Saving Our World–Chapter Fourteen–Do Flatulent Animals Harm Our Climate?

There has been a lot of talk about livestock and the production of methane gases. If they truly wanted to take care of the problem, go back to grass fed cows, the grass when it grows absorbs CO2 more then the grain when it is growing. Besides cows and other livestock have been around for hundreds years, the only problem seems to be now that we are also producing a lot of CO2 from other sources as well. However, I will include both sides of the story, so that the reader can make up their own minds.

As Beef Comes Under Fire for Climate Impacts, the Industry Fights Back

In at least two states this year, beef and dairy industries have successfully beat back government food initiatives linking livestock to global warming.

In California, a state legislator introduced a bill called the California Climate-Friendly Food Program, with the goal of promoting plant-based foods in schools and reducing greenhouse gas emissions linked to livestock.

Within a few months, references to climate change were stripped out of the text and title. The bill instead became the California School Plant-Based Food and Beverage Program.

On the other coast, in Maryland, the state’s Green Purchasing Committee launched the Carbon-Intensive Foods Subcommittee to study which foods have the largest carbon footprints and to steer the state away from buying those foods. The administration of Gov. Larry Hogan disbanded the committee months later.

In both cases, the states’ farm and beef lobbies got their way. 

Over the past year, as landmark reports advised consumers to eat less meat and dairy because of their climate impacts — and as plant-based alternatives gained traction — the American beef and dairy industries have been pushed further into defensive mode.

“It is astounding, the level of fear and pushback from the meat industry on our efforts to address the very real, substantial climate impacts of meat production,” said Kari Hamerschlag, deputy director of the food and agriculture program at Friends of the Earth, which helped develop the California legislation and is behind other legislation intended to expand state-level spending on plant-based foods. 

“They don’t want to cede an inch on climate change,” Hamerschlag added.

Early this year, the EAT-Lancet Commission, in a major scientific report, urged a “comprehensive shift” in the world’s diet. In July, the World Resources Institute, the United Nations and other groups released a massive report finding that the world needs to produce 50 percent more food without expanding the food system’s carbon footprint. And in August, the United Nations Intergovernmental Panel on Climate Change released a report calling for a major overhaul in the global food system.

All of them recommend lowering consumption of meat, dairy and carbon-intensive foods, especially in developed countries.Stripping Mention of ‘Climate,’ Disbanding a Committee

California Assemblymember Adrin Nazarian introduced a bill in February that would allocate $3 million to give schools a rebate for increasing the number of plant-based meals they serve. The original bill contained language that said beef and dairy production released more greenhouse gases and had the word “climate” in the title. 

But the state’s powerful beef and dairy industries opposed the bill, largely because of the explicit connections it made between livestock production and climate change. Lawmakers removed the language, the lobby withdrew its opposition — and the bill moved forward. It now awaits further movement in a state committee.

“We were opposed early in the process but removed our opposition in the Assembly Education Committee after substantial amendments were taken to the bill removing the involvement of the Air Resources Board [California’s climate regulator] in the school lunch program, among a handful of other issues with the bill,” said Justin Oldfied, vice president for government affairs with the California Cattlemen’s Association, in an email to InsideClimate News  

“The changes they wanted weren’t about the substance,” said Kyle Ash, director of government affairs with the Physicians Committee for Responsible Medicine, which advocates for vegetarian diets. “It’s about whether they look bad or not because the bill adds legitimacy to the fact that animal-based diets are higher in carbon emissions.”

In Maryland, the state’s Green Purchasing Committee, an interagency government group charged with “promoting environmentally preferable purchasing” by state agencies, launched the Carbon-Intensive Foods Subcommittee to study which foods released higher amounts of greenhouse gases. 

After the group produced a list of carbon-intensive foods, which included beef and dairy, the executive vice president of the Maryland Cattlemen’s Beef Association called it a “hit list of foods,” according to a trade media publication. The association and the National Cattlemen’s Beef Association sent a joint letter to Gov. Hogan, a Republican, asking him to disband the committee because, they said, it was operating with a political agenda

The following month, in August, state officials said they were disbanding the committee, writing that “it has become very clear that these are complicated issues that require solutions beyond the scope of the subcommittee.”

“After much review, we have jointly determined that the goals of this subcommittee are similar to those of other state programs, and have decided that our resources would be better focused on bolstering those efforts,” they added.Message From Scientists Is Clear

Emissions from livestock account for about 14.5 percent of total greenhouse gas emissions, globally, and roughly two thirds of those emissions come from cattle — mostly from methane burped by cows, growing feed and clearing land for grazing and feed crops.

In October of last year, the journal Nature published a study, saying that, in order to feed the expected 9.7 billion people on the planet in 2050 — and meet the Paris climate accord goals — the world will need to shift toward plant-based diets, in addition to reducing food waste and adopting new farming technologies.

“We find that no single measure is enough to keep these effects within all planetary boundaries simultaneously, and that a synergistic combination of measures will be needed to sufficiently mitigate the projected increase in environmental pressures,” the authors wrote.

But the message to the world’s eaters was simple: Eat less meat and dairy.

At the Five Rivers cattle feeding operation in Kersey Colo., nearly 100,000 cattle are fed to market weight. The U.S. is the world’s largest producer of beef, and Five Rivers is the world’s largest cattle feeding company, with nearly 1 million cattle across six states. Credit: Georgina Gustin/InsideClimate News

The following month, the EAT-Lancet Commission published its study coming to the same conclusion. That was followed by the sweeping report by the Intergovernmental Panel on Climate Change, saying that a shift toward less carbon-intensive food presented “major opportunities for reducing GHG emissions.”

“Examples of healthy and sustainable diets are high in coarse grains, pulses, fruits and vegetables, and nuts and seeds; low in energy-intensive animal-sourced and discretionary foods (such as sugary beverages),” the report said. 

“Staying within a 2-degree trajectory — it won’t happen if you don’t bring down animal sources of food globally, and in most regions and places where beef is produced, and that includes the U.S.,” said Marco Springmann of Oxford University, the lead author of the Nature study and and one of the authors of the EAT-Lancet Commission report.

The U.S. is the world’s largest producer of beef. In 1960 it produced 16 billion pounds of beef and in 2018, 27 billion pounds. This year, the U.S. could produce more than 27.4 billion pounds — a record. The average American consumes nearly three times the global average, at 57 pounds per capita.Industry Wants Supply-Side Solutions

The American beef industry says that the headlines over the past year that blare recommendations to cut beef consumption oversimplify the issue.

In a recent study published in Agricultural Systems, researchers did a full life-cycle analysis — the gold standard for determining a product’s greenhouse gas emissions — and found that beef cattle produce about 3.7 percent of the United State’s total greenhouse gas emissions, nearly half of total agricultural emissions, which are about 9 percent. That analysis includes emissions from birth to slaughter. Most of that comes from methane from cow belches. 

“Methane is our biggest challenge,” said Sara Place, a co-writer of the study and senior director of sustainability for the National Cattlemen’s Beef Association, which funded the research. “This industry is interested in solutions.”

Place says there should be more emphasis on the industry’s potential to cut emissions, rather than just recommending people cut back on their beef consumption for climate-related reasons. “There’s this argument that we can’t improve the supply side — that we have to cut demand,” Place said. “That’s our challenge: How can we as scientists cut emissions and bend that curve back down.”

The American beef industry points to Place’s research, which was done with scientists from the U.S. Department of Agriculture, as evidence of how the U.S. cattle industry has become more efficient, producing more meat with fewer cattle. In other countries, emissions from cattle are higher, according to the United Nations Food and Agriculture Organization. 

Some researchers also note that the number of cattle in the U.S. has fallen from 97.8 million in 1960 to 88.5 in 2014, while the number of pounds produced has risen over the same time — a figure that shows how relatively efficient the industry has become.

“Maybe — just maybe — American farmers and ranchers deserve some credit for efficiencies that for decades have decreased greenhouse gases,” wrote Frank Mitloehner, a professor of animal science at the University of California at Davis, a staunch industry defender, in a recent blog post.Meat Production Has Skyrocketed

Still, critics say, 3.7 percent of emissions is a relatively high number because overall U.S. emissions are so much higher than most countries. And, they note, that total methane emissions from U.S. livestock have risen by nearly 20 percent from 1990 to 2016

“People say: Oh, it’s not a big number. But if you divide it by total greenhouse gases in the U.S., which you can argue are very high and should be much lower, it is,” Springmann said. “The U.S. system produces the fourth-largest amount of greenhouse gases in the world. It’s a high number if you put it in a global context.”

Beef’s carbon footprint is well established. For every gram of beef produced, 221 grams of carbon dioxide is emitted, compared to 36 for pork. And for every calorie from beef, 22 grams of carbon dioxide is emitted, compared to 3.5 from pork. 

Global meat production has skyrocketed — by more than 370 percent — since 1960, straining resources and consuming land. With demand for beef and dairy expected to soar, feeding the world — and staying within a safe carbon budget — will be impossible without major shifts in consumption patterns.

Tim Searchinger, author of another report this year advocating for lower animal protein consumption, agrees that the emissions intensity of U.S. beef is lower than in other countries. But, he says, the demand for livestock-based foods from consumers in the U.S. and other high-income countries has major climate impacts nonetheless. (Among developed countries, the U.S. consumes more beef, per capita, than any other country, after Argentina.)   

Searchinger has pointed out that most life cycle assessments (LCA) of beef production don’t account for land-use change and deforestation — to make way for grazing and growing grains — in other places. 

“If your LCA doesn’t take into account land use, then your LCA is leaving something pretty important out,” he said. “The amount of carbon we lose from vegetation and soils to produce a kilo of beef is much higher than the emissions from even methane and nitrous oxide from producing beef.”

Chart: How Does Land Use Contribute to GHG Emissions?

He says that any land devoted to food could store more carbon if left as forest or restored to its native vegetation. So every acre of land is critical for carbon storage, given growing global food demands.

“We need to have land available to reforest. We need to avoid clearing land. Every time we consume less beef, that provides — at the very least — the opportunity to use less land,” he said. “Each of us has the power to avoid that land-clearing. So if I don’t eat beef, the next guy can eat more without clearing land.”Pressure Coming From Consumers, Too

These latest attempts by the industry to beat back initiatives linking livestock to climate impacts are only the most recent. During the development of the influential 2015 U.S. Dietary Guidelines for Americans, which are reviewed and revamped every five years, the meat industry, along with its allies in Congress and the U.S. Department of Agriculture, successfully tamped down nutritionists’ recommendations to eat less red meat for environmental reasons. 

Much of the pressure on the industry is also coming from consumers as dietary choices are starting to shift.

The number of vegans and vegetarians, especially among millenials, is small but rising, and many American consumers say they’re choosing to eat less meat.  

Lobbyists are working to stop meat alternatives, such as the Impossible Burger, from being labeled “steak” or “burger.” Credit: ROBYN BECK/AFP via Getty Images

Plant-based alternatives — from companies like Impossible Foods and Beyond Meat — are jockeying for shelf space in the meat sections of grocery stores and landing on the menu at fast food chains. Industry analysts have said the market for these plant-based burger alternatives is enormous, potentially reaching $100 billion in 15 years. 

The industry has started fighting off attempts to market plant-based alternatives as “steak” and “burger.” 

This year, at least two dozen states considered bills to limit those terms to products that come from animals.

“The issue in the legislative debates is whether or not consumers are being deceived,” said Dan Colegrove, a lobbyist for the Plant Based Foods Association, which fought the bills. “We contend, no, that consumers know exactly what they’re doing.”

Colegrove said he was unaware that any particular lobby was behind these bills, or that any “model” legislation was developed by an interest group. 

“You don’t see this kind of growth in retail sectors. Clearly something’s going on,” Colegrove said, noting that the lobbying push was being driven by the significant interest in plant-based alternatives. “I think this issue is not going to go away next year.”

Livestock – Top Emitter of Greenhouse Gases

According to the 2021 report “Greenhouse gas emissions from animal-based foods are twice those of plant-based foods” published in Nature Food, the livestock sector is responsible for 20% of all human-caused GHG emissions and 60% of food system GHG emissions (twice that of plant-based foods).

We recommend this 2021 figure as an updated replacement for the 14.5% cited in the FAO’s 2013 report.

The report also notes that if the livestock sector were a country, it would be the second largest GHG emitter — more than the United States and almost as much as China.

Methane – More Powerful GHG

Livestock account for 37% of human-related methane production. Methane is important because it is a much stronger greenhouse gas. In technical terms, it has a higher global warming potential (GWP).

Using the standard 100-year time-frame, methane is considered to be between 20-28x stronger than carbon dioxide. Using the preferable 20-year time-frame, the impact of methane is increased to 84x stronger.

While the 100-year time-frame is more common, the Intergovernmental Panel on Climate Change (IPCC) supports the use of a 20-year time-frame and the benefits of reducing meat consumption.

Furthermore, methane has a much shorter lifespan (about 12 years compared to the hundreds for CO2). Thus, reducing methane production has a much more immediate impact. Given the dire nature of climate disruptions, the speed of change is a critical issue. 

Carbon Dioxide – Multiplied

Animals are very inefficient converters of calories. They eat much more food (calories and protein) than they produce. (See the section below for details about the inefficiency of feed conversion ratios.)

Thus, all the land, water, energy, and processing used to produce plant foods is multiplied when we feed the plants to animals. The carbon footprint is further increased by meat-specific processes such as:

-transportation of grain to farm animals

-water, energy, etc. to raise the animals

-transportation of live animals to slaughter

-water, energy, etc. used in the slaughterhouse

-water, energy, etc. used for packaging into store meat

-continuous refrigeration

-transportation of packaged meat to stores

In short, the extra food that must be produced to raise animals, combined with the extra processing required to turn them into food, leads to much greater carbon dioxide and other GHG emissions.

Feed Inefficiency Ratios

It is widely accepted that animals consume more food than they produce. The differences occur around determining how much more food they consume and to what extent animal feed competes with food for people.

The numbers below represent Feed Conversion Ratios (FCRs) for grain-fed livestock. The chart demonstrates how much more food the animals consume than they produce.

Grain-fed and/or factory-farmed is the norm for the vast majority (>98%) of meat produced in the United States. See below for different concerns about grass-fed cattle.

The chart below indicates a reliable (though notable higher) set of FCRs. Click the link to find more details on Feed Conversion Ratios.

feed conversion inefficiencies

Live weight ratios are much smaller (more efficient) than the more realistic edible weight ratios.

Since these ratios represent live weight, they will be further increased during the slaughter and packaging processes. The inefficiencies can more than double when liquid weight is removed – the weight of the water, blood, and other bodily fluids. Further weight loss occurs with the removal of bones and other non-consumable body parts.

Factors that affect the ratios include: type/quality/moisture of feed, animal age, breed, number of offspring, and a host of other variables.

Regardless of the exact numbers, raising grain (soy, corn, wheat, etc.) for animal feed is many times more resource-intensive and GHG-producing than raising food for direct human consumption.

As illustrated above in the CO2 section, meat-specific processes further multiply the GHG-impact.

Grass-Fed Cattle – Worse for Climate Change?

Choosing grass-fed beef instead of grain-fed is popular for health, environmental, and animal welfare concerns. However, in some respects grass-fed beef is worse for climate concerns.

The digestive processes in ruminant animals (such as cows, sheep, and goats) triple the methane production when consuming grass, hay, and other forage associated with grazing.

Proponents point to the carbon sequestration benefits of grazing, but given the strength of methane as a greenhouse gas (see above), the relatively small amount of carbon sequestration pales in comparison to the immense negative impact that methane has on climate change (especially given the half-life differences).

The negative impact of grass-fed cattle is furthered by the decrease in photosynthesis that occurs when trees are cleared for grazing land. Photosynthesis is a powerful way to proactively reduce GHGs already in the air (not just reduce the amount of new GHGs put in the air).

Recommendations for grazing give more than two acres per cow. While not all that land is tree-bearing, deforestation is a dangerous reality. Some proponents also point to the use of marginal land, but marginal land is a small minority of land used for grazing.

According to the UN’s Livestock’s Long Shadow:

“Livestock now use 30 percent of the earth’s entire land surface, mostly permanent pasture but also including 33 percent of the global arable land used to producing feed for livestock, the report notes. As forests are cleared to create new pastures, it is a major driver of deforestation, especially in Latin America where, for example, some 70 percent of former forests in the Amazon have been turned over to grazing.”

Finally, public perception and greenwashing are key concerns. Grass-fed beef only accounts for 3% of beef production in the U.S., yet it is often referred to as the viable replacement by advocates and used as an “excuse” to eat beef by individuals (even though other forms of beef and other meat are also frequently consumed).

Greenwashing occurs, when the public is mislead about fully grass-fed versus partially grass-fed but grain-finished. Even if unintentional, it can also be argued that overstating the environmental benefits of grass-fed beef (such as omitting the climate consequences) is itself a form of greenwashing.

Conclusion & Recommendation – Minimize/Eliminate Animal-Sourced Foods

Statistics vary greatly based on which components are measured, how they are measured, predispositions of researchers, and a host of other variables. As such, we strive for transparency and use ranges for statistics as appropriate.

Regardless of the specific calculation, there is agreement that there are immense benefits for the climate and other environmental concerns in reducing the consumption of animal-sourced foods.

Our recommendation is to minimize (ideally eliminate) animal-sourced foods.

The term “minimize” is used to reflect the realities of culture, economics, and food security in particular areas, while still promoting the most reduction possible. Ideally, eliminating all animal-sourced foods for those who can.

Similarly, regardless of the final number used for FCRs, it is an immense waste of limited resources, especially in an increasingly populous world.

Even poultry, which consume “only” twice as much food as they produce, are two-fold wasteful. Poultry only seem efficient because they’re compared to large mammals. Further, the feed convertor inefficiencies do not include the additional land, water, and energy used in all livestock production.

Finally, grass-fed beef is not the answer. Grazing increases methane emissions and the deforestation causes a great loss in photosynthetic capacity is lost.

Even more so, there are massive amounts of grazing land currently in use that could regenerate and increase photosynthetic (thus carbon-capturing) capacity if grazing was decreased.

As a side-note, locally-produced meat is also an inadequate alternative.

According to research by the University of Iowa, transportation only accounts for 11% of the carbon food print. This is not nearly enough to counter the inherent resource-intensive and climate-unfriendly nature of producing animal-sourced foods. The majority of carbon stems from production, processing and preparation, not transportation.

To be clear, the point is not to dismiss alternatives to and critiques of factory farming systems. The point is to demonstrate the immense benefits of minimizing the consumption animal-sourced foods (regardless of production methods) as part of any environmental, social or food justice actions.

A Convenient Untruth

Ruminants, and particularly cattle, are habitually cast as climate villains, responsible for large amount of greenhouse gas emissions. According to a much quoted United Nations Food and Agriculture Organization (FAO) figure, livestock are responsible for 14.5 percent of human greenhouse gas emissions. Eighty percent of these emissions come from ruminants, half being methane, and a quarter nitrous oxide.

As a result, there are innumerable scientific papers comparing the environmental impact of dairy and beef unfavorably with pork and poultry, with vegetarian diets, with milk substitutes, with test-tube meat and so on. Virtually all of these papers and the FAO’s figure of 14.5 percent are flawed because they employ a formula for equating the climate impact of methane emissions with that of carbon dioxide—through the unit known as “CO2 equivalent”—which is highly misleading.

Nearly all the mainstream media and the public remain unaware of what is in effect a calumny against ruminant livestock farmers. Myles Allen and colleagues at the Oxford Martin School at Oxford University, UK, have published useful material designed to explain this dubious accounting to non-scientific readers.

Comparing apples and pears

Methane (CH4) and carbon dioxide (CO2) act upon the global temperature in very different ways. For the first few years after it has been released into the atmosphere, a given quantity of methane will have a much stronger global warming impact than the same amount of CO2. The standard metric for equating the two gases, Global Warming Potential (GWP100), currently estimates that over 100 years a kilo of methane has 28 times as much global warming effect as a kilo of CO2, or 34 times as much if you take into account certain feedback mechanisms. The FAO’s calculation that livestock cause 14.5 percent of all anthropogenic greenhouse gas emissions is based on the 34 figure.

However, methane degrades in the atmosphere relatively quickly—it has a half-life of about 10 years—whereas CO2 is cumulative; that is to say a single emission of CO2 will remain in the atmosphere for many hundreds of years, and a series of them will accumulate, continually increasing the amount of global warming.

The difference in behavior between the two gases can be seen in the graphs (right). If emissions of the two gases are rising, then the global warming effect also rises, but more steeply in the case of CO2. If emissions of the two gases are constant, then the warming effect of methane is relatively constant, whereas the warming effect of CO2 increases as it accumulates in the atmosphere. Finally, if emissions of both gases are falling, then the net warming effect of methane begins to drop (in other words the drop in emissions has a cooling effect), whereas the warming effect of CO2 continues to increase, albeit at a slower rate, and only becomes constant when emissions cease altogether.

This means that a single pulse of CO2 can be equated to a sustained increase in the emissions rate. A farmer who has been keeping the same number of cattle on their land for several decades will not be increasing global warming significantly because the methane will be disappearing from the atmosphere almost as fast as it is being added. The same applies to a nation, or indeed the world, if its total cattle population remains stable over a number of decades.

But a single emission of CO2, say from using a tractor to spread artificial fertilizer, will remain in the atmosphere and continue to have a warming effect more or less indefinitely. And repeated emissions of CO2 from annual use of diesel and applications of fertilizer will accumulate in the atmosphere, causing the global temperatures to increase. GWP100 fails to account for this crucial difference, resulting in perverse assessments of the relative performance of the two gases and frequent exaggeration of the role played by methane.

There are none so blind …

None of this is really news. There have been plenty of scientific papers analyzing the problem. Myles Allen comments:

“Researchers have debated for decades about the adequacy of this approach … The point was made in the first major climate report produced by the Intergovernmental Panel on Climate Change (IPCC) way back in 1990. Those early discussions were loaded with caveats: Global Warming Potentials, which underpin the traditional practice of CO2 equivalence, were introduced as “a simple approach … to illustrate the difficulties inherent in the concept.

“The problem with developing a concept is that people might use it. Worse they might use it and ignore all the caveats that attended its development. This is more or less what happened with GWPs as used to create CO2 equivalence.

“The science caveats were there, and suggestions for alternatives or improvements have continued to appear in the literature. But policy makers needed something (or thought they did) and the international climate negotiations community grasped the first option that became available, although this has not been without challenges from some countries.”

This doesn’t entirely explain why the FAO, who ostensibly exist to support farmers, should adopt a metric that is so unfavorable to ruminant husbandry. There is a suspicion that FAO economists feel comfortable with GWP100 methodology (at its higher exchange rate of 34:1) because of its bias in favor of intensive fossil-fuel dependent sectors, such as pig and poultry factory farms, and against ruminant livestock herders reliant on biomass. In their original assessment in 2006, the FAO stated that “by far the largest share of emissions come from more extensive systems where poor livestock holders often extract marginal livelihoods from dwindling resources,”—a jaundiced, inaccurate view of peasant farming.

Allen and his colleagues note that the GWP100 methodology particularly impacts upon countries with a relatively high share of methane in their emissions portfolios, “which tend to be either middle income countries with large agricultural sectors … or less developed countries where agricultural emissions dominate because their energy sector is small.”

An alternative metric

They propose an alternative metric which they call “GWP.” Instead of measuring a pulse emission of CO2 against a methane pulse of the same mass, GWP compares a pulse emission of CO2 with an increase in the emission rate of methane. The methane emissions resulting from adding an extra cow to a herd for an indefinite period would be directly comparable to a one-off single emission of fossil fuel CO2.

The discrepancy between the two metrics can be large, especially if emissions are declining. Under the conventional GWP100 methodology, if a source of methane undergoes a reduction of 25 percent in methane emissions over 30 years it will over that period cause global warming equivalent to 810 tons of CO2 for every ton of methane emitted in year one. Under the more accurate GWP methodology it results in global cooling equivalent to 462 tons of CO2. According to USDA data, the U.S. cattle herd declined by around 20 percent from 114 million head in 1984 to 93.6 million head in 2017, a period of 33 years. Assuming that methane emissions per cow are broadly the same over the whole period, this means that methane emissions from the U.S. herd currently have no net global warming impact, and are probably having a global cooling effect.

The cart before the horse

The adoption of GWP would be a great improvement over the current employment of GWP100. It provides a much fairer assessment of the climate impacts of ruminant husbandry as compared with those of intensively farmed pigs and poultry, or vegan substitutes. Many of the scientific papers comparing the impact of meat and plant-based diets would have to be reconsidered.

However, if policy-makers and politicians were doing their job and reducing CO2 emissions in line with the pathways mapped out by the IPCC to limit global warming to a rise of 1.5 degrees above pre-industrial levels, then it is questionable whether we would need any metric at all, because substantial reductions in methane emissions would be a consequence of reductions in CO2.

The increase in methane levels in the atmosphere since 2000 is in the order of 4 percent (much less than the increase in CO2 in the atmosphere over the same time). Since a constant flow of methane over time does not cause any substantial increase in global warming, it would take a relatively modest decline in methane emissions to stabilize methane levels in the atmosphere at a level that causes no increase. IPCC estimates of what is necessary to achieve stability range between a 6.1 percent drop and a “less than 30 percent” drop in methane emissions. Most recently, in the pathways which it proposes to limit global warming to 1.50, the IPCC advocate a drop in methane emissions of “35 percent or more relative to 2010 levels”. Net emissions of CO2, on the other hand, because they are cumulative, have to be reduced to zero by 2050.

The IPCC also points out that “non-CO2 emissions can be reduced as a result of broad mitigation measures in the energy sector.” In other words, as we progressively reduce fossil fuel use and CO2 emissions to zero, reductions in methane emissions are likely to follow:

-About one third of anthropogenic methane emissions result directly from the extraction of fossil fuels, particularly gas, which is partially composed of methane. If and when the use of fossil fuels declines to zero, we can expect the associated methane emissions to decline correspondingly.

-Another one-sixth of methane emissions come from landfill. As we transition from fossil fuels to a circular bioeconomy, and abandon throwaway plastics, landfill will become increasingly rare and associated methane emissions will also diminish.

-Another third of anthropogenic methane emissions are derived from livestock. But we can reasonably expect these to decline as well, as a result of reduced fossil fuel availability. Artificial fertilizers will become more expensive, leading to reduced animal feed production; and livestock will be competing for grazing and forage land with the demand for biomass energy.

Some methane will no doubt rebound in other forms—for example, from leaky biogas plants, compost heaps and so on. But the point here is that methane emissions are not the driver of global warming; they are better understood as a symptom or function of a system currently driven by fossil fuel extraction.

There is a danger that the increasing clamor for a reduction in livestock emissions will upstage the effort to reduce the use of fossil fuels—that would be a case of putting the cart before the horse. It doesn’t matter how many people go vegan, or how little meat we eat, it will not stop global warming. Only one thing will do that—reducing net carbon emissions from fossil fuel extraction to zero.

The caveat

Nonetheless, there are strong reasons for immediately reducing meat consumption in rich countries, since the wealthy of the world eat more than their fair share. It is vital that livestock numbers do not increase around the world because that would generate more methane in the atmosphere and cause global warming. It is also vital that wide expanses of tropical forests are not cleared to support livestock—that would increase CO2 emissions. We must stop felling forests in South America to provide soy to feed to livestock in factory farms. To ensure that these scenarios do not happen, the limited amount of meat and dairy that can be sustainably produced must be distributed more equitably. The strongest argument for reducing meat consumption in industrialized countries is one of environmental justice.

Resources, “As Beef Comes Under Fire for Climate Impacts, the Industry Fights Back: In at least two states this year, beef and dairy industries have successfully beat back government food initiatives linking livestock to global warming.” By Georgina Gustin;, “ANIMAL AGRICULTURE & CLIMATE CHANGE.”;, “A Convenient Untruth.” By Simon Fairlie;