A carbon footprint is the total amount of greenhouse gases, including carbon dioxide and methane, that are generated by our actions. It serves as an indicator to compare the total amount of greenhouse gases emitted from an activity, product, company, or country. Carbon footprints are usually reported in tons of emissions (CO2-equivalent) per unit of comparison, such as per year, person, kg protein, km traveled, and alike. For a product, its carbon footprint includes the emissions for the entire life cycle from the production along the supply chain to its final consumption and disposal.

A commonly used definition of carbon footprint is as follows: "A measure of the total amount of carbon dioxide (CO2) and methane (CH4) emissions of a defined population, system, or activity, considering all relevant sources, sinks, and storage within the spatial and temporal boundary of the population, system, or activity of interest". Carbon footprints are different from a country’s reported per capita emissions, which focus on the greenhouse gas emissions associated with production, while carbon footprints focus on the greenhouse gas emissions associated with consumption.

The average carbon footprint for a person in the United States is 16 tons, one of the highest rates in the world. Globally, the average carbon footprint is closer to 4 tons. To have the best chance of avoiding a 2℃ rise in global temperatures, the average global carbon footprint per year needs to drop to under 2 tons by 2050.

Carbon footprints can be calculated for individuals, businesses, and other organizations using various tools. Some factors that contribute to a persons carbon footprint include daily commute, food consumption, clothes buying, and waste disposal. By making small changes to our actions, such as eating less meat, taking fewer connecting flights, and line drying our clothes, we can start making a big difference in reducing our carbon footprint.