Joseph Poore
BBC future
Consuming foods that produce a low amount of carbon helps reduce emissions, but some foods can actually even absorb carbon from the atmosphere, leaving a better climate behind.
We all know that production of most food creates greenhouse gas emissions, causing climate change.
These emissions come from hundreds of different sources, including tractor fuel, fertilizer, and bacteria in cow intestines.
Food production makes a quarter greenhouse gas emissions produced by humans.
However, there are foods that remove more greenhouse gases than they emit, often referred to as "carbon negative".
It leaves behind a better climate than the one it found.
Greater production and consumption of these foods could help reduce the carbon footprint of what we eat, and in some cases, restore ecosystems in the process.
As plants grow, they take in carbon dioxide (CO2) from the air, but when we (or animals) metabolize these plants, that CO2 is usually released directly into the air.
Due to current emissions, we must permanently remove carbon from the atmosphere, storing it deep in the sea, rocks, soil or trees.
There are few food products and manufacturing practices that do this.
Moreover, it is already possible to convert your entire diet to carbon negative, although in today's world this would require significant changes in the diet of most people.
Seaweed
As seaweed and other microalgae grow, they absorb CO2.
Seaweed parts are separated and sink to the deep seabed where some of that carbon is stored.
These removals are relatively poor-quality per kilogram of seaweed.
For seaweed-based food to be carbon negative, the supply chain must be very carbon efficient, with minimal transportation, packaging and processing.
Locally sourced seaweed therefore has the potential to be carbon negative (although this represents a minority of cases today).
However, buying seaweed can provide encouraging the restoration of vast areas of seagrass forests that have been destroyed.
It's an environmental benefit that goes beyond climate change mitigation.
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Bacterial products
Bacteria that break down methane They can be found in several different environments that consume it to obtain energy.
This is very useful because methane is a powerful greenhouse gas.
Every kilogram of it causes 30 times more warming from CO2 over a hundred-year period.
If we eat these bacteria, we metabolize them, emitting CO2.
Therefore, eating products containing these bacteria would convert a powerful greenhouse gas (methane) into a much less powerful gas (CO2).
Bacteria also require other nutrients, such as nitrogen and phosphorus.
But research shows that they can use processed nutrient-rich wastewater streams, such as food waste or animal manure, as a food source.
Products from these bacteria, such as protein powders or meat substitutes, tend to be extremely carbon negative, although they are not available in stores today.
However, in 2023, Finnish solar food launched ice cream in Singapore that contains protein made from different types of bacteria, showing that it would a market for bacterial food products could exist.
Blueberry and celery
In wet peatlands, organic carbon can be accumulates faster than it decomposes and there are few products that can be grown on such surfaces.
Among them are blueberries, cranberries and celery.
Food grown in this way has potential to be carbon negative, if its supply chains also become highly carbon efficient.
This is not usually the case for fresh blueberries, which are often packaged in plastic and shipped by airplane. around the world, from countries like Peru, which is why they become food with an extremely high carbon footprint.
While carbon-negative peatland products do exist, they are very rare and difficult to find in stores at the moment, but it is another area to look into.
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Nuts, olives and citrus fruits
Planting trees on agricultural land stores carbon.
In the past 20 years, the global area under nut trees has doubled, and much of this expansion has occurred on arable land.
Even when you factor in the entire supply chain, the typical nut product you buy in stores today, removes about 1,3 kilograms of CO2.
These removals continue until the trees reach maturity, usually around their 20th year.
If they are used to make long-lasting wood products at the end of their life, this carbon can remain stored for much longer.
Regeneratively grown food
Many regenerative practices, such as tillage or planting hedges, can increase the amount of carbon stored in soil or vegetation.
For example, British regenerative tillage company Wildfarmd says it is removing about 1,5 kilograms of CO2 for every kilogram of wheat which are grown by the producers with whom it collaborates.
Some companies with carbon-efficient supply chains are already claiming to be converting their own products into carbon-negative ones.
Brewery Gypsy Hill in London, for example, claims to produce carbon-negative beer and has done a massive life cycle assessment that supports this.
However, for foods with high emissions, such as beef, Research has shown that it is unlikely that regenerative practices can achieve carbon negativity.
Some regenerative practices can increase emissions elsewhere in the food system.
An Argentine farm, where cattle graze on bushes at a lower intensity, says its beef removes 0,3 kilograms of CO2 per kilogram.
To achieve this, 500 square meters of pasture and arable land are needed per kilogram of beef.
If every beef farm used that much land, we would have to convert another three billion hectares of land (an area the size of Africa) into arable land to meet current demand for beef.
The need for carbon labels
It's very difficult to have carbon negative food today, but it's starting to be solved.
Massive carbon monitoring and labeling schemes, covering the full life cycle of a product, are being implemented worldwide.
In New Zealand, farms now have to more own greenhouse gas emissions, and in France, the government plans national implementation carbon capture.
Once these programs are fully implemented and supported by law, it will be much easier for everyone to recognize carbon negative foods.
Earth-saving food
Despite their potential as carbon-negative food products, they may always make up only a fraction of our diets.
There are not enough products with carbon-negative potential, and regenerative practices probably cannot eliminate high-emission foods.
We also need other strategies for carbon negativity.
If we stop we cultivate the land, it will likely return to its previous state of forest landscape or natural grassland.
If you can produce the same amount of food with less land, the land that is freed up will most likely absorb carbon.
One way to save land is to increase its yields: to produce more on the same surface area.
But the increase in yield is mostly only a few percent per year at best, and not nearly enough to save enough land to make the product carbon negative.
That requires something much stronger.
Some products use so much land compared to their replacements, that their country could actually create negative emissions.
By saving that land, you free up the land for vegetation to re-grow, which will then absorb carbon from the air.
On average, for example, beef uses 100 square meters of land per 100 grams of protein, while plant-based foods, such as beans or tofu, use about five square meters for the same amount of protein.
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An analysis using a leading climate model showed that if we all stopped consuming animals and permanently switch to plant-based foods, we could restore 3,1 billion hectares of arable land such as forests and natural grasslands.
That's an area the size of the US, China, the EU and Australia combined.
If you looked at our planet from space, it would be transformed.
It would be removed. eight billion tons of CO2 every year over the next hundred years or so, as vegetation grows again and carbon in the soil re-accumulates.
This huge amount of carbon removed would eliminate all food emissions and make our diet carbon negative.
On average across the world, our average food-related emissions would go from around 2.000 kilograms of CO2 equivalent per year to -160 kilograms of CO2 equivalent per year.
Carbon capture and new technologies are important for our shift to carbon negativity.
But shifting from products that use a lot of land (usually meat and dairy) to those that require less land (mostly plant-based foods) is probably the most effective way to turn our diets into carbon negative.
* Joseph Put is director of the Oxford Martin Program on Food Sustainability and studies the environmental impact of global agriculture and how to reduce it
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