Two of Pittsburghers’ favorite things, beef and beer, are the biggest sources of planet-warming greenhouse gas emissions in the local food system, according to a new study by a team of 19 Carnegie Mellon students.

The study found that Allegheny County’s entire food system produces 3.7 million tons of carbon dioxide emissions per year, with each person responsible for 3.1 tons — equivalent to each of us driving 7,600 miles in a car.

The food system includes everything that gets food from the farm to the table, such as production, packaging, transportation, distribution, refrigeration and food waste going to landfills.

“What we tried to do for the first time is to put together an overall picture to give policymakers an idea of where the biggest impacts are, and where actions to change the system could be beneficial,” says Ed Rubin, a professor of engineering and public policy at CMU and faculty advisor for the project.

“We couldn’t find any other major metropolitan areas that had done something like this,” says Rubin.

By weight, beer was the single most consumed food product in the county, representing 29% of of the total. Beef represented less than 3% of total food consumed, but 34% of all greenhouse gas emissions, by far the largest source. Beer was second at 10%.

“Emissions associated with most meat products, and especially beef, are roughly ten times higher than the equivalent weight of vegetables,” explains Rubin.

Feeding cows is very energy-intensive, and of course cows also produce methane, a powerful greenhouse gas.

Image courtesy of CMU.

In other areas, the study found that Pittsburghers consume 73% of their food at home, and 27% at food service locations like restaurants and cafeterias.

The project was a massive undertaking, and involved 19 students, two project managers, two faculty advisors and an expert review panel that included city government officials, local nonprofits and supply chain experts.

The collected data points to ways to significantly reduce greenhouse gas emissions in Allegheny County.

What stands out in the things we can control? “One is the effect of changes in diet,” says Rubin. “Meat products, and beef in particular, are far greater generators of greenhouse gas emissions than other types of meats and seafood, and especially vegetables. Any significant shift away from meat and towards vegetables and fruits can have a significant impact.”

Food waste is another major source of greenhouse gases in the food system. About 370,000 tons of food end up in the trash each year in Allegheny County. There are greenhouse gas emissions embodied in this wasted food, as well as further emissions in trucking it to the landfill. When it decomposes, it also emits greenhouse gases.

“One of the surprising numbers for me is how much food is wasted,” says Rubin, who says it’s close to 30% of all food in Allegheny County. “Reduction in food waste is the second-most significant way in which local action could reduce carbon footprints.”

The study mentions that Allegheny County gets support from organizations that can utilize surplus food before it’s wasted, such as 412 Food Rescue and the Greater Pittsburgh Community Food Bank.

Food storage is also a major greenhouse gas emitter.

“Think about refrigerators,” notes Rubin. “A lot of our food supply requires refrigeration to keep from spoiling and the major energy source is electricity. A lot of our electricity still comes from burning fossil fuels in power plants that supply electricity.”

He adds, “The students found that many of the refrigerators that are used in homes and restaurants are not nearly as efficient as newer models. Actions to modernize equipment can go a long way towards reducing that energy consumption.”