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What does the global shift in diets mean for climate change?

Posted on 13 October 2020 by Guest Author

This is a re-post from Carbon Brief by Josh Gabbatiss

To limit global warming while feeding an expanding population, every part of the food system from farming to refrigeration will likely need to become cleaner and more efficient. 

At the same time, there is growing recognition of the important role people’s diets will need to play in achieving international climate targets.

The food people eat is heavily influenced by culture, geography and wealth, but governments can also play a key role in influencing dietary change, through everything from farming subsidies to healthy eating guidelines.

In this Q&A, Carbon Brief examines how diets are already changing and what will be required to ensure the world’s food consumption is “climate-friendly”.

What is a ‘climate-friendly’ diet?

There has been extensive discussion of what constitutes a “climate-friendly” diet. While there is no universally accepted answer and no internationally agreed guidelines, the scientific consensus has converged on a handful of key features.

Chief among these is the importance of keeping animal products – particularly red meat, such as beef, and dairy – to a minimum. 

Nevertheless, the impact of meat and dairy on the climate is a complex and contentious issue, which is explored in far greater depth in Carbon Brief’s interactive explainer.

Other elements of climate-friendly diets are a diverse array of minimally processed grains, tubers, fruits and vegetables, preferably varieties that are less likely to spoil and do not rely on energy-intensive transport, such as planes. (Although food transport is a relatively small consideration for overall emissions.)

This article will focus primarily on the consumption of red meat and dairy products, as these have been the main focus of efforts to curb dietary emissions.

It will also mainly address greenhouse gas emissions from food, while recognising that there are several – often, but not always aligned – issues at play when optimising diets, including health, adequate nutrition and other environmental impacts.

Why do people’s diets need to change?

Concerns about the impact of meat and dairy consumption on the climate and the wider environment are not new.

However, over the past decade there has been a growing focus on sustainable diets that can feed the millions of people around the world who are malnourished or obese, while remaining within planetary limits.

paper published in 2007 stated that the emissions from meat “warrant the same scrutiny as do those from driving and flying”. Two years later, the influential British economist Lord Stern suggested eating meat would, ultimately, become as unacceptable as drink driving.

Nevertheless, so far diets have not been subject to the kind of political attention that has driven action to decarbonise other high-emitting sectors.

Prof Tim Benton, who leads the energy, environment and resources programme at Chatham House, tells Carbon Brief the climate-food link has been “given legs” by the Intergovernmental Panel on Climate Change (IPCC) setting out the climate benefits of dietary shifts.

The launch of the IPCC’s special report on climate change and land in 2019 made it clear the goals of the Paris Agreement require a focus on food systems, with much of the resulting news coverage focusing on the scientists’ references to dietary change.

Dr Hans-Otto Pörtner, a co-chair of one of the IPCC’s working groups, said at the time they “don’t want to tell people what to eat…But it would indeed be beneficial, for both climate and human health, if people in many rich countries consumed less meat, and if politics would create appropriate incentives to that effect.”

There is already much discussion around efforts to create a “Paris-compliant” food system by reducing emissions per unit of food produced, as well as using “climate-smart agriculture” and “sustainable intensification” to feed a growing population.

However, as a recent letter by a group of medical professionals to the Lancet points out, dietary change has been relatively “neglected” in international climate politics. 

An analysis in 2018 of existing nationally determined contributions (NDCs) found that, while 96 addressed agriculture and 88 mentioned food waste, none mentioned diets. 

recent report produced by a group of organisations including the UN Environment Programme (UNEP) confirmed that no national climate plans explicitly discuss sustainable diets. 

It concluded that adding diets and food waste to NDCs could set a course for cutting emissions by an extra 12.5bn tonnes of CO2 equivalent (GtCO2e) each year, 20% of the reductions needed to deliver on the Paris Agreement’s 1.5C target by 2050.

Meanwhile, without wealthier countries curtailing their consumption of red meat and dairy products, in particular, it is likely they will exceed regional targets and make the Paris Agreement targets of 1.5C or “well below” 2C warming harder to reach. 

One study found that at current rates of emissions growth from the sector, livestock could take up 37% and 49% of the global emissions budget “allowable under the 2C and 1.5C target, respectively,” in 2030.

People denouncing the impact of industrial livestock on the planet.People denouncing the impact of industrial livestock on the planet at COP25. Credit: Marcos del Mazo / Alamy Stock Photo.

Failure to implement “animal to plant protein shifts” would make drastic changes from other sectors “far beyond what are planned or realistic” necessary, wrote Dr Helen Harwatt, an environmental social scientist at Harvard Law School.

Dr Jonathan Doelman, a scientist working on integrated assessment models at the Netherlands Environmental Assessment Agency, tells Carbon Brief that dietary change features “more and more” in pathways to Paris targets. “It’s getting harder and harder to get to 2C or 1.5C with normal measures,” he says.

One reason for this is that dietary change not only reduces emissions directly, but also means more land is made available as livestock pasture is freed up. 

In many future scenarios, this sparing of land makes space for the mass rollout of bioenergy with carbon capture and storage (BECCS) and afforestation projects. Dietary changes could mean there is less risk to food security as these projects compete with agriculture.

Doelman describes such changes as a “win-win” as there is also less risk that emissions from food production will be outsourced to other countries:

“You are basically 100% sure it will help, whereas, indeed, if you just put more forests in the UK and don’t care about what happens to the food production you displace, you don’t know if it’s actually a net gain for the climate.”

Dr Paul Behrens, a researcher who focuses on the environmental impact of human consumption at Leiden University, tells Carbon Brief that dietary change also has many extra benefits:

“It may be possible to hit the Paris Agreement with some heroic assumptions on how you could use sequestration without dietary change, but you’re not going to address water scarcity, soil degradation, biodiversity loss and eutrophication.”

The release of the EAT-Lancet planetary health diet in 2019 – described as the “first attempt to set universal scientific targets for the food system” – marked a “watershed” moment, with a call for a reduction of more than 50% in global meat consumption.

The study, produced by 37 scientists, provoked concerns from the food and agriculture industry, and a statement from the Italian government said its recommendations could “end up being nutritionally deficient and even dangerous”.

But the report’s authors are clear that in their view reaching the Paris Agreement targets is “not possible” by just decarbonising the global energy system, stating:

“Transitioning to food systems that can provide negative emissions (i.e. function as a major carbon sink instead of a major carbon source) and protecting carbon sinks in natural ecosystems are both required to reach this goal.”

Are people in high-income nations eating more climate-friendly diets?

Globally, there is no doubt the consumption of high-emissions food products has increased substantially in recent decades.

Food and Agriculture Organization of the United Nations (FAO) data shows that production of milk has more than doubled and meat more than quadrupled over the past 60 years. Production of beef, the food with the largest emissions footprint, has doubled.

What is more, analysis conducted by Chatham House shortly before the Paris Agreement in 2015 found that in Brazil, China, the UK and the US, public understanding of the link between diet and climate change was “very low”. 

Despite this, there are suggestions that high-income nations, particularly in Europe, have started shifting towards more plant-based diets.


Quinoa salad bowl in healthy vegan restaurant. Vienna, Austria. Credit: Glenstar / Alamy Stock Photo.

This apparent trend has seen the French president backing a citizens’ call for a 20% reduction in meat and dairy consumption, as well as Germany described in a report by the US Department of Agriculture as leading a “vegalution” – vegan revolution – in Europe.

The growth in vegetarian eateries and plant-based alternatives appears to be matched by the public’s eagerness, with 63% of Germans, 51% of Canadians and 50% of British people trying or willing to reduce their meat consumption, according to various surveys.

Moreover, while health and animal welfare are frequently cited as factors behind these choices, polling has also shown consumers highlighting the environment as an important factor in their decisions. 

However, Laura Wellesley from Chatham House says that while the landscape has changed since she started working on this topic before COP21 in Paris, the extent to which behavioural changes are actually taking place is “still unclear”.

The chart below shows how per-capita meat consumption is changing across Europe, based on food balance sheet data from the FAO. Contrary to the idea of a shift to plant-based foods, overall meat consumption has seen a general increase, although most nations have experienced declines in red meat intake.

Changes in per-capita consumption in a selection of European countries of red meat (red), specifically beef, mutton and goat, over time, as well as pork (dark blue) and poultry (light blue), in grammes per day. The data is an overestimation of actual consumption as it is derived from per capita “food supply”, which does not account for food waste at the consumer level. The FAO updated its methodology for calculating food supplies in 2014, which it says may result in some discrepancies with previous data. Source: FAO. Chart by Carbon Brief using Highcharts.

Overall per-capita meat consumption is roughly twice the global average in Europe and dairy consumption is around three times higher, according to FAO data. Meat consumption in Australia and the US is even higher.

According to Benton, a key driver behind the decline in consumption of beef and lamb in some “western” countries is “red meat is bad” public health messaging that stretches back to the 1970s.

Meanwhile, high levels of meat consumption in nations such as Spain and Austria have been attributed in part to subsidised animal farming that results in cheap, easily available products.

Eastern European countries, including Romania and Bulgaria, see lower overall meat consumption, which can be linked to lower average incomes.

Dr Marco Springmann, a population health scientist at the Oxford Martin Programme on the Future of Food tells Carbon Brief that, while some wealthier nations have shown a drop in per-capita red meat and dairy consumption, it is generally coming from a very high level. 

The notion of a recent shift to vegetarianism and veganism is largely based on a combination of national diet data, consumer surveys and industry and retailer reports on plant-based foods.

However, Springmann says national dietary surveys have “huge problems”. Specifically, they are often based on self-reporting and there is evidence people in high-income nations under-report consumption, particularly for products they feel they should not be eating.

The UK government’s “family food” survey even includes the disclaimer: “It is a widely recognised characteristic of self-reported diary surveys…that survey respondents tend to under-report”.

“If people really ate only what is reported in the national dietary survey of the UK, everybody would be underweight by quite a bit,” says Springmann.

Meanwhile, the global “alternative meat” market was worth $14bn last year, according to research by Barclays, with particular interest among young people for dairy- and meat-free options. 

This is just 1% of the global meat industry, although the same research predicted this could rise to 10% by 2029.

However, there is scepticism among experts. Wellesley tells Carbon Brief that in the UK the optimism of the  “Greggs vegan sausage roll moment” should be treated with “a degree of caution”:

“We have had behind-the-scenes conversations with major retailers who have said that although meat alternatives sales have increased, so too have sales of conventional meat options.”

As the charts above indicate, declines in red meat tend to be made up for by an increase in pork and particularly poultry consumption.

While emissions from these products are far lower per gramme than red meat, there are concerns about some of the knock-on effects of their increased consumption, particularly due to their reliance on soy as an animal feed.

Soy production is a major contributor to deforestation in South America. Pig and poultry farming in the UK consume 29% and 53%, respectively, of the solid “cake” derived from soy which is used to feed animals and, to a much lesser extent, humans.

Separately, a report by the European Environment Agency found that, while the EU had seen a 14% overall decline in per-capita beef consumption from 2000-2013, the environmental benefits were “somewhat offset” by a 15% increase in consumption of cheese, another product that comes with a considerable emissions footprint.

While red meat is still widely recognised as having the largest climate impact, some scientists and NGOs have emphasised the need to address all animal products when targeting more climate-friendly diets.

“My personal viewpoint…is that what you really need to be doing is cutting your consumption across the board, of all kinds of animal products,” Dr Tara Garnett, leader of the Food Climate Research Network tells Carbon Brief.

How are diets changing around the world?

Garnett tells Carbon Brief that, in her view, globally, there is increasing awareness of the impact that land-use change, deforestation and livestock methane is having on the climate. 

However, she notes that outside of “northern” nations, an appreciation of the role people’s individual diets play in driving climate change is “less clear” to her. 

Dr James Bentham of the University of Kent, who recently published a study based on FAO data examining worldwide dietary trends, tells Carbon Brief there has been a “global convergence” in diets.

As people in western European nations, alongside countries such as the US, eat less red meat and dairy, inhabitants of emerging economies in Asia and South America tend to eat more of these products than they did in recent decades. 

This trend can be seen in the chart below, based on FAO data for meat, with nations such as Brazil showing a significant increase in per-capita consumption while the US and Australia remain fairly steady.

Based on his analysis – which stretches from 1961 to 2013 – Bentham notes:

“The [per-capita] decrease in the west is not huge – and is not as large as the increase in China, South Korea and Japan, and then there’s just the fact that there are so many more people in East Asia than in the whole of the west.”

Changes in per capita consumption in various nations of red meat (red), specifically beef, mutton and goat, over time, as well as pork (dark blue) and poultry (light blue), in grammes per day. The data is an overestimation of actual consumption as it is derived from per capita “food supply”, which does not account for food waste at the consumer level. The FAO updated its methodology for calculating food supplies in 2014, which it says may result in some discrepancies with previous data. Source: FAO. Chart by Carbon Brief using Highcharts.

Meat and dairy consumption have been considerably higher in Latin America than Africa and Asia for some time, with beef widely seen as a staple for the poor as well as the rich due to comparatively low production costs.

In Brazil, where the beef industry has a particularly high environmental impact and farming is the largest cause of national emissions, one study described discussions in the country of the diet-climate link as “marginal”.

Meanwhile, for many people eating large amounts of meat is still not an option, as evidenced by the fairly low rates of consumption in African countries. However, growing populations alone are still expected to result in nations such as Kenya and Nigeria significantly increasing their demand in the coming decades, even if per-capita intake remains low.

Researchers have noted that, when it comes to diets, there is no “one-size-fits-all” approach, arguing that many poorer nations will likely need to increase their dietary emissions to ensure their populations are eating healthily.

One recent study found that in 36 countries, home to around 2.5 billion people, the adoption of EAT-Lancet’s “planetary health” diet would increase agricultural emissions per capita by over 10%. 

Dairy plays a big role in this, as it is both emissions-intensive and also recognised as important for preventing stunted growth in children.

In a relationship that has been dubbed “Bennet’s law”, when people become wealthier their rising incomes tend to correlate well with rising meat and dairy consumption. Benton tells Carbon Brief:

“Eating meat for most societies around the world has been a high status activity…So there is quite a kind of anthropological determinism in that the more you develop from an economic perspective the more likely you are to eat more meat.”

However, Springmann notes this transition is not necessarily inevitable: 

“As countries become richer, food industries become more interested in those countries, and they run heavy marketing campaigns to get people hooked on those cheap and processed food products.”

Benton agrees this trend is not “set in stone”, pointing to the example of India as a nation that, for various cultural, religious and economic reasons, has retained low levels of meat consumption. (It is, however, the world’s largest milk producer and its livestock sector is responsible for more emissions than road transport.)

A family eating vegetarian street food in Bodh Gaya, India.A family eating vegetarian street food in Bodh Gaya, India. Credit: Eye Ubiquitous / Alamy Stock Photo.

Devinder Sharma, a food and trade policy analyst, says that, while India is “blessed” with a largely plant-based food tradition, he attributes rising emissions from emerging economies to the imitation of both western diets and industrial farming practices. “The problem is mostly coming from western countries,” Sharma says.

“Gradually people are realising that a reduction in meat consumption is what is ideal for the world to survive…but that realisation is very slow,” he tells Carbon Brief.

Ultimately, the relatively small changes in western diets will likely not be sufficient from a climate perspective, especially if other nations continue increasing their consumption of meat.

This is, perhaps, especially true for China, where supporting meat production has been government policy in recent decades and almost a third of the world’s meat is consumed. Much of the growth in global beef consumption has been driven by China.

Total consumption of red meat (beef, mutton and goat) in key economies, millions of tonnes, based on food supply data. The data is an overestimation of actual consumption as it is derived from per capita “food supply”, which does not account for food waste at the consumer level. The FAO updated its methodology for calculating food supplies in 2014, which it says may result in some discrepancies with previous data. Source: FAO. Chart by Carbon Brief using Highcharts.

In 2016, some English-speaking media reported that the Chinese government’s new dietary guidelines aimed to reduce meat intake by half, in a move backed by celebrities and welcomed by campaigners.

However, Li Shuo from Greenpeace East Asia tells Carbon Brief that much of the hype is “unfortunately based on misleading interpretation of the policy”. He adds: “I did not observe any change that the guidelines created for the dinner table.”

When will the world reach ‘peak meat’?

Amid discussions around diets and climate change, the concept of “peak meat” has emerged, with speculation around when the world will arrive at such a point.

In a letter to Lancet Planetary Health last year, scientists called for governments to “declare a timeframe for peak livestock” and incorporate this into their updated nationally determined contributions (NDCs) to the Paris Agreement.

They argue that, in wealthier nations, cutting demand for livestock products and not simply outsourcing production to other countries will be essential to create “Paris-compliant agriculture sectors”.

There is evidence that peak meat may be close. FAO forecasts suggest that in an unprecedented trend, after falling last year, meat production is once again on track to drop in 2020. Meat consumption per capita is projected to fall by nearly 3%. 

While red meat production is set to decline slightly, with a 0.8% drop in beef, the main driver of this change is falling pork production, as the chart below indicates.

Trends in global meat production, millions of tonnes, including FAO projections for 2019 and 2020 indicated by the shaded grey area. “Red meat” includes beef, mutton and goat. Source: FAO. Chart by Carbon Brief using Highcharts.

However, this projected decline comes in unusual circumstances. Meat production has been hit twice this year, first by the outbreak of African swine fever which was already devastating pig farms in China and Vietnam and which has largely driven the fall in global pork output.

The other key event was the Covid-19 pandemic, which has disrupted all meat markets and supply chains due to labour shortages and facilities closing down temporarily.

The FAO did not specifically estimate the impact of coronavirus, but as the organisation’s chief economist Upali Galketi Aratchilage tells Carbon Brief:

“It is possible to think that meat production decline would have continued at the 2019 rate without the impact of the pandemic and that the pandemic aggravated it further.”

Demand for meat has also dropped alongside production, as reduced sales in the food service industry due to Covid-19 closures have only been partially offset by increases in retail sales.

Prior to the pandemic production of beef (the meat with the largest environmental footprint) was already slowing down, even in nations such as the US and Brazil. On a per-capita basis, global beef consumption peaked in the 1970s.

A stall selling meat on the street in Hong Kong.A stall selling meat on the street in Hong Kong. Credit: Sergio Delle Vedove / Alamy Stock Photo.

While this seems like progress towards achieving overall peak meat, Aratchilage adds that prior to the pandemic they did not anticipate a global drop in demand for all meat products:

“Our data do not indicate such a fall at the global level, though consumption declines are observed in a few specific countries.”

Dr Helen Harwatt, who led the call for “peak livestock”, tells Carbon Brief signs of changing consumer habits are promising, but would not be enough to bring about the changes required:

“Not only do we need changes to happen on a much larger and more rapid timescale than what market signals from a relatively small group of consumers alone can deliver, we need system level changes to be implemented.”

Can dietary guidelines help achieve climate targets?

Given the slow progress away from high-emitting foods, experts have concluded that interventions from official agencies and governments are likely to be necessary.

But despite the clear links between diets and climate change, fashioning policies in this area is still “politically toxic”, according to Simon Billing of the UK’s Eating Better, a coalition of civil society organisations.

This point is echoed by Jillian Semaan, who worked at the US Department of Agriculture during the Obama administration’s controversial attempts to encourage healthy eating in schools. 

“Let’s be very honest, people do not like having their government tell them what to do,” she tells Carbon Brief:

Perhaps unsurprisingly, examples of targets being proposed by authorities to specifically reduce emissions from people’s diets are rare. 

The EU’s recent “farm to fork” strategy indicated the importance of plant-based diets, but fell short of setting the targets proposed by NGOs.

In its guidance on achieving net-zero emissions by 2050, the UK government’s Committee on Climate Change (CCC) recommends reducing consumption of “the most carbon intensive foods” – beef, lamb and dairy products – by 20%.

The CCC says this recommendation is in line with recent dietary trends in the UK, with the committee’s land analyst Indra Thillainathan saying this was chosen over another scenario in which red meat and dairy consumption was cut by a more ambitious 50%. (However, the 50% target still appears as part of the CCC’s “further ambition” scenario.)

The chart below shows that the CCC’s recommendations do indeed appear to be in line with trends in UK diets, based on self-reported surveying by the government.

Recent trends in red meat, specifically lamb and beef, consumption (red) and dairy consumption (blue), with dotted lines indicating the 20% reduction target set by the Committee on Climate Change (CCC) and the 50% target which “may be needed, depending on progress in other sectors”. Source: Family Food statisticsCCC. Chart by Carbon Brief using Highcharts.

Despite this, the CCC says current downward trends “are not likely to be sufficient” to deliver the required changes. 

The UK government has accepted the CCC’s net-zero target, but it has been more ambivalent about the dietary guidance. In one BBC News interview, former climate minister Claire Perry described telling people to eat less meat as “the worst sort of nanny state ever”. 

This attitude is not unique to the UK, with authorities in other nations, including Germany and Ireland, showing hesitance in advising people to eat less carbon-intensive foods. Meanwhile, US vice president Mike Pence recently accused his Democrat opponents of trying to “cut America’s meat” as part of their proposals for tackling climate change.

Billing tells Carbon Brief this is is partly to do with the fact that awareness among the public of the need for dietary changes to achieve climate targets is still fairly low:

“Politicians understand that I think and, therefore, they don’t like talking about it. We know in the climate community that it has to happen if…you’re going to get anywhere near net-zero.”

However, many governments already “tell people what to eat” via national dietary guidelines. Many researchers, NGOs and the FAO itself have identified these guidelines as an important opportunity to substantially reduce emissions. 

As of 2016, an FAO report found just four countries – GermanyBrazilSweden and Qatar – specifically referencing environmental concerns in their official dietary guidelines. Since then, more including Canada, Norway and Switzerland have joined the list.

Others, including the UK, France, the Netherlands and Estonia, had “quasi-official” guidelines produced by government-affiliated entities that mentioned the environment.

Meanwhile, attempts to incorporate such considerations into US and Australian guidelines have been shelved after opposition from the meat industry and farmers.

Instead, while dietary guidelines tend to vary depending on the culture they emerge from, health is generally seen as their priority. Fortunately, as Benton tells Carbon Brief:

“There is a commonality between what is a healthy diet and what is a low-footprint diet, primarily because the healthier diet is one that is richer in fruit and vegetables and lower in animal products.”

The CCC’s Thillainathan notes that the UK government’s healthy eating guidance, the EatWell Guide, recommends a much higher level of reduction than the CCC’s guidance, calling for an 82% cut from current levels of beef and lamb consumption.

recent study led by population health scientist Dr Marco Springmann, found that the global implementation of dietary guidelines would cut food-related emissions on average by 13% – equating to 550MtCO2e – across all 85 nations with such guidelines.

Adoption of World Health Organisation dietary recommendations would be associated with a similar reduction in emissions of 12% on average, the study found.

The impact that national guidelines could have on emissions, as well as the dominance of red meat and, to a lesser extent, dairy in the footprints of each nation, can be seen in the chart below. Ofte

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Comments 1 to 29:

  1. Humans are omnivores after millenia of evolution, eating a wide variety of food groups in rough balance, so extreme diets go against our nature whether vegetarian, or atkins and paleo high meat diets, so I would need very good science based proof they are good for us. They all look like quackery to me.

    I see the merit it lower red meat consumption for climate, efficiency, cost and health reasons, but some land looks like it only really suits cattle grazing so eliminating all red meat seems unrealistic. I think a mixed diet of some red meat, some fish, some chicken and also beans for protein and grains and fruits makes sense and its what I eat and enjoy. Humans are omnivores, so don't reinvent that wheel.

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  2. Diet really touches a nerve for many people (myself as well if I'm honest). 

    It feels a little bit like the same "third rail" effect of accepting population limits. Immediate humid emotionality swiftly leading to various avoidance mechanisms. 

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  3. @Doug_Bostrom,

    Eat what you want, just make sure it is produced on land increasing in soil carbon rather than decreasing in soil carbon.

    If it is decreasing in soil carbon, meat multiplies the effect by using more acreage. You should eat less or go completely vegetarian.

    On the other hand, if it is increasing in soil carbon, the multiplier works in your favor and you'd actually be beneficial to increase your intake of meat and decrease your grain consumption.

    Unless of course the farmer was using an integrated system growing both grains/vegetables and animals on the same land at the same time, then we get to go back to the first statement. Eat whatever you want!

    Why pasture cropping is such a big deal.

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  4. nigelj,

    It is important to keep the discussion on the recommendations suggested by the studies and reports that this article is based on.

    The recommendations are for a shift of diets 'towards' vegetarian. There is an extensive history of Vegetarians living full healthy lives. The Vegan diet does not have as much real life case history, but the Vegan diet is not relevant to the issue being discussed.

    One thing I learned about exercise and strength training nutrition is that it is well established that the human body will only process the protein benefit from about 4 oz (100 gm) of meat in a meal. So eating more than 4 oz of meat in a meal is wasteful. And unless you are into muscle-mass building you do not need to eat meat as part of every meal. So there is lots of opportunity for people to change their diet to limit the harm they are doing.

    Even the lower-income portion of the population in wealthier nations could likely change their diet significantly in the recommended direction without any special mineral or vitamin supplements and without needing to develop the increased food awareness and understanding of a Vegetarian (though increased food awareness and understanidng would be great for everyone to have). And the wealthier portion of the population could dramatically change their diet in climate change helpful ways.

    What also needs to be mentioned is that any meat that is consumed needs to be produced in less harmful, more helpful ways, because achieving all of the Sustainable Development Goals is required, not just Climate Action.

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  5. As Anne Mottet (Livestock Development Officer at the FAO) has said: "people are continually exposed to incorrect information about livestock and the environment that is repeated without being challenged", however it is disappointing to see Skeptical Science contributing to this.

    To a degree, this is fairly understandable as if you're looking at reports on the environmental impact of foods, it can be hard to find good, objective information, as even reports from professional scientists sometimes seem to verge closer to advocacy than science, but here are some things to look out for:
    - Does it use 100 year carbon dioxide equivalent emissions factors to account for short-lived atmospheric emissions? If so, this is a red flag and you should probably stop paying attention to the author(s) other than being wary of further misinformation from them, see LINK1, and LINK2. Methane has a half-life in the atmosphere of about 10 years, so if cattle herd sizes remain the same over the lifetime of methane in the atmosphere they will maintain the same amount of additional methane in the atmosphere year on year. In simplistic terms, their contribution to warming is equivalent to a closed power station. Note that the amount of cattle in Europe and North America is actually lower than it was in the 1960's whilst India has fewer cattle than it did in the 1980s, (, so their associated methane emissions have actually dropped. This is a classic bit of information that is often unknown/ignored by those pushing the line "the importance of keeping animal products – particularly red meat, such as beef, and dairy – to a minimum". Even professional scientists like Mike Berners-Lee do this.
    - Does it count rainfall as a water consumption i.e. does it distinguish between green water and blue water? For animals grazing on grass, the blue water consumption is pretty much zero: LINK3.
    - Are the soil benefits of grazing accounted for? "Soil C sequestration from well-managed grazing may help to mitigate climate change" ( along with the provision of organic fertiliser, which reduces dependence on and impacts of fertiliser production and use.
    - Does it compare indirect emissions with direct emissions in a flawed comparison? This error was committed in the 'Livestock's Long Shadow' report and despite a lot of effort to correct it, the damage it caused still persists (LINK4).
    - Do reports which link beef to land clearing accurately represent the process that they are reporting on? Often they misrepresent a more complex process in which livestock farming plays a part by associating all of the impacts with livestock (LINK5).
    - Do the reports accurately represent what livestock eat, the vast majority of which is stuff that we can't eat? See LINK6.

    From what I have seen, if you're trying to eat to maximise the sustainability of society, you'd probably be best to try and focus on nutrient density, meaning that most people would probably eat more eggs, fibrous veg, fish, and meat, and less flours, cereals, added fats and oils (mostly the unsaturated ones), sugars, and grains, which are much lower in nutrient density and satiety than meat, and are significant contributors to the obesity and diabetes problems we face, and are also responsible for most of the agricultural monocultures and (fossil fuel dependent) fertiliser and pesticide use. Maximising nutrient density and satiety means that you need to eat less (LINK7, Marty Kendall also has a lot of good information on his Optimising Nutrition site), so reducing your impact and you'd probably waste less food ( The other really good thing you could do is support regenerative systems of food production - focussing on best practice and the appropriateness of where crops are grown can make a huge difference. From the 2017 FAO study that I've linked above, it was calculated that a 21% increase in world meat production could require 95m hectares more land (an increase of 4%). This is an increase in land demand however note that it is based on the following conservative assumptions:
    - up to 15% improvement in feed conversion ratio, which compares to, for example, the halving of feed conversion ratios over the last thirty years for poultry and pigs in Brazil, Thailand, and Europe;
    - constant yields on grasslands, i.e. no improvements from regenerative agriculture (

    If you're trying to maximise your chances of food security, then reducing livestock farming, which contributes to food security by producing some of the most nutrient dense food we can eat from stuff we can't eat, on land where nothing else could be produced seems a bad idea.

    If you're trying to find the best thing to do to maximise the sustainability of society, and you're in the richest 10% in the world, you should probably try to cut back on burning stuff. There are some excellent resources on Gapminder on this. If you haven't seen it already, this is a good place to start: LINK8. Most of the environmental communications against meat seem to me to be misdirection, either consciously or subconsciously. This seems to be for one of two reasons. It seems to be used as a means to look as if effective action is taking place whilst avoiding discussion and implementation of more effective actions e.g. what's an easier sell - you don't need to change your consumptive lifestyle and can have food that looks, tastes, and feels pretty similar to what you eat now but is "plant-based" (whatever the marketers choose that to mean) and therefore doesn't have the impacts of animal products, which may be fine if you don't look too closely at the nutrient density or impacts of whatever is in what you are eating, and the benefits of animal products, or you have to consume less (don't buy/build that thing, don't go that trip, switch that off)? It can also be the case that those propagating the information are so blinded by their anti-animal agriculture ideology, and so disconnected from nature, that they are unable to objectively reason. This is bad enough in itself, but when this is present amongst scientists, it borders on an abuse of their position - people are depending on them for rigorous, objective analysis, and if they are unable to do this, then they are unable to do their job pretending that they are causes more harm than good.

    From all that I have seen and read over the last few years, a nutrient dense omnivorous diet produced using regenerative agriculture is the most sustainable for us as a species. I am just an enthusiastic amateur however, so if you have better information, I'd be interested in seeing it, though all of the publications I have seen that promoted reductions in animal product consumption have been based on the kinds of misinformation I've highlighted above.

    Apologies for the long post but I've seen this kind of misinformation a lot and I think it's important that information like this is represented as accurately as possible as I think that people generally want to aid the sustainability of society, but are too busy to spend much time researching, so misinformation is believed if it is repeated often enough or people trust the source. Decisions based on bad information are dangerous as the consequences are often worse than the problem you tried to solve.

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    [DB] Activated hyperlinks and shortened those breaking page formatting.

  6. Alan Russel @5

    Regarding your comments:

    "Note that the amount of cattle in Europe and North America is actually lower than it was in the 1960's whilst India has fewer cattle than it did in the 1980s, (, so their associated methane emissions have actually dropped. This is a classic bit of information that is often unknown/ignored by those pushing the line "the importance of keeping animal products – particularly red meat, such as beef, and dairy – to a minimum". Even professional scientists like Mike Berners-Lee do this."

    Firstly this is a tacit admission that cattles methane emissions are a problem, and less cattle equals less of a problem.

    Secondly, although the numbers of cattle have decreased in some places, the production of cattle overall globally have increased in recent decades according to your charts. The charts below also show numbers of cattle globally increasing from 1890 - 2014. If you click on things you can get the exact numbers each year.

    "From what I have seen, if you're trying to eat to maximise the sustainability of society, you'd probably be best to try and focus on nutrient density, meaning that most people would probably eat more eggs, fibrous veg, fish, and meat, and less flours, cereals, added fats and oils (mostly the unsaturated ones)....."sugars, and grains, which are much lower in nutrient density and satiety than meat, and are significant contributors to the obesity and diabetes problems we face, and are also responsible for most of the agricultural monocultures and (fossil fuel dependent) fertiliser and pesticide use. Maximising nutrient density and satiety means that you need to eat less (LINK, Marty Kendall also has a lot of good information on his Optimising Nutrition site), so reducing your impact and you'd probably waste less food ( "

    I disagree. The core problem is expressed in this commentary:

    Conversation LINK

    "Meat production is highly inefficient – this is particularly true when it comes to red meat. To produce one kilogram of beef requires 25 kilograms of grain – to feed the animal ( and clearly huge areas of grass) – and roughly 15,000 litres of water. Pork is a little less intensive and chicken less still....The scale of the problem can also be seen in land use: around 30% of the earth’s land surface is currently used for livestock farming. Since food, water and land are scarce in many parts of the world, this represents an inefficient use of resources."

    This just isnt sustainable with a growing population and multiple demands on uses for land. If we lived mostly on grains, fruits and vegetables we would need far less land. It should be very obvious we could get all the calories we need from much less volume of grain and vegetables etcetera than volume of meat.

    The lower nutrient density of grains and vegetables doesn't matter because they require less land to farm despite us needing to eat a larger volume, and we can largely get what we need from eating them.

    Diabetes is not caused by eating grains or fruits. Its caused by eating too many grains and fruits to the point it causes obesity. Vegans as a group do not appear to have diabetes problems.

    Your comment neglects to mention the vast numbers of cattle fed on grains that require fertilisers.

    And we dont absolutely need artificial fertilisers to grow grains for our own direct consumption, although productivity would fall.

    That said, red meat is a good source of iron and protein and cattle fed just on grass doesn't require fertilisers and is quite a sustainable option in that specific sense, so there is probably a place for some level of open grasslands cattle farming. I think its actually intensive dairy farming that is the least sustainable option because its so inefficient by requiring so many grains and so much piped water and it also typically pollutes local water ways quite badly.

    I think the best solution is just to reduce red meat consumption to about one half or one quarter of what developed countries typically consume. There are many reasons and its the combination that are compelling. consumption of red meat has already declined in the UK.

    "The other really good thing you could do is support regenerative systems of food production ..."

    Regenerative farming in general terms mostly make sense, and is supported by good evidence.

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  7. I said @6 above "It should be very obvious we could get all the calories we need from much less volume of grain and vegetables etcetera than volume of meat." This is nonsensical. I'm not sure what I was thinking. Please just ignore it.

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  8. @6 7 Nigel, 

    That's not the only nonsensical thing you said Nigel.

    "Firstly this is a tacit admission that cattles methane emissions are a problem, and less cattle equals less of a problem."

    That statement is pretty wrong too. If cattle numbers are dropping and methane levels are rising, it is a probable falsification of the hypothesis that cattle emissions were the problem. There are plenty of other sources of methane that actually are the problem, natural gas leaks are the most likely culprit. However, grain production is way up there on the list because in the overwhelming majority of cases it destroys the ecosystem function of grasslands, which are a net sink for methane. Haber process nitrogen made from natural gas, commonly used to raise grains, is also rising. Cattle raised properly on grasslands can restore ecosystem services, and do not need haber process nitrogen to do it.

    You also said, 

    "Since food, water and land are scarce in many parts of the world, this represents an inefficient use of resources."

    Also wrong. Cattle properly raised on grasslands restore degraded land, they do not "use" those limited resources, they are part of a system that generates those limited resources. We all know they generate food. But commonly misunderstood is they generate water too.

    Effect of grazing on soil-water content in semiarid rangelands of southeast Idaho

    Notice that the best result for soil moisture is properly grazed land? Even better than no grazing at all? What do you suppose would happen if we plowed that land to grow grain? In case you didn't know, Google "dust bowl images" for a graphic explanation.

    The proper use of animals, especially ruminants, generates new fertile land, food for human use, and water cycles. It does not use them up, it generates more of each.

    Feedlots are a different matter. This is why I have asked multiple times on this forum that people use their words carefully. It's not the animals that is the problem, it's the way we raise or food that matter. Actually animals are a great help in this regard.

    “As the small trickle of results grows into an avalanche — as is now happening overseas — it will soon be realized that the animal is our farming partner and no practice and no knowledge which ignores this fact will contribute anything to human welfare or indeed will have any chance either of usefulness or of survival.” Sir Albert Howard


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  9. Red. Nigel did not say that cattle are the problem, he said that cattle are a problem. And that there contribution to the overall problem will be a function of how many there are. I don't see that as "nonsense".

    As you point out, not all cattle will contribute the same amount, as other factors come into play, but you've made a strawman out of Nigel's comment.

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  10. Regarding Alan's remark (fling) regarding Skeptical Science promoting misunderstanding of animal husbandry and consumption of meat contributing to GHG, I feel complled to point out that we've covered this elsewhere and that the conclusions of that effort belie Alan's claim:

    How much does animal agriculture and eating meat contribute to global warming?

    This is one of our more popular debunkings (or in this case perhaps "calibration improvement"). 

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  11. RedBaron @8

    Thank's for the technical information. There's some good stuff there, but I have a few criticisms about a couple of things.

    Firstly I did indeed not say cattle are 'the' problem as BL points out. Clearly many things contribute to the increase in atmospheric methane in recent decades, not only cattle. Many studies have confirmed that.

    "If cattle numbers are dropping and methane levels are rising, it is a probable falsification of the hypothesis that cattle emissions were the problem."

    Cattle numbers are not dropping overall globally which is obviously what matters. Both the links provided by Alan Russel and myself showed that.

    "Cattle properly raised on grasslands restore degraded land, they do not "use" those limited resources, they are part of a system that generates those limited resources...."

    Strawman. The statement I posted was cattle use a lot of land compared to crop farming. This is a simple fact. Nothing you have said changes that. It's something we have to consider. You appear to be looking at it from quite a narrow perspective.

    But I don't disagree about the positive relationship you describe between cattle and resources. I did say I think grazing cattles on open grasslands has value. I agree cattle farming properly done can improve the land and sequester carbon, to an extent. Theres some good evidence. The trouble is so many things operate in the opposite direction. Warming causes soils to release carbon over time and also nitrogen oxides so dont get carried away with what can be achieved.

    On balance I go along with lower red meat consumption for climate and other reasons. Obviously fewer cattle equals less of a methane problem. And properly managed environmentally sustainable grasslands farming requires low cattle density so probably lower numbers than currently, assuming the same area of land is used for cattle grazing. Its certainly unlikely to increase in area. This is consistent with a lower red meat diet.

    That said, it seems to me that its really unlikely the entire world would go vegetarian, and some grasslands aren't very suitable for cropping or forestry, so we should clearly graze them in the most environmentally sustainable way possible as per your general prescription.

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  12. I see numerous valid points from all contributors so far, suggesting that this is a complex problem and indeed it is.

    A big question is: Is it possible to have the 987.5 millions cattle in the current World inventory all graze in sustainable fashion? Immense areas of tropical forests have been destroyed to make room for cattle, what is the full analysis on that? Even if we can have close to a billion sustainable heads of cattle, can you then add to that all the other livestock and still have a sustainable system?

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  13. PC @12 says "A big question is: Is it possible to have the 987.5 millions cattle in the current World inventory all graze in sustainable fashion? "

    I don't think you can. I can briefly describe the scenario in New Zealand. In recent decades, intensive dairy farming has expanded to the point our soils are degrading and most of our rivers have become seriously polluted unfit for wading let alone swimming.

    Some of these problems have been mitigated by keeping stock away from rivers by fencing and planting trees near rivers to reduce runoff etcetera, and this has reduced bacteria levels significantly, but has hardly even dented nitrate levels. It appears the only way to truly control the problem is to reduce stocking density, so absolute numbers of cattle. Its hard to see why it would be different in other countries.

    It's not viable to resolve the problem by increasing areas for dairy farming to reduce stocking ratios. There are numerous competing requirements for land including massive government schemes to plant trees as carbon sinks. And its hard to get beyond the fact that meat requires vastly more resources for a given quantity of calories compared to grains and vegetables.

    Of course it depends on how one defines sustainability, another hellishly difficult problem but theres a general consensus in the country that turning our rivers into open sewers that are unfit for wading let alone swimming isnt terribly sustainable and certainly isn't acceptable. The debate is about how much pressure, rules and costs its acceptable to put on farmers to fix the issues.

    Then there is less intensive cattle farming on open grasslands where density ratios aren't so high and feedstock is primarily grass as opposed to grains. This is more sustainable, but only to a degree. To get the sort of carbon sequestration RB talks about requires rotational grazing, and quite low stocking rates, lower than presently. There was a research paper on this in one of your weekly research summary columns some months ago.

    As you rightly say its a really complicated issue. People also don't like being told what to eat. Theres a lot of conflicting advice even before you get to the climate issue. However a couple of things stand out to me. The trend in some countries like the UK seems to be just starting to move towards eating less meat, especially red meat, and towards more plants and maybe fish for a range of different reasons, not just climate issues.

    It's this range of issues that appears to be combining and leading to change. I think  looking at history, that change often seems to happen when a number of things suggest change is appropriate, not just one causative factor. It adds up. Lower meat consumption may spread to other countries eventually. But it seems unlikely to me this will be particularly quick, or lead to global vegetarianism, so that leaves a lot of space for getting grazing systems and chicken farming as sustainable as possible. I'm not sure how sustainable battery cage farming is. I doubt that the chickens would consider it particularly sustainable, if they could be consulted :)

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  14. I find it hard to agree with the premise on a lot of this. Cattle don't need grain fed to them, only forage and maybe hay if you have a dry season or winter. Thus you only need to cut and bale the forage, and that's it no more inputs required. The cattle can even cut and bale the forage themselves if you're so inclined. It is a little harder to manage sheep(and to a lesser extent goats). But raising chickens and pigs without grain inputs is a huge amount of work. Grain cropping requires huge energy investment even with no-till. Rumination is one of the greatest evolutionary advancements, so maybe don't just pick on cattle as there a lot of ruminants walking the earth. The non ruminant/livestock methane production just comes out after digestion as their feces breaks down. And for anyone like myself who has stood in a rice paddy in Thailand, let me tell you it reeked, so I question the methane numbers there as well

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  15. wayne,

    I am inclined to agree with you about non-cattle food production needing to be better understood and helpfully corrected to be more sustainable. But I am less inclined to disagree with the opportunity, and the need, to dramatically reduce cattle rearing. Correcting how cattle are reared is indeed required, along with reducing how much beef people eat and the resulting reduction of cattle reared for human eating.

    The 2015 Sustainable Development Goals always need to be kept in mind. They are based on massive amounts of research and improved understanding that, like all improved understanding, is open to further improvement (the 2030 update will incorporate those improvements and recognize the progress made toward achieving the 2015 SDGs).

    The SDGs point to the need to reduce the unsustainable harm done by all human activity, not just food consumption. And they identify the need to address the way that economic competition for popularity and profit has a history of creating harmful results, including creating Desperate Poverty as measures of wealth increase faster than the population.

    Some people may claim that the real problem is the total global population increase. I do not disagree. But it is important to remember that harm being done, including the creation of Poverty, has happened while wealth increased faster than the population. And the recent global population study published in the Lancet indicates that achieving the SDGs will reduce the peak global population. So achieving the SDGs, all of them, is the answer to almost everything humanity needs to have a lasting improving future on this one amazing planet we are certain that humanity can thrive on as a part of the robust diversity of life that had developed.

    The harm done to the robust diversity of life on this planet, including harm by actions related to rearing massive numbers of cattle for wealthier humans to eat, is harm done to the future of humanity.

    A lame but common claim that also needs to be addressed is the claims that reduction of harmful environmental impacts can only be done by having increased wealth. The counter-argument is simple. "Harm Done does not justify Money Made and is certainly not excused by a portion of the money made being applied to partially correct the harm that was done by activities that created the appearance that money was made".

    Economics are an unnatural game made up by humans. The economic game can be responsibly governed to limit the harm done and increase the helpfulness achieved by the players in the game. That results in the understanding that the Libertarian Free Market thinking that some people want to promote are actually some of the most harmful ideas humans have ever come up with. It is undeniably incorrect to believe that Good Results will be developed if there is more freedom for people to believe whatever they want and behave however they wish in competition for Superiority relative to Others. All human actions need to be governed by the need to not be harmful and the desire to be more helpful. The economic games would need to be dominated, governed, by people who think and behave that way in order for Adam Smith's "Invisible Hand" to be Helpful rather than Harmful.

    Humans have been coming up with different versions of those unjust justifications for Superiority of Some relative to Others (including those Political Nationalists), including beliefs that humans are separate from, and Superior to, the rest of life on this planet, for a very long time.

    Humanity needs to pursue expanded awareness and improved understanding and apply what is learned to develop a robust diversity of ways for the diversity of humans (more complex than the binary belief) to live as sustainable parts of the robust diversity of life.

    Advancement of humanity is not necessarily indicated by technological achievements or measures of wealth. It is measured by how sustainable global human activity is, and its harmlessness.

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  16. I concur with Philippe Chantreau @12's statement:

    I see numerous valid points from all contributors so far, suggesting that this is a complex problem and indeed it is.

    The complexity of the agriculture's contribution to manmade climate change extends beyond CO2 and methane emissions. For example. it includes the use of nitrogen fertilizer as addressed in:

    Nitrogen fertiliser use could ‘threaten global climate goals’ by Daisy Dunne, Science, Carbon Brief, Oct 7, 2020 

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  17. one planet @ 15 much of what you said may be true, but is irrelevant if people are going to continue to promote these energy/methane/CO2eq numbers that are beyond questionable. But I guess it makes people feel better when they are eating their "organic" baby carrots and rice, and that's all that matters right!?!

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  18. wayne @ 17,

    What you state needs a more detailed presentation. I do not understand how your comment applies to what I presented, not even the part where you appear to agree with what I presented.

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  19. One planet, I'm afraid I don't undertand what you're saying in this response either

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  20. wayne,

    I am referring to much more that needs to be corrected than the climate impacts.

    But just focusing on the climate impacts, climate impacts need to be ended - all of them. And reduced impacts are reduced impacts - steps in the right direction.

    You seem to be arguing that there can be math done that says that some climate impacts are OK because of comparison to other climate impacts. It is not about which ones are OK or better or worse. None of them are OK.

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  21. one planet, no I'm saying that the math is wrong, that it is thermodynamically impossible and using it to justify your life decisions or as a template for behaviour change is probably a mistake

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    Moderator Response:

    [DB] "the math is wrong, that it is thermodynamically impossible"

    In the same manner that stating that a dog's tail is a 5th leg does not make it so, stating that "the math is wrong, that it is thermodynamically impossible" without citing a credible source or showing your calculated analysis does not make it so. 

    You'll need to substantiate your position in order to be taken seriously.

  22. ok moderator let's start with rice cultivation, which literally doesn't pass the smell test. Rice cultivation is responsible for 22% of global agricultural methane emissions and 11% of total anthropogenic methane emissions.

    Smith P, Martino D, Cai Z, Gwary D, Janzen H, Kumar P, McCarl B, Ogle S, O’Mara F, Rice C, Scholes B, Sirotenko O. Agriculture. In: Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt KB, Tignor M, Miller HL, editors. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge: Cambridge University Press; 2007. pp. 498–540.

    United States Environmental Protection Agency. Global Anthropogenic Non-CO2 Greenhouse Gas Emissions: 1990–2020 [Internet]. 2006. Available from: Adobe/PDF/2000ZL5G.PDF 

    Then there's the N2O

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  23. Wayne... As far as I can tell, your statement "the math is wrong, that it is thermodynamically impossible" isn't supported by your references at comment #22. 

    Can you be a little more specific?

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  24. Hi Rob @23 that's why I said it was a start :) and was just adressing the impact of rice cultivation. Do we not think that 22% and 11% methane contributions compare unfavourably with those of cattle?

    Organisms vary in their efficiency of feed conversion. Ruminants or foregut fermentation is one of the greatest developments in evolution since it's arrival some 50 million years ago. The benefit and efficiency of this system can be seen in their almost complete dominance of the herbivorous meso/megafauna. Virtually all non-ruminants or complete hindgut fermenters have since that time faced extinction. Out of some 450 ungulates today only about 25 non ruminants survive.

    See (Demment MW, Van Soest PJ (1985) A nutritional explanation for body-size patterns of ruminant and nonruminant herbivores. Am Nat 125: 641–672) for an explanation on the distribution and relative efficiencies of these different fermentation systems. Notice that non-ruminants are fermenters as well, just that one of the fermentation products ie., methane comes out the back instead of the front.

    This does not just apply to different digestive/fermentation systems but the inputs and outputs themselves.

    Feeding high nutrient/digestable feed to ruminants may result in lower enteric methane outputs (Boadi, D. A., Wittenberg, K. M., Scott, S. L., Burton, D., Buckley, K., Small, J. A. and Ominski, K. H. 2004. Effect of low and high forage diet on enteric and manure pack greenhouse gas emissions from a feedlot. Can. J. Anim. Sci. 84: 445–453.), but see their qualification and comparison to IPCC estimates

    A concern when evaluating animal feeding and management strategies to determine greenhouse gas mitigation potential is that significant emission reduction in one part of the production system may be negated if emissions are increased in another part of the production system. Table 6 demonstrates that inclusion of whole sunflower seed in general resulted in significantly lower (P < 0.05) total daily emissions of CH4 and NO2 expressed as CO2 equivalents. The observed reduction in total emissions is attributed to a significant reduction in enteric CH4, which contributed 95 to 96% of the total non-CO2 emissions from the feedlot. Enteric emissions by feedlot cattle fed a typical barley-based finishing ration were 72% of that estimated by IPCC (Tier 1). Use of whole sunflower seeds in the high forage:grain diet resulted in even lower emissions relative to estimates. Similarly, manure pack emissions in the current study were approximately 50% of that estimated using IPCC (Tier 1) coefficients.

    Indeed over 7.5 times more CH4 kg–1 dung (DM basis) was emitted from grain-fed compared to their hay-fed counterparts.

    Jarvis, S. C., Lovell, R. D. and Panayides, R. 1995. Patterns of methane emissions from excreta of grazing animals. Soil Biol. Biochem. 27: 1581–1588

    Thus the "thermodynamically impossible" comment, but it goes much further than that.

    People do realise that sheep and goats are just small ruminants and cattle are just large ruminants. You can even have cattle and sheep that approach each other very closely on a size basis. On the basis of size alone one of the biggest thermodynamic constraints will be the surface area to volume ratio, smaller organism will be energetically less efficient than larger ones, "having to run all day just to stay in one place". This is literally highschool physics and biology.

    Monogut organisms like ourselves and for simplicity sake chickens and pigs cannot handle the feed inputs that hindgut and forgut fermenters can, generally requiring higher quality feed from both a nutrient and digestive quality standpoint. But those feed inputs didn't arrive out of the blue, they required huge (relative) inputs and resulting outputs. By focussing on enteric emissions we are missing the forest for the trees. 

    I can deal with monogut efficiency and energy inputs/outputs of cash crops later as I am running out of time, but these conversations always remind me of how little people understand about their food whether it be wheat, corn, chicken or cows

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  25. wayne,

    Thankyou for re-presenting the rice example as a part of your thinking regarding this issue.

    My comment is that the sustainability of all food production needs to be the objective. From a climate impact perspective the status quo plant and animal growth activity, not its expansion or other impacting things humans do to grow the food, is not an issue in the planet's surface/atmospheric cycle. The issue is human activity that is harmfully changing things like increasing ghg's in the atmosphere.

    There have been many study reports regarding the ghg impacts of different types of agriculture. The general, and consistent or common, conclusion of those investigations appears to be as presented in this OP - reduced meat consumption and changes of how the reduced amount of meat is produced or obtained would be beneficial from a climate impact perspective.

    My concern is the broader Sustainable Development Goals which include biodiversity loss and other harmful unsustainable impacts of human activity. Expansion of food production that negatively impacts biodiversity is also harmful and needs to be reduced.

    It may be that rice and meat consumption need to be reduced, and for more reasons than the climate impacts. Rice has less nutrient value than potato. And over-consumpton of meat has serious health implications.

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  26. Wayne @24, I have no dispute with the studies you quote. And yes several things contribute to methane emissions including cattle and other animals, and rice paddies and leaking gas pipelines. The point  is reducing red meat consumption is one of the easiest ways to reduce emissions.

    Reducing areas in rice cultivation doesnt really make sense and just isnt going to happen. Billions of people are reliant on rice for basic nutrition. Red meat is a much easier target as its not essential in the diet and its such an inefficient use of resources. I think thats pretty much the essence of the issue. 

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  27. nigelj@26,

    I agree that lots of people 'rely' on rice for basic food needs.

    I would say that the more fortunate people 'choosing' to eat rice may be more helpful regarding climate impacts, and other impacts, if they reduced their rice consumption and replaced it with lower impact alternatives.

    With global population still increasing, increased areas for rice cultivation would be a concern from a climate and biodiversity impact perspective (and other impacts). And reducing the extent of areas already under rice cultivaton would, like reducing areas needed for cattle raising, be helpful from a biodiversity perspective.

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  28. Like most foods, rice is similar. It's not rice that is the problem, but how we raise the rice that matters.

    The System of Rice Intensification (SRI)…
    … is climate-smart rice production

    It's not meat that matters, but how we raise that meat. Rice, wheat, meat, timber, you name it. There are right ways to raise it and wrong ways to raise it.

    “Yes, agriculture done improperly can definitely be a problem, but agriculture done in a proper way is an important solution to environmental issues including climate change, water issues, and biodiversity.”-Rattan Lal

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  29. RedBaron@28,

    Agreed. Pursuing Sustainable Development, which humanity needs to pursue in order to have a lasting improving future, aspires to develop the most sustainable ways of living. That involves doing everything more sustainably, endlessly pursuing better ways of doing things.

    The less fortunate seldom have the luxury of choice and have limited ability to learn about their choices. The more fortunate have 'No Good Excuse'.

    Differences in the impacts of the ways of growing different foods should be the basis for the choices that more fortunate people make. The more fortunate a person is, the more helpful and less harmful their choices should be required to be (the ball and chain of being more fortunate is the obligation to Be Better).

    A related point is that unnecessary over-consumption, like eating more than 100 g of meat in a meal or eating meat in 2 meals a day, needs to be ended. The less fortunate have no role to play in that effort. That one is totally on the more fortunate. And the more fortunate a person is the greater the expectation, or requirement, for them to actually be Better Examples that way (that ball and chain of more responsibility for the more fortunate to be less harmful and more helpful).

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