Yes, eating meat affects the environment, but cows are not killing the climate

Frank M. Mitloehner, University of California , 29/10/2018
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Cattle grazing on public lands near Steens Mountain, Oregon. BLM/Greg Shine, CC BY 
Frank M. Mitloehner, University of California, Davis


AS the scale and impacts of climate change become increasingly alarming, meat is a popular target for action. Advocates urge the public to eat less meat to save the environment. Some activists have called for taxing meat to reduce consumption of it.

A key claim underlying these arguments holds that globally, meat production generates more greenhouse gases than the entire transportation sector. However, this claim is demonstrably wrong, as I will show. And its persistence has led to false assumptions about the linkage between meat and climate change.

My research focuses on ways in which animal agriculture affects air quality and climate change. In my view, there are many reasons for either choosing animal protein or opting for a vegetarian selection. However, foregoing meat and meat products is not the environmental panacea many would have us believe. And if taken to an extreme, it also could have harmful nutritional consequences.

Global livestock production by region (milk and eggs expressed in protein terms). FAO, CC BY-ND

Setting the record straight on meat and greenhouse gases

A healthy portion of meat’s bad rap centres on the assertion that livestock is the largest source of greenhouse gases worldwide.

For example, a 2009 analysis published by the Washington, D.C.-based Worldwatch Institute asserted that 51 percent of global GHG emissions come from rearing and processing livestock.

According to the U.S. Environmental Protection Agency, the largest sources of U.S. GHG emissions in 2016 were electricity production (28 percent of total emissions), transportation (28 percent) and industry (22 percent). All of agriculture accounted for a total of 9 percent. All of animal agriculture contributes less than half of this amount, representing 3.9 percent of total U.S. greenhouse gas emissions. That’s very different from claiming livestock represents as much or more than transportation.

Why the misconception? In 2006 the United Nations Food and Agriculture Organization published a study titled “Livestock’s Long Shadow,” which received widespread international attention. It stated that livestock produced a staggering 18 percent of the world’s greenhouse gas emissions. The agency drew a startling conclusion: Livestock was doing more to harm the climate than all modes of transportation combined.

This latter claim was wrong, and has since been corrected by Henning Steinfeld, the report’s senior author. The problem was that FAO analysts used a comprehensive life-cycle assessment to study the climate impact of livestock, but a different method when they analyzed transportation.

For livestock, they considered every factor associated with producing meat. This included emissions from fertilizer production, converting land from forests to pastures, growing feed, and direct emissions from animals (belching and manure) from birth to death.

However, when they looked at transportation’s carbon footprint, they ignored impacts on the climate from manufacturing vehicle materials and parts, assembling vehicles and maintaining roads, bridges and airports. Instead, they only considered the exhaust emitted by finished cars, trucks, trains and planes. As a result, the FAO’s comparison of greenhouse gas emissions from livestock to those from transportation was greatly distorted.

Researchers have identified multiple options for reducing greenhouse gas emissions from the livestock sector. Red bars represent the potential range for each practice. Herrero et al, 2016, via Penn State University, CC BY-NC-SA


I pointed out this flaw during a speech to fellow scientists in San Francisco on March 22, 2010, which led to a flood of media coverage. To its credit, the FAO immediately owned up to its error. Unfortunately, the agency’s initial claim that livestock was responsible for the lion’s share of world greenhouse gas emissions had already received wide coverage. To this day, we struggle to “unring” the bell.

In its most recent assessment report, the FAO estimated that livestock produces 14.5 percent of global greenhouse gas emissions from human activities. There is no comparable full life-cycle assessment for transportation. However, as Steinfeld has pointed out, direct emissions from transportation versus livestock can be compared and amount to 14 versus 5 percent, respectively.

Giving up meat won’t save the climate

Many people continue to think avoiding meat as infrequently as once a week will make a significant difference to the climate. But according to one recent study, even if Americans eliminated all animal protein from their diets, they would reduce U.S. greenhouse gas emissions by only 2.6 percent. According to our research at the University of California, Davis, if the practice of Meatless Monday were to be adopted by all Americans, we’d see a reduction of only 0.5 percent.

Moreover, technological, genetic and management changes that have taken place in U.S. agriculture over the past 70 years have made livestock production more efficient and less greenhouse gas-intensive. According to the FAO’s statistical database, total direct greenhouse gas emissions from U.S. livestock have declined 11.3 percent since 1961, while production of livestock meat has more than doubled.

Demand for meat is rising in developing and emerging economies, with the Middle East, North Africa and Southeast Asia leading the way. But per capita meat consumption in these regions still lags that of developed countries. In 2015, average annual per capita meat consumption in developed countries was 92 kilograms, compared to 24 kilograms in the Middle East and North Africa and 18 kilograms in Southeast Asia.

Still, given projected population growth in the developing world, there will certainly be an opportunity for countries such as the United States to bring their sustainable livestock rearing practices to the table.

In developing countries, raising livestock such as these goats in Kenya is an important source of food and income for many small-scale farmers and herders. Loisa Kitakaya, CC BY-SA

The value of animal agriculture

Removing animals from U.S. agriculture would lower national greenhouse gas emissions to a small degree, but it would also make it harder to meet nutritional requirements. Many critics of animal agriculture are quick to point out that if farmers raised only plants, they could produce more pounds of food and more calories per person. But humans also need many essential micro- and macronutrients for good health.

It’s hard to make a compelling argument that the United States has a calorie deficit, given its high national rates of adult and child obesity. Moreover, not all plant parts are edible or desirable. Raising livestock is a way to add nutritional and economic value to plant agriculture.

As one example, the energy in plants that livestock consume is most often contained in cellulose, which is indigestible for humans and many other mammals. But cows, sheep and other ruminant animals can break cellulose down and release the solar energy contained in this vast resource. According to the FAO, as much as 70 percent of all agricultural land globally is range land that can only be utilized as grazing land for ruminant livestock.

The world population is currently projected to reach 9.8 billion people by 2050. Feeding this many people will raise immense challenges. Meat is more nutrient-dense per serving than vegetarian options, and ruminant animals largely thrive on feed that is not suitable for humans. Raising livestock also offers much-needed income for small-scale farmers in developing nations. Worldwide, livestock provides a livelihood for 1 billion people.

Climate change demands urgent attention, and the livestock industry has a large overall environmental footprint that affects air, water and land. These, combined with a rapidly rising world population, give us plenty of compelling reasons to continue to work for greater efficiencies in animal agriculture. I believe the place to start is with science-based facts.The Conversation

Frank M. Mitloehner, Professor of Animal Science and Air Quality Extension Specialist, University of California, Davis

This article is republished from The Conversation under a Creative Commons license. Read the original article.


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  1. Lark ReLlez, 04/11/2018

    There is a new published climate discovery that provide a new paradigm for understanding Earth’s warmth and letting cows off the hook! 🙂 It turns out that the gas molecule CO2 contributes ~0.04% toward warming:

  2. Albrecht Glatzle, 04/11/2018

    Dear David Lovelock, ALL CO2 emitted by livestock respiration and forage digestion is part of the natural Carbon cycle. Not a single C-atom is emitted by an animals that had not been previously bound in biomass and that will not be offset again (usually within one year) by the fotosynthesis of regrowng herbage. The only additional CO2 emissions in cattle production come from fossil fuel combustion during the production and marketing process, from soil degradation or from land use change. Yet I want to remind that manmade CO2 in the air has been shown to be highly beneficial for nature, agriculture and global food security. On the other hand there is no prove of any notable CO2 influence on the climate. Furthermore there is no livestock fingerprint neither in the geographical methane pattern nor in the historical evolution of average methane concentration.

  3. David Lovelock, 03/11/2018

    Clearly at least two conclusions should be drawn here . 1. if we are to count the carbon emissions from livestock , we must also count where this carbon came from i.e. from the air via plant growth during the last plant growth cycle . . 2. this article must be compulsory reading for politicians , regulators and those who would want reduction in animal food production .

  4. David Lovelock, 03/11/2018

    Great to see some VERY significant corrections to the claimed GHG emissions as a percentage due to ruminant animal production . Further I would argue most of what are called emissions from these animals are in fact only part of a cycle . The carbon part of these emissions was almost completely derived form CO2 in the air in the last plant growth cycle . Plants using energy from the sun combine CO2 from the air with water to form sugars /protiens/ carbohydrates etc for growth . Animals digest these carbon products for energy/growth and hence gain ability to grow , move ,reproduce etc. As a result some carbon dioxide and methane are released . The CO2 goes back to the air where it came from , i.e. solar energy has been converted to muscle , bone ,cartilage etc just part of the great cycle of life . But the methane you ask ? The Methane emitted has a half life in the air of a year or so and breaks down naturally into those essentials of life , water and CO2. So the beef and lamb growth is just part of the so called “carbon cycle ” which covers a few moths at most , CO2 from the air, through plants ,through animals back to the air . The CO2 etc out the exhaust of the transport of this product and from the electricity generators for its processing is part of a cycle to , but one of millions of years i.e. CO2 from the air to plants to coal/oil millions of years ago ,burnt to release energy and CO2

  5. Albrecht Glatzle, 31/10/2018

    It is a pleasure to read again from you, Frank Mitloehner!
    While I do agree totally to the title of your most interestiing article, I do not share a number of details you mentioned:
    1) The scale and impacts of climate change do not become increasingly alarming. Climate change has always happened and what we see at present is fully in line with the average climate during the past 10.000 years (Holocene) since the end of the last ice age. Nothing extraordinary! There is irrefutable scientific evidence that there were numerous pronounced warm periods in preindustrial times (witnesses e.g. by prominent tree trunks conserved in moors and glaciers well above the present day tree lines). In fact IPCC tools are definitely uncapable to explain the extended warm periods at times of preindustrial GHG-concentraions (as these tools are almost totally GHG- and aerosol dominated!). So how could I trust the IPCC explanation of the present day warming is correct? Impossible!
    2) Air quality is not worseing when CO2-concentration increases from 0,03 to 0,04% in the air. To the contrary, manmade CO2 has been shown to be beneficial for nature agriculture and global food security: More gross primary production, more vegetation cover worldwide, especially in the dry areas, higher leaf area index, improved water use eficiency of plants and considerable yield increases. The rise of methane concentration by half a molecule in a million of air molecules does not mean air quality worsening either. In fact, there is no discernible livestock fingerprint neither in the geographical methane distribution nor in the historical evolution of the mean methane concentratioin in the air. So, livestock is irrelevant for the global methane budget.
    Thus, as beef producers we should change our strategy: We have a wealth of evidence on our side when we claim that there is no dangerous anthropogenic climate change. Most manmade GHG-emissions are beneficial. Livetock influence on climate is a myth which has to be fought against. Once we start combatting the most essential nutrient of life, CO2, or try to defend ourselves for emitting traces of GHGs we are on the worng pathway and on the loser side.

  6. Tom Brinkworth, 30/10/2018

    Rus, there’s a big world outside your little bubble!

    The climate system operates on a timescale foreign to us – a single degree shift over 50 years is quite rapid.

    Learned individuals do know what greenhouse gases are “doing”. Through research, greenhouse gases have come to be understood as magnifiers – trapping solar radiation beneath the ozone layer. Warming is a side effect of this reaction.

    Climate change has been occurring for millions of years, but the concerning question is at what pace? Because current increases are relatively unprecedented and have happened to coincide with major advancements in human economies and societies.

    The article itself, while minimising and misleading, at least acknowledges that cattle and other ruminants ARE having an effect on the climate.

  7. Lee McNicholl, 30/10/2018

    This should be compulsory reading for anyone who rates themselves as an informed environmental journalist. They should then sit an exam run by MLA. If they fail they should be sent to a “re-education camp ” staffed by previously “re-educated” staffers from that recently dis-credited ABC Catalyst programme. If that fails we might have to ask Donald T how to deal with the endless fake news pedaled by the deceitful vegan brigade !!

  8. Andrew Dunlop, 30/10/2018

    Animal agriculture if managed correctly, is actually beneficial to the environment. Every farmer knows that increasing the organic matter content of his soil improves soil fertility, structure, soil biota and reduces erosion and soil loss. Any farmer worth his salt is doing his best to increase soil organic matter and therefore sustainability. Soil organic matter is a carbon sink and one that appears not to have been considered as worthy as it should be. Undertaking a program of pasture improvement (replacing native pasture with improved perennials) will greatly reduce greenhouse gas emissions per kg animal protein as it
    1. Speeds up the carbon cycle resulting in higher production on plant material both above and below the soil.
    2. Increases soil organic matter directly and through return on manure to the soil which is then incorporated by dung beetles.
    3. Increases the efficuency of water usage as low production native pastures are replaced by highly productive improved perennials.
    4. Reduces green house gas emission as productivity increases (cattle for example take 2 years to reach slaughter weight instead of 4).
    5. Reduces methane emission as improved high quality forage is digested more efficiently.
    6. Reduces leaching and acidification of soils as deep rooted active perennial species replace native pastures.

    I believe there are huge opportunities in animal agriculture to reduce greenhouse emissions, improve water use efficiency and to sink carbon through increasing soil organic matter.

  9. Robert Spark, 30/10/2018

    And yet, vegans will tell you eating meat is the biggest cause of climate change.

  10. Val dyer, 29/10/2018

    From looking at the graph, maybe it is time to avoid chicken, eat beef and fly around the world less often! And tell Richard Branson that fake meat will will not help the environment as it uses too many artificial ingredients.

  11. Greg Campbell, 29/10/2018

    It’s a wonderfully concise contribution to the debate on cows and methane. A debate where the greater passion and time of those opposed to animal agriculture seems to often overwhelm the voices of farmers, and indeed science itself. Professor Mitloehner is to be further applauded for staying online on The Conversation and politely debating and promoting current science to those souls who for a variety of reasons, passionately oppose the farming and eating of meat.

  12. Russell Pearson, 29/10/2018

    I have been hearing about climate change and green house gasses for quite some years now, however I have failed to notice anything any different.
    I’m over 80 and have spent most of my life involved with cattle and of course watching the weather. I cannot see any evidence of changes. I remember droughts in the late 40’s the 60’s, early 70’s and the current drought. I do not know what these “greenhouse” gasses are doing, and I’m quite sure anyone else does either!
    The big drought of the 1890’s 1902 was similar to this one, without the “get-out”methods and transport that we have today.My wife’s family lost over 30,000 cattle at Rawbelle in that drought.
    Climate change has been going on for millions of years, and will continue to do so.
    We have excavated massive lumps of petrified logs on our Blackall property Terrick Terrick, so it wasn’t always a 490 mm average rainfall, however our records from 1882 until 2018 tell us that’s what it is.!
    We certainly believe pollution should be controlled, especially in areas of dense population and industry.
    However to suggest that cattle and other ruminants are effecting the climate is ludicrous

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