The Food and Agriculture Organization of the United Nations estimates that "a third of all the food produced in the world is never consumed," totaling about 1.3 billion tons of waste a year. The United States alone wastes 40% of all food, worth an estimated $165 billion.
This waste decays in landfills and, without oxygen present, emits methane, which is a more potent greenhouse gas than carbon dioxide. Consequently, food waste creates an overwhelming 3.3 billion tons of greenhouse gases annually and US greenhouse gas emissions account for 19% of the world's total emissions, second only to China.