Much of the recent limelight for agricultural emissions reductions shines on one option that our report found had limited potential: increasing carbon sequestration in soils through practices broadly referred to as “regenerative agriculture.”
…if the world fails to reduce emissions in other sectors like energy and transport, we’ll need to rely ever more heavily on land solutions, exacerbating food and environmental pressures.
Janet Ranganathan, Richard Waite, Tim Searchinger and Jessica Zionts – May 12, 2020, WRI.org Print
Agriculture needs to close an 11-gigaton greenhouse gas (GHG) gap between expected emissions in 2050 and those needed to hold global warming below 2oC. Several noteworthy reports have proposed a range of mitigation options. Our World Resources Report: Creating a Sustainable Food Future, issued jointly with the World Bank and the UN, laid out 22 solutions to cut emissions by two-thirds, while still feeding a likely population of 10 billion in 2050. Yet much of the recent limelight for agricultural emissions reductions shines on one option that our report found had limited potential: increasing carbon sequestration in soils through practices broadly referred to as “regenerative agriculture.”
Regenerative agriculture has become the darling of many policymakers, food companies and farmers. Advocates claim a triple win: climate change mitigation, increased profit for farmers and greater resilience to a changing climate. Our view is that the practices grouped as regenerative agriculture can improve soil health and yield some valuable environmental benefits, but are unlikely to achieve large-scale emissions reductions.
Here, we explain the practices people are calling regenerative agriculture, examine their climate change mitigation potential, and evaluate their place among other agriculture mitigation options.
1. What is regenerative agriculture?
Although regenerative agriculture has no universal definition, the term is often used to describe practices aimed at promoting soil health by restoring soil’s organic carbon. The world’s soils store several times the amount carbon as the atmosphere, acting as a natural “carbon sink.” But globally, soil carbon stocks have been declining as a result of factors such as the conversion of native landscapes to croplands and overgrazing. One goal of regenerative practices is to use some of the carbon that plants have absorbed from the atmosphere to help restore soil carbon.
Practices grouped under regenerative agriculture include no-till agriculture — where farmers avoid plowing soils and instead drill seeds into the soil — and use of cover crops, which are plants grown to cover the soil after farmers harvest the main crop. Other practices include diverse crop rotations, such as planting three or more crops in rotation over several years, and rotating crops with livestock grazing. Sometimes any practice that involves reduced fertilizer or pesticide use is considered regenerative agriculture.
2. Do regenerative agriculture practices generate environmental benefits?
There is broad agreement that most regenerative agriculture practices are good for soil health and have other environmental benefits. No-till reduces soil erosion and encourages water to infiltrate soils (although it can require greater use of herbicides). Cover crops do the same, and can also reduce water pollution. Diverse crop rotations can lower pesticide use. And good grazing practices — such as moving cattle around frequently, adding legumes or fertilizers, and avoiding overgrazing — can increase vegetation and protect water sources.
3. What about the potential of regenerative agriculture practices to mitigate climate change?
The thinking behind regenerative practices as a climate mitigation strategy is to remove carbon dioxide out of the air by storing it as organic carbon in soils. While practices like adding manure can increase soil carbon, the feasibility of scaling such practices over large areas to substantially increase soil carbon and mitigate climate change is much less clear.
Our own report analyzing mitigation options in the food and land sector concluded that the practical potential was at best modest due to several challenges, including:
- Uncertain benefits: There’s limited scientific understanding of what keeps soil carbon sequestered, and, as a result, uncertainty about whether regenerative practices actually sequester additional carbon. For example, there is an active scientific debate about whether no-till, the primary practice relied upon by proponents of regenerative agriculture to generate climate benefits, actually increases soil carbon when properly measured. Studies on grazing land found that the effects of grazing on soil carbon are complex, site-specific and hard to predict, although grazing practices that increase the amount of grass growing generally sequester some carbon. Even putting aside these uncertainties, maintaining enhanced soil carbon levels is practically challenging. For example, in the United States, the vast majority of farmers who practice no-till also plow up their soils at least every few years, reversing most, if not all, of any short-term carbon storage benefit.
- Faulty carbon accounting: Carbon must be added to soils to increase soil carbon, and this carbon must ultimately come from plants that absorb carbon from the air. But if the direct sources of carbon would have otherwise been stored or used elsewhere, it simply moves carbon from one place to another, achieving no additional reduction in emissions. Calculations of carbon benefits from soil carbon sequestration on a specific farm often omit off-farm effects that produce emissions elsewhere, as illustrated in the graphic. For example, manure is filled with the carbon and nutrients absorbed originally by plants and eaten by animals. For that reason, adding manure to a field increases soil carbon where it is applied. But because there is a limited supply of manure in the world, using it in one place almost always means taking it from elsewhere, so no additional carbon is added to the world’s soils overall. The global supply of crop residues is also limited. If residues used as animal feed (which is common in Africa) are used to increase soil carbon on a farm, farmers may need to expand cropland into forests or grasslands to replace the animal feed, releasing carbon stored in these natural ecosystems’ soils and plants. Converting cropland to grazing can build soil carbon, and might be advisable where cropping is marginal. But if the crops replaced by grazing are ultimately grown elsewhere by cutting down forests or grasslands, it can result in a net increase in greenhouse gas emissions. This same need to replace food elsewhere exists if regenerative practices reduce the amount of livestock or crops produced on a given land area (and studies of many practices so far have shown mixed yield effects). The failure to count these off-farm effects especially matters if soil carbon benefits are claimed as carbon offsets.
- The need for large quantities of nitrogen: Another limitation on storing soil carbon is the need for nitrogen, which usually comes in the form of fertilizer. For carbon to remain in soils for more than a short time, scientists generally agree that it must be converted into microbial organic matter. This requires around one ton of nitrogen for every 12 tons of carbon sequestered (in addition to the nitrogen used and removed by the growth). Applying more nitrogen to agricultural lands to increase soil carbon would be problematic, whether added through fertilizer or nitrogen-fixing legumes. Only some of the added nitrogen would likely be captured and turned into soil carbon; much would escape into waterways, where it would fuel algal growth and water pollution. Some would be converted by soils into nitrous oxide, a powerful greenhouse gas. It’s true that in many parts of the world, farmers already apply more nitrogen than the crop actually uses, but they do so to compensate for the fact that some of the applied nitrogen escapes into the air and water. To use more of this nitrogen to build soil carbon, farmers must find ways to prevent that nitrogen from escaping. Planting cover crops is one way, since their roots capture nitrogen that would otherwise leach out, creating some potential to build stable soil carbon. Yet overall, the need for nitrogen poses a major but often overlooked limitation to soil carbon gains.
- Scaling across millions of acres: According to a recent study, the use of cover crops across 85% of annually planted U.S. cropland could sequester around 100 million tons of carbon dioxide per year. Such an unprecedented achievement would offset about 18% of U.S. agricultural production emissions and 1.5% of total U.S. emissions. However, while the use of cover crops has been expanding in the United States, they still occupy less than 4% of U.S. cropland and face barriers to wider adoption, such as costs and limited time to establish them before winter begins. Cover crops should be actively promoted given their potential to improve soil health, reduce nitrogen pollution and create climate benefits, but their realistic potential for soil carbon gains is uncertain at this time.
Given these challenges (described in more detail in our report), we consider large estimates of climate change mitigation potential for agricultural soil carbon to be unrealistic. Many published claims of massive potential do not address these scientific and practical challenges. One recent paper, for example, estimated that if all the world’s agricultural land sequestered 0.5 tons of carbon per hectare per year, it would achieve about 2.5 gigatons of carbon storage per year, offsetting 20% of annual global greenhouse gas emissions. Another claims it is possible to draw down a trillion tons of carbon dioxide into agricultural soils – an amount that exceeds the entire amount of soil carbon lost since the dawn of agriculture. Based on current evidence, these levels of emissions-reduction potential aren’t plausible.
However, soils naturally store massive amounts of carbon, and the scientific understanding behind this process is still emerging. If future research finds new ways to sequester carbon or dramatically changes our understanding of existing approaches, our conclusions would change. A WRI research paper details some actions policymakers can take now to accelerate such research.
4. What can we do now to mitigate climate change in the food and agriculture sector?
Fortunately, there are many other ways to rein in agricultural greenhouse gas emissions. WRI identified 22 solutions organized into a five-course menu:
- Reduce growth in demand for food and other agricultural products;
- Increase food production without expanding agricultural land;
- Protect and restore natural ecosystems;
- Sustainably increase fish supply; and
- Reduce greenhouse gas emissions from agricultural production (with a limited role for soil carbon sequestration and a much larger role for reducing emissions from cattle, manure, fertilizers, rice cultivation and energy use).
Many of these solutions are ready for scaling and come with co-benefits for farmers, consumers, food security and the environment. As governments seek to build back economies and food companies chart ambitious climate strategies, we recommend decision-makers select from this broader menu to close the agricultural emissions gap and contribute to a sustainable food future.
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Some items in the menu require more farmers to implement best practices that already exist today. Others need consumers to change behavior, or governments and businesses to reform policies. The challenge is sufficiently large, however, that many solutions will require technological innovations. Advancing them is a major theme of our report. Here are 10 important examples:
1) Plant-based meat
Globally, per gram of edible protein, beef and lamb use around 20 times the land and generate around 20 times the greenhouse gas emissions of plant-based proteins. Affordable plant-based products that mimic the experience of eating beef could reduce growth in global beef consumption, while still satisfying meat-lovers. Fortunately, companies such as Impossible Foods and Beyond Meat are already making headlines by creating plant-based “beef” that looks, sizzles, tastes and even bleeds like the real thing.
2) Extended shelf lives
About one-third of food is lost or wasted between the farm and the fork. Fruits and vegetables are a common food item wasted in more developed markets. One breakthrough to address this is the emergence of inexpensive methods that slow the ripening of produce. Companies are already investigating a variety of natural compounds to do so. For example, Apeel Sciences has an array of extremely thin spray-on films that inhibit bacterial growth and retain water in fruit. Others include Nanology and Bluapple, whose technologies delay decomposition.
3) Anti-gas for cows
About a third of all greenhouse gas emissions from agricultural production (excluding land-use change) come from “enteric” methane released as cow burps. Several research groups and companies are working on feed compounds that suppress the formation of methane in cows’ stomachs. Dutch-based DSM has a product called 3-NOP that reduces these methane emissions by 30% in tests, and does not appear to have health or environmental side effects.
4) Compounds to keep nitrogen in the soil
About 20% of greenhouse gas emissions from agricultural production are related to nitrogen from fertilizer and manure on crops and pastures. The majority of these emissions come from the formation of nitrous oxide as microorganisms transfer nitrogen from one chemical form to another. Compounds that prevent these changes, including coatings on fertilizers and so-called “nitrification inhibitors,” can reduce nitrogen losses and increase the amount of nitrogen taken up by plants, leading to lower greenhouse gas emissions and less water pollution from fertilizer runoff. Without a regulatory push, research into such technologies has stagnated, but great potential remains. Some new compounds have emerged in just the past year.
5) Nitrogen-absorbing crops
Another way to chip away at nitrous oxide emissions is to develop crop varieties that absorb more nitrogen and/or inhibit nitrification. Researchers have identified traits to inhibit nitrification in some varieties of all major grain crops, which others can now build upon through crop breeding.
6) Low-methane rice
Around 15% of greenhouse gas emissions from agricultural production come from methane-producing microorganisms in rice paddies. Researchers have identified some common rice varieties that emit less methane than others, and they’ve bred one experimental strain that reduces methane emissions by 30% in the laboratory. Despite this promise, there is no consistent effort in any country to breed and encourage the uptake of low-methane rice varieties.
7) Using CRISPR to boost yields
Two broad items on the menu for a sustainable food future involve boosting yields on existing cropland and producing more milk and meat on existing grazing land. One way to boost crop yields sustainably (without over-application of fertilizers or over-extraction of irrigation water) is to unlock traits in crop genes that increase yields. CRISPR technology, which enables more precise turning on and off of genes, has the potential to be revolutionary in this regard.
8) High-yield oil palm
Dramatic growth in demand for palm oil, an ingredient found in everything from shampoo to cookies, has been driving deforestation in Southeast Asia for decades, and now threatens forests in Africa and Latin America. One way to reduce this threat is to breed and plant oil palm trees with 2-4 times the production per hectare of conventional trees. Potential for higher-yielding oil palm trees already exists. The company PT Smart, for instance, has a variety with triple the current average yield of Indonesia’s oil palm trees. These high-yield varieties need to be used in new plantations and when farmers restock current plantations with new trees (typically done every 20 or more years).
9) Algae-based fish feeds
Another element of a sustainable food future is to reduce pressure on wild fish stocks. As the global fish catch has peaked, fish farming, or “aquaculture,” has grown to meet world fish demand. However, aquaculture can increase pressure on the small wild fish species used as feed ingredients for larger farmed fish. One technological innovation to circumvent this challenge is to create substitute feeds using algae or oilseeds that contain the omega-3 fatty acids found in wild fish-based oils. Some companies are moving to produce algae-based aquaculture feeds, and researchers have created a variety of canola that contains omega-3s.
10) Solar-powered fertilizers
The production of nitrogen-based fertilizers uses vast quantities of fossil fuels and generates significant emissions, roughly 85% of which result from the production of hydrogen to blend with nitrogen. Many have invested in solar energy to produce hydrogen for fuel-cell vehicles, but similar technologies can also help produce low-carbon fertilizers. Pilot plants are under construction in Australia.
Rapidly Deploying Technology for a Sustainable Food Future
Despite their potential, none of these measures are moving forward at adequate speed and scale. Research funding for agricultural greenhouse gas mitigation is miniscule and needs to be increased, in part by making better use of the $600 billion in existing public support each year for agriculture globally.
In addition, although many of the technologies above have the potential to save money even in the near-term, many cost more than their conventional counterparts today. Increasing their uptake will require not only more public research funds, but also flexible regulations that give private companies stronger incentives to innovate. For example, in areas where technologies are underdeveloped, such as compounds that reduce enteric methane, governments could commit to requiring the use of these compounds if a product achieves a certain level of cost-effectiveness in mitigation (such as $25 per ton of carbon dioxide equivalent). As another example, governments could require fertilizer companies to increasingly blend in compounds that reduce nitrogen loss.
The good news is that for virtually every type of advancement needed in the food system, small groups of scientists with limited budgets have already identified promising opportunities. Today’s plant-based burgers that taste like real beef were developed and brought to market in fewer than 10 years.
Feeding a growing world population in the face of climate change and resource constraints is an enormous challenge. The technological innovations listed above aren’t the only ones the food system needs, and of course we won’t solve the challenge through technology alone. However, just as in other sectors like energy and transport, technological innovation is an essential ingredient of a sustainable future.
LEARN MORE: Read the full World Resources Report: Creating a Sustainable Food Future
TAGS: shifting diets, Sustainable Development Goal 12, Sustainable Development Goal 2, agriculture, climate change, food, food loss, food security, food waste
TAGS: agriculture, climate change, food
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7 Things to Know About the IPCC’s Special Report on Climate Change and Land August 08, 2019
Here are a few of the main takeaways:
1. The way we’re using land is worsening climate change.
About 23% of global human-caused greenhouse gas emissions come from agriculture, forestry and other land uses. Land use change, such as clearing forest to make way for farms, drives these emissions. Additionally, 44% of recent human-driven methane, a potent greenhouse gas, came from agriculture, peatland destruction and other land-based sources.
2. But at the same time, land acts as a tremendous carbon sink.
Despite increased deforestation and other land use changes, the world’s lands are removing more emissions than they emit. Land removed a net 6 gigatonnes (Gt) of CO2 per year from 2007 to 2016, equivalent to the annual greenhouse gas emissions of the United States. Further deforestation and land degradation, though, will chip away at this carbon sink.
3. The very land we depend on to stabilize the climate is getting slammed by climate change
Scientists found that land temperatures increased 1.5˚C (2.7˚F) between 1850-1900 and 2006-2015, 75% more than the global average (which factors in temperature changes over both land and ocean).
This warming has already had devastating impacts on the land, including wildfires, changes to rainfall and heat waves. Further impacts will impair land’s ability to act as a carbon sink. For example, water stress could turn forests into savannah-like states, compromising their ability to sequester carbon, not to mention harming ecosystem services and wildlife. The report found that “the window of opportunity, the period when significant change can be made, for limiting climate change within tolerable boundaries is rapidly narrowing.”
4. Several land-based climate solutions can reduce emissions and/or remove carbon from the atmosphere.
The largest potential for reducing emissions from the land sector is from curbing deforestation and forest degradation, with a range of 0.4–5.8 GtCO2-eq per year. We’ll also need large-scale changes to the way the world produces and consumes food, including agricultural measures, shifting towards plant-based diets, and reducing food and agricultural waste.
In addition to reducing emissions, the land sector can also remove carbon dioxide from the atmosphere. The report found that afforestation and reforestation have the greatest carbon removal potential, followed by enhancing soil carbon and using bioenergy combined with carbon capture and storage (BECCS), a process that uses biomass for energy and then captures and stores its carbon before it is released back into the atmosphere. That being said, the authors note that most estimates do not account for constraints like land competition and sustainability concerns, so these solutions’ actual carbon-removal potential could be significantly lower than most models suggest.
5. Many land-based climate solutions have significant benefits beyond curbing climate change.
The report found the following solutions have the greatest co-benefits: managing forests, reducing deforestation and degradation, increasing organic carbon content in soil, enhancing mineral weathering (a process of speeding up rocks’ decomposition to increase their carbon uptake), changing diets, and reducing food loss and waste. For example, increasing soil’s carbon storage can not only sequester emissions, but also make crops more resilient to climate change, improve soil health and increase crop yields.
6. Some land-based climate solutions carry significant risks and trade-offs, and need to be pursued prudently.
For one, it will be important to consider the net carbon benefits of any intervention; for example, planting forests on native grasslands could actually lower the amount of carbon stored in soil, hampering an important carbon sink. Some interventions may lower emissions, but cause other changes that ultimately increase temperatures. For example, planting a dark evergreen forest at high latitudes would lead to darker surfaces, especially during winter when snowpack would be covered, thus increasing the absorption of solar radiation—much like changing from a white shirt to a dark shirt on a sunny day. Planting certain tree or plant species may threaten other species and ecosystems. And most biological carbon sinks will eventually reach a saturation point where they can’t absorb any more carbon. Also, future forest carbon uptake is not guaranteed, since forest fires and pest outbreaks are likely to increase in a warmer world.
7. In particular, land-based climate solutions that require large land areas could threaten food security and exacerbate environmental problems.
Land-based emissions-reduction and carbon-removal efforts that require large land areas – for example, planting large-scale forests and growing plants for bioenergy – will compete with other land uses like food production. This can in turn increase food prices, worsen water pollution, harm biodiversity, and lead to more conversion of forests to other land uses, thus further increasing emissions.
Furthermore, the report found that if the world fails to reduce emissions in other sectors like energy and transport, we’ll need to rely ever more heavily on land solutions, exacerbating food and environmental pressures.
Learning from the IPCC Land Report
Perhaps the most overarching insight from the IPCC report is that land use and climate stability are a delicate balancing act: Getting it right can reduce emissions while creating significant co-benefits; getting it wrong can fuel climate change while worsening food insecurity and environmental problems.
WRI’s recent World Resources Report lays out 22 solutions to create more sustainable food and land systems. We can feed the world while curbing climate change, protecting forests and growing economies—we just can’t do it the way we’re doing things now.
