According to the Intergovernmental Panel on Climate Change (IPCC), food waste is one of the largest “invisible” sources of greenhouse gases. It is estimated that up to 8 % of global emissions is directly or indirectly connected with what ends up in the trash. In practice, this means that if food waste were a separate country, it would be classified as the world's largest emitters – right after the USA and China.

One of the biggest problems is not so much the waste of food during production or distribution, but its ending up in landfills. Organic matter such as food scraps, fruit and vegetables decompose in landfills without access to oxygen, creating methane – a gas that has a short-term warming potential up to 80 times higher than carbon dioxide (CO₂).

Composting as a solution – but at what cost?

One of the main climate solutions that cities and municipalities are implementing is organic waste disposal to the curb – similar to the separate collection of plastics or paper. This waste is then processed by composting or in biogas plants, thus preventing it from being disposed of in landfills.

However, a recent study has shown that such programs also have their limits. An analysis of households involved in the expansion of organic waste programs revealed that:

• Households increased their waste disposal by 45 %, which shows that people are willing and able to sort more.
• The cost of these programs however, they were nine times higher than the social benefit in the form of reduced methane emissions.
• On average, the cost of avoiding one ton of CO₂ equivalent emissions in the US has climbed to 478 USD/ton.

For comparison: international climate policies consider effective solutions to be those that cost approximately $50–100/ton CO₂e.

Why are the results so different?

Researchers emphasize that cost estimates are very heterogeneousSome municipalities, especially large cities, already have landfills with systems for methane captureIn such cases, the benefit of expanded composting is relatively small because methane from landfills is already largely captured and used for energy production.

On the contrary, in smaller cities or regions without modern technologies, every kilogram of waste is landfilled significantly higher methane potentialThere, expanding composting would have a greater climate impact, although still at a higher cost than alternative measures.

What does this mean?

The results show that Composting alone is not a universal solution to the climate crisisThe study authors warn that the climate benefits of organic waste programs are difficult to defend if they are evaluated solely through reductions in methane emissions.

Does this mean we should stop composting? No. Its benefits are many-sided:

• reduces the volume of waste in landfills,
• improves soil quality and water retention,
• enables the production of biogas as a renewable energy source.

However, from a climate investment perspective, cities and countries should carefully consider: where expanding these programs makes the most sense – and where it is better to invest, for example, in preventing food waste itself, in modernizing landfills, or in methane capture technologies.

Global picture: we need comprehensive solutions

Food waste is a reflection of our inefficient consumption. Solving it with just one measure is not enough. The greatest climate sense is:

1. Preventing food waste already in the production, distribution and consumption stages.
2. Improving warehousing and logistics in developing countries, where up to a third of the harvest rots before it reaches consumers.
3. Landfill modernization and expanding methane capture.
4. Sensible deployment of composting programs where they will bring real benefits at reasonable costs.

The climate crisis requires solutions that are effective, systemic and financially sustainable. Food waste clearly shows us that The fight against emissions is also a fight for the meaningful use of resources – and that not every ecological measure is automatically the best climate solution. Co2AI