Knowledge for better food systems

FCRN Blogs : Tara Garnett

FCRN Response to the Sustainable Food Trust commentary on Grazed and Confused.

Dear Sustainable Food Trust

Thanks for your response to our report.

I think many of your comments indicate that we share quite a bit of common ground, even though we have some differences.

Before replying to your points in detail, we thought it would be best to remind you of what our report explicitly does and doesn’t do, and say.

First of all – as emphasised on several occasions – our report’s focus was this: we looked at the role of grazing animals in the net greenhouse gas balance.  We don’t ask if they are better for biodiversity or whether these systems are more humane, or whether feeding human-edible grains to animals is a bad idea. We know that there are many other really important issues that need to be addressed, and that this report doesn’t cover.  We list some of them in Box 2 (p13) and return to them again in our research recommendation at the end of the report.  We have also as individual researchers, written on these other issues in the past (and we’re very happy to send you papers and references). In the preface, we try and contextualise our work as follows:

Ultimately in the context of planetary boundaries on the one hand and the need for human development (in its widest sense), the ‘big question’ that needs answering is whether farmed animals fit in a sustainable food system and if so, which systems and species are to be preferred. This report does not address this enormous and difficult question, particularly if sustainability is defined in its proper and widest sense. But by exploring a smaller one – the role of grazing ruminants in contributing to, or mitigating climate change – we hope to contribute some of the sub-structural knowledge we need if the big question is, ultimately, to be answered.

The second point to stress is that our report is not a comparative assessment of different livestock production systems or animal types.  We look at grazing systems and consider their role in the net GHG balance because this is an area of contestation.  In concluding that they contribute more emissions than they remove, we are not therefore concluding that intensive systems are to be preferred or that they are somehow less problematic.  That’s your inference of our results, not our motivation nor our conclusion. On the contrary – you will see that we say this (p124):

“… it does not follow that intensive production systems offer a better alternative. The shift to intensification changes the nature of the problems, and by some measures, makes things worse.”

We also touch upon the problems caused by the shift towards monogastric production and towards intensification in Section 1.41 (pp 23-24), and the rebound effects caused by gains in efficiency in Box 14, p100.

We note too that “all food production has damaging impacts, as compared with a baseline of no human presence on the planet.”

And while our report was global in its scope we emphasise the need to consider the specific context, a point we return to below.

As to your specific comments, we take each of them in turn, as follows:

1. You say: “The only way to produce human-edible food from grassland is to graze it with livestock and with the increasing global population it would be highly irresponsible to stop producing meat, milk and animal fats from grassland, since this would cause even more rainforest to be destroyed to produce soybean oil and meal, as well as palm oil.”

We reply: First of all, it’s worth pointing out that grasslands themselves don’t provide humanity with a great deal of protein.  Grazing systems contribute a tiny amount (about 1g out of around 27g of terrestrial animal protein, or 80g of protein from all sources that the average human eats each day).  We say that their role (in providing both food and livelihoods) can be vital in certain contexts.  And we also point out that, since grass is also a feed source for animals in mixed systems that total will be higher, although still lower than current average meat consumption. 

We find it problematic that many livestock today are reared on large quantities of grains that are potentially edible to humans.  And you will note that we explore (5.4.1 p105 onwards) a ‘livestock on leftovers’ scenario in which explore how much animal protein could be available to us if we avoided this feed-food competition.  Our analysis is based on three separate studies, which were in fact authored by most of the members of the research team (8 out of the 11 of us). These conclude – and our report reiterates – that this ‘leftovers’ approach (which we suggest is very much aligned with your thinking) might well be a sensible way of providing livestock products for a growing population.  However, we note two points.

First, this approach – as do all food provisioning approaches – comes with costs, particularly in terms of greenhouse gas emissions – and so any critical and objective consideration of the challenges we face will require us also consider counterfactual uses of the land currently used for livestock (and crop) production. Using land for activity x precludes its use for activity y.  So choices need to be made.

Second a ‘leftovers’ approach would need to go hand in hand with a very considerable reduction in per capita animal consumption (if damaging deforestation is to be avoided) – in line with our overarching conclusion that we need to be eating fewer animal products, at least as far as high consumers are concerned.

We also do not accept that cutting back on meat inevitably requires more cropland to be brought into production, since there are a huge range of variables to consider (the potential to increase yields, actions to reduce food waste, not feeding grains to livestock, and trajectories of demand – as discussed in section 5.3 of the report – see in particular Box 14). You of course know and have voiced your concern that a third of human edible crops globally are fed to livestock – and we share your concern. You will doubtless be aware of work that points out that the more we reduce our demand for animal products the less pressure we put on land use, including cropland use: see for example Erb et al 2016, Schader et al. 2015 and more recently this one – Röös et al 2017 the latter two involving several members of our project team.

2. You say: “ruminants may be responsible for up to 3% [sic – we think this is a typo and you mean a third?] of global methane emissions (up to 5% of anthropogenic emissions) and possibly up to 6% of direct global anthropogenic GHG emissions. However, this includes emissions from India, which has by far the largest population of cattle of any country, but where for religious reasons a high proportion of bovine animals at the end of their lives are not used as a source of human-edible protein.” 

We reply: Cattle reaching the end of their lives in India may or may not be used for food, but the females would have been used for milk earlier in their life and demand for dairy products in India is projected to grow rapidly in coming years.  It is also the case that many beef animals nevertheless end up being consumed, albeit illicitly and you will doubtless be aware that India is also the world’s third largest exporter of bovine meat (largely buffalo – also ruminants - but there is also some beef in the mix). More generally we are not sure what your point is here and why these animal emissions shouldn’t “count”?

3. You say: “net emissions from ruminants are at least 1-2% lower than this, when we consider soil carbon sequestration under grassland, the carbon sequestration and storage by hedgerows, hedgerow trees and parkland trees on grassland and the higher levels of methanotrophic bacteria (which use methane as an energy source) under permanent and unfertilised grasslands, compared with croplands.”

Our response to this assertion is broken down into three parts:

  • First, we are not quite sure how you arrived at your figure, but our estimate of the sequestration potential is lower than yours – even though it is an estimate of the optimistic potential rather than the current reality (most livestock systems are not optimised for sequestration). We also make the point that the sequestration potential is time-limited (as soils reach equilibrium) and reversible.
  • On hedgerows and so forth: why should they be credited to the animals? If we go down that route then arguably you could ‘debit’ them for the foregone sequestration potential of the land, were it to be allowed to revert back (at least in the UK) to woodland.  In this diagram copied from the report we showed that in fact a plant based scenario could potentially make available more land for sequestration than any of the scenarios based on livestock.  We emphasised that this diagram is purely schematic and illustrative – to show that there are always options and alternative possibilities - and that there will be a balance of costs and benefits however you choose to use land.  But we feel you are mistaken to suppose that a reduction in meat consumption (including of ‘grass fed’ meat) would lead to the loss of sequestration from currently grazed lands – since we are certainly not suggesting ploughing them up - and we reiterate the point that cutting back on meat does not entail an increase in arable cropland requirements.

Original source: Röös et al (2016).

  • As to the methanotrophic bacteria argument, this has been debunked separately by one of the co-authors elsewhere  and we repeat it here: “It is true that where there is methane, there are methanotrophs, but the issue with ruminants is that the methane emitted doesn’t come into contact with the soil (unlike termite emissions where the methane passed through the soil material in the termite mounds). Put a tunable diode laser or a quantum cascade laser across a field of cattle and you can directly measure the methane going into the atmosphere - this is a measurable, observable fact - the methanotrophs in the soil hardly make a dent on the emissions. The methanotrophic activity in the soil (even when there is a relatively large methane sink on the unfertilized grasslands) is nowhere near large enough to oxidise the vast methane emissions from the cattle. Methanotrophy exists, no question, but the methane sink capacity of even the largest methane sinks is nowhere near large enough to oxidise all of that CH4. Cattle emit around 300g of methane per day = 110 kg of methane per year. The maximum soil methane sink strength (found in old growth forests with virtually no nitrogen deposition or pollution) is around 17kg methane per hectare per year. So in the very best case (maximum soil sink strength), methanotrophs could oxide around 16% of their own annual emissions - even if the ruminants were only ever breathing methane into the soil. I have heard the methanotroph story many times - but the numbers simply don’t stack up. Most grasslands (even natural, unfertilised systems with ruminant grazing) have a much lower methane sink capacity than the maximum (17 kg/ha/yr) given above for unpolluted old-growth forests (check out Kevin Tate’s 2015 paper: Soil methane oxidation and land-use change - from process to mitigation in Soil Biology and Biochemistry, 80, 260-272) - the numbers don’t add up. It is like saying a drinking glass stores water, so if you empty a bathtub of water into it, you won’t spill any water. The statement that the glass stores water is correct, but the suggestion that no water will be spilled is absurd. It is not an issue of whether the glass can store water (it can) - it is an issue about how much. Assuming a stocking rate of only 1 cow per hectare, show me any grassland system that can oxidise methane at a rate of 110 kg/ha/yr (the amount emitted by the ruminant on that field) – this is orders of magnitude above recorded methane oxidation rates.”

4. You say: “while all efforts should be made to reduce emissions associated with manure management, we are concerned that technological fixes based on synthetic chemicals used in attempts to reduce methane emissions from cattle could have unforeseen negative consequences on ruminant metabolisms and effects on fat composition which would be detrimental to human health”.

We reply:  Nowhere in the report do we advocate these approaches and we don’t understand why you think we were.  We simply review the efforts that have been made (see box 11 p73) and highlight some of the dangers inherent in these approaches.

5. You say: “the number of intensively produced ruminants should be reduced, but the total number of extensively managed ruminants should be increased”

We reply: We agree and disagree.  Our overarching conclusion is that we need to curb the growth in animal production and associated consumption and place the onus for doing so on high consumers in line with a ‘fair shares’ contraction and convergence approach.  We say: “the ongoing assumption that production needs to meet the demands of high consuming individuals in affluent countries and increasingly in other parts of the world too needs questioning”

We have already pointed out in our preliminary comments above that we do not think intensive production constitutes a solution and remind you that we state this in the report (page 124: “… it does not follow that intensive production systems offer a better alternative. The shift to intensification changes the nature of the problems, and by some measures, makes things worse.”).

And so, we agree that the numbers of intensively managed ruminants should be reduced. 

As to the number of extensively managed ruminants, much depends here on several variables:

  • the extent to which we are successful in decarbonising other aspects of the global economy (transport, industry, the built environment, etc.) – the more success we have there, the more ‘slack’ there is in the system for food related emissions, and as part of that for animal production related emissions.
  • The extent to which we prioritise soil carbon sequestration on grasslands.  Livestock productivity and soil carbon sequestration objectives don’t always hand in hand – the relationship is very context specific.    
  • The extent to which society prioritises other environmental goals, such as biodiversity protection. We do not discuss biodiversity in the report (since this will be the focus of our next piece of research) but we do note that some grasslands effectively operate as monocultures and offer nothing for biodiversity. If we choose to assign more importance to biodiversity protection it may be that on some grasslands stocking rates will need to be altered (often going down) while on others, livestock may need to be removed altogether, implying reductions in animal protein availability. 

As we have said before, we have choices, and all choices imply costs, which we need to think about carefully.

6. You say: “global analyses of direct ruminant emissions and emissions associated with land use change such as the felling of tropical rainforests to make way for cattle grazing cannot and should not be used to influence agricultural policy in countries to which the same factors do not apply;”

We reply:  We agree.  In fact, in Chapter 5 of the report we looked at the historical drivers of land use change but also point out that the drivers of land use change are now changing, because of growing demand for pig and poultry products and shift towards intensification - and we consider the issues separately for three regions of the world (South America, North America, Europe).  For example, in Latin America we write:

“… the locus of land use change has shifted and so the damage continues, albeit in a different incarnation. With all eyes on the trees, the agricultural sector has moved onto the less charismatic grass. The Cerrado – despite its vast carbon stores, unique biodiversity and the fact that much of the biome actually includes forests and shrubs as well as grassland – has attracted the intense interest of both the arable and livestock sectors.”

We discuss the complex interplay between different drivers of land use change.  And we show that we are now facing a double threat from different branches of the livestock sector – demand for feeds for the intensive pig, poultry and dairy sector is emerging as a new threat, but at the same time the problems caused by cattle grazing have not actually gone away.  We also point out Europe was deforested (for pasture land) a long time ago – just because that is now the way things are here, does not mean that there aren’t alternative options for using land, that might be better for biodiversity – although biodiversity was not something we were able to explore in this work.  It’s an area that requires a great deal more thought and we intend to focus on the biodiversity implications of grazing (and other livestock) systems in a subsequent study.

7. You say: “most existing grassland should continue to be grazed, though at a reduced stocking density in some situations, as this is the only practical way to produce human-edible food from farmland that is unsuitable for crop production and ploughing.”

We reply: This would appear to contradict your comment 5 (above) where you say that the total number of extensively reared ruminants should be increased.  Presumably if there is a decrease in ruminant numbers on some grasslands there will need to be an increase on others (I, as you suggest, overall numbers are to be increased).  We certainly agree that ruminants are pretty much the only way to produce food from grasslands and that therefore grass-fed animals (whether in grazing only, or in mixed systems) have a role to play in sustainable food systems.  But we note their high emissions – which given the climate challenges we face are problematic.  Additionally, to repeat the point we made above, we wonder why you assume that the only or at least primary function of grasslands should be to provide food?  Since many (although not all) grasslands are the products of deforestation or other forms of land clearance an alternative option may be to rewild them.  As we noted in the report, this would not necessarily have significant implications for food security since the amount of food grasslands contribute is actually quite low (although of critical importance to certain communities, as we point out in the report itself). A rewilding approach is a possibility that we neither advocate nor reject in the report - we don’t form a conclusion either way on it. Our role as researchers is to point out the possibilities – to articulate that there are many ways of using land in order to provide ourselves with food, and these different configurations will give rise to a different balance of costs and benefits.  We, as a society, need to know what these are and look at them objectively.

8. You say “we see potential to convert some grassland to vegetable production, but believe this should be integrated with livestock farms, form a relatively small proportion of the area on each farm under grass, and be managed in rotation, so that land used to grow vegetables is returned to grass after a maximum of three years (to rebuild carbon levels, soil structure and biological life), while other grassland is then brought into the rotation.”

We reply: We agree. But we also note that in some contexts – in many parts of Africa, for example - land constraints are such farmers do not have the ‘space’ for rotations; the consequence being that continuous rotations have ended up reducing soil fertility significantly.  This is a difficult situation with no easy solutions.

9. You say: “grass and grazing animals should be reintroduced into arable crop rotations, especially in parts of the UK and parts of the world suffering from soil degradation, with a corresponding reduction in commodity crop production.”

We say: We agree: a better integration of livestock and cropping is desirable for various reasons including to avoid point source pollution and make good use of manure. However, there is no room, environmentally speaking, for more animals.  We also think it is important to explore other possibilities such as stockless rotations (including in organic systems) since the priorities are to avoid any further land use change (including for biodiversity reasons) and to tackle greenhouse gas emissions.  This implies a reduction in animal numbers and associated animal product consumption.

10. You say: “consumers should be encouraged to reduce their consumption of intensively produced pork, poultry and beef reared on low forage/high grain diets, through the introduction of taxes on the use of nitrogen fertiliser, with the funds reused to support farmers changing their production systems through the introduction of crops and techniques recognised to increase soil carbon levels.”

We reply: We agree that consumers should be encouraged through a diverse range of policy approaches to reduce their consumption of intensively reared animal products – and that overall animal numbers should be reduced. See our point 5 which discusses our views on numbers of extensive ruminants.  We also agree that farmers should be encouraged, again through a range of policy approaches, to farm in ways that among other environmental actions, build soil carbon and soil fertility.

11. You say: “In part, our conclusions are based on the fact that, as the report’s authors acknowledge, they only consider greenhouse gas emissions (GHG). In contrast, we base our assessments on:

  • an analysis of a much wider range of factors, which include:
  • the huge importance of GHG emissions;
  • practices which result in soil carbon sequestration and distinguish most grazing systems from most continuous arable cropping systems
  • emissions of ammonia, a major air pollutant and a minor indirect source of additional GHG emissions from intensive livestock production;
  • soil degradation, both in the UK and in countries from which we import food;
  • biodiversity loss, both in the UK and in countries from which we import food;
  • antimicrobial resistance – the use of antimicrobials in pig and poultry production accounting for over 85% of all farm antimicrobial use;
  • the overuse of reactive nitrogen and water-soluble phosphate fertilisers in food production and the wide range of problems this is causing;
  • the harmful impacts of certain pesticides used in food production;
  • drinking water quality and river catchment management and their relationship to land use;
  • a wide range of social and cultural issues, including the extent to which increasing mechanisation in crop production and intensification of livestock production are resulting in the increasing cultivation of monocultures, dramatic increases in farm scale and the demise of small to medium-sized family farms, something which has a large number of negative consequences”

We reply: we agree that we have massive problems with agriculture as it stands – in both the cropping and the livestock sectors. We agree with the list of problems you identify.  We list others in the report too (see box 2 page 13).

We deliberately decided to consider only the question of greenhouse gas emissions and climate change not because we don’t think other issues are important - we do and they are - but because the climate change issue is complex enough as it is, there is a great deal of confusion in this area, and our report is already very long.

Of course, one could argue that it is precisely this ‘single issue’ approach to investigating problems and solutions that has got us into the mess we’re in in the first place.  We certainly agree that systems thinking is essential - and many of us involved in this report apply this approach in our work.  However, ‘systems thinking’ should not morph into ‘woolly thinking’ or ‘argument swapping.’  We strongly felt it was necessary to examine the climate change question on its own terms to understand it fully, and also so as to avoid the risk of jumping, without following through, from one line of argument to another.  That in our view is inconsistent thinking. Note that two of the authors (Tara Garnett and Elin Röös) in fact wrote a fairly detailed report published in 2016 (see Lean, mean, green, obscene...?  What is efficiency and is it sustainable?)  which argued that the whole concept of environmental efficiency is problematic in many ways. That report may be of interest to you.

12. You say: “We feel one of the fundamental weaknesses of the report is that it attempts to reach conclusions based on a global assessment. We believe that different approaches are needed in different countries and regions due to the varying soil, climate and water-availability factors, as well as current meat consumption patterns.”

We reply: We agree. Context specificity is crucial and you will find that we stressed the context specificity of the sequestration potential at many points in the report – see for example pp 58-61. But it’s also the case that often, sweeping claims are made about the climate (and other) benefits of grazing systems based on extrapolating from the local to the global.  We tried to show that the local is often not globally applicable.  All scales of assessment are important – we need global appraisals of the situation as well as local perspectives.

13. You say: “‘Grazed and confused’ cites a report from FAO authors, Gerber et al. (2013) which calculated that livestock production globally is responsible for 14.5% of global anthropogenic emissions. However, it fails to cite a second report largely by the same group of authors published in the same year (Opio et al. 2013) which comments on the methodology used in the Gerber et al. 2013 report (for more detailed examination of these issues see Young, R 2017b). This states, “Given the year of reference (2005), latest trends could not be fully reflected (e.g. reduction of deforestation rates in LUC). A sensitivity analysis was conducted showing that the period of the analysis has an important influence on results” (Opio et al. 2013, p. xv).

“In relation to these two FAO reports it is important to point out that on page 106 of the Gerber et al. 2013 report the authors acknowledge that they only considered land use change in South America and the Caribbean. They did not, for example, consider rainforest destruction in SE Asia and central Africa to produce palm oil to replace animal fats in human diets. And they did not look at countries like the UK where significant areas of forest were being planted at this time on UK farms and where no forests were being felled to make way for grazing animals. In complete contrast, large areas of grassland was being ploughed and converted to continuous grain or vegetable production.”

We reply: We’re not quite sure what your point is here.  We agree the 14.5% figure cannot be perfectly reliable (and we actually give a range in estimates – see p39).  We also agree that emissions (and the composition of those emissions) will change over time.  It’s possible that some livestock-associated LUC emissions may have reduced in recent years, while others may have increased and this will play out differently in different parts of the world, with implications for the exact figure one chooses to use for grazing related GHG emissions. You will doubtless be aware of recent research suggesting that livestock-related methane emissions have previously been underestimated .

The main conclusion of this report is that if we want to achieve some measure of climate stability – then the food system must play its part.  Grass-fed systems will not deliver salvation, and cuts in consumption of all livestock products (including pig and poultry meat) makes the 2-degree goal more feasible.  This is true at a global level, but also likely to be so for the UK – see for example Lamb et al 2016.

14. You say: “At the same time, they also only cite efficiency in terms of protein production. Yet, dietary fats account for 36% of energy intake in the UK and today people increasingly get their dietary fats from former rainforests in the form of palm oil and soybean oil, whereas before the mid-1980s they predominantly came from grasslands via animal fats. Even today, despite the claims and assumptions made about animal fats and human health, grassland still provides a not insignificant proportion of dietary fats via dairy products and red meat, without which demand for palm oil in particular would increase still further, with all the negative impacts that would have. The failure to take this into account further distorts the evidence base used in the report.”

We reply:  We don’t want to comment on the nutritional aspects of animal fats, since we didn’t consider the health dimension at all.  We agree that from a climate (and resource effectiveness) point of view it makes sense to use the whole animal carcass, including the fat component.

On the availability of fat, generally, recommendations (depending on the country) are to limit fat intakes to about 30-35% of total energy intakes.  For a 2300 kcal diet this works out at about 75-90g / person / day. ​

If we keep vegetable output constant, reduce the availability of animal fat sources and assume the global population will to grow to 9-10 billion then the provision of fat at those levels could be challenging.  We agree that this issue requires more investigation, investigation which takes into account both maximum and any minimum nutritional requirements for fats.  ​

15. You say: “The authors acknowledge that ‘[A]voiding carbon release by acting to halt degradation or conversion to croplands is even more important than trying to sequester it from the atmosphere’. Yet they fail to explain how this can be done. Our analysis of the scientific evidence is that continuous arable cropping inevitably results in substantial reductions in soil carbon. In addition, at least five peer-reviewed studies by teams of scientists have found that, contrary to previous claims, no-till systems do not increase total soil carbon.

Most croplands have lost 40-50% of their carbon, and some soils (predominantly lighter soils and peat soils) continue to lose large amounts, though soils with a significant clay fraction do tend to stabilise at a lower level, only losing more via erosion when that occurs. While some of that carbon loss was associated with the production of grain for intensive ruminant production, most of it was associated with the production of feed for pigs and poultry and the production of crops for direct human consumption. These historic carbon (and nitrous oxide) losses should be included in an assessment of the GHG emissions associated with comparative assessments of different food systems, and failure to do this biases the evidence in favour of pigs and poultry and against grazing animals.”

We reply: there are a number of argument bundled up in this point.

Taking the last point first: you are concerned about the carbon loss implications of growing grains to feed intensively reared pigs and poultry as well as ruminants.  We are too. To repeat the point that we made earlier: we did not conduct a comparative analysis of intensive versus extensive or ruminant versus monogastric systems in order to decide “which is worse?”! We just looked at the GHG balance of grazing systems because we were interested to know if the claims that have been made are true.  We concluded that they emit more than they remove.  This does not imply endorsement of the intensive livestock sector.  We make clear the need to curb the growth in animal production and associated consumption of all kinds and whatever the system.

On your point about croplands leading to declines in carbon – we agree on this point too.  We need to address and improve many aspects of current production. We don’t think it’s a case of ‘grazing systems build soil carbon and cropping systems don’t’.  While conversion from grassland to cropland will cause losses in soil carbon for croplands already in existence there are a whole range of opportunities for improving cropland management (not just no-till) that can maintain or increase soil carbon stocks.  In the report, we emphasise the need to avoid conversion of grasslands to croplands – but we also note that there are ways of maintaining carbon stores in grasslands and even increasing them, without rearing animals on them.

You make a larger point which is essentially about the need for animals in a sustainable food system, and as part of that in crop production.  We discuss this below in our response to your point 17.

16. You say: “Clearly the authors are confused. They cite recent research (Mottet et al. 2017) and could also have cited Wilkinson and Lee (2016) and Wilkinson (2011) who find that ruminants eat grass (which humans cannot eat, and concentrate feed for cattle is largely based on the residues from grain and oilseed crops processed for humans: Brewers’ and Distillers’ grains, Millers’ offal (small and other grains not suitable for human consumption), sugar beet pulp, and oilseed by-products like rapeseed cake, whereas pigs and poultry largely consume grain that would be suitable for human use, cattle are actually significantly more efficient in converting non-human-edible food into high quality protein and therefore less in competition with humans for food than pigs and poultry. Yet because these conclusions are the opposite of what campaigners have believed for many years the authors appear unsure what to make of them.

They present a range of options for the way forward, each of which they then shoot down; and they leave us with the question of how can we meet the growing demand for animal protein. Part of their confusion results from the extent to which they jump about between production systems, switching from extensive ruminants to the problems associated with intensive ruminants and monogastric animals, in a way which leaves the reader feeling that somehow this also relates to extensive ruminant production.

Part of this confusion relates to their assumption that if we keep ruminants at all they need to be providing 50-60g of protein per day to a rapidly growing population. We would suggest that ruminants should be used where they can best play a role in utilising human-inedible food and that any protein shortage should then be made up by less intensively managed pigs and poultry largely fed on waste human food, and by increased cultivation of legumes.”

We reply: we agree with your final sentence… but we too are confused by your interpretation of what we write in our report.

As already mentioned above, in section 5.4 (p 105 onwards) we discuss three studies (Röös et al, Schader et al, Van Zanten et al) – which were co- authored by 8 of the 11 authors on this report – which specifically explore scenarios in which make use of ruminants’ ability to convert human-inedible grass, by-products and food waste into human edible animal protein.  The purpose of these studies was to explore what the implications of those scenarios might be. The conclusions of these studies are that:

  • a ‘livestock on leftovers’ approach gives us less animal protein in than we currently eat in high consuming countries and less than the projected per capita average globally for 2050.  This leads us to the conclusion that if we adopt this option we need to cut down on the amount of meat we eat.  And as you know, the conclusions of the report are that we do indeed need to cut down on the meat we eat – we do not see a livestock future where ongoing growth in animal production and associated consumption is possible, without creating huge problems for climate change mitigation (and for other issues too – although these were not the focus of the report and so we won’t discuss them further here).
  • A leftovers scenario solves some problems and creates others.  All approaches to providing our growing population with food and all configurations of land use and agricultural production create problems.  We need to be honest about them.  For example, in the case of a livestock on leftovers approach, while this makes use of agricultural by-products, land unsuited to cropping, and food waste, GHG emissions are higher than in a scenario with even lower meat consumption.  Also, alternative ways of using grassland (for biodiversity, or biomass production) or for using food waste are precluded.   As academics, our role is to explore these options as objectively as we can (while acknowledging and seeking to counter our own personal biases) and to communicate these findings to others so that informed decisions can be made.  Advocacy is not our role.  Ultimately society (which of course as individuals we are part of), needs to weigh up these options, and we recognise that these are likely to play out differently in different parts of the world. 

17. You say: “Another fundamental point which the authors fail to recognise is that continuous crop production is simply not sustainable, organic matter levels decline, soils lose their structure, crops become increasingly prone to weeds, pests and diseases. Apart from fruit and nut trees, grassland is the only crop which rebuilds soil fertility while producing food for human consumption, albeit indirectly. This should not be confused with the serious soil degradation caused by the over-grazing of livestock in dry regions. Closer inspection often reveals that those guilty of this are trying to subsist in countries where the rainfall is too unreliable for crop production and where over-grazing is often caused by small-holders being pushed forcefully or economically off the better land which is then used for irrigated crops exported to developed countries, such as the UK.”

We reply: You make two points. The first is about the problems caused by crop production, the second by overgrazing, often caused by smallholders being pushed off the land by commercial agriculture.

On the second point: we agree both about the problems of overgrazing and also (in many cases) about its causes.

Your first point – about the problems caused by crop production – is also about the necessity of having livestock in a sustainable food system.

A few responses here.

We agree that monocultural arable crop production is highly damaging and that soil degradation is a global concern. We need to find better ways of producing food.  This is likely to entail more widespread use of agricultural practices such as soil carbon building crop rotations including perennial crops, the use of cover crops, intercropping etc., and more research and experimentation into new forms of agriculture, both those that involve an animal and those that don’t (for example research into stockless organic systems involving green manures, compost, biogas digestate, etc.).

We also go back to the point we made right at the start of this report. We recognise that there is a ‘big question’ that needs answering: “whether farmed animals fit in a sustainable food system and if so, which systems and species are to be preferred.” (p 7 of the report).  We don’t address this questionwe only look at a smaller, albeit important one – “the role of grazing ruminants in contributing to, or mitigating climate change” since this provides some of the knowledge we need if the big question is to be answered. 

We don’t have the ‘answer.’  But we do say that an agriculture that relies very heavily on livestock will undermine attempts to maintain urgently needed climatic stability.

18. You say: “Including common land and rough grazing, 71% of UK farmland and 70% of global farmland is under grass for sound agronomic and environmental reasons. If this land were converted to cropland there would be a loss of organic matter equivalent to GHG emissions averaging 250 tonnes of CO2 equivalent (CO2 plus N20) per hectare over approximately 25 years [the N20 would mostly be lost within a couple of years, the carbon more steadily, but tapering towards the end of the period]. In many cases there would also be progressive loss of tree cover and hedgerow density, which would further reduce the carbon sequestration currently occurring.

We would also point out that in the UK approximately 60 litres of milk is produced for each kilo of soyabean meal used in dairy production, whereas 1 kilo of whole soybeans only makes 7.5 litres of a soybean drink, formerly called milk.

The only sustainable way to obtain food from grassland is to graze it with ruminants. With the growing global population it would be irresponsible not to do that.”

We reply: Nowhere in the report do we suggest that we should convert grassland into cropland -  in fact we emphasise in several places that this would be a bad thing to do for climate change and for other environmental reasons.  But we challenge your conclusion that the only thing to do with that land is to produce food on it.  A shift away from meat-heavy diets would reduce both the amount of pasture land needed to rear animals and the amount of cropland needed to grow animal feeds (we share your concerns in this respect) which would reduce overall pressures on land use.  This means that cropland requirements need not increase.  And as to grassland, we repeat the question we asked earlier (point 7): why should one assume that the (main) purpose of grassland is to provide food?  As we note in the report (pp112-113):

“…grasslands are not an ecologically cost-free resource. Many grasslands receive fertiliser applications and other inputs, they may be ploughed periodically, and the pasture may be managed as a perennial monoculture. A production system that uses less arable but more grazing land may be less, but it may equally be more, damaging to the environment (across a suite of environmental indicators – with the net GHG balance just one of them) than one which uses more arable but less grazing land, depending on the specifics  of the management regimes.

Crucially, there are counterfactual uses for grazing land to consider. The land could potentially be used in other ways, which would yield a different balance of costs and benefits for soil carbon sequestration, food provision and biodiversity conservation.”

Humanity uses vast tracts of land to provide itself with food. Much of that is to rear animals, in a variety of different systems.  In some parts of the world livestock grazing and biodiversity are antithetical – in others, they can co-exist.

We end this response by repeating our conclusions (bold added for emphasis):​

“The inescapable conclusion of this report is that while grazing livestock have their place in a sustainable food system, that place is limited. Whichever way one looks at it, and whatever the system in question the anticipated continuing rise in production and consumption of animal products is cause for concern. With their growth, it becomes harder by the day to tackle our climatic and other environmental challenges."