Why not the “carbon footprint” that many others are talking about? The calculation is the same, but the term “carbon footprint” is misleading because it gives the impression that it’s all about carbon. When we think of greenhouse gases, we usually think of carbon dioxide. It’s the most important greenhouse gas in terms of human impact on the environment, but it’s actually less important for food production. Carbon dioxide is responsible for about 65% of global warming. However, methane and nitrous oxide are two other important greenhouse gases that are often of much greater importance for life cycle assessments of food products. In agriculture, methane emissions come primarily from the digestive system of ruminants, manure management and rice production. Methane is a very potent greenhouse gas, but it does not remain in the atmosphere for as long as carbon dioxide. Nitrous oxide is released from arable land. A small fraction of all available nitrogen in the soil is converted to nitrous oxide, a potent and long-lasting greenhouse gas. Nitrous oxide emissions also come from manure handling and the production of synthetic fertilizers.
Food production also causes carbon dioxide emissions, particularly when fossil fuels are used for machinery and transportation in the supply chain, changes in soil carbon stocks, and from the production of packaging material.Our goal is to assess how much each edible item in the grocery store contributes to global warming. For many food products, it's nitrous oxide that has the biggest non-carbon impact on the climate. That's why we use the term "climate footprint."