Pressures such as population growth, urbanization, and land degradation are straining the global agrifood system — the network connecting all steps of the food supply chain from growing crops in the field to waste elimination or disposal. In turn, the system is a major contributor to greenhouse gas emissions, highlighting an urgent need for transformative change. upenn
Professor Zhengxia Dou of Penn Vet notes that almost a third of all food produced for human consumption is never eaten but lost or wasted, which not only impacts food security but also squanders vital resources such as land, water, and energy. upenn
Why Landfills Are the Worst Option
Dou describes a landfill as a "biological amplifier." Food waste contains carbohydrates and other organic compounds, and when buried in a landfill, it decomposes anaerobically to produce methane — a greenhouse gas with a warming effect more than 80 times that of carbon dioxide over a 20-year timespan. Her conclusion is unequivocal: "Anything you can do with food waste recycling is better than sending it to a landfill." upennupenn
The Three Recycling Methods Studied
The research, published in Nature Food, analyzed data from 91 field-based studies conducted under diverse conditions in 29 countries. It focused on three proven approaches: upenn
1. Composting — breaks down organic waste while conserving valuable nutrients. upenn
2. Anaerobic Digestion — the process by which organic material is broken down and produces a mixture of methane and carbon dioxide known as biogas, which can be used as a renewable energy source. upenn
3. Refeeding — repurposes suitable food waste into animal feed. upenn
Striking Findings: The U.S., EU, and China
The U.S., the European Union, and China produce enormous amounts of food waste, are major contributors to GHG emissions and resource consumption, and Dou describes them as methane "super emitters" from food waste disposal. upenn
The study modeled a scenario in which food waste currently sent to landfills in all three regions was redirected equally across the three recycling methods. The estimated reduction in GHG emissions in the U.S. alone would be equivalent to offsetting the methane produced by nearly 9 million dairy cows — more than 90% of the entire U.S. dairy cow population. upenn
The Hidden Power of Refeeding
Dou is a strong advocate for converting suitable food waste into animal feed because it carries the additional benefit of reducing conventional feed usage, thereby sparing the use of natural resources and fertilizer. upenn
The numbers bear this out: more than 5% of China's total cropland currently devoted to maize and soybean production could be spared if suitable food waste destined for landfills were recycled through refeeding. This freed land could be used for producing human food to enhance food security, or taken out of production entirely for conservation purposes. upenn
A Call to Individual Action
Beyond policy and industry, Dou brings the issue home. "We are part of the equation. So, to solve the problem, we need to be aware of the food loss and waste issue and try to cut down our own footprint by reducing our own food loss and waste." upenn
Penn Dining has already taken steps in this direction — repurposing food through donations, surplus animal feed, biofuel creation, and composting, always aiming to keep waste out of landfills. Staff plan menus carefully, train chefs, and continuously review waste data to cut down unnecessary waste. upenn
Conclusion
The study concludes that food waste composting, anaerobic digestion, and repurposing to animal feed are all practical and viable options — field-proven, low cost, and highly effective in mitigating emissions with multiple resource conservation benefits. The findings serve as a global benchmark for countries building food waste management strategies for a more circular, sustainable agrifood system. upenn