The foods that reverse climate change 396k1t

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% 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 s for 70% 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. It contains an assortment of microbes that help them extract as many 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.

"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, as Nielsen explains to James Wong in the video below, for many people giving up beef is not a reasonable solution.

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 crops 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.

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.

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 s 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 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. Watch the video below to find out more about how this can help to fix more carbon into the soil.

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" 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.