Rotting food is supercharging the climate crisis. Here’s what to do about that.
Every day more than 1 billion meals are left uneaten, the result of excess production, spoilage or poor meal planning.
From a food security perspective, this mountain of discarded food – 60 per cent of which comes from households – is problematic. But it creates other problems as well. As it decomposes in landfills, rotting food releases enough methane to make it one of the major drivers of planet-warming greenhouse gas emissions.
As the world looks for quick and practical ways to bring down temperatures, the focus has turned to food. In June 2026 the UN Secretary-General issued a Call to Action on Methane, calling for action across three sectors: fossil fuels, agriculture and waste. In the waste sector, the call emphasizes the need to reduce organic waste, divert organics from landfills, end open dumping and build more circular, low-methane waste systems.
“Every meal rescued, shared or never wasted is food put to better use. It is also methane avoided,” says Martin Krause, Director of the Climate Change Division at the United Nations Environment Programme (UNEP). “At a time when the world is searching for practical ways to slow warming quickly, tackling food waste may be one of the most immediate and cost-effective climate solutions available.”
How food waste is making climate change worse
Food waste – from spoiled crops to unfinished meals – is responsible for up to 10 per cent of total global greenhouse gas emissions. That’s nearly five times the emissions produced by the aviation sector.
One of the most potent types of food-related emissions is methane, which traps 86 times more heat than carbon dioxide over a 20-year period. Methane is responsible for nearly one-third of global warming to date, and food waste is a key contributor.
When organic matter such as uneaten food is buried in deep in landfills and deprived of oxygen, it interacts with microorganisms to produce methane. In the United States of America alone, municipal solid waste landfills are the third-largest source of human-related methane emissions.
Methane may be a potent climate pollutant, but it is also short-lived – it breaks down much faster in the atmosphere than carbon dioxide. This means that cutting emissions today from sources such as food waste can deliver climate benefits within decades, acting as an “emergency brake” on global warming.
Less food waste means less methane
The most effective way to reduce methane from food waste is to stop food from being wasted in the first place. That is the goal of the Food Waste Breakthrough, which aims to halve food waste by 2030 and cut methane emissions by up to seven per cent.
Several nations have embraced this philosophy. Brazil is focused on reducing waste before it reaches the bin through two national waste management plans. Meanwhile, in the city of Rio de Janeiro, UNEP is working with municipal officials, schools, communities and food-related businesses, like supermarkets, to reduce food waste.
As well, in Kenya a new initiative supported by the UNEP-convened Climate and Clean Air Coalition is recovering surplus food from across the agricultural value chain and redirecting it to early childhood education centres in underserved communities.
What about food scraps that cannot be prevented?
Food waste only produces methane when deprived of oxygen. Properly separated from other rubbish and composted in an oxygen-rich environment, organic matter breaks down into carbon dioxide – still a greenhouse gas but one that warms much less than methane over the short term.
In Africa, where more than half of municipal solid waste is organic, 11 governments with funding from the UNEP-convened Climate and Clean Air Coalition have committed to reducing methane emissions by incorporating waste pickers into the formal waste management system, training them on how to sort and compost organic waste. Not only has this initiative improved the livelihoods of waste pickers, it has also led to the establishment of community composting sites and raised public awareness on the importance of waste separation.
As an alternative to composting, black soldier flies can be used to recycle organic material. In many parts of the world, specialized facilities breed the flies, which in their larval stage consume food waste. Once they become adults, the flies die quickly and can be used in high-protein animal feeds. Black-soldier-fly-based waste management is being used villages and cities in countries like Uganda and Malawi.
Momentum is growing but world needs to move faster
In 2019, the UN General Assembly proclaimed September 29 as the International Day of Awareness of Food Loss and Waste.
Co-facilitated by UNEP and the Food and Agriculture Organization (FAO), the day marks a global shift towards recognizing food waste as a collective problem, one the impacts both the sustainability of food systems and the climate on which humanity depends.
Through the Declaration on Reducing Methane from Organic Waste, launched two years ago, more than 60 countries pledged to cut waste-sector methane emissions by 30 to 35 per cent below 2020 levels by 2030. They also committed to tackling the root causes of methane emissions by prioritizing waste prevention and by converting organic waste into compost or biogas.
“Rapidly scaling food waste prevention efforts on an international level could deliver substantial methane reductions, even within the decade,” says UNEP’s Krause. “Focusing on food is one of the easiest and quickest ways to tackle warming, and the climate gains could be tremendous. But to take full advantage of this opportunity, we have to move faster.”
The Food Waste Breakthrough
At the 30th United Nations Climate Change Conference in Belém, Brazil, UNEP and its partners launched the Food Waste Breakthrough, bringing together governments, businesses and cities to halve food waste by 2030 and cut methane emissions by up to 7 per cent. Brazil is a country champion, putting food waste prevention into practice through national policy and city-level action. Fellow country champions Japan and the United Kingdom of Great Britain and Northern Ireland have achieved food waste reductions of 53 per cent and 22 per cent respectively, showing what policy, partnerships, strong data systems and changes in consumer behaviour can deliver.
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