The foods that reverse climate change

The way we produce food has accelerated climate change, but can sustainable production methods help to reverse it?

Ocean Rainforest
Seaweed harvested by Ocean Rainforest, a company in the Faroe Islands that grows premium quality seaweed for sale and for research. Image: BBC

In a greenhouse-sized plastic box within a cattle shed in Denmark stands Daisy – farming’s hope for a sustainable future. Daisy has everything she needs. Food is carefully measured and delivered to her and water is on hand. She won’t be detained for long either, just long enough for her food to have the desired effect – we need Daisy to start burping.

Overseeing the cow’s welfare is Mette Nielsen, a professor in animal sciences at Aarhus University, who explains the purpose of Daisy’s confinement. Inside the box, every burp, belch and gaseous emission can be measured. Cows’ burps are rich in methane, a greenhouse gas, and only by recording them in this way can we start to unravel how to mitigate the damage livestock farming can do to the climate.

The cattle industry contributes 40 per cent of all methane emissions from food production. They’re not the biggest contributors, that title goes to rice, but researchers are keen to clean up their act. It is part of a new wave of farming methods and high-tech solutions aimed at turning farming from being a climate change problem to a part of the solution.

Agriculture as a whole, and the deforestation that sometimes accompanies it, contributes nearly a quarter of greenhouse gas emissions. Farming also accounts for 70 per cent of water usage worldwide.

This is not only changing the climate, but also affecting our ability to grow food in the first place. Drought, flooding, high temperatures and rising sea levels are turning productive parts of our planet into places that are incapable of growing food.

But what if we could produce food in a way that not only reduces the impact farming has on the planet, but could even be beneficial for the climate.

Cattle are ruminants, meaning part of their digestive system (the rumen) is designed to ferment low-nutrition foods like grasses and leaves. Inside their digestive system, however, is an assortment of microbes that help them extract as much nutrients as they can from their food. Unfortunately, some of these microbes produce methane that is then released from the rumen. And it is here that Nielsen has turned her focus.

BBC Nielsen cow

Mette Nielsen, a professor in animal sciences at Aarhus University, and BBC Follow the Food presenter James Wong with a cow in a box. Image: BBC

“It’s not the cow that produces the methane, it’s these microorganisms called Archaea,” she says. “So if we could just block this process and persuade the Archaea not to produce the methane we would basically have a climate neutral cow.”

While some might argue that giving up cattle farming altogether might be the best way to mitigate climate change, for many people giving up beef is not a reasonable solution.

Nielsen and other researchers are instead interested in the methane-inhibiting properties of an unlikely source: seaweed. Asparagopsis, a warm-water seaweed species grown in Australia, contains a compound called bromoform that when used to comprise as little as 2 per cent of a cow’s diet, reduces the animal’s methane emissions by up to 98 per cent.

There are, however, questions over whether cows like the taste of bromoform – in some experiments livestock reduced the amount they ate after the seaweed was introduced to their diet. Bromoform can be carcinogenic in humans, although there it is little research to show whether this is transferred into any meat and diary products. Many people are also already exposed to low levels of bromoform through tap water. 

While research is ongoing to prove that a seaweed cattle feed additive is safe and effective at reducing methane emissions in cows, one green application is beyond doubt – as a human food.

On the south-west coast of Vancouver Island in British Columbia, Canada, scientists and farmers at Cascadia Seaweed are working to grow their seaweed farms to be the largest in North America. Not technically a plant, the macroalgae is one of the few vegan sources of the vitamin B12 and only requires the sea and sunlight to grow.

The cultivation process begins by harvesting reproductive patches, called sori, from blades of seaweed and bringing them to a nursery. Once there, spores are released and attach to spools of twine. After 45 days, the seedlings are developed enough to be deployed at sea where they are attached to cultivation lines and grow into kelp. “We only use local species, we don’t do anything invasive, and we collect our sori in the same areas where we plant seaweed,” says Cascadia Seaweed’s chief executive, Mike Williamson.

Not only does seaweed farming emit few greenhouse gases, seaweed is 20 times more effective at sequestering carbon than land plants, according to a 2019 study by Harvard University. “When seaweed grows, a certain amount of it sloughs off into the deep ocean and stays in the sediment forever,” says Williamson. “That’s permanent carbon sequestration.”

At the same time as it stores carbon, seaweed also absorbs excess nutrients from fertilisers that get washed into rivers and the oceans. While fertilisers have helped to boost crop yields on land, excess amounts washed into waterways can alter habitats and damage marine life. At the same time, synthetic fertilisers release potent greenhouse gases into the atmosphere during their manufacture and once they are on the fields.

One solution is to use farming techniques that use these chemicals more carefully. New technology is enabling large scale farmers to reduce their use of water, fertilisers, pesticides and herbicides while at the same time boosting their profits. Precision agriculture, as it is known, aims to target the right amount of water and chemical treatments to only where they are needed, avoiding widespread spraying and wastage.

One such development is the use of silica nanoparticles that release fertiliser and pesticides at a slow, steady rate, reducing the amount and frequency with which they’re used. Some of these solutions also contain microorganisms to help jumpstart soil regeneration.

Alternatively, Blue River Technology hope to reduce chemical usage with their See and Spray technology, and have partnered with agricultural machinery manufacturer John Deere to bring it to life. By using artificial intelligence to selectively target weeds with herbicide, they’re able to avoid indiscriminate spraying that blankets an entire crop and its surrounding soil with chemicals.

Blue River Technology say they spray between 10 per cent and 30 per cent of the volume of chemicals normally used in traditional farming methods. Cameras attached to a self-propelled sprayer connect to computer processors that use a machine learning algorithm to recognise the captured image in milliseconds. Based on this information, the machine determines whether to spray the herbicide or not. The AI is trained for a couple of seasons so it can recognise the weed and tell it apart from the crop. So far has been used in fields of corn, cotton and soy.

If successful, See and Spray could potentially be a significant cost-saving measure for farmers given that in 2019, almost US$33bn (£25bn) was spent across the globe on herbicides and that number is increasing. At the same time, it helps to mitigate the effect of surplus chemicals on the environment.

But a new wave of farmers are hoping to cut out their use of artificial fertilisers and pesticides altogether by allowing the natural microorganisms that live in the soil to flourish instead.

“Regenerative agriculture in its basic form is not disturbing the soil… it’s leaving that life in the soil where it is and just feeding it,” says Tom Morphew, chief executive at Full Circle Farms in Sussex, UK.

Regenerative agriculture in its basic form is not disturbing the soil… it’s leaving that life in the soil where it is and just feeding it.

Tom Morphew, chief executive, Full Circle Farms

While industrial farming has brought about dramatic increases in crop yields and made it possible to feed a rapidly growing population, some practices can degrade the soil. Much of this disruption comes from the use of chemical fertilisers, herbicides, and insecticides, which can affect the natural balance of fungi, bacteria and other organisms living in the soil, says Morphew. “We’ve broken that system of life in the soil. There’s nothing holding our soil together.”

This has another unfortunate side-effect – soils can start to release carbon into the atmosphere. Harmful agricultural techniques have “shifted the global cropping soil from a carbon sink to a carbon source, contributing to the global climate crisis”, says Yichao Rui, a soil scientist at the Rodale Institute, a non-profit based in Pennsylvania, US, that supports research into organic farming. Now “we need to maximise the carbon inputs and minimise the carbon outputs”, says Rui.

Maximising the amount of carbon that can be stored in the soil requires keeping fields covered with living plants all year long to encourage deep root growth, which helps to transfer the carbon gathered from the atmosphere by the plant to the dirt. Soil-dwelling fungi feed on the carbon delivered by the roots and provide the plants with other nutrients in return. Applying microbe-rich compost to topsoil also helps. “Soil microbes play a very important role in decomposing these carbon inputs from plants and converting them into the form that can be sequestered,” says Rui.

Regenerative farmers like those at Full Circle Farms avoid excessive tilling to help maintain the soil structure and the fungal communities living in it. This, together with other practices such as using cover crops and companion planting, are aimed at helping turn the soil back into a carbon store again. There are some doubts, however, about how much of an impact these approaches can have in terms of pulling carbon back into the soil, particularly over the long term.

But it may be possible to increase the amount of carbon that can be stored in the soil. With the help of precision gene-editing techniques, some researchers are developing new varieties of crops capable of sucking up more carbon from the atmosphere. 

It would be difficult to eliminate agriculture’s environmental impact entirely, even in light of these advancements. Some scientists believe the answer might involve taking farming indoors or underground, where leafy vegetables grow without soil or sunlight. Indoor farming not only eliminates arable land use, but requires no pesticides and significantly reduces water usage.

Crops grown in this way are watered using aeroponics, where plants grow roots through cloth, or hydroponics, which uses water in place of soil. While innovative, it isn’t yet feasible to apply these techniques to staple crops that require a lot of space, like cereals, and the approach is relatively energy intensive.

An alternative may be seawater greenhouses, which use only seawater and sunlight to grow food, even in inhospitable desert environments. Using seawater instead of freshwater relieves some of the environmental stresses of growing veg in this energy intensive way.

If seawater can be used to grow vegetables, could we create edible commodities out of other unlikely sources?

Outside of Toronto, Canada, Entomo Farms has a vision to use cricket protein as a global food security and environmental solution. Crickets contain as much protein per 100g as beef along with a variety of other key nutrients, according to a report on edible insects by the UN Food and Agriculture Organization (FAO), and up to three times as much B12. “Research shows that not only are those concentrations far higher, but they are more absorbable,” says Entomo Farms co-founder, Jarrod Goldin.

And unlike beef and pork, insects like crickets emit comparatively low greenhouse gases and require very little feed, land, or water, according to the FAO. The challenge will be making insect protein palatable to unaccustomed taste buds.

Another approach is seeking to use greenhouse gases themselves in our food. Carbon capture technologies make use of CO2 captured from a concentrated source, such as a cement plant, or direct air capture which removes carbon dioxide from ambient air. The captured CO2 can be stored permanently in the Earth. But when carbon capture technology isn’t used to sequester carbon, the CO2 can be repurposed to create products like vodka and sparkling water.

Coca-Cola has partnered with Climeworks, a Swiss direct air capture company, to use captured CO2 to give the sparkling water Valser its fizz. Once the bottle is opened the CO2 is released back into the air, but the alternative to using captured CO2 in drinks is to take natural gas safely stored underground or use byproducts from manufacturing. Air Company, a New York-based startup, recently launched Air Vodka, the first spirit in the world to use ethanol made from captured CO2. The CO2 is collected and combined with renewable hydrogen produced by water electrolysis to create the alcohol.

While vodka may not solve global food security issues, these consumer products are helping to create demand for carbon capture technology, which if scaled up could play a role in reducing CO2 emissions. This could be the thin end of the wedge for new, green foods.

There is no silver-bullet approach to making agriculture more sustainable, but those at the vanguard of change are proving there are solutions. The combination of technological innovation, new ways of farming and changing consumer demand will create a meaningful shift in the world’s food footprint. The tools, technology and practices that could completely transform food production from an environmental burden to a green solution are coming. Whether we use them is up to us.

In a new eight-part multi-platform series, Follow the Food, sponsored by CortevaAgriscience™, BBC World News and explore the stories behind feeding the world’s ever-growing population.

Follow the Food will air at 0130 and 0830 GMT on Saturdays and 1430 and 2030 GMT on Sundays on BBC World News for eight weeks from 28 January 2021.

Audiences can also visit for special features, and @BBC_Future for the latest from the series.

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