In fact, some people tie their diet into only buying locally grown food. Such a person is called a “locavore.”

Based on this concern, Christopher L. Weber and H. Scott Matthews, both from Carnegie Mellon University, conducted one of the first studies that systematically and comprehensively assessed the life cycle of greenhouse gas (GHG) emissions (thus, its effect on climate change) and food production, against long distance distribution.

They studied all stages of growing and transporting food consumed in the United States. The two researchers used data from the U.S. Department of Commerce, Department of Agriculture, and Department of Transportation, along with other sources.

The two researchers found that food in the United States travels, on average, 1,020 miles (1,640 kilometers) to be delivered and 4,200 miles (6,760 kilometers) for its life-cycle supply chain.

They also found that the average U.S. household generates 8.1 metric tons of greenhouse gases (in carbon dioxide equivalents) per year directly as a result of food consumption. (In all, the average U.S. household generates 60 metric tons annually.)

Although food is transported long distances in the United States, the researchers found that the “production” phase of food to consumers (the agricultural production and industrial preparation stages) contributes more to GHG emissions (83%) than its transportation phase (11%), with the final delivery from producer to retailer only contributing 4%.

They specifically found that red meat contributed about 150% to GHG emissions, much more than chicken or fish, for instance.

What advice does Weber and Matthews give to consumers? Please read on.