Can Our Diet Choices Help the Climate? The Science of Carbon-Negative Eating

While most foods contribute to greenhouse gas emissions, some can actually absorb carbon from the atmosphere, improving the climate. These "carbon-negative" foods could help reduce our environmental impact and even restore ecosystems.

Plants naturally remove CO2 from the air as they grow. However, to combat climate change effectively, carbon must be permanently stored in soil, trees, or the ocean. Some foods and farming methods help achieve this, making it possible—though challenging—to create an entirely carbon-negative diet.

Kelp: The Ocean’s Carbon Sponge

Kelp and other macroalgae absorb CO2 as they grow. When parts break off and sink to the deep ocean, some carbon remains stored. However, for kelp-based foods to be truly carbon-negative, they must have low-impact supply chains with minimal transport and processing.

Methane-Eating Bacteria: A Future Superfood?

Methane-oxidizing bacteria consume methane, a gas 30 times more potent than CO2. Eating these bacteria (e.g., in protein powders or meat alternatives) converts methane into CO2, significantly reducing its warming effect. Though not yet widely available, bacterial-based foods could be a future climate-friendly option.

Carbon-Storing Crops: Blueberries, Celery, and Tree Nuts

Some foods grown on restored wetlands, such as cranberries and celery, can accumulate carbon in peatland soil, making them potentially carbon-negative. Similarly, nut and olive trees absorb CO2 as they grow, storing it in their wood. However, supply chain factors like transportation and packaging can impact their overall carbon footprint.

Farming methods that increase soil carbon—such as no-till agriculture and planting hedgerows—can help remove CO2. Some farms already claim to produce carbon-negative products, like beer, by following these practices. However, high-emission foods like beef are unlikely to ever become carbon-negative due to their large land requirements.

The Role of Carbon Labelling

Identifying carbon-negative foods is difficult, but new labeling initiatives are emerging. In New Zealand, farms must report their emissions, and France is implementing national carbon labels. These efforts will make it easier to choose climate-friendly foods.

On the other hand, the most effective way to make diets carbon-negative is by replacing land-intensive foods (such as beef and dairy) with plant-based alternatives. A global shift away from animal agriculture could restore 3.1 billion hectares of farmland to natural ecosystems, removing massive amounts of CO2 over time.

Source: Joseph Poore, Director of the Oxford Martin Programme on Food Sustainability. January, 2025.