Agriculture, Forestry + Other Land Use

Together, Agriculture, Forestry and Other Land Use (AFOLU) account for around 18.4% of the world’s annual GHG emissions.

Those emissions include not just carbon dioxide (CO₂) (mainly from clearing tropical forest to make pasture for cattle, and from the decay of organic matter in soil), but also nitrous oxide (N₂O) (produced by runoff from fertilizer and by manure), and methane (CH₄) (produced by cattle digestive systems, by the decay of organic matter in submerged rice patties, and by many other sources).

We cannot limit warming to 1.5 or even 2 degrees C without cutting these emissions sharply. In fact, if we continue with agricultural business-as-usual, then even if we were to instantly cut all our other emissions (from industry, transportation, and so on) to zero, AFOLU emissions alone would be enough to warm the world well beyond 1.5 degrees, and bring it close to 2 degrees. So, we need to cut AFOLU emissions dramatically.

Source: Our World in Data

Cutting these emissions would be a very difficult task even if everything else stayed the same. But the world is changing in ways that will make the task much harder.

1. The global population is growing. Around 8 billion people are alive today. Demographers expect that number to peak at about 10.4 billion around 2086, before beginning slowly to decline.
2. The number of people around the world who can afford to eat diets heavy in meat and dairy is rising rapidly, as hundreds of millions of people climb out of poverty and into the global middle class each decade.
3. The climate is already changing. With each passing decade, droughts, floods, and other extreme weather events will put increasing stress on crops and livestock, reducing yields.

So, we need dramatically to cut agriculture and land use emissions even as we feed more people, and more people who want to eat meat, in a world of increasing climate disruption.

And that’s not all. We need to do all this while working to solve two other environmental crises that our current agricultural system has caused.

• The first is the destruction of habitats, ecosystems, and species, as we convert forests, wetlands and savannahs into cropland and pasture.

Deforestation in the Amazon. Credit: Wikimedia

• The second is the pollution of waterways and oceans by fertilizer runoff, which creates algal blooms that deprive other marine creatures of oxygen, resulting in huge ocean dead zones each year.

Dead zone in the Gulf of Mexico. Credit: Phys.org

All of this means that climate solutions in the AFOLU sector will be very different from solutions in the energy sector. In the energy sector, there’s one big thing we need to do: stop burning fossil fuels. And there’s one general recipe for doing most of it: we need to switch to powering things with clean electricity, either directly (e.g. using heat pumps to heat buildings) or indirectly (e.g. using electricity to produce e-fuels for long-haul aviation).

In the AFOLU sector, we will need many different solutions. (We will discuss only some of the biggest on this page.)  As diverse as these solutions are, many of them do share a common theme: we need to produce more calories and protein per acre of land, more per input of water, more per input of fertilizer, more per unit of fertilizer runoff, and more per unit of GHG emitted. To see why this is the case, we need to start by looking at the way humanity uses land.

Land use, agricultural sprawl, and the consequences for biodiversity and climate

About 71% of the earth’s land is habitable – the other 29% consists in ice caps, deserts, glaciers, salt-flats, and the like. 1000 years ago, we used about 4% of habitable land for agriculture, and 96% was available to natural ecosystems and the species they contained. Today, humans use around half of all habitable land for agriculture – and that fraction is growing each year, as we convert forests, savannahs, and wetlands into pasture and cropland, especially in the tropics. In his brilliant book, Regenesis: Feeding the World without Devouring the Planet, George Monbiot calls this agricultural sprawl.

Agricultural sprawl is the main driver of earth’s biodiversity crisis. As we cut forests, drain wetlands, and plow savannahs under to make room for agriculture, we destroy whole ecosystems, and drive the animal and plant species that depend upon them for their habitats to extinction. We are doing this most in the world’s most biodiverse places, the tropical rainforests of Brazil, Indonesia, the Democratic Republic of Congo, Madagascar, and elsewhere. The IUCN Red List identifies 28,000 known species threatened with extinction. Agriculture is responsible for 24,000 of these. And rainforests contain many more species that have never been identified.

Agricultural sprawl also directly drives the climate crisis. The natural ecosystems that agricultural sprawl encroaches on are almost all carbon sinks. These include not only forests, which store carbon in living trees, but also peatlands, which store up the carbon from hundreds or even thousands of years of dead organic matter and prevent it from decomposing, and grasslands, whose deep-rooted perennial plants sequester large amounts of carbon underground. Even the most climate-friendly forms of “regenerative agriculture” manage to sequester only a fraction of the carbon sequestered by the much more diverse natural ecosystems they replace. Land that has already been converted to agriculture is land that could be a carbon sink if it were rewilded. And when new lands are converted to agricultural use, most of the carbon that they have been sequestering is released to the atmosphere. (This is why “agriculture, forestry, and land use” (AFOLU) has to be considered together as a single sector.) 

Meat

Many factors contribute to agricultural sprawl, but one is much bigger than any of the others: our appetite for meat.

(Credit: Our World in Data)

77% of agricultural land is devoted to feeding livestock – either by providing pasture, or by growing crops, like corn and soybeans, to feed to livestock. (33% of all cropland is for crops to feed to animals.) But livestock provides only 18% of the calories that humans consume, and only 37% of the protein. Beef alone is responsible for roughly half of the land used for US diets, and half of the emissions they produce – but it provides only 3% of the calories.

The main reason for this difference between the huge amount of land we use for cows and other livestock and the small contribution they make to human nutrition is that animals – especially “ruminant” animals like cows, sheep and goats – convert only a small fraction of the calories and protein that they eat into calories and protein that humans can eat as meat. This means that an enormous amount of land is needed to feed those animals enough to produce all the meat that humans consume. Producing 100 grams of protein from beef, for example, requires 48 times more land than producing 100 grams of protein from peas.

(Credit: Our World in Data)

This is why humanity’s appetite for meat is the primary driver of deforestation and habitat destruction around the world – most famously in the Amazon, where vast swathes of rainforest are burned each year in order to create pasture for cattle (which can then be sold as “grass fed” or “pasture raised”) and cropland on which to raise soy for cattle feed.

The chart below helps to give a sense of just how badly our demand for meat has crowded other animal species off the earth.  Our domesticated animals (mostly cows) together weigh twenty seven times more than all the wild land mammals left on earth put together.

Source: Visual Capitalist

Deforestation and habitat destruction are not the only ways that meat production contributes to the climate crisis.

• Bacteria in the guts of cows and other ruminant animals produce large quantities of methane – a powerful greenhouse gas – which these animals release by burping.
• Animal manure produces further methane emissions, and also produces 27% of anthropogenic emissions of nitrous oxide, another powerful greenhouse gas.
• Runoff from fertilizer applied to the crops used to feed animals is another large source of nitrous oxide.

Altogether, livestock production (including the deforestation and land use change it causes) is estimated to be responsible for 14%-15% of all anthropogenic GHG emissions.

These problems are large now, and they are getting larger as the global population grows and more people join the global middle class each year. As people climb out of poverty, they are able to move from the plant-based diets to which the global poor are limited, to diets with more meat and dairy. Something like 40% of the world’s population is expected to make this shift by 2050, increasing total global consumption of animal-based foods by 70%. If everything else stays the same, this would mean a dramatic increase in GHG emissions; and it would mean clearing an additional 1.5 billion acres of forests, savannas, and wetlands for crops and pasture – an area nearly twice the size of India – and driving thousands of the species that depend on them to extinction.

Solutions to agricultural sprawl

Shifting dietary choices

A natural place to start, in thinking about solutions to the problems that expanding agriculture poses for the planet, is with a hypothetical: if everyone in the world switched to an entirely plant-based diet, we could feed the world’s current population with only 25% of the land we now devote to agriculture.

Rewilding the 75% of current agricultural land that would be freed without animal agriculture would solve the biodiversity crisis, slash GHG emissions and create enormous new carbon sinks to pull CO₂ from the atmosphere. (In fact, A 2020 study in the journal Nature argued that rewilding just 15% of the highest-priority converted lands could avoid 60% of expected extinctions, and could sequester 299 gigatons of CO₂, which is 14% of total emissions since the Industrial Revolution.)  Even with population growth, eliminating meat consumption would allow us to use far less land, and emit fewer agriculture-related GHGs than we do now. And as we can see from the chart above, we could gain most of these benefits without going vegan or vegetarian, just by removing beef, mutton and dairy from our diets. This is because poultry and other non-ruminant animals are much more efficient than ruminants at converting the calories and protein they consume into calories and protein that humans can eat.

These are all excellent reasons for individuals to choose to eat less meat (especially red meat) and dairy. (In fact, as Saul Griffith points out in Electrify, this is one of only a handful of choices we can make as individual consumers that add up to something significant in the climate fight.) Moreover, there’s evidence that this choice can be contagious, and can lead to slow shifts in culture. This is especially true when it is not framed as an all-or-nothing choice between being a burger-a-day meat-eater or a “pure” vegan, but is instead framed as a choice to reduce meat and dairy consumption. (Some people who make this choice call themselves “reducetarians.”)  And in fact, in many rich countries, including the US and much of Europe, the number of people who choose plant-based diets is growing.)

As significant as these individual choices are, reductions in meat and dairy consumption occurring in the developed world are now vastly outweighed by the increase in meat and dairy consumption due to population growth and the growth of the global middle class, as hundreds of millions rise out of poverty. This is why statements about what would happen if the world went vegan (or even reduced meat consumption) are merely hypothetical: the world as a whole is rapidly moving in the opposite direction. Efforts to educate consumers all over the world about the environmental (and health) consequences of heavy meat consumption are certainly worthwhile. So are efforts to change cultural practices around meat more broadly – so that, for instance, beef might be thought of as a delicacy for special, festive occasions, rather than as daily staple. On an optimistic view, these might be able to slow the trend toward ever greater meat consumption. But it would be very unwise to bet that education and cultural change alone will stop these trends. And we need to stop them rapidly in order to stop biodiversity and climate disaster.

Alternative proteins for people and animals

Here’s a second hypothetical statement: if we had a source of protein that cost less than meat from livestock and tasted just as good, many people might eat it instead, at least some of the time. Many, many startups (and some already established, diversified food companies) are now trying to make this hypothetical real.

Plant-based proteins

Companies like Beyond Meat (first product launched in 2012) and Impossible Foods (first product launched in 2016) already produce well-known plant-based burgers and sausages that taste pretty good. These companies hope to bring down costs as they scale up production – but right now, they’re still significantly more expensive than animal meat, and most people think they’re not as tasty. So long as this is true, they’re unlikely to make much of dent in demand for animal meat. However, plant-based milk, cheese and yogurt are already cutting significantly into sales of dairy products from animals – making up 15.3% of US dairy sales in 2022, and achieving $21.6 billion of sales and globally. And while plant-based meat products are still a much smaller share of the total market, new generations of startups are innovating to create plant-based chicken, fish, eggs, beef, and more that will come closer to the cost and taste of animal products.

Growing plant-based meat :

• uses 47% – 99% less land per kg than meat from animals;
• uses 72% – 99% less water per kg;
• causes 51% – 91% less aquatic nutrient pollution per kg;
• emits 30% – 90% less GHG per kg.

Here are some of the hundreds of companies working to bring plant-based proteins to market:

(Scroll down in database to see more companies.)

This list is drawn from a database maintained by the Good Food Institute (GFI), a nonprofit think tank and network working to promote alternatives to animal protein by funding and sharing research in science, technology, and public policy, along with business innovation.

• Read GFI’s 2023 report on the state of the plant-based meat, egg, dairy and fish industry for an excellent introduction to what is happening in the field.

Cultivated Meat

Other start-ups are trying for something even more ambitious: they’re working to make real animal cells reproduce outside of an animal, in large, metal tanks called bioreactors, and then to assemble them (for instance, by 3D printing them onto “scaffolding” made of fungi) into steaks, or cuts of chicken or fish, or other kinds of meat. The great advantage of this “cultivated meat” is that it’s really meat, from the very same cells that animals are made of, and so it should taste the same. And whereas animals take months or years to grow, and crops take months, animal cells can double in twenty four hours. The disadvantage, for now, is that, while cultivated meat has already been produced successfully in small pilot facilities and served in a few restaurants, it is still very expensive; and as GFI explains in detail, a great deal of further scientific and technological work will be needed to produce it at a scale large enough to make a difference (and to bring costs down). No one has done this yet. But according to GFI, as of 2022, at least 156 publicly-announced companies are working on it. Here are companies drawn from their database:

• Read GFI’s excellent 2023 State of the Industry report on cultivated meat and seafood.

You might have seen recent, splashy headlines claiming that the cultivated meat could be worse for the climate than meat from animals. These were all based on a single, pre-print study that has not yet been through peer-review, and that is contradicted by many other studies. It is based on the assumption that cultivated meat will be produced using the same technologies that are used for biopharmaceuticals. However, technologists working on cultivated meat, and scientists studying their work, have pointed out that this assumption does not correspond to the plans or practices of the companies actually developing cultivated meat. (In part, this is because if cultivated meat were produced in this way at scale, it would forever remain too expensive to achieve any market share.)  Studies with more realistic assumptions estimate that cultivated meat could:

• use 95% less land than animal meat;
• use 78% less water;
• emit 93% less air pollution;
• emit 92% less GHG.

Several of the companies closest to bringing cultivated products to market are starting with hybrid meats, made of both plant-based and cell-cultivated ingredients. This approach can take advantage of many of the flavor and textural advantages of cultivated meat without yet solving all of the technological and cost challenges of pure cultivated meat.

Fermentation (Traditional, Biomass, and Precision)

A third approach is to cultivate microorganisms, such as bacteria, fungi, or microalgae to produce alternative proteins. We have done forms of this for thousands of years: in traditional fermentation, microorganisms process and modify some ingredient – as when bacteria turn milk into cheese or yogurt, or a fungus turns soy into tempeh. But in newer approaches, microorganisms are engineered to create entirely new foods or ingredients. This can take a number of forms.

• In modern biomass fermentation, the grown microorganism (for instance, microalgae) is itself the edible product. It may then be used as an ingredient in other foods – including in plant-based meat. For instance, MyForest Foods makes meatless bacon from mycelium biomass.
• In precision fermentation, the microorganism is not the ingredient itself, but it is used like a tiny factory to produce a protein, fat, enzyme, or other ingredient. The product can then be extracted and used as an ingredient in plant-based or cultivated meat, eggs, dairy, or seafood – or in other products entirely. For instance, Zero Acre Farms uses precision fermentation to create a cooking oil.
• (An approach related to precision fermentation is plant molecular farming, in which living plants, rather than microorganisms, are used as factories to produce proteins, enzymes, and so on. For instance, Nobell Foods uses soy plants to make vegetarian casein (a protein otherwise found in cow’s milk). While this is not fermentation, we are following GFI in grouping it together with precision fermentation, since both involve engineering living organisms to produce desired molecules.)

Fermentation opens exciting possibilities. As many as a trillion species of microorganism exist on earth, and the technology to fine-tune these microorganisms to produce specific, desirable outputs is advancing rapidly. We can tune microorganisms to produce not only proteins, but compounds that give foods the flavors and nutritional profiles we want. Microorganisms reproduce extremely quickly (whereas animal cells can take 24 hours to double in a bioreactor, bacteria can double in 20 minutes), so that in some cases they can be harvested every few hours, rather than in the months that it takes plant crops to grow. And while on many approaches microorganisms are fed with sugar or other plant biomass, companies like Solar Foods and Air Protein feed their microbes almost entirely with carbon dioxide captured from air and hydrogen gas produced by electrolyzing water. A recent study indicates that, even accounting for the land used by the solar panels that power this process, an approach like this could produce protein using thirty to sixty times less land than is needed even for soy protein. (And soy itself requires roughly seventy times less land than beef for the same amount of protein.)

Here’s a video from Air Protein laying out the company’s vision:

Microbial proteins are in early days; it’s hard to say if or when fermentation will produce products that can win enough consumers over to displace significant amounts of meat. But they don’t have to do that to have an enormous impact. If fermented protein can compete on price with plant-based proteins like soy, we could begin by feeding it to livestock, and it could free up some of the 33% of all cropland that we currently use to feed animals, as well as some of the 2.9 billion hectares we devote to pasture. Likewise, before it serves as a stand-alone dish on our dinner plates, microbial protein might serve as an important ingredient in our foods (especially processed foods), displacing both animal-based ingredients (including dairy and eggs) and plant-based ingredients like soy. Again, this could make significant inroads into our land-use and GHGs emissions.        

GFI identifies 126 companies working on fermented proteins in 2022. Here are some of them.

• Read GFI’s excellent 2023 State of the Industry Report on Fermentation: Meat, seafood, eggs and dairy.

⇒ Listen to this excellent, wide-ranging My Climate Journey podcast interview with Bruce Friedrich, the founder of Good Food Institute.In this interview, Friedrich explains GFI’s mission, and gives a great survey of the prospects for alternative proteins as a climate solution and the work that still need to be done to make it happen.

One of the most important points that Friedrich makes is that even though our food system as a whole is responsible for around a quarter of all GHG emissions, the pollution of waterways and oceans, antibiotic resistant bacteria that could cause a pandemic, and the extinction of countless species because of deforestation and habitat destruction, the amount of money we invest in solutions to these problems, including those that GFI champions, is a tiny fraction of the money we invest in climate solutions related to energy. The support that governments give to these solutions through public policy and the resources that universities and philanthropies put toward them is similarly tiny. If you’re looking for a way to have an impact on the climate fight, this is an excellent place to look, because it needs so much more attention, and so much more talent, than it currently receives. If want to learn more, GFI offers a free, five-session online course called “The Protein Transition: The science behind alternative proteins.” And if you’re a student, check out GFI’s excellent Student Resource Guide, as well as their page on how to establish a student group to press your university to support research on alternative proteins. And whether you’re a student or a professional, check out their alternative protein careers portal.

Strategies to reduce the impact of animal agriculture

Alternative proteins are moonshot efforts: if they can compete with animal products on taste and price, they could completely transform our agricultural system, and even our relation to the earth. But we do not know if, when, or how fully they will succeed. So, while we work hard on efforts to develop them, we also need to work on more incremental improvements to the food system at the same time. Here are three, important ways that we can reduce the climate and environmental impacts of the livestock we continue to raise.

Black solider fly larvae. Credit: UKTN

Startups Duckweed Bio and Lemna grow duckweed (also called lemna), an extremely fast-growing freshwater aquatic plant, as a way to produce high-protein animal feed using livestock manure as a nutrient source – preventing nutrient runoff and nitrous oxide and methane emissions from the manure in the process. (Another startup, Plantible Food, is working to use duckweed to make a high-protein ingredient in human food.)

Duckweed growing ponds. Credit: Plantible Foods

Both insects and duckweed grow far more quickly than crops like soy, using far less land and water and far fewer nutrient inputs, with much lower GHG emissions. If either or both these can scale to become an economical source of livestock feed, it could significantly reduce the impact of livestock on both biodiversity and climate.

Enteric Methane Reduction

The majority of the climate impact of cows and other ruminants comes from their digestive tracts. Microbes decompose and ferment food in ruminants’ stomachs, producing methane as a biproduct, which animals release into the atmosphere mostly by burping. This enteric methane is the largest source of emissions from beef production, and accounts for 3.7% of total global anthropogenic GHG emissions – a proportion set to increase as beef consumption rises.

Credit: The Breakthrough Institute

Start-ups are developing a number of ways to reduce enteric methane emissions. A number of startups like Blue Ocean Barns are working to find economical ways to grow and harvest a type of red seaweed called Asparagopsis taxiformis as a feed additive that disrupts the enzymes that produce methane in a cow’s stomach. The Dutch multinational DSM produces a pharmacological compound called 3-NOP that does something similar. And Mootral produces a blend of essential oils and other ingredients—including garlic and citrus extracts—that change the chemical makeup of a cow’s gut in a way that limits the growth of bacteria that release methane. Others startups and research labs are studying other sorts of food additives.

All of these approaches are in fairly early stages. More science is required to test their efficacy, and more work needs to be done to make them affordable for farmers. Red seaweed is difficult to farm economically at sufficient scale, for instance. A difficulty facing approaches that rely on food additives is that most enteric methane is produced by cows grazing on pastures, rather than by cows in feedlots. To reach these pastured cows, additives will have to be formed into mineral blocks for the cows to lick, or something similar. A startup called Akrea Bio is working to circumvent this challenge with a vaccine for cows that would reduce enteric methane. Another startup, Zelp, uses masks on cows to capture (and then oxidize) cow burps, rather than preventing them.

Credit: Zelp

Here are some companies working on ways to reduce enteric emissions.

• Read this article from Climate Tech VC for a helpful survey of the whole space.

Manure management

Animal manure pollutes streams and waterways with nutrients, and it releases nitrous oxide, a powerful GHG, into the atmosphere. Manure deposited by animals directly onto pasture and rangeland is responsible for the majority of these effects (shown as “Land N₂O” on the Our World in Data emissions pie chart at the beginning of this page). The effects of manure on pasture can be reduced by planting specific plants and grasses that are especially good at using excess nitrogen; but this sort pasture management can be expensive, and its effects are not large. A smaller proportion of nitrous oxide and nitrogen pollution comes from manure in intensive feeding operations (shown as “manure management” in the pie chart above). These effects can be reduced in a number of ways, such as cooling manure, separating liquid and solids, aerating manure, applying chemical nitrification inhibitors, composting, or feeding the manure to anaerobic digesters, which produce biogas that can be used for energy.

What about regenerative grazing?

“Regenerative” grazing practices seek to manage pasture in a way that increases biodiversity and soil health, and as a result sequesters carbon from the atmosphere as soil organic carbon. A central practice is adaptive multi-paddock (AMP) grazing, a system that attempts to mimic natural herbivore grazing by bunching livestock together, and then rotating them quickly among different areas of pasture, so that each area is first intensively grazed, trampled, and fertilized by manure, then given time to recover. (In conventional grazing, by contrast, cattle are left to move wherever they like in a large pasture over an entire season – with the result that they overgraze the particular plants they prefer most, which eventually reduces the number of plant species on a field.) Evidence that AMP grazing can improve soil health and increase soil organic carbon compared to conventional grazing practices is incomplete, but it is promising enough to suggest that a large scale transition from conventional to regenerative grazing would almost certainly support soil ecology and biodiversity, and could have real climate benefits as well.

Many proponents of regenerative grazing read the evidence as pointing to an even more tantalizing prospect: carbon-neutral beef. Evidence is very limited, but one careful study shows that, at least in some conditions, AMP grazing can increase carbon sequestration in soil so much that it cancels out the enteric methane, nitrous oxide and other GHGs that the grazing cows and their manure emit, making the grazing process carbon-neutral or even carbon-negative. (The same study notes that it may be a temporary effect, because after some years of AMP management, pasture soil may become “saturated” with organic carbon, so that less additional carbon is sequestered each year. Once this happens, the GHG emissions from cattle raised on that pasture would no longer be balanced out; but biodiversity and soil health benefits would remain.) 

Unfortunately, the idea that regenerative grazing could give us carbon-neutral beef ignores the huge role that cattle play in agricultural sprawl and land use change. When we graze cows on pasture during the final months of their lives, we produce only half as much beef per acre as when we “finish” cows in feedlots, even accounting for the land needed to produce the crops for feed in feedlots. If ranchers who finish their cattle in feedlots were to transition to raising pasture-fed beef instead, this would reduce the amount of beef available to meet demand on world markets, and the price of beef would rise globally – giving cattle ranchers in countries like Brazil strong incentive to clear more forests and wildlands. So, even if pasture-raising cattle really is “carbon-neutral” when analyzed locally, it may still be a disaster for both biodiversity and the climate when viewed from within a more holistic perspective on the global food system.

Even if we could wave a magic wand and cut global the demand for beef in half overnight, it would be far better for both biodiversity and the climate (though not for cows) if we rewilded the land that this would free up, rather than using it to switch from feedlot finishing to pasture finishing. AMP grazing may be better than conventional grazing; but wild ecosystems with natural herbivores and predators can host more biodiversity and sequester more carbon than even the most sustainably-managed pastures.

(Note: In a 2013 TED talk, Zimbabwean rancher Allan Savory claimed that a system similar to AMP grazing could sequester enough carbon from the atmosphere into soils to return the atmosphere to pre-industrial levels. We’re mentioning it here, because Savory’s TED talk went viral, has been viewed close to 9 million times, has started a movement among cattle ranchers, and has led some big beef producers to advertise “climate-friendly beef.” His claims were further amplified in a popular Netflix documentary movie narrated by Woody Harrelson. However, despite its popular appeal, there is no evidence at all to support this claim, and very strong evidence against it.)

Crops

We’ve concentrated on animal agriculture so far, because it’s the largest source of GHGs in the AFOLU sector. But every part of this sector is a source of GHGs (and of other, serious environmental harms). Producing nitrogen fertilizer emits carbon dioxide, and the fertilizer itself releases nitrous oxide when it is spread on fields. Rice fields emit methane when they are flooded. Soils lose carbon when they are plowed. Crop wastes emit carbon dioxide when they are burned on fields after harvest. And forests emit carbon dioxide when they are cleared to make room for crops. We will need to reduce all of these emissions in order to feed ten billion people without cooking the planet.

A place to start, in thinking about this problem, is with the fact that our ability to feed eight billion people today (and to feed many of them meat) is a modern miracle. It is possible only because the amount of food that we are able to produce on an acre of land (the “crop yield” of the land) has increased, year after year, for more than sixty years. The result is that while the amount of land used to grow crops has increased, it has not had to increase nearly as much as global population in order for food production to keep up. The chart below shows the production of cereal crops like rice and wheat – but you can find similar charts for the yields of all sorts of crops at Our World in Data.

Source: Our World in Data

We’ve been able to increase crop yields by using more productive crop varieties and more fertilizer, by irrigating farm lands, and by increasing mechanization. But the gains have not been evenly distributed around the world. The nations of Sub-Saharan Africa, in particular, have had some of the smallest gains in productivity.

Source: Our World in Data

This “yield gap” between nations with low agricultural yields and other nations has been disastrous for low-yield nations. It has meant, first of all, that people in these nations have suffered from malnutrition and food insecurity. It has also meant that even when people in these nations have had enough to eat, they have had to expend a high proportion of their income, and their labor, to get it – so that children cannot attend school, because their labor is needed to work fields, for instance, and so that little spare income is available for things like housing and healthcare.

And whereas countries with growing crop yields have been able to feed growing populations without devoting more land to agriculture, in low-yield countries, feeding a growing population has required expanding agricultural land.

Source: Our World in Data

This trend toward expanding crop land is particularly concerning in Africa. Whereas the populations of other parts of the world are expected to level out and then decline in coming decades, the population of Africa is set to grow through the 21^st Century – from 1.4 billion people – 17% of the world’s population – today, to 4 billion – 40% of the world’s population – by 2100. If crop yields do not improve, this will mean converting enormous swaths of forest,  savannah and wetland into agricultural land – at tremendous cost to ecosystems and the species that depend upon them and, as the carbon stored in those ecosystems is released, to the atmosphere.

Source: Our World in Data.

In order to continue to feed the world’s growing population, crop yields will need to continue to increase everywhere – and they will need to increase most in the places, like much of Sub-Saharan Africa, where they are now lowest. And in order to do this without further cooking the planet, we need to do this while lowering agricultural emissions. How can we do this?

Nitrogen Fertilizer Production and Use

Nitrogen fertilizer use has been one of the keys to increasing yields – and its absence has been a big reason that low-yield countries have stayed low-yield. Nitrogen is essential for photosynthesis, and it is an ingredient in the amino acids that proteins are made of. Nitrogen makes up 78% of the atmosphere – but it exists there in the inert form N₂, which plants cannot use. In nature, the main path from atmospheric N₂ to nitrogen that can be used by plants and animals begins with microbes that live freely in soil or in the roots of legumes and other plants. These take nitrogen from the air and “fix” it into biologically available forms, such as ammonia (NH₃). Lightning also fixes atmospheric nitrogen into a form that plants can use. But the modern crop yields on which our current global population of 8 billion people depends were enabled only in the early 1900s, when the German chemists Fritz Haber and Karl Bosch developed a way to combine atmospheric N₂ with Hydrogen (H₂) at very high pressures and temperatures to create ammonia (NH₃), which may be used as fertilizer or further processed to create urea fertilizer (CH₄N₂O). Now, a century later, it is estimated that an astounding 80% of the nitrogen in human bodies was fixed through the Haber-Bosch process.

Nitrogen fertilizer contributes to climate change both when it is produced and when it is used. The Haber-Bosch process requires hydrogen as an input. This is usually obtained by burning fossil fuels in order to subject fossil methane gas (CH₄) to a high temperature, high pressure process that splits the carbon from the hydrogen, releasing the carbon to the atmosphere as CO₂. Then, more fossil fuels are burned to produce the extremely high temperatures and pressures necessary to combine the hydrogen with nitrogen in the Haber-Bosch process. Producing fertilizer in this way is responsible for about 1.5% of global GHG emissions. (These emissions show up under the “industry” and “energy use in industry” sectors of the emissions pie-chart.)  Then, when it is spread on fields, nitrogen that is not used by plants is washed away, releasing nitrous oxide in the process. This accounts for another 4.1% of global GHG emissions.

Given that parts of the world like Sub-Saharan Africa need to use more nitrogen fertilizer, how can we reduce emissions from fertilizer globally? A large part of the answer is that many parts of the world use too much now. Globally, only about 42% of fertilizer that is spread on fields is used by crops. The rest is washed away, winding up in oceans and the atmosphere. But this global average “nitrogen efficiency” masks large differences, as the map below shows.

Source: Carbon Brief

According to a 2015 study, if global average nitrogen efficiency rose to 67% (just short of the 71.6% that the US achieves), total fertilizer demand could be reduced by 48% by 2050.

Precision farming

The main cause of nitrogen inefficiency is not simply farmers applying more fertilizer than plants can use. Plants need different amounts of nitrogen at different times in their growth cycle. But farmers often opt to apply fertilizer in slower seasons, like after harvesting in the autumn or before planting in the spring. This means that fertilizer sits unused on soil for long periods, where much of it may be washed away before plants are able to absorb it.  

“Precision farming” is a general-purpose name for farming practices that use detailed data about what is happening in fields so as to apply inputs, such as fertilizer, water, herbicides and pesticides, only when and where they are needed, in the amounts that are needed. Many companies are working on very high-tech approaches to precision farming. For instance, instead of dousing a whole field with the same amount of fertilizer, a tractor’s computers may use data from sensors on drones and artificial intelligence to determine how much fertilizer is needed in different parts of the field, and may use variable rate spreaders to dispense precisely the amount that is needed (and can be absorbed) in each spot.

Computerized map of a farm, showing soil nitrogen levels. Credit: FS22 Modhub

Computerized control of tractor with variable rate fertilizer spreader. Credit: FS22 Modhub

Highly mechanized approaches are likely to be too expensive for farmers in many parts of the world for the foreseeable future. However, the approach can work with technologies as simple and affordable as a mobile phone. For instance, the non-profit Precision Agriculture for Development uses cellphones to give farmers customized, data-informed advice about the application of fertilizer and a host of other inputs, in ten different developing countries. And even lower-tech approaches can achieve many of the same results. For instance, agronomists have developed charts like the one below to allow farmers to see exactly when their plants are ready for fertilizer.

Distributed, green fertilizer production

The Haber-Bosch process operates most efficiently at huge scale. So, although the world produces about 185 million metric tons of ammonia each year (80% of which is used for nitrogen fertilizer), this production is concentrated in only a few hundred enormous plants around the world, some of which produce over a million tons per year. These plants emit not only enormous quantities of GHGs but also other, local pollution. Ammonia (or a derivative of it) is then shipped – sometimes thousands of miles – from these huge facilities to the farms around the world where it is needed, further adding to the emissions footprint.

A Haber-Bosch ammonia plant. Credit: New Scientist

Two startups, Nitricity and Atmonia are seeking to decarbonize the production of nitrogen fertilizer, by substituting emissions-free processes for the Haber-Bosch process. And both are seeking to decentralize production, and so avoid the emissions required to transport fertilizer long distances from large, centralized facilities. Nitricity has invented a small plasma reactor that imitates the way in which lightning fixes nitrogen in the air. Atmonia has invented a nitrogen electrolyzer to do something similar. Both processes require no inputs besides electricity, air and water. The Nitricity reactor is small enough that it can be located on a farm, powered only by a small solar array, and used to produce fertilizer on-site. The Atmonia unit is larger – but still small enough to be sited close to the farms that will use its product. Nitricity’s process brings a further benefit: it produces fertilizer in nitrate form, which is more readily absorbed by plants than the urea fertilizer that most Haber-Bosch plants produce. (Urea is used, not because it is best for farmers, but because it is easiest to store and transport.) Using nitrates produced on site may allow for a significant increase in fertilizer efficiency, and a significant decline in nitrous oxide emissions.

Leguminous cover crops

Microbes that grow symbiotically in the roots of leguminous plants and fix nitrogen from the air are a key part of the natural nitrogen cycle. Traditional and indigenous systems of agriculture make use of this natural fertilizer source, either by planting legumes alongside other plants (as in the Native American “three sisters” system of planting bean, squash, and maize (corn) together), or planting legumes as “cover crops” during the time when fields would otherwise lie fallow. These techniques can reduce the need for synthetic fertilizer significantly. Nitrogen fixed in this way is taken up by plants more efficiently than synthetic fertilizer, resulting in less nutrient runoff and less nitrous oxide in the air. (We will discuss other benefits of cover cropping under “regenerative agriculture” below.) However, these practices are not always feasible or economical for farmers. Planting crops together (as in the three sisters system) is not compatible with the mechanized, labor-sparing methods practiced by most large farms. In cold climates, when the final harvest is close to the first frost, cover crops may not have time to grow; and in warm climates, there may be two or three harvests per year, leaving insufficient time for cover cropping in between.

Microbial Fertilizers

Startups like Kula Bio and Pivot Bio are working to create nitrogen-fixing soil microbes, like those found in the roots of legumes – but that can work with plants like corn, wheat, and sorghum. These microbial soil amendments can cut the need for synthetic fertilizer by up to 80% now – and startups are working to produce versions that will eliminate that need. Here are some of the companies working this area:

What about organic farming? 

Organic farming prohibits the use of synthetic fertilizer. In its place, it uses a host of practices, including cover cropping and crop rotation, to build soil health, supplemented by manure as an alternative nitrogen input.

There are many possible environmental benefits to organic farming, and some of its practices (including cover cropping) may have real climate benefits. However, the best evidence suggests that taken as a whole, whatever the local environmental benefits of organic farming, it is not a solution to agriculture’s climate problems, in particular. This is for two, different reasons.

1. Manure is often take up by plants less efficiently than synthetic fertilizer, resulting in more nutrient runoff and more nitrous oxide emissions.
2. Organic farming often has lower crop yields per acre than non-organic. This means that if the world were to convert to organic farming, more land would need to be converted to agricultural use to produce the same amount of food – resulting in more emissions (and more biodiversity loss) as forests and other wildlands are cleared.

The claim that organic farming has lower yields is disputed. Proponents of organic farming point to studies showing individual organic farms with yields as high or nearly as high as conventional farms. However, a 2017 meta-analysis found that across nearly 750 agricultural systems, organic farming had lower yields than conventional farming. (The same study found that the organic farms had more nutrient runoff, and had similar GHG emissions.)

What seems to be the case is that organic farms, especially smaller ones, are sometimes able to use human labor to make up for the yield-enhancing benefits provided by the chemical inputs and mechanized processes of conventional farming. Weeds can be controlled by hand weeding, for instance, instead of by the application of chemical herbicides. This increased labor-intensiveness makes food produced by organic farms more expensive. However, in large parts of the world, not enough people want to work (or work at the wages farmers can afford to pay) as agricultural laborers. And where organic farms cannot find the extra labor, their yields per acre are significantly lower than those of conventional farms.

Soil Carbon and Regenerative Agriculture

Crop farming contributes to GHG emissions in another way, in addition to carbon dioxide from land use change, methane and nitrous oxide: it releases organic and inorganic carbon stored in soils. This happens when soil is left bare and exposed to the elements, and so is lost to erosion, or blown away by winds. And it happens when the complex soil biomes composed of plant roots, insects, mycorrhizal fungi and other microbes are impoverished and degraded by the practice of monocropping, or by being doused with herbicides, pesticides, or fertilizers, or by the physical disruption of tilling or plowing – so that they give up much of their organic carbon. (These emissions of carbon are represented in the “cropland” sector in the Our World in Data emissions pie-chart at the top of this page.) In the 12,000 years since the Agricultural Revolution, the world’s soils are estimated to have lost a whopping 133 billion tons of carbon. By comparison, in the time since the Industrial Revolution, humans have emitted about 450 million tons of carbon.

“Regenerative Agriculture” refers to a broad and open-ended suite of practices and techniques that aim to maintain or restore soil health, and with it soil’s ability to sequester carbon. It includes cover cropping, intercropping (in which different crops are interspersed on the same field), agroforestry (in which crops are grown alongside trees), integrating livestock on arable fields (for instance by growing grass for animals to graze in the time between food crops), no-till or low-till farming (in which mechanical disruption of the soil by plowing or tilling is avoided as much as possible), and a host of other techniques.

⇒ Read this excellent introduction to regenerative agriculture and the debates surrounding it by George Cusworth and Tara Garnett.

Research into the benefits of these practices has shown promising results, but there is still considerable uncertainty around many of them, as well as variability across contexts, so more research is needed. We will not attempt to discuss the whole suite of regenerative practices, but will mention two ways in which innovation might help to avoid some of the difficult trade-offs involved in one of the most prominent regenerative approaches, no-till annual cropping.

In conventional agriculture, soil is plowed (cut through and turned over) or tilled (more lightly scraped) two or three times a year, before each planting. This is done to break up and loosen the soil, and also to kill weeds (or cover crops) that might otherwise compete with the crop to be planted. However, this also degrades or destroys the mycorrhizal fungi networks and other microbes that make up healthy, living soil, and it exposes the topsoil to the air, where the living organic matter within it quickly dies, decays and is released to the atmosphere as CO₂ – and where the soil itself may be washed or blown away.  

No-till agriculture aims to avoid these effects, and keep soil intact, by using a drill seeder or similar machine to press seeds down into intact soil. Early evidence about the ability of no-till farming to sequester carbon was very encouraging – as a result, some government programs now pay farmers to use no-till techniques, and some private marketplaces will pay farmers who do this, so that they can sell carbon offsets based on the carbon that the no-till farming is supposed to sequester. However, the story has more recently been complicated. Some more recent studies have found that no-till farming can increase soil organic carbon in soil near the surface (where earlier studies took measurements), but decrease it deeper in the soil, with the result that there is no net increase overall. Other studies suggest that while the practice of no-till on its own might not help soil to sequester carbon, it may do so when used in conjunction with cover cropping. And studies point out that most no-till farmers still need to plow up their soil every few years to combat perennial weeds and soil compaction – so that much or all of the organic carbon that had been built up over the previous years is released. However, quite apart from the question whether or how much no-till farming can help soil to sequester carbon, there is widespread agreement that it is good for soil ecology, that it helps to prevent erosion, and that it has other environmental benefits.

However, no-till farming comes with a difficult trade-off. Because it does not kill weeds mechanically, by breaking through their roots and plowing them under, it usually relies on large quantities of chemical herbicides, such as glyphosate, to kill weeds before each planting. Alternatively, small organic farming operations, with an abundance of workers, may hand-weed fields, but this is too labor-intensive to be practicable on most farms, and it is expensive for the farms that do use it.

Automated precision agriculture as a solution

High-tech precision agriculture may make soon make it possible to avoid this dilemma. A number of startups are developing robotic tractors that use sensors and artificial intelligence to map every plant in a field, so that they can recognize and kill weeds. Some do this by spraying a small jet of herbicide directly at individual weeds, using far less this way than would be used to douse an entire field. Others use lasers to burn individual weeds. The Small Robot Company uses bolts of electricity. Watch their tractor in action:

Many of these companies are developing tiny, solar-powered robotic tractors that can scoot between rows of crops, and that are so light that they do not compact soil in the way that full-size tractors do. While these robotic tractors may initially be expensive, some of the companies developing them envisage continuing to own and operate the tractors themselves, but then selling weeding (and other forms of precision agriculture) as a service, so that farmers pay no up-front costs.

Here are a few of the companies developing these technologies.

Perennial crops

Plowing or weeding is necessary because most of the world’s staple agricultural crops (wheat, rice, corn, and so on) are “annuals” – that is, they are plants that live their entire life cycle within a single year. In nature, by contrast, most areas are dominated by perennials – plants with a multi-year lifecycle.

In Regenesis, George Monbiot explains this contrast, and its implications:

[Annuals] tend to colonize ground in the wake of catastrophe: a fire, a flood, a landslide, or a volcanic eruption that exposes bare rock and soil. They survive, in these circumstances, only until perennial plants return and start to mend the broken land, whereupon they are usually overwhelmed.

       But it’s not hard to see why our ancestors selected them. Plants that colonize bare ground have evolved to grow fast and invest much of their energy in seeds, rather than in deep roots or dense foliage, so that they can spread as far as possible before the new land closes up. Their seeds tend to be large and to germinate freely.

       The problem is that in cultivating annuals, we must keep the land in the catastrophic state they prefer. Every year, we must clear the soil of competing plants, puncture or turn it, and plaster it with the nutrients required to raise a crop from seed to maturity in a few months. However sensitively it is conducted, annual grain production relies on sustaining an ecological disaster for its success. (pp. 179-80)

Monbiot goes on to point to a network of researchers centered on The Land Institute, in Silana, Kansas, which has been working for more than 40 years to create an alternative: perennial staple crops. As Monbiot says, if we had perennial crops with the right features, “we would not depend on smashing living systems apart to produce our food” (p. 180). The deep roots that perennial plants grow over years not only create healthy, organic carbon storing soil ecosystems; they make these plants much more resilient to the storms and droughts that climate change will bring.

The roots of perennials (left) and annuals (right). Credit: The Land Institute

The Land Institute is attempting to create these perennial crops either by cross-breeding annual crops with their wild perennial cousins, or by selectively breeding wild perennial species that have some of the right qualities, such as high and consistent seed yield, synchronous flowering and seed maturation, and seed retention. The work is slow and painstaking. It requires growing a crop to maturity, choosing the few specimens in the crop with the best attributes, cross-pollinating them, and then growing another crop from these, over and over again. Researchers have begun to accelerate this process using techniques such as gene sequencing, genomic prediction, and marker-assisted selection. Still, since each perennial crop takes more than a year to reach maturity, this process of gradual improvement takes decades.

This approach has had one notable success so far: in 2018, researchers at Yunnan University in China, working in partnership with the Land Institute, released a perennial rice to farmers for commercial use. The variety is a hybrid of a Chinese annual rice variety and a wild African perennial of the same genus. A 2022 study found that:

• A single planting is able to produce eight consecutive harvests over four years.
• It accumulates both nitrogen (fixed by soil microbes) and organic carbon in its soil.
• It makes soil better able to hold water that the plants can use.
• Farmers strongly prefer it over annual varieties, because it saves them 58.1% of labor and 49.2% input costs in each regrowth cycle.

The Land Institute is also working on creating perennial varieties of wheat, sorghum, oilseeds, legumes, and a grain they’ve named “Kernza,” which is a domesticated version of a distant relative of annual wheat called “intermediate wheatgrass.” So far, Kernza is closest to success: it produces a tasty, edible grain – but with only about one third the yield of annual wheat.

The possibility of perennial crops with yields and qualities comparable to annual ones is a bit like the possibility of alternative proteins that are as cheap and tasty as meat from animals: if it comes to pass, it could usher in a new era of agriculture that is far more ecologically benign than today’s; so we should work on it and pour talent and resources into it. (It’s crazy that a tiny, visionary, underfunded research institute in Salina, Kansas is having to do most of the world’s research on perennialization.) But it would be unwise to bet that perennialization will come to our rescue any time soon; so we should continue to work hard on incremental improvements to farming with annual crops.

The plant varieties that the Land Institute is working on are not the only perennial food crops: trees are, of course, perennials; and so foods that grow on trees, from fruit to nuts to cacao and coffee are perennial crops. There is scope to increase the use of recognized tree crops as a sustainable food source, especially in multistrata agroforestry, where other food crops are grown in their shade. Just as exciting: a startup called Terviva has found a way to process the beans from a tree, the Pongamia, that had never previously been used for food because its beans are too bitter, but that grows in large swathes of India. Terviva’s processing de-bitters the beans, allowing us to use them as a source of both protein (for instance, in flour) and of premium oil, with qualities akin to olive oil. Pongamia trees grow readily on arid, degraded land; they require almost no fertilizer, because microbes in their roots fix nitrogen; they are extremely draught tolerant; and they can produce more nutrition per acre than soybeans (which are one of the world’s most productive crops, but also one of the most environmentally destructive).

⇒ Read this terrific article on Pongamia, Terviva’s efforts to bring it into the food system, and the impact it could have.

Reducing Food Waste

So far, we’ve talked about ways to produce the same amount of food while producing fewer emissions and less biodiversity loss. But there is another way to reduce emissions and biodiversity loss: we can grow less food. We can do this, without making people go hungry, because one third of the food that humanity produces is never eaten. If we could eliminate food waste, we would free up all the land that was used to grow that food, and we could spare all the resources that went into it – the water, fertilizer, transportation, packaging, refrigeration and so on, as well as human labor and financial capital. This would save the world a trillion dollars per year. And it would eliminated the GHGs that those resources emit at every step of the way – as well as all the methane that the wasted food itself emits when it decomposes in landfills. If food waste were a country, it would be the third largest emitter, just behind the China and the US. If we could eliminate food waste, we would take that country off the map.

It’s unlikely we’ll come close to eliminating food waste – but we can certainly reduce it. Accomplishing this is not one, single problem, however. We waste food in different ways, for different reasons, at every step of the way from farm to fork. In developing countries, consumers waste very little of the food they buy, but bad roads, lack of refrigeration, inadequate packaging, and (often) high heat and humidity all cause significant waste long before food reaches the consumer. In rich countries, more food is discarded by retailers (for instance, because it is bruised or cosmetically unappealing or nearing its “sell-by date”), and by consumers who simply leave food on their plates, or let food spoil in their fridge.

Credit: World Resources Institute

In poor countries, better infrastructure, from roads to refrigerated storehouses, could make an enormous difference. In rich countries, changes in consumer behavior can help. Policy changes can help to nudge some of these along. When university cafeterias eliminate trays, people take less food at one time, and waste less. “Sell by” dates on food are almost meaningless, but they drive both consumers and grocery stores to throw away vast quantities of food – as this hilarious, but also fascinating and informative episode of Climate Town explains:

In rich and poor countries alike, start-ups are working on ways to address food waste all along the supply chain. Check out some of these examples:

Biofuels

Eight percent of the food crops grown globally are wasted in another way – by being used to make biofuels. Biofuels are based on a plausible-sounding idea. Plants pull carbon from the atmosphere through photosynthesis and incorporate that carbon into their biomass. When the biomass is harvested, it can be processed and refined into fuels like ethanol or biodiesel, which are chemically similar to fossil fuels, though not identical. These biofuels can be mixed with fossil fuels or combusted on their own in engines that are made to handle them. When they are combusted, they release their carbon back to the atmosphere as CO₂ – but the carbon that they release is carbon that plants have anyway absorbed from the atmosphere. So, in theory, the only extra CO₂ that this process should put into the atmosphere is the CO₂ produced in the course of growing, harvesting, refining and transporting the crop and the biofuel made from it. Thus biofuels are represented as “low carbon fuels” ­– in contrast to fossil fuels, which bring more carbon up out of the earth.

Biofuels became popular idea in the US and other parts of the world at the time of the oil crises of the 1970s. They were initially promoted as a way to reduce dependence on imported oil, and more recently as a low-carbon way to fuel our vehicles. Both of these claims made some sense a few decades ago, but the world has changed in two ways since then.

1. A series of careful studies have shown biofuels can have a carbon footprint worse than that of ordinary gasoline, once land use change is taken into account – and that they drive up the price of food, and cause habitat destruction. In 2008, for instance, a new US mandate to mix ethanol in gasoline reduced US corn exports and raised the price of corn on world markets, which in turn helped cause a global food crisis that year and drove record deforestation in the Amazon as Brazilian farmers raced to plant more soybeans.
2. With cheap renewable power and electric vehicles, we now have a better way to power ground transportation – one that was not feasible when biofuels first came on the scene. Skeptics of solar power point out that solar panels take up a lot of land that could be used for other purposes, like growing food. But using corn ethanol to fuel a car requires eighty five times more land per vehicle mile than is needed to power an EV with solar. Put another way: the one million acres Wisconsin devotes to corn produce enough energy to fuel 700,000 passenger cars for a year. Solar panels on that same land could power 60 million EVs for a year.

The political and economic power of agricultural lobbies has kept policy mandates requiring biofuels and lavish subsidies for them in place. The US government still requires a 10% blend of ethanol in gasoline. Climate-forward states like California support the use of biofuels, including soy biodiesel, through “low-carbon fuel standards.” And the European Union’s new climate policies could convert 20% of the continent’s farmland to growing crops for biofuel and biomass power. The biofuel trade associations that back these policies point to studies that underplay or simply ignore the land-use changes they induce.

Biofuel is also promoted as a way to make Sustainable Aviation Fuel (SAF). The case for biofuel here is a bit better than the case for surface transportation, because we have fewer economical ways to decarbonize aviation. However, so long as the SAF is made from food crops (or from crops grown on land that could be used for food crops), the same problems with land-use changes, and the GHGs (and other harms) they brings about, remain. And there are other possible routes to decarbonizing aviation, including electrification (for short-haul flights), hydrogen, e-fuel-based SAFs, and biofuel SAFs made from agricultural waste, rather than food crops. (We discuss the alternatives in more detail in our page on TRANSPORTATION.)

In the effort to decarbonize industry, a number of sectors beyond liquid fuels are also looking to biomass as a source of carbon that has not been pulled from the earth. Companies are making bioplastics and other biomass-based chemicals as a replacement for conventional plastics and chemicals that are made from fossil fuels. Startups like Charm Industrial want to use plants as a way to capture carbon which can then be sequestered underground. Many, but not all of these companies recognize the importance of land-use change, and so are seeking to use waste biomass, rather than specially grown crops. However, as recent studies have shown, there is simply not enough waste biomass to use for every worthy climate purpose, and it will therefore be important to prioritize uses, even for waste biomass.

As waste gets scarce, it will also be important to ensure that demand for waste biomass does not, in practice, create economic incentives for further land-use change, in order to produce more “waste.”  In fact, something like this is already happening in some sectors. European power plants burn wood pellets imported from forests in the Southern US, Canada, and Eastern Europe to create “low-carbon” electricity. While these are supposed to come from wood residuals that would otherwise be left to rot, investigators have found that they are instead fueled by clear-cutting – in some cases, of primaeval old-growth forests. This is one more reminder that land is a precious resource, and it is finite – so that uses of land that seem sustainable when viewed in isolation may not be sustainable at all when viewed from a systems-perspective.

⇒ Listen to this great Volts pod to understand the ways that burning biomass for electricity is a costly disaster for climate, biodiversity, and environmental justice:

Further Resources

Here are a few, great resources to jump off from, as you explore this space.

• TABLE is a collaboration between the University of Oxford, the Swedish University of Agricultural Sciences and Wageningen University and Research. Its website hosts a terrific set of explainers, on all aspect of the food system and its connections to climate change and the environment, from agroecology to food sovereignty to rewilding. They’re informed by the latest science and scholarship, and full of great further resources. They also have a research library, free online courses a podcast, community discussions forums, and more. Highly recommended.
• World Resources Institute (WRI) is home to some of the best and most thoughtful research on the relation between agriculture and climate. Start with this great report, Creating a Sustainable Food Future. Then look at some of their other blog posts and reports like The Global Land Squeeze.
• Project Drawdown has done more than anyone to raise awareness of the power of nature-based climate solutions, including those related to food and farming. Read their report, Farming our way out of the Climate Crisis, explore the many nature-based climate solutions they identify (look under “solutions by sector” on their home page), and explore the other great resources throughout their site.
• Our World in Data‘s essays and charts on the Environmental Impacts of Food Production, on Forests and Deforestation, Biodiversity, and Land Use are all phenomenally good.
• Cropped is a great newsletter from Carbon Brief on the intersection of Food, Nature, and Climate.
• The Good Food Institute (GFI) has an immense wealth of resources about every aspect of the challenge of creating and scaling up alternative protein, including a free online course on the science of alternative proteins. There’s also a Guide for students and newcomers to the alternative protein space, a separate guide for college students to start an Alt Protein student group at your university and lobby your university to conduct research and teach courses on alternative proteins, and information for all ages on community events and careers.
• The Climavores Podcast is a great, wide-ranging and well-informed discussion of the many connections between food and climate.
• The Reversing Climate Change Podcast with Nori is wide-ranging podcast about strategies to remove CO₂ from the atmosphere, but many of their episodes are interviews with leaders in regenerative farming and related approaches.
• George Monbiot’s book, Regenesis: Feeding the World without Devouring the Planet , is a brilliant effort to think about the food system as a whole. This page is strongly influenced by it.
• Bren Smith’s book, Eat Like a Fish: My Adventures Farming the Ocean to Fight Climate Change, makes the case that we can look to farming seaweed in the ocean as an important, climate and environmentally friendly way to take pressure off of land-based agriculture.