The Conservatives are proposing a form of free market education, based largely according to them on the Swedish (and also American and Canadian) model of the last 20 years. The problem is, there's no convincing argument what they're doing is constructive.

They want to allow parents to effectively choose which school they want their portion of the schools' budget to go to, in essence forcing schools to compete for students.

There are two main problems with the Conservatives' position, perhaps symbolic of the current trends in politics - firstly, their policy is not right-wing enough, because it fails to allows schools to turn a profit (as Swedish schools can) and hence will likely lead to charitable institutions and small collabratives setting up minor that have little impact on the system; and secondly, it is far, far too right-wing, because it totally fails to promote equality and fairness in the educational system.

If you know me, you'll not be massively surprised to hear that the second issue is where my personal bone of contention is to be found. Newsnight recently found the Swedish model to be unimpressive as a piece of pioneering social organization, noting that in recent years "not only are standards generally down, there are strong indications that the new schools have increased social segregation".

It seems to me blindingly obvious that this is precisely what you would expect from such a crude attempt to make the school system more dynamic.

Obviously, you won't hear me disagreeing with the Conservatives' statement that giving

many more children access to the kind of education that is currently only available to the well-off: safe classrooms, talented and specialist teachers, access to the best curriculum and exams, and smaller schools run by teachers who know the children’s names

is a good thing (although I might well dispute, based on personal experience and the teachers who I know, the claim that one only gets such attention in the public and private school system). And it's trivially true that opening more schools will improve class sizes and, assuming that their budget is not effectively reduced during this process, also improve teaching quality and time (we could look here to up-and-coming countries like China, where 7AM-6PM state-funded schooling is reality for many people, as Ken Livingstone pointed out earlier this week).

Of course,

The Swedish people generally approve of the new system. About 10% of all students of compulsory school age now attend the new schools, and in the upper secondary level it is about 20%.

In fact, the Conservatives' draft schools' manifesto has much in the way of increased spending recommendations and increased powers, intervention and supervision: they will

• allocate increased pay budget control for headteachers (allowing them to "pay good teachers more", rather than the converse, it seems implied);
• "pay the student loan repayments for top maths and science graduates for as long as they remain teachers";
• "legislate so that teachers can ban any items that cause disruption in the classroom";
• "reinforce powers of discipline";
• "set up technical Academies across England, starting in at least the twelve biggest cities";
• "fund 400,000 new apprenticeship, preapprenticeship, college and other training places over two years"

and so on. Hardly the anti-nanny state, fund-cutting image we're used to, is it? The point is the Conservatives are basically in favour of creating more schools and educational institutions and allocating more funds to the school sector. Sure, the usual pro-discipline measures are there, but what's that really but increasing how heavily then government intervenes in day-to-day life? (I'm not against it, but many Conservatives seem to claim to be.)

But really, the basic principle of allocating funds in an essentially market-controlled manner is going to do exactly what it does in every other market - create some really huge, bloated organisations (Tesco, Whitehall, I could go on), crows out many smaller specialist instutitions, and result in bizarre competitions that end up not being beneficial to student, or (more likely) teachers. Put in this light, the apparently reasonable approach of having

more unannounced inspections, and failing schools will be inspected more often – with the best schools visited less frequently [and] any school that is in special measures for more than a year will be taken over immediately by a successful Academy provider.

seems somewhat more likely to result in the rapid construction of very large, monocultured schools, with presumably the same old problems with discipline, management, class sizes, and inefficiency.

Surely this will result in 'good' schools (presumably judged by the local media as much as anyone more qualified) receiving far too many applications to cope with, and hence either taking in too many pupils to manage adequately, or turning away vast swathes of candidates (based on what, one wonders) who would be forced to turn to 'worse' schools, creating significantly more inequality in the educational system, in the short and medium term at least.

Impressively, the Conservatives appear intent on doing this without even offering a monetary incentives to the people owning the schools. Regardless, having schools compete for students might also make for a considerably more high-pressured environment, both for students and teachers.

And even the other celebrated Conservative goals (particularly of 'liberating' schools from the tyranny of the 'politicised' national curriculum) seem thin when you consider even their idols Sweden enforce their curriculum.

Also, an interesting comment is to be found in this draft manifesto - the Conservatives will

end the bias towards the inclusion of children with special needs in mainstream schools.

I don't know what everyone else makes of this, but it sounds fascinatingly dangerous to me.

I went to see Ken Livingstone today.

Ken Livingstone is an interesting man. He is variously described as outspoken, "bold and imaginative", a disgrace, and Trotskyist. Whatever you think of him, I believe that more politicians like him could be a good thing.

I don't mean more left-leaning, or more environmentalist, or more liberal (well, actually, I do think these are good things, but that's really not what I'm getting at) - what I mean is forthright, open and frank. I like Vince Cable. I also have massively more respect for people on the right, like maybe Boris Johnson, and hell, even John Bolton, who state their (frequently wrong...) views openly and, yes, divisively, than those who studiously avoid the controversial in what they have to say, even when it is massively important to the electorate.

Yes, this is heavily directed at Cameron and Osborne and their ilk, people who leave you confused about their long-term vision, and their commitment to their policies.

But it is equally heavily directed to the Blairite school (although I certainly feel Cameron and Osborne - and Clegg, come to that) and the whole culture of 'professional' politicians (I use the word in the same way one describes 'professional fouls' in football) who exist, publically, as sort of ethereal ghosts in the machine, who do not represent with any confidence any values or schools of thought, but rather just give glimpses into an unknowable Whitehall existence.

Perhaps the world would be a better place if politicians (in fact, this is largely directed at higher-ranking ministers and their shadow counterparts) could step away from not just party line, but from the strange brand of modern political pseudo-realism which permeates all attempts at political debate. It is endlessly refreshing to hear people talking coherently about their own personal views, and putting forward reasoned, historical or just plain true arguments about important stuff.

Just my two cents.

Ken Livingstone was speaking at the Cambridge Union on Wednesday 17^th February 2010. He was mayor of London from 2000 to 2008, winning his first election as an independent candidate, and returning as a Labout party candidate in 2004. His achievements include introducing the first same-sex civil partnership register, before the government followed suit 3 years later, overhauling the public transport system, and introducing the congestion charge and other environmental measures. He was succeeded by Boris Johnson, but plans to run again for the role next term. Previously, he had served from 1981 as Leader of the greater London Council until the post was abolished by Margaret Thatcher in 1986. He is currently an adviser on urban planning in Venezuela, where we works with Hugo Chávez who he says is "just like me".

How sure are you?

Oddly, even though it's apparently one of the most fundamental questions to ask, we are often not very good at accurately judging and reporting our certainty of our own knowledge of the world.

I just got back from a stimulating and entertaining talk by the excellent Professor David Spiegelhalter entitled Quantifying Epistemic Uncertainty at the Trinity Mathematical Society.

He talked variously about the vagaries of different ways of interpreting probabilities (particularly the frequentist, Bayesian and 'metaphysical' interpretations, of which more below) and how they relate to our understanding of information in crucial areas like healthcare. He then went on to illustrate (with an excellent practical example in which he involved the whole group) exactly how our understanding of certainty can be quantified (or at least put in a useful frame) and used for the training and adjustment of accurate forecasts.

Metaphysical Understanding

The 'metaphysical' interpretation involves conceiving of possible futures, in an attempt to personalize risk. The article linked to above references this interactive demonstration which you might like to play around with, and maybe even use as the basis for a little experiment of your own. His argument is that the best way of getting people to understand the risks involved in individual lifestyle choices (like the purchase and use of statins) is to phrase it in terms of what could happen to them over 'multiple lives'.

If I am told there is a 10% chance I will suffer a heart attack or stroke in the next 10 years, lowered to 8% by taking statins, then my understanding of this changes according to whether I think of this in terms of, say, a 20% cut in the chance I suffer such an event; or for every 50 people taking statins, one 1 avoid a heart attack.

It is always clear that the mode of presentation of statistical information is of prime importance, and juxtaposition of statistics allows intuitive understanding of relative magnitudes to dominate over any attempt at a full understanding of, say, the worth of a treatment.

He contests that thinking in terms of 'future mes' is the most natural and valuable way to present what are by their very nature subjective statistics and risks. In 2 out of every 100 lives I lead, I would avoid a heart attack because I took statins.

Scoring Rules

The main body of the talk, however, was devoted to understanding the concept of a scoring rule. The idea is that, given some questions, and a subject who is answering them and providing an estimate of their own confidence in the result, you want to know how to reward (or penalise) the subject in order to get the most reliable information out of them about their own confidence.

For example, consider a meteoriologist forecasting the weather - if they are predicting weather with some stated percentage of confidence, how do you give them the incentive to be truthful and accurate and assess their accuracy?

The basic idea, stripped down to the simplest case of a binary event (e.g. will it rain tomorrow?), is to allocate some score S to every a probabilitistic forecast (or set of forecasts). In fact, we always assume we have several foecasts. Then the overall score should be higher when the forecaster is most reliably accurate at declaring uncertainty, and lowest when the forecaster routinely makes incorrect forecasts with high confidence.

Specifically, we call a scoring rule a proper scoring rule if the expected score is maximised (or more generally optimised) if and only if the actual probability of the event is exactly equal to the forecast probability.

For example, take a test with a quadratic (Brier, after the man who created the score around 1950) score, , where x is 0 or 1 according to whether or not the event occurs and q is the estimated probability it does. Then if the forecaster believes that there is a probability p that it does occur, the expected score (from his point of view) is which is equal to . So clearly, the forecaster maximizes his expected payoff by setting his projected likelihood q to exactly what he truly believes it to be, p.

Note that not all scoring rules are proper - not even all likely seeming candidates are. For example, you can check encourages forecasters to exaggerate (i.e. to pick q to be always either 0 or 1).

You can easily conduct an experiment using a scoring rule with any group of people - give them a multiple-choice test (two options each time for these simple rules) and get them to write down a 'confidence' probability for their answer - say 5/10 for a total guess and 10/10 if they are entirely certain. Then give them the corresponding score according to whether their answer was correct and their stated confidence, and you are left with a set of overall scores indicating who was the most honest and reliable answerer. This works very well (especially with punishing negative scores for high-confidence mistakes) as both a party game and statistical exercise.

A sample (quadratic) set of numbers are (listed as confidence, score given correct, score given incorrect):

• 5: +0, -0
• 6: +9, -11
• 7: +16, -24
• 8: +21, -39
• 9: 24, -56
• 10: 25, -75

A few different scoring rules are illustrated here.

In the long run, i.e. over several forecasts and experiments, we can 'decompose' (see this article also) the sum of the Brier score above into three components: Uncertainty, Reliability and Resolution. (Note the linked article uses a Brier score which is lower for better forecasts - this corresponds to dropping the leading 1 term in the above definition and making the remaining expression positive.)

1. Uncertainty provides a measure of how naturally diverse the events are (maximised when the event occurs 1/2 of the time for a binary event like we are considering). The Brier score is higher (worse) when the uncertainty is naturally larger, reflecting the fact that it is more difficult to give accurate predictions in this case.
2. Reliability shows how far from the truth the forecasts were, on average; so a figure of 0 indicates perfect accuracy, whilst larger values show more deviation.
3. Resolution shows how much the forecasts differ from the overall average score - note that one can achieve very high levels of reliability simply by constantly predicting the climatic average; resolution is higher when the forecasts are 'more definite' than this, and so is substracted from the score to improve it for higher resolution. It precisely equals (and hence cancels out) the uncertainty in the score when the predictions are always definite (0 or 1).

Spiegelhalter also noted that one can actually justify the construction of a semi-frequentist, semi-Bayesian theory of probability - and in fact derive the standard axioms of probability as theorems in this alternative, 'deeper' formulation of the subject.

It's possibly worth considering the slightly more fickle aspects of this method - encroaching on the field of game theory, in fact, as one considers less local tactics and maybe even psychological aspects to the situation. Most notably, it may be the case that maximizing expected score leads to non-optimal behaviours, and with human error and tendency to bias confidence included the situation becomes a lot less clear. Scoring rules are fairly heavily used (as suggested by the terminology and examples) in meteorology and similar areas, but the field seems to be studied rather less than one might hope. Still, something to do over the holidays...

David Spiegelhalter is the Winton Professor of the Public Understanding of Risk here at the University of Cambridge. He works largely with public-sector outreach and educational projects and the media, but also teaches an advanced course in Applied Bayesian Statistics, and retains a research interest in several practical areas of statistics, especially healthcare. He also runs the website Understanding Uncertainty, a resource for easy to read statistical treatments of various topics. He was talking at the Trinity Mathematical Society (TMS) on Monday 15^th of February 2010.

*Please Note* This is as yet unmoderated, and un-proof-read document. Feel free to point out omissions. Thank you. It continues from Vegetarianism, Part 1: History.

The main motivations (or justifications) for switching to a vegetarian diet can be classified as follows:

• Practical
• Environmental
• Health
• Ethical
  • Religious grounds
  • Non-religious grounds

I shall now discuss each of these categories separately, attempting to draw on real evidence, and to present arguments, counter-arguments and so on, as to the viability and tenability of the associated positions where there is any dispute.

Practical Concerns

The two main practical issues with meat-eating relate to cost and availability. These are both highly geographically and temporally dependant factors. Both of these seem likely to have contributed significantly to the sharp rise in Western meat consumption over the past five to six centuries. The capitalist model has ensured a continuingly growing supply of meat at falling prices (giving rise to a large subset of animal-rights ethical objections, as welfare cutbacks to improve efficiency are clearly necessary without major scientific breakthroughs). It is clear that this rise was driven by the association of meat with positive aspects of life (wealth, health and so on), so it is possible that, had there not been the initial lack of availability of meat except to the upper classes, contemporary meat consumption might have been greater.

Many fairly irrelevant associations can be seen today influencing the younger generation’s choice of food, and may be justifiably attributed to medieval attitudes regarding meat’s importance as a symbol of authority, wealth and ‘manliness’ (watch some burger adverts if you don’t believe me), and the naïve assumption that meat ‘is’ food. (Etymologically speaking, this is actually correct – the Old English mete meant food, as opposed to drink, and derives from the Proto-Indo-European mat or met, meaning measure – hence ‘meter’.)

This latter prejudice, derived partly from the practical issue of availability of a suitably varied vegetarian diet in the West – the shortage of nutrients, minerals and protein now recognised as a serious issue with uneducated vegetarianism by all doctors – and partly from religious and cultural assumptions about the role of meat, and is still present today. Comparatively rarely do non-vegetarian customers in restaurants order ‘vegetarian options’, which are often separated, instead choosing a meal which is centred on the choice of meat (beef, lamb, chicken…) and which frequently has a large quantity of whatever meat it contains.

However, it is generally the case that vegetarian meals are cheaper and easier to prepare. This influences both the choice of people, and organizations which feed people (‘soup kitchens’ and similar organizations often serve soups and salads with no meat, for instance.)

Also, it is evident that restaurant prices can influence people eating out – even if the vegetarian submenu is limited, the meals are often at least a third cheaper.

The issue of limited availability of vegetarian options is mentioned above. It is important to note the importance of fairly rare (regionally speaking) foodstuffs or vitamin supplements to vegetarian diets, if they are to have healthiness similar to omnivorous diets (which are generally less regionally dependent, since meat producing animals provide much of the required human intake of vitamins, minerals and so on, but can themselves live on a vast variety of landscapes – an issue particularly to poor and isolated communities in areas with large amounts of human-indigestible vegetation.) In the case of vitamin B12, including compounds like cyanocobalamin, scientific research has actually concluded that, based on current knowledge [1] [2] [3] [4], uncontaminated plant sources cannot reliably provide sufficient levels for full health, leading to supplements being taken by many vegetarians (intriguingly, the sources for other herbivorous animals are often, for example, plants which are infested with insects, whilst vegetarian humans in recent history have often got B12 by consuming contaminated plants – where faecal contamination is not uncommon.)

There are also practical objections to ‘unconditional’ vegetarianism. The two most serious issues cited pertain independently to the two different worlds of highly connected economies, and poor disconnected and isolated regions.

The more attractive of these arguments is the latter, due to its strong emotional appeal (as opposed to the former, which is of a type resented by most economical cynics). The central thesis is that many communities cannot, for geographical, financial and logistical reasons, subsist on a vegetarian diet. Obvious examples are many African communities living mainly off quite arid land surrounding their homes. In such locations, the human body is generally not sufficiently efficient to live on an herbivorous diet; grazing animals generally have to process the local, human-indigestible plant life first. Elsewhere around the world, we find a large portion of available plant life to be inappropriate for human consumption, and people with little access to other crops or supplements therefore generally find it difficult to avoid eating some flesh.

This objection is, of itself, of no direct consequence to individual dietary/lifestyle decisions in the West. However, these societies help firstly to illustrate the historical, and current, impracticability of ethics taking an immediate driving seat everywhere. It is clear that this argument is in no way an attempt to dissuade people from adopting a vegetarian diet, or from attempting to dissuade others from eating meat – rather, it is a way of putting into perspective our current conception of meat consumption.

The other concern, more relevant in modern societies, but less appealing to people arguing in revolutionary and ideological terms, is based on the fact that the large amount of industry relying directly and indirectly on meat consumption supports a substantial portion of the economy. Concerns about unemployment are sometimes cited as a serious problem with a world lacking a meat production sub-economy. Farmers in area with poor soil or inappropriate environment for crop growth – including insufficiently large areas of fertile land to make crop growth profitable – are of immediate concern, whilst the whole butchery industry, and a large chunk of the food preparation industries, would cease to exist.

Obviously, there is no suggestion (from any educated, thoughtful omnivore) that since an instant removal of all meat industries would create an almighty employment vacuum, the gradual change of dietary habits is unacceptable. The argument is that the interconnectedness of the economy surrounding food production means that any shrinkage, even gradual, would bring about a loss of confidence in quite a large sector. Also, the vast swathes of agricultural economy which currently rely on meat production could feasibly fail, in the worst case scenario (which can fairly readily be argued to be highly unlikely).

A common, and immediately obvious, refutation of this argument is that the loss of meat farming and processing industries would be compensated for by growth in industries in synthetic ‘meat’ synthesis, and other supplementary techniques. However, in response to this, it is relatively easy to see that this new industry would not be so reliant on large agricultural economic systems, but rather on small-scale, high-tech farming systems. For example, the well known British meat ‘analogue’ ‘Quorn’ is a mycoprotein, meaning it is a processed version of an edible fungus that is high in protein content. Specifically, the soil mould Fusarium venenatum is grown in massive fermentation tanks, being fed on glucose sugar; non-essential minerals and vitamins are added to improve its nutritional value. Of course, other meat substitutes are derived more or less directly from plant products (seitan from wheat, tofu from soybeans and so on) – but omnivores can simply point out that this doesn’t necessarily help people in the meat industry living in places where they cannot start growing the appropriate crops (whether in rich, densely populated regions, or poor, arid regions). The surviving remnants of this objection are therefore mainly the justified claims that (many of) the jobs in processing would not be lost, but rather transferred to meat substitute management. It is, however, difficult to see the role of what are traditionally, and (currently) by necessity and choice, meat farming and exporting cultures, in the absence of interest in their products. Without what seem currently to be radical changes in the support of poor communities and possibly irrigation of land and similar initiatives, it seems likely that many areas would suffer.

Another important objection attacks the economic soundness of the argument, and the assumptions leading to the summary at the end of the previous paragraph. Historically, shifts in emphasis within industries have been commonplace, and cultures and societies have ‘moved with the times’. This has never been without casualties – the specialists, and the skilled manual labourers (and the unskilled, in the case of mechanization) – but it is widely, if reluctantly, perceived as part of the natural journey of industry. Mostly, of course, these decisions have been highly beneficial to the industry, and society at large because of this – however, it is also clear that these decisions have mainly been made precisely because they were expected to be beneficial (whether to avoid a systemic problem, or to massively improve efficiency or quality). It is questionable whether a much more controversial and more ethically motivated shift or reform in industry would necessarily be of any gain. Nonetheless, though, this argument definitely holds water. Industries die out regularly, and unemployment figures tend to stabilise at a point of equilibrium which is not particularly harmful. If such a shift is considered worthwhile, then it seems likely that our economy, at least, would recover even with the meat industry forced to gradually shed workers due to levels of demand falling out of the operational parameters of the natural supply and demand model of economics.

Whether poor areas would be able to cope with the bottom falling out of the meat (and associated product) export market is a different matter, but perhaps also an irrelevant one. Vegetarians could feasibly argue for a system whereby it is encouraged that meat producing regions feed poorer areas – maybe even are subsidized to do so – whilst financial and scientific aid is given to the former to help them convert to a more ethical/sustainable/suitable system, if that is even necessary. Places which rely on producing food for animals being grown for meat would have to be treated similarly. It seems likely, however, that richer countries would have to compensate somehow for the reduction in cash flow which would inevitably ensue, but that this would prevent any serious repercussions for these vulnerable and economically sensitive groups.

Some statistics which it is interesting to know are that the livestock industry as a whole (these statistics are from a piece on grazing generally, not just for meat production, but they may be of some interest anyway) accounts for 40% of all agricultural produce, and employs around 1.3bn people, very nearly 20% of the world population. This clearly includes many animals not grown for meat, but it is nonetheless a very impressive statistic. The livestock sector is also the fastest growing agricultural sector.

Finding ways to increasing meat prices is occasionally suggested by meat eaters (and less hard-line vegetarians) as a practical compromise, or as an intermediate first step, to trying to eliminate meat from diets. One idea is that by finding areas such as animal treatment and welfare, and forcing all companies – especially large corporations – in meat farming to meet substantially increased standards of animal welfare (see the section on ethics) far beyond the simple exclusion of what are currently termed battery animals etc., and all companies importing meat to demonstrate that it meets some equivalent standards. Apart from obviously improving the treatment of the creatures, the hope is that increased costs would encourage people to eat less meat, helping to deal with the other issues associated with meat consumption such as carbon dioxide emissions. Clearly, such an approach would have opposition from many people used to low meat costs, but many people consider the current situation unsustainable, for reasons outlined below.

Environmental Concerns

The association of vegetarianism with ‘green’ environmental causes stems partly, as seen in the first half of this two-part blog, from historical associations of personality and moral views.

However, the environmental issues behind vegetarianism provide some of the clearest and most readily documentable arguments for its adoption. There are many ways in which (capitalist, mass-production-scale) meat production and consumption affect the environment detrimentally. The diversity of issues in fact warrants the subdivision of environmental concerns into subcategories:

• Land use and degradation (leading to loss of habitat, biodiversity, forestry – causing climate change – and resources)
• Water use
• Air, water and land pollution

It is important to note, before we begin disseminating information on these topics, that vegetarianism can also have significant problems with relation to some of the above issues, and that meat production can benefit the environment in certain situations.

Land Use and Degradation

There are two main reasons for meat production claiming large areas of land, corresponding roughly to the division between factory and free-range animal farming.

The first issue is that of the land required to provide food for meat-bearing animals, especially those in factory farms, since they do not graze on the land they occupy. It is well known (even historically) that the consumption of mass-produced meat gives a very poor efficiency ratio, in the sense that only a low percentage of the energy the animals take in from their diets is passed on to the human ‘predator’.

This is generally true for the phenomenon of ‘secondary’ energy absorption from plants – for poultry and beef, the ratio of energy input to protein output varies from 4:1 to 54:1 (poultry is generally the most efficiently produced meat, followed by turkey, whilst lamb and beef are the least). 1996 China, according to one report working in the ‘grain equivalent’ of a diet, showed that a vegetarian diet ‘costs’ 3 times less grain than a typical affluent diet, although the food energy intake of the affluent diet is only 15% greater than the vegetarian’s, who get over twice the plant protein.  The US Department of Agriculture reports that growing crops for farm animals occupies 80% of the country’s agricultural land – animals raised for food there consume 90% of the soy crop, 80% of the corn and 70% of its grain. 33% of the world’s arable land is used to produce feed for livestock. There is a clear argument for the view that this land – and/or crop – could be put to better use.

David Pimentel, a scientist from Cornell University said, over 11 years ago, that

If all the grain currently fed to livestock in the United States were consumed directly by people, the number of people who could be fed would be nearly 800 million.

According to his report, Americans provided for by only grass-fed livestock would continue to exceed the RDA of both meat and dairy protein

Land set aside as grazing for creatures, for any reason, is also recognized as being in some ways irresponsible, as it contributes noticeably to desertification and also corresponds to lower biodiversity in most cases – areas devoted to animal agriculture overall represent 30% of the world’s surface, and 70% of arable land.

These concerns are far from imaginary; Pimentel also says that, in 1997, 90% of US ‘cropland’ is losing soil at 13 times the sustainable rate; fertile Iowa loses topsoil at 30 times the rate of soil formation – it has used half its topsoil in around 150 years of farming, but this quantity of soil takes thousands of years to form.

These topics are concerning in a time of unstable climate, especially when a massive percentage of Amazonian forests have been converted for use as pasture and for growing feed crops – 70% of former forests there are now used for grazing.

Removing forests which are helping to reabsorb carbon is not necessarily the best of ideas, especially when we consider that the global livestock sector itself is responsible for around 18% of our CO2 equivalent emissions, more than transport (mainly because it produces such potent gases: only 9% of our carbon dioxide, but 65% of nitrous oxide – mostly from manure – and 37% of our methane).

This sort of scale of problem is only compounded when we look at projected figures for meat and animal product consumption. Global meat production was forecasted (2 years ago) to more than double between 2001 and 2050, from 228m to 465m tonnes. Similarly, milk output was expected to increase from 580m to 1043m tonnes.

It is hoped that these issues can be controlled by environmental tactics such as soil conservation, and silvopastoralism in the world of forestry, the more careful location of livestock et al, and further increases in efficiency of feeding and breeding systems, but this seems a sticking plaster on a bloated system.

However, obtaining meat is not necessarily always a problem for the environment. One small note is that small-scale hunting of wild animals helps keep populations in check in some circumstances; where natural predators and dangers do not limit a population, such practices can be necessary for the well-being of the wider ecosystem (should someone do this to us?!)

Also, it has been documented, particularly in studies of the rapidly developing China, that ‘integrated’ food production systems which feed unusable organic material from farm and restaurant waste to robust animals, such as pigs, can actually increase the energy efficiency of the system.

This backs up the suggestion that massively cutting down on meat consumption around the world (especially in high-intake countries such as the US, which has an average meat consumption around 40 times that of Bangladesh) and returning to grass-fed pastures, and waste-fed animals, at the expense of factory farming, would greatly improve the environmental footprint of meat consumption.

However, the capitalist market can be expected to continue to exploit the natural world until regulation, necessity or demand forces companies to stop.

Yet it remains important to check any enthusiasm for dropping local meat production in favour of importing cereals and other crops – it is notable that air transport, refrigeration and freezing, and various horticultural techniques and practices can drive up the fossil fuel cost of vegetarian diets in some cases, past the point of locally sourced organic meat.

Also, the global farming community’s reliance on fossil fuels means that plant- growers may also find it difficult to reach sustainable levels of production (even though they generally use 8 times less fossil fuels than for equivalent amounts of animal protein.)

Water Use

Another concern is the prodigious rate at which one of our most valuable natural resources is used. The concept of ‘virtual water’ describes this, so that since 1kg of grain and hay requires around 1000 litres of water, based on the approximation that each kilo of beef takes 100kg of hay and 4kg grain to produce, around 100,000 litres of virtual water are required to produce a single kilogram of beef.

Comparison of water requirements for animal and plant protein show a factor of around 26 times more for meat in areas with sufficient rainfall not to need much irrigation, or around 4.4 where intensive irrigation is required.

Also, overgrazing tends to disturb the natural water cycle by reducing the replenishment of water resources, both surface and buried.

Air, Water and Land Pollution

We have already discussed greenhouse emissions briefly, and so omit them here. Also, since most of the pollutant effects are due to the production of feed crops, they are not immediately relevant (except in so far as a feed crop is produced more cheaply and hence hazardously than crops intended directly for human consumption.)

The remaining serious pollutant agents are really consequences of animals’ waste and treatment. Animal waste itself will readily penetrate into the water system, but so will hormones and antibiotics from large herds. Chemicals from associated industries like tanneries have a lesser input.

The main consequences of these pollutants entering the water system, apart from the obvious problems of contaminated water, include eutrophication of water bodies and coral reef degeneration – both of these have a large impact on biodiversity. In the South China Sea, it is also estimated that livestock are the central source of phosphorous and nitrogen contamination, which also impacts negatively on marine diversity. Generally, the presence of livestock and man-made environmental changes tend to affect habitats; the growth of feed crops has a similar effect.

(More to come...)

You've gotta read this Something Awful page, linked from XKCD.