Food System Overview

Impacts of the Food System

The larger food system consists of food production, processing, distribution, retailing, and cooking. However, most greenhouse gas emissions associated with the broader food system are in production: crop growing, feed production, and land use change.

Emissions from cookstoves are estimated from Bailis et al. ¹ at 1.0 to 1.2 billion tons CO₂e per year, and include only traditional biomass cooking fuel and not modern energy for cooking. The remaining figures are reported by Poore and Nemecek ².

Most greenhouse gas emissions in farming and livestock are not directly associated with energy. In the United States, the larger food production uses energy as follows.

Sources: Canning et al. ³, IEA ⁴, CBECS ⁵, RECS ⁶.

Food Trade

Biomass, of which food is a major component, is widely traded internationally.

Source: Global Material Flows Database ⁷.

With transportation a relatively minor component of the food-energy nexus, a movement toward local foods has limited potential to save on energy consumption. In some cases, localized production can increase energy consumption by requiring that food be grown in a climate that is not optimal ⁸. An exception is that air-shipped foods typically have higher lifecycle emissions than other options ⁹.

Recent work ¹⁰ has suggested that "food-miles" comprise 19% of total emissions of the agricultural system, higher than what other studies have reported. However, this study uses a more expansive notion of food-miles than most others, including emissions from the transportation of fertilizers, pesticides, machinery, and other upstream inputs.