Pasture feeding of cattle, sheep and goats certainly appears more natural compared to large scale factory farming of pigs, chickens or fish. Industrial livestock production consumes half of all crops globally (including fodder crops), produces enormous quantities of waste, facilitates the spread of disease and causes animal welfare issues.
But pasture-raised animals produce disproportionate levels of greenhouse emissions, deforestation and land degradation, and are by far the most inefficient source of food.
Of all the foods we can eat, pasture-raised meat is by far the most polluting and wasteful. Of the land that humanity uses, three-quarters is devoted to pasture. From this land we derive 7% of our calories and 15% of our protein (if all dairy products are included) . But dairy cows are fed less on pasture and more lot-fed in modern production, so if we exclude dairy products, what we derive from pasture-fed red meat (cattle, sheep and goats) is just 2% of our calories and 7% of our protein intake . This is grossly inefficient production from such a huge area of land.
Cattle, sheep, goats and buffalo are ruminants (which rely on methane-producing bacteria in their stomachs to digest food). Ruminants are the single greatest source of methane, well ahead of fossil fuel gas leaks, landfill, biomass burning or coal , as shown in this diagram.
Warming from methane alone is likely to exceed Paris agreement limits, but cuts to methane emissions are an essential, low cost and powerful means of meeting Paris targets .
Creating pasture for livestock is the major cause of deforestation. In South America, the leading deforestation continent, 86% of forest destruction has been for livestock pastures (71%) and feed crops (14%) . A recent sample study of deforestation in Indonesia (second only to Brazil in deforestation) found that grazing was responsible for almost as much deforestation as palm oil production .
Sadly, climate change is just one of the crises we face. Biodiversity loss is an even more pressing concern. The most effective means we have to slow biodiversity loss and extinctions is to return land to native habitat , and grazing land gives us by far the greatest opportunity for this. Some believe that we will need more cropland for a plant-based world, but existing cropland can support the projected human population of 11 billion on a plant-based diet . This is because half of all crops (including fodder crops) are fed to animals, not humans, wasting a lot of food in the process.
The world is in the grips of the sixth great extinction. The cause – human impact. Biodiversity, the web of life that we depend on for food, water and health is being destroyed. Plants and animals are becoming extinct 1,000 times faster than past natural rates of extinction .
Past extinction events have wiped out as much as 85% of life on Earth, and the current extinction rate is judged to be as serious as past events. Loss of biodiversity is now considered to have passed a planetary boundary, which by definition endangers all life on Earth
Humanity’s impact on our planet is extreme. Of the land that we now use, a few percent is built up (cities, infrastructure, transport and mining), a quarter is cropland, and about three-quarters is devoted to grazing livestock (cattle, sheep and goats). A global plant-based diet decreases agricultural land needs by 76% and has been found to be the most effective means we have of halting the 6th great extinction by returning this land to native habitat .
Eating exclusively grass-fed animal products will not meet current demand. A 2018 study found that United States pasture land could only support 27% of the current beef supply if they were exclusively grass-fed . Similarly, a 2018 Canadian study found that if the United States Department of Agriculture dietary guidelines were adopted globally, an additional one billion hectares (equivalent to the area of Canada) would be required .
This is a shocker! A 2019 article on the BBC Future website quoted a source who said that some areas in sub-Saharan Africa are so degraded that crops cannot be grown but livestock can, and are an essential part of their livelihood.
The truth is the opposite! Sub-Saharan Africa has suffered continual extreme droughts in recent decades, with the worst of these droughts even killing off livestock. Kenya, suffering extreme drought, has seen the Masai traditional herders accept the changed climate and move away from livestock raising to a more sustainable livelihood of raising crops. In recent years, a quarter of the country’s cattle have died and at least 5,000 former herders have become crop growers . The Kenyan government believes that in time, all traditional herders will change from livestock to growing crops due to the new climate reality .
As China’s experience has shown, the only way to restore degraded lands is to remove the livestock and revegetate .
Intensification of agricultural (producing more with less land) is often seen as a solution to the growing demand for food and limited agricultural land available. However, as intensive animal production grows, the demand for feed has exploded. Feed crop yields have not improved as expected, in fact in most areas yields are starting to fall. Combined with the lack of new agricultural land, these factors will prevent the expansion of intense livestock production.
Projected demand for food in a business-as-usual scenario, particularly for feed crops, is estimated to require an additional 280 million hectares of agricultural land, an area the size of Europe . In recent decades, one-fifth of the Earth’s vegetated surface has been declining in productivity, driven by multiple factors including intensive agricultural practices . Already, the cultivation of livestock and animal feed has dramatically altered landscapes around the world. Nearly half of global cropland is used for livestock feed production . Aquaculture is also consuming 22% of caught fish, which is certainly not sustainable . Clearly we are discovering the limit of finite resources, where intensive livestock production will soon be limited by feed supply and dwindling natural resources .
Yes, this is certainly a natural cycle by which grass takes in carbon dioxide, cattle eat the grass and produce methane, which eventually breaks down into carbon dioxide.
However, when carbon is in its methane form, this is a gas which explodes if lit, and as we know is a far more potent greenhouse gas than carbon dioxide. This, together with the explosion in ruminant numbers, has completely upset the natural balance.
By itself, methane has been responsible for 24.3% of human-caused radiative forcing (warming) over the industrial era between 1750 and 2011; however, as it naturally breaks down in the atmosphere methane produces other greenhouse gases, which have been responsible for a further 12.4% of global warming. These ‘downstream’ gases are carbon dioxide (causing 0.7% of warming), ground level ozone (9.1%) and stratospheric water vapour (2.6%), so that together with the downstream gases, methane has been responsible for 36.7% of radiative forcing (warming) according to the 5th IPCC Assessment Report, 2013 .
This comes as a surprise to many, and flags methane as a greenhouse gas that cannot be dismissed on any grounds. The graphic below shows that ruminants are responsible for the lion’s share of methane emissions.
And livestock numbers have exploded. The total weight (biomass) of livestock today is more than four times the weight of all the megafauna on earth 10,000 years ago .
Livestock population number are extreme. In 2016 we kept 82 billion animals for meat, milk and eggs . That’s a lot of mouths to feed, particularly because they are all young, growing fast, with large appetites.
These systems are beneficial for soil health and soil carbon, but at present the only peer-reviewed evidence confirming that soil carbon increases can offset ruminant emissions were performed at extremely low stocking rates and relied on considerable external nutrient inputs. Adopting these measures is costly, requires more land than we have, or is not possible on rangelands where the majority of ruminants are grazed.
Among some smaller producers there is considerable attention to improving soil health and soil carbon in grazing pastures, using methods initially popularised by Alan Savory. This is a very positive move, because grazed pastures have suffered extreme degradation globally. Two billion hectares of farmland has become unproductive and abandoned due to degradation and desertification. Half the world’s original topsoil has been lost and a third of arable land is degraded. It is predicted that if we continue with ‘business as usual’ we will exhaust our ability to farm altogether before the end of this century.
Drylands, where most stock are grazed, are particularly vulnerable to degradation and eventually to desertification. Climate change, particularly changes to the intensity and frequency of droughts, accelerates the degradation process.
While grazing practices can improve soil, this comes at the expense of productivity. Only with substantial external inputs can both production and soil health/carbon be increased. Without external inputs, either soil is improved, or production, but not both.
The Food Climate Research Network has published a report on this topic, Grazed and Confused, that shows soil can gain carbon but this offsets a small fraction of ruminant emissions .
This is because livestock use 83% of all farmland, but produce only 37% of our protein and 18% of our calories .
The farmland devoted to livestock includes not only grazing pastures, but half the current cropland, for livestock feed. Grain and oilseed crops (maize, rice, soybeans, wheat and many other grains) are consumed by humans directly (55% of calories), by livestock (36%) and used for biofuel (9%). In addition to this, all fodder crops (sorghum, alfalfa, legumes and other hay grasses and some vegetables) are destined for animal consumption. Fodder crops are equivalent to an additional 35% of grain and oilseed crops by weight [161, 158].
We need all these feed crops because each year we breed 82 billion animals (2016 figure) for meat, eggs and milk. That’s a lot of mouths to feed!
In the United States, just 27% of crop calories are for food, whereas 67% of crop calories are fed to animals, and an Australian study found similar proportions for domestically consumed (not exported) grain crops. The process of feeding livestock then eating them is very wasteful: for instance 100 calories of grain produce just 12 calories of chicken or 3 calories of beef .
Any human activity using land competes with native animals, so yes, there will always be wildlife killed due to any activity we do: agriculture, cities, roads, dams etc. This myth compares deaths in Australia when mice ‘plagues’ are poisoned, compared with the death of a single animal for beef. It ignores deaths due to deforestation due to beef production and alternative crop production methods such as organic or agro-ecological farming.
This myth stems from a 2011 article in The Conversation that contrasted the number of lives lost from beef fed on rangeland grasses, compared to earthworms, snakes, lizards and mice killed when growing and harvesting grain . The study compared the usable protein of each system as produced in Australia, finding that 25 times more animals were killed producing the equivalent amount of protein from grain. Most of the lives lost were mice, poisoned when they were in high numbers. A mice ‘plague’ occurs on average four-yearly, with numbers growing to 500-1,000 mice per hectare, 80% of which are then killed by poison.
BUT, what the author conveniently ignores is the half a million hectares (5,000 square kilometres) of deforestation each year for beef production in Australia. That’s about 13-14 square kilometres of bushland cleared each day for beef production. The state of Queensland, home to four fifths of Australia’s deforestation, accurately reports causes of deforestation, finding that over 90% of all tree clearing is for beef production (including some clearing for sheep) and that most of the clearing since the mid 1980’s has been of old growth (virgin bushland)  .
Clearing this bushland results in 1,000 to 2.000 birds dying for every 100 ha of tree clearing , meaning that somewhere between 500 million and a billion birds die each year due to tree clearing. Between 1985 and 2015, more than half the populations of threatened birds have disappeared due to loss and fragmentation of habitat , and more than 60% of native birds surveyed have lost more than half their natural habitat .
Between 1983 and 1993, tree clearing caused the deaths of at least a billion reptiles in Australia, more than 100 million reptiles each year . Apart from these, the various mammals rarely find alternative suitable habitat. Tree clearing is the major cause of the current crisis of koala populations - they have lost a million hectares of habitat since 1999: they are being wiped out .
ALSO, for feedlot beef and other livestock, the article ignores the fact that most crops feed animals, not people. The Beyond Zero Emissions Land Use Report found that two-thirds of domestically consumed crops (not including exported crops) were for animal consumption. Therefore, any wildlife killed in crop production and harvesting is two-thirds due to livestock (for meat, milk, eggs), not due to plant-based consumers.
NOT ONLY THAT, but when crops are fed to livestock, the process is highly wasteful. The most efficient ‘protein converter’, chicken, still produces one kilogram of protein for five kilograms of plant protein feed. In this case, five times more wildlife are killed for every kilogram of chicken protein eaten (assuming animals are killed in growing and harvesting the crops).
WHICH BRINGS US to the assumption that plant-based consumers eat those crops where mice ‘plagues’ are controlled by poison. Clearly this is not the case for organic production, therefore anyone eating an organic plant-based diet is avoiding this killing.
Therefore this article is misleading, ignoring the wildlife killed in broadscale tree clearing, ignoring the fact that most crops are fed to animals, ignoring the multiplication of wildlife deaths due to inefficient protein conversion, and ignoring the fact that crops can be produced in a way that avoids the extensive use of poison to kill mice. This article is disappointing from a news source that prides itself on its ‘scholarly’ accuracy.
The total weight (biomass) of livestock today is more than four times the weight of all the megafauna on earth 10,000 years ago .
Megafauna includes all mammals (herbivores and carnivores) over 44kg in weight.
In 2016 we raised 82 billion animals for meat, eggs and dairy. They exist because we breed them. When demand declines, supply (breeding) will also decline.
Broiler chickens (the majority of the 82 billion animals) take just 5 weeks from hatching to slaughter, so these numbers will decline quickly if there is less demand. Even dairy cattle are exhausted after about 5 years, when they are killed for their meat. In our current livestock production systems, no animal reaches its full life term, they are all grown quickly and harvested (slaughtered) as soon as possible.
80% of all soybeans are fed to animals . In the Cerrado of Brazil, large scale deforestation is making way for soybean production, however these crops are almost exclusively genetically modified (‘Roundup Ready” to suite industrial agricultural practices) feed crops, destined for export to Asian and European livestock .
To meet consumer demand, soy used for human consumption is mostly organically grown, which has a far lower environmental impact. Soy, as a legume, grows in a symbiotic relationship with nitrogen-fixing bacteria, thereby requiring far less external fertilizer or nutrient inputs. Soy is also tolerant of wide climate variation, and is grown across all continents. A vegan world would see only a small fraction of the soy imports that are now required for livestock feed.
Indonesia is second only to Brazil for deforestation, and, yes, palm oil production has been identified as causing 23% of deforestation in that country, slightly above deforestation for pasture, which caused 20% of deforestation . Likewise, large scale soy and corn (maize) cropping has been identified as the cause of 14% of deforestation in South America (the world leader in deforestation), where 71% of deforestation was for grazing pasture . These crops are almost exclusively feed crops, not for human consumption but for livestock [164, 165].
Taken together, deforestation for palm oil or human food crops is dwarfed by deforestation for grazing pastures and livestock feed. Also little known is that 15% of the income from palm oil production is from palm kernel expeller (what is left after oil is extracted), which is predominantly sold for dairy cattle feed.
Although some technologies hold great promise for mitigating climate change, none of these solutions has been adopted on any meaningful scale, mainly due to cost, safety concerns and the threat of unintended consequences.
There is, however, an extremely large scale, low cost, safe, natural means of extracting carbon dioxide from the atmosphere: forests.
Crowther Labs in Switzerland has found that existing unproductive or unused degraded land can be used to grow 720 billion trees. This will draw down the equivalent of two decades of current emissions and, along with fossil fuel mitigation, restrain global warming to less than 2°C .
There are many organisations now working with renewed ambition on reforestation projects such as the UN-led Bonn Initiative, the Trillion Trees project, and others. A set of reforestation protocols has been developed for Forest Landscape Restoration, together with detailed mapping of these areas. Continuing deforestation (at 15 billion trees per year) undermines reforestation efforts, however there are several major initiatives aimed at reducing deforestation including the UN’s REDD+ initiative.
There are multiple benefits to large scale reforestation other than climate, including biodiversity, land degradation, deforestation itself, nitrogen pollution, water cycles, water and food security.
Organic farming also has great potential to store huge amounts of carbon in soil, if adopted on a large scale.
By far the largest potential reforestation lands are those lands now used for grazing pasture (75% of current human land use). Avoiding red meat and dairy (which are now derived from pasture land) would have a profound impact. One study found that revegetating 41% of existing pasture land would draw down 27 years of current emissions .
Human-caused methane emissions make up about 59% of total emissions, the remaining being natural (mainly wetland) emissions .
In natural systems, sources and sinks of methane vary with seasons and wet/dry years particularly, but a study in Australia looked at the contribution of multiple methane sources, finding that ruminants were responsible for all but a small fraction of emissions . Australian grazing systems are predominantly rangelands, where feral animals and termites were thought to be rampant. These findings are set out in carbon dioxide equivalent terms below.
The current human population is dwarfed by the livestock population. In 2016 we kept 82 billion animals for meat, milk and eggs . That’s a lot of mouths to feed, particularly because they are all young, growing fast, with large appetites.
If humanity were to swap to a plant-based diet, we could easily feed 10 billion people .
Eating locally produced food is beneficial on several levels - nutrition, waste, economy and climate. And it is logical to think that food shipped or flown across the world would have a far bigger climate footprint. But many studies have found that the type of food determines climate impact far more than transportation, particularly for emissions-intensive animal products. Food production (on-farm) causes 81% of emissions, whereas all processing and distribution (including transport) causes 19% .
In the USA, food transport contributes just 11% of food’s climate impact, and the majority climate impact is from production (on-farm) . This study found that one day per week of eating plant-based food reduced emissions more than buying all locally-sourced food. A comprehensive study of transport-related emissions of foods found that while air travel is far more emissions intensive than shipping, the transport-related emissions of foods are dwarfed by emissions intensity of their production, even though there is great variation in food types and markets consumed .
Food production is globalised, but by far the greatest commodities shipped internationally are livestock feed crops. South America, the leading continent for deforestation, is among the world’s largest exporter of feed grain and seed. While that pork or chicken meat may be local, its feed may well have come from Brazil. These embedded food miles are hidden.
Until recently, even among the climate science community, many had a dismissive attitude to methane’s climate impact. However, we know now that methane emissions alone (even ignoring carbon dioxide) will push the world into dangerous climate change, beyond 2°C warming .
But methane has a silver lining: it is the most effective means we have to moderate and slow global warming in coming decades, simply due to its short lifespan. Reducing livestock methane emissions is the most effective way to do this. Reducing animal product consumption by half will be enough to avert dangerous global warming [135, 136].
Waste is serious - up to a third of all food is wasted, causing greenhouse gases, water use, forest loss, land degradation, habitat loss for food that is never eaten. Waste occurs on the farm, processing, distribution chains and in our kitchens. Thankfully, minimising waste is the focus of many government and industry campaigns, as well as retail chains and public awareness campaigns.
But if we are concerned about waste, then the most effective step we can take is to minimise the waste embodied in our food. If we feed crops to animals, then eat those animals, we waste up to 97% of the food value. The most efficient meat for converting protein is chicken, but even here we waste 60% of the protein fed to the chicken. Eating plants, at the lowest level on the food chain, is the best way to prevent food waste.
Considerable research on calorie and protein conversion efficiency has given us clear measures of waste. An example is the table below from Cassidy and others, showing that raising animals, then eating those animals is far more wasteful than losses due to current production, supply chain and end-user waste :
Table 1. Livestock conversion efficiencies in calories and protein. Feed to food calorie conversion efficiencies for milk, eggs, chicken, pork, and beef, are shown from left to right. Conversion efficiencies are modified from .
Calorie conversion efficiency (%)
Protein conversion efficiency (%)
Sadly, waste nitrogen is considered the greatest environmental pollutant of our time, causing lifeless waterways, toxic tides and hundreds of ocean dead zones.
The originating source of this pollution is nitrogen fertilizer, which is applied to crops and dairy pastures. Feed crops are fed to livestock, then intensive livestock production concentrates this nitrogen pollution, where it has a devastating impact on ecosystems when it evaporates into the air, seeps into groundwater or escapes containments in times of extreme rain events and floods.
In Europe, 83%-88% of nitrogen pollution has been found to be from livestock production .
Synthetic nitrogen fertilizer has enabled the ‘green revolution’ to feed humanity’s rapid population growth, however the world is now awash in reactive nitrogen. Nitrogen is all around us. The air is mostly made up of stable nitrogen, but nitrogen in its reactive form is the basis of life: nitrogen is the essential building block of proteins. When we apply nitrogen fertilizer to growing plants, proteins are created. When people eat plants, some of these proteins become part of our bodies, but most is lost, in our effluent. If we eat animals rather than the plant directly, this waste is multiplied in the process. The most wasteful example of this process is beef production. If we eat beef, just 4% of the nitrogen is taken up as protein in our bodies [152, 153].
Some reports have argued that livestock play a valuable role in subsistence communities, as a means to accumulate wealth for those who do not own land, and provide food security when crops will not grow such as in times of drought. This argument is now known to be flawed in the new extreme climate, where livestock numbers can be wiped out by extreme drought.
Sub-Saharan Africa has suffered continual extreme droughts in recent decades, with the worst of these droughts even killing off livestock. Kenya, suffering extreme drought, has seen the Masai traditional herders accept the changed climate and move away from livestock raising to a more sustainable livelihood of raising crops. In recent years, a quarter of the country’s cattle have died and at least 5,000 former herders have become crop growers . The Kenyan government believes that in time, all traditional herders will change from livestock to growing crops due to the new climate reality . Because of these efforts, these regions are able to cope with the current drought which is causing people in Somalia and other areas of the Horn Of Africa to stream into Kenyan refugee camps to escape famine.
The success of this transition can be explained in part by the findings in a 2011 study released by the Netherlands' University of Twente, which revealed that it takes significantly less water to grow plant sources of protein, calories and fats than it takes to grow livestock .
Media reports  of record fire and smoke in the Amazon have been questioned by some commentators. They claim that these fires are not unusual, and that recent publicity condemning these fires is politically motivated, aimed at recent government moves to relax restrictions on deforestation.
NASA conduct rigorous, global, daily fire mapping using two satellites. They report that 2019 fire levels were the highest for this time of year (August) since 2010, and provide graphs of fire occurrence, as shown in the graphic here from their report .
Brazil conducts their own fire analysis, noting that there were 51,000 fires in August 2019, and that for the period January to August, this is 71% higher than the previous year, and 50% higher than the previous five years .
A few people still have persistent doubts that human activity is causing climate change. Certain industries and lobby groups have done a good job of seeding doubt in the public mind. But most people can now see for themselves that our climate is far out of balance.
Skeptical Science  is the work of a team of volunteer scientists and experts who answer skeptical questions and claims with the best available evidence. Their work addressing arguments  is very comprehensive and worth reading, for all of us. Link to their website here.
- Climate change is just part of a natural cycle
- Changes are due to sunspots/galactic cosmic rays
- CO2 is a small part of the atmosphere - it can’t have a large heating effect
- Scientists manipulate all data sets to show a warming trend
- Climate models are unreliable and too sensitive to carbon dioxide.