Global warming: “carbon-negative” foods that help reverse climate change

When plants grow, they take in carbon dioxide (CO2) from the air, but when we (or animals) metabolize them, this CO2 usually returns directly to the atmosphere.

However, due to continued emissions, we need to permanently remove carbon from the atmosphere, storing it in the deep sea, in rocks, in soil or in trees.

There are some food products and production practices that achieve this. In fact, already It is possible to make your entire diet carbon-negativealthough in today’s world it would require substantial changes in the way most people eat.

As they grew up, Kelps and other macroalgae absorb CO2. Some parts of these algae break off and descend to the ocean floor, where some of that carbon is stored.

These amounts are relatively small per kilogram of algae, so for algae-based foods to be carbon negative, the supply chain has to be very carbon efficient, with a minimum transportation, packaging and processing.

Therefore, locally sourced kelps have the potential to be carbon-negative (although this represents the minority of cases today). However, purchasing seaweed can be a incentive to restore the vast areas of kelp forests that have been destroyed; an environmental benefit that goes beyond climate change mitigation.

Methanotrophs are a group of bacteria found in various environments that consume methane to obtain energy. This is very useful because the Methane is a powerful greenhouse gas, and each kilogram causes a warming 30 times greater than that of CO2 on a time scale of 100 years.

If we eat these bacteria, we metabolize them, and release CO2. Therefore, eating products containing these bacteria would convert a powerful greenhouse gas (methane) into a much less potent one (CO2).

Bacteria also need other nutrients, such as nitrogen and phosphorus, but research shows that nutrient-rich waste streams, such as food waste or animal manure, can be used as a nutrient source.

Products derived from these bacteria – such as protein powders or meat substitutes – are very likely to be carbon-negative, although there are none in stores today.

However, in 2023, Finnish Solar Foods launched an ice cream in Singapore that includes a protein made from another type of bacteria, showing that there could be a market for food products of bacterial origin.

In wet peatlands, organic carbon can accumulate faster than it decomposes. Some products can be grown there, such as different types of blueberries and celery. Foods grown in this way therefore have the potential to be carbon-negative, if their supply chains are also made highly carbon-efficient.

This is not usually the case with fresh blueberries, which are often packaged in plastic and flown from countries like Peru, making them high-carbon foods. Although carbon-negative peat products do exist, they are currently very rare and difficult to find in stores.

Plant trees in farmland stores carbon. Over the past 20 years, global nut area has doubled, and much of this expansion has occurred on cropland.

Even taking the entire supply chain into account, the typical nut product purchased in stores today removes around 1.3kg of CO2 per kg.

These absorptions last until the trees reach maturity, usually at 20 years. If trees are used to make durable wood products at the end of their useful life, this carbon can remain stored for much longer.

Many regenerative practices, such as not tilling the soil or planting hedges, can increase the amount of carbon stored in the soil or vegetation. For example, British regenerative agriculture company Wildfarmed reports the elimination of 1.5 kg of CO2 for every kg of wheat produced by the farmers it works with.

Some companies with carbon-efficient supply chains already claim to have made their products carbon-negative. London brewer Gipsy Hill, for example, says it produces carbon-negative beer, and has carried out a robust life cycle assessment to back it up.

However, in the case of foods with high emissions, such as beefresearch has shown that it is Regenerative practices unlikely to achieve carbon negativity. Additionally, some of those practices can increase emissions in other parts of the food system.

For example, an Argentine farm, where cattle graze at low intensity among bushes, certified that its beef eliminated 0.3 kg of CO2 per kg. To achieve this, he needed 500 square meters of pasture and cropland per kilo of meat.

If all beef farms used this much land, we would need to convert another 3 billion hectares (an area the size of Africa) to cropland to meet our current demand for beef.

In general, it is very difficult to identify carbon-negative foods today. But that is being solved. Robust safety systems are being implemented around the world. carbon tracking and labelingwhich take into account the complete life cycle of the products.

For example, In New Zealand, farms must quantify their greenhouse gas emissions, and in France, the government is planning to implement carbon labeling nationwide.

Once these systems are fully operational and supported by regulation, it should be much easier for everyone to identify carbon negative foods.

Despite all the potential of carbon-negative foods, they may always constitute only one small part of our diet; There simply aren’t enough products with carbon-negative potential, and regenerative practices probably can’t offset high-emitting foods. So we also need other strategies for carbon negativity.

Yeah we stopped cultivating the landit will most likely become a forest or natural grassland again. So if the same amount of food can be produced with less land, the land that is freed up will likely absorb carbon.

One way to save land is increase performance: produce more on the same amount of land. However, yield increases are typically a few percentage points per year at most, and are nowhere near enough to save enough land to make a product carbon negative. Something much more powerful is needed.

Some products use more land compared to their alternatives that replacing them can generate negative emissions. This is because saving land frees up land for revegetation, which would absorb carbon from the air.

For example, beef takes up an average of 100 square meters of land for every 100 grams of protein, while plant foods, such as beans or tofu, take up about 5 square meters for the same amount of protein.

An analysis carried out with a leading climate model revealed that if we all stopped consuming animals and permanently switched to plant-based diets, we could return 3.1 billion hectares of land from cultivation to forests and natural grasslands.

This is an area the size of the United States, China, the European Union and Australia combined.

If we looked at our planet from space, it would transform. 8 billion tons of CO2 would be removed per year for about 100 years, as vegetation regrew and soil carbon reaccumulated.

This huge amount of carbon removed would offset all emissions from food and would make our diets carbon negative. Per person, on a global average, our average food-related emissions would go from about 2,000 kg of CO2 equivalent (CO2eq) per year to 160 kg of CO2eq per year.

Although carbon-informed labeling and new technologies are vital to our shift towards carbon negativity, shifting from land-intensive products (generally meat and dairy) to land-low-using products (generally plant foods) is probably the most effective way to make our diets carbon negative.

* Joseph Poore is director of the Food Sustainability Program at Oxford Martin. Research the environmental impact of global agriculture and how to reduce it.

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