As the world population soars – hurtling towards more than nine billion by 2050, according to experts – we’re beginning to worry about how we’re going to feed so many extra mouths, given our finite planet and its limited resources. Already, there are nearly a billion who go hungry every day, who are considered ‘chronically undernourished’ by the UN, so what is going to happen when there are two billion more people vying for resources? The UN’s Food and Agriculture Organization (FAO) has claimed food production must increase by 70 per cent based on 2005/06 levels, but a growing number are pointing out that curtailing food waste and losses would also go a long way towards solving the problem.

Indeed, a recent report released by Aalto University in Finland, ‘Lost food, wasted resources’, revealed that by halving food losses worldwide, it would be possible to sustain a further one billion inhabitants on current world food production levels. The study found that a quarter of the world’s food supply is lost throughout the food supply chain (FSC), and that the figure could be halved ‘if the lowest loss and waste percentages achieved in any region in each step of the FSC could be reached globally’.

While consumers in rich countries are most often blamed for the profligate waste of food (and we do waste a lot of food, to be sure), food loss and waste can occur at every stage of the FSC. Typically, ‘food loss’ is considered to occur before the distribution and consumption phases and can come in the form of: ‘agricultural losses’ involving mechanical damage or spillage during harvesting and sorting; ‘post-harvest losses’ resulting from poor transportation or storage conditions – such as a lack of refrigeration – as well as spillage and inadequate handling; or ‘processing losses’ due to errors or faults in any of the long list of procedures to which we subject our food, such as: cleaning; classification; de-hulling; soaking; winnowing; milling; cooking; moulding; extrusion; and so on. ‘Food waste’ is considered to happen during the retail and consumer stages and can result from things like quality standards (the notorious ban on ‘wonky’ veg, for instance), and the discarding of edible (or once edible) food by both supermarkets and consumers.

Estimates vary widely as to how much food is cumulatively wasted from field to fork and beyond, with Aalto’s suggestion of a quarter dwarfed by the most-often quoted estimate of ‘as much as half of all food grown is lost or wasted before and after it reaches consumers’ – first put forward by the Stockholm International Water Institute in 2008.

Conventional wisdom holds that food waste in poor countries with limited infrastructure occurs before items reach consumers, whereas richer countries see most waste from the consumers themselves. A 2010 review by Julian Parfitt (then at Resource Futures), Mark Barthel (of WRAP) and Sarah Macnaughton (at Isis Innovation), ‘Food waste within food supply chains’, explains: ‘In the developing world, lack of infrastructure and associated technical and managerial skills in food production and post-harvest processing have been identified as key drivers in the creation of food waste... The situation contrasts with that in developed countries where our interviewees forecast the majority of food waste continuing to be produced post-consumer, driven by the low price of food relative to disposable income, consumers’ high expectations of food cosmetic standards and the increasing disconnection between consumers and how food is produced.’

Nearly all commentators agree that we still don’t have a complete picture of the worldwide food waste situation, though. For the UK, WRAP has produced fairly detailed ‘resource maps’ showing where food is lost in the supply chains for fish, fruit and vegetables, and meat. The organisation’s latest figures conclude that while UK households produce 7.2 million tonnes (mt) of food waste a year, food manufacturing accounts for just 3.2mt, retail and distribution for only 0.37mt and the hospitality sector for 0.7mt.

Food waste campaigner Tristram Stuart, however, questions the reliability of these statistics: “What [WRAP] failed to make clear is that the data for those figures are provided by the businesses themselves and very often unrepresentative reports from the most efficient businesses”, he tells me, adding that the reports include omissions of some of the very wasteful stages in the FSC, including fish disposed at sea, and food wasted on farms. He also alleges that “all the waste that arises overseas, which results from the policies that we have in the United Kingdom... is off our balance sheet”, a significant matter as the UK currently imports 48.2 per cent of its food, according to 2011 Defra statistics. Stuart concludes: “To say that all of the food waste comes from the consumer is not only untrue, it’s ideologically suspect.”

Stuart’s own extensive research has turned up some sobering statistics (40-60 per cent of European fish are discarded at sea, he says, and 24 to 35 per cent of school lunches end up in the bin, for example). He’s also peered into numerous bins to uncover evidence that vast quantities of food are routinely wasted by supermarkets themselves (he notes that we can’t rely on corporations to tell us what’s actually happening at the back of their stores), as well as at slaughterhouses (offal consumption has halved in Britain and America in the last 30 years), in factories, at greengrocers, by bakeries (ever seen a store selling a sandwich made from the ends of a loaf of bread?), and on farms because of supermarket policies. He says: “I’ve seen farmers who routinely waste 20-40 per cent of their harvest because of the cosmetic standard, and who occasionally waste an entire harvest – because there’s a little bit of grass growing in their spinach or their peas don’t meet the sweetness test that their pea freezing manufacturer demands or there’s a little bit too much carrot root fly in some of the carrots – the list goes on – and they’ll just destroy an entire crop. Or, it gets wasted because the supermarket changes its order.”

In an attempt to combat the lack of empirical data on how much food is actually wasted worldwide, Stuart devised a proxy measurement system for his book Waste: Uncovering the global food scandal. He explains that the system is based on “the nation-by-nation food availability data, which is published by the United Nations, and also the edible food harvests, on a nation-by-nation basis.

You can compare that to what is actually likely to be being consumed in those countries, which you can gather from not-massively-reliable diet intake studies, and surveys that deal with what people are actually eating, as well as from obesity levels. And the difference between food supply and food intake is an indication of how much food is being wasted.” Though he admits the methodology lacks “sufficient robustness to give you a detailed picture of a particular country”, he is confident enough in the data to conclude that most rich countries actually have between three and four times the amount of food they need to feed their populations.

This surprising figure includes food that is fit for human consumption, such as imported maize and soya, but fed which is to livestock instead, a subject about which Stuart is passionate: “[In Europe], we import 40 million tonnes of soya from South America to feed our livestock. And obviously that contributes to the deforestation of the Amazon – so we’re killing the most biodiverse habitat in the world to produce something that fattens our livestock.” What Stuart finds most galling about the situation is that we could be feeding our livestock food waste instead and avoid importing the expensive feed that is making livelihoods like pig farming increasingly unviable.

Now, of course, there are UK and EU regulations to stop people feeding many forms of food waste to pigs or other animals, put in place following the foot and mouth outbreak in 2001. Currently, food waste from households and catering firms cannot be fed to animals, nor can any food from a commercial firm that is handled under the same roof as meat – unless there is a demonstrable system in place that prevents other material ever coming into contact with meat. (And supermarkets are increasingly taking advantage of this bit of the law, with Sainsbury’s, for instance, implementing a separation scheme to send all its bread waste to animals.)

Currently, the European Commission is reviewing whether or not to allow chicken byproducts to be fed to pigs (and vice versa), according to Stuart, and, in the UK, Defra has at least commissioned a study into feeding catering waste to animals. Elsewhere in the world – including Japan, South Korea (and other parts of Asia), Africa and the Americas – feeding waste to animals is more actively promoted. Stuart advocates the process as a 6,000-year-old environmental and agricultural success story, adding: “There is no scientific evidence to suggest that if you have a proper, biosecure process for cooking food waste to render it safe, that we should not be feeding it to animals.” Industrial plants to cook food and digitally monitor it to ensure pasteurisation, Stuart asserts, would be relatively cheap and easy to build.

Governments in the UK have, over the past few years, come out strongly in favour of anaerobic digestion as the preferred method of treatment for food waste – a policy Stuart questions.

He claims that feeding food waste to pigs would save 11,600 kilogrammes (kg) of carbon dioxide per tonne (helped along, no doubt by avoided crop growth, transportation and deforestation), compared to just 448kg saved through AD. What’s more, he makes clear that simply having something to do with the food waste (whether that be feeding it to pigs or popping it in a digester) does not mean we have solved the problem of food waste: “The reason we’ve been pumping all this public money into AD is because we need to avoid sending stuff to landfill”, he tells me. “Anaerobic digestion solves the problem of landfill. It does not solve the problem of food waste.”

And should campaigners like Stuart succeed in overturning bans on feeding food waste to pigs, it doesn’t mean the growing AD industry will crumple: “The great news is that you can have your cake and eat it, because you can feed your food waste to your pigs, they produce a lot of faeces, and that is excellent feed for an anaerobic digester, to turn your pig poo into methane. And that is the proper observation of the food waste pyramid.”

It is only proper observation of the pyramid, of course, if the pigs are only fed food that is not fit for human consumption, and we are sadly miles off achieving that. Given the grim statistics he encounters, Stuart seems surprisingly optimistic about our odds of getting there, though: “Our society and other societies have made much tougher decisions and made more dramatic changes than are actually required to end the global food waste scandal.” But what steps will lead us in the right direction?

Tim Lang, Professor of Food Policy at City University, London, tells me that, in government’s case, the first thing it has to do “is recognise its own role”, both in creating the current levels of waste and in fixing the problem. Pre-Second World War studies showed that only one to three per cent of food was wasted in British homes. Food was relatively much more expensive at the time, and many were malnourished. Lang explains that it was actually the rationing system during the Second World War (which incorporated evidence of nutrition on public health) that “hardwired” into government the idea “that food should be available and consumed by people according to their biological needs”. He cites the 1947 Agriculture Act as significant, explaining: “The assumption was that if we just produce more food, the price will come down and it’ll be more affordable and that public health will gain. It was a very good policy model given the preceding evidence. What it didn’t anticipate was the world that we now have, which is where food costs an average of about 9-12 per cent of people’s household disposable incomes, and where food is so cheap and so disposable that it is not valued.”

The old model, Lang claims, is obsolete, and “the full costs of food need to be incorporated into the price of food”, namely: environmental impacts, public health and social effects.

He adds: “We need a new framework, which will shift the food system from its gross waste and inefficiencies – all done for very good reason 70 years ago – into a new direction. And, there’s got to be a recognition that the great god before whom all social forces bow, the consumer, is part of the problem. The consumer has got to be totally re-educated, has got to be changed.”

Lang criticises the government attitude of “Leave it to Tesco”, as does Stuart, who has been lobbying government to make supermarkets publically publish how much food they waste. “The reasons supermarkets give when you ask them why they don’t report how much food they waste, is that it’s ‘commercially-sensitive data’. And what they mean by that is that if they publish how much food they waste, their competitors can lean over their shoulder, learn how they have been more efficient, and reduce waste, and thereby gain the competitive advantage. In other words, the reason not to publish food waste data according to the supermarkets is because everyone will stop wasting so much food!”

Stuart acknowledges that steps are being made in the right direction, with initiatives such as the Courtauld Commitment, but adds that it’s “woefully insufficient”. That the supermarkets have so easily surpassed their five per cent waste reduction target (for both product and packaging wastes) means “the target has been proved to be preposterously unambitious”, he alleges. (Speaking to Resource, WRAP defended the voluntary agreement, noting: “Targets have been surpassed, but not necessarily easily achieved. A lot of hard work and effort has been put in to reach these by the signatories.”)

In the meantime, food wasted by consumers is actually falling at a faster rate, with WRAP statistics showing that annual UK household food and drink waste has fallen by 13 per cent (1.1 million tonnes) since 2008. While it’s undoubtedly a huge improvement, it means that, in line with other rich countries, we’re still wasting a quarter of the food we buy – 7.2 million tonnes a year, in the UK’s case. And so, continued consumer awareness raising – through Love Food Hate Waste and other means – is doubtless vital. “I believe that it’s us – the public, the consumer or citizen – that has the power to bring about this change”, Stuart says. “By changing our own behaviours, obviously, but also by demanding that the businesses that bring us food change their behaviours to be in line with our expectations – at the moment, we’re giving money to supermarkets that are trashing the planet, and not asking any questions about it.”

With billions of new neighbours on the way, it’s certainly about time we started asking some questions...