Potential contributions of food consumption patterns to climate change

Anthropogenic warming is caused mainly by emissions of greenhouse gases (GHGs), such as carbon dioxide, methane, and nitrous oxide, with agriculture as a main contributor for the latter 2 gases. Other parts of the food system contribute carbon dioxide emissions that emanate from the use of fossil fuels in transportation, processing, retailing, storage, and preparation. Food items differ substantially when GHG emissions are calculated from farm to table. A recent study of approximate to 20 items sold in Sweden showed a span of 0.4 to 30 kg CO(2) equivalents/kg edible product. For protein-rich food, such as legumes, meat, fish, cheese, and eggs, the difference is a factor of 30 with the lowest emissions per kilogram for legumes, poultry, and eggs and the highest for beef, cheese, and pork. Large emissions for ruminants are explained mainly by methane emissions from enteric fermentation. For vegetables and fruits, emissions usually are <= 2.5 kg CO(2) equivalents/kg product, even if there is a high degree of processing and substantial transportation. Products transported by plane are an exception because emissions may be as large as for certain meats. Emissions from foods rich in carbohydrates, such as potatoes, pasta, and wheat, are <1.1 kg/kg edible food. We suggest that changes in the diet toward more plant-based foods, toward meat from animals with little enteric fermentation, and toward foods processed in an energy-efficient manner offer an interesting and little explored area for mitigating climate change. Am J Clin Nutr 2009; 89(suppl): 1704S-9S.