think about how diets in cities impact their environmental impacts, this could have huge effects across the United States."

Chains and links

Looking at the team's maps of carbon hoofprints, one of the most apparent things is how much it varies across the country. And while that likely isn't shocking—the U.S. is a large and diverse country—the reasons why are more nuanced than people might suspect.

For instance, it'd be natural to assume cities with higher meat consumption per capita would have a higher per capita hoofprint. But the team found the correlation between those variables was actually quite low. 

Another obvious candidate are the emissions from transporting meat from the rural areas where it's produced to the cities that consume it. While that is a piece of the puzzle, the researchers found it's not a particularly big one.

"There's not a single emissions value for the meat we consume," said Rylie Pelton, a research scientist at the University of Minnesota's Institute on the Environment and co-leader of the study. "That's because the supply chains are different in different locations. And also the impacts of production—the ways that beef, chicken, pork and feed are produced—are different in those different locations. That all matters from an emissions standpoint."

To illustrate this point, consider how the country's second largest city, Los Angeles, gets its beef, the meat with the largest carbon hoofprint. L.A.'s beef comes from processing facilities in 10 counties. But the meat that's processed in those facilities comes from livestock raised in 469 counties by feed that's sourced from 828 counties.

Each stop and product along that supply chain has its own processes with an associated carbon footprint, such as using fertilizer for growing feed and managing manure on farms. That's combined with transporting a variety of goods across the physical extent of the full chains, which can stretch thousands of miles. The team considered these wide-ranging factors in evaluating the carbon hoofprint for more than 3,500 locations. 

"This is really the first systematic and analytical effort to map what we call urban-land teleconnections. It's understanding that cities have massive impacts beyond their borders," said Joshua Newell, a senior investigator on the study and a SEAS professor at U-M. "It is our hope that this study provides an example of how we can foster better understanding between two different places: One largely urban and one distinctly rural where our food is produced."

The team's analysis relied on the Food System Supply-Chain Sustainability, or FoodS3, platform initially developed at the University of Minnesota to study the country's corn supply chain. Over the course of eight years, the hoofprint team, led by Pelton and Goldstein, built a framework to apply the platform to a broader set of questions pertaining to meat (the team pointed out that the platform is being used to study other agricultural products could also be extended to nonagricultural commodities that cities rely on, like steel, as well).

The researchers hope that their hoofprint study provides new perspectives that can inspire more creative solutions at various points of the supply chain.

"We can start identifying linkages between cities and the rural areas that produce our food," Pelton said. "If we can identify those links, there might be opportunities for cities to engage with those distant locations, to help provide financial incentives and support in general to adopt certain practices that would ultimately help their own carbon footprint."

Jennifer Schmitt, a senior author of the study and senior research scientist who leads the FoodS3 team at Minnesota, agreed.

"We are all connected," she said, summarizing what, to her, was the take-home message of the study. By keeping that in mind, people can work toward solutions that are sustainable not just environmentally, but economically.

For example, while city residents could stop eating pork to shrink their carbon hoofprint, that puts a financial strain on hog farmers. Instead, urban residents could talk to their city government about sponsoring equipment, such as anaerobic digesters, at hog farms to reduce their environmental impact.

"My hope is that this is the beginning of an urban-rural conversation," Schmitt said. "I get that that may seem ideal, but whatever. I'm an idealist."

Dimitrios Gounaridis, assistant research scientist at Michigan, and Nathaniel Springer, research scientist at Minnesota, also contributed to the study.

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