One-third of all food produced for humans annually is lost to waste. The decomposing matter produces half of all the emissions generated by the global agrifood system. What if, instead of focusing solely on how to curb and avoid food waste, we turned the challenge on its head—and looked at what we can make with all that discarded food?
This was the approach of a new Nature Food study: it looked at turning food waste into compost, renewable energy, and recycled animal feed before it reaches the landfill, and found that not only would this tackle the problem of festering waste, but it could also turn discarded food into a solution. In fact, recycling this matter would reduce CO2 emissions by about a tonne for every tonne of repurposed food waste. In countries like China, this would add up to an almost 20% emissions reduction in the agricultural sector.
Preventing food waste is a top priority. Yet it may take decades to recalibrate the global food system to put a stop to the monumental scales of food loss and waste. In the meantime, tried-and-trusted methods already exist to turn food waste into a resource, instead of dumping it into a landfill.
The researchers looked at three of these. The first is anaerobic composting (AC), which fixes the available nitrogen and phosphorus in leftover food, and turns it into organic fertilizer. The second is anaerobic digestion (AD), wherein microbes break down food scraps, releasing biogas that can be used as energy. Finally, they looked at the potential of feeding food waste to farm animals, a process they call ‘re-feed’. Two of these methods—AC and re-feed—could help close the agricultural loop, returning resources back to the food system.
They gathered evidence from 91 studies that looked at the emissions generated by the operation of these three measures, then compared that with food waste disposal in landfills, open dumps, or via incineration, which is another common practice. They mainly focused on data from three regions that produce the most food waste globally: the United States, the European Union, and China.
For these three regions, the trend was clear: repurposing food waste produced a significantly lower footprint than tossing it in landfills, dumps, or incinerators. Each tonne of food waste recycled through AC, AD, or re-feed, would in turn reduce greenhouse gas emissions by roughly a tonne, compared to conventional disposal methods.
Strikingly, keeping food waste out of landfills would reduce emissions by 39 million tonnes of CO2-equivalent in the United States, 20 MtCO2e in the European Union, and 115 MtCO2e in China. To put that into context, say the researchers, repurposing food waste through AC, AD, and re-feed would be enough to offset the emissions of nine million dairy cows in the United States: that’s 90% of the country’s milk-producing population.
Looking more broadly, efforts to repurpose food waste in the United States, the European Union, and China would offset at least 10%, 5% and 17% of the greenhouse gas emissions from agriculture in each place, highlighting the value of these approaches as a mitigation tool.
The team looked also beyond emissions, to show that large amounts of nitrogen and phosphorus could be mined from the redirected food waste. For instance, if just a third of the available food waste was recycled through anaerobic composting in China, this would generate 10 million tonnes of compost containing close to 300,000 tons of nitrogen and 61,000 tons of phosphorus.
Another opportunity lies in land savings, especially through the recycling of food waste into animal feed. Another example from China showed that re-feed could free up to 9.3% of the land area currently devoted to maize and soybean farming for feed. Rewilding this freed land could sequester further tons of carbon.
There are some potential risks to recycling food waste, such as feeding meat waste to livestock, which can lead to disease outbreaks. So re-feed would require strict regulation to ensure the suitability of food waste. But the main challenge would be bringing global governments on board with recycled food waste: their support will be needed in the form of policies, regulations, and economic incentives to drive its use, the study argues.
With the existing technologies, this feels more doable in the short-term than the larger reimagining of the food system that will be needed to dramatically cut food waste. Already, a food waste reuse blueprint is emerging from countries including South Korea and Japan, where AC, AD, and re-feed are commonplace, making these countries pioneers of the ‘zero-landfill’ movement.
Waste reduction remains the priority, for humanity’s sake as well as the ecosystems on which we depend. But until we get there, recycling this rich resource can go some way to reducing the damage.
Wang et. al. “Food waste used as a resource can reduce climate and resource burdens in agrifood systems.” Nature Food. 2025
Image: based on Yarchii via Flickr. ©Anthropocene Magazine
