When I was at primary school in East Yorkshire in the 1970s, it was part of our lunchtime routine to scrape any remaining food on our plates into the pig bin. My journey home after school went past the pig farms where piglets romped around muddy fields and gobbled up our leftovers. I like to think that this was my first introduction to the circular economy. I didn’t know then about resource use, carbon and climate change, but using good resources for useful purposes felt like part of the natural order of things. It simply made sense.

Forty years later, and we are faced by the shocking fact that around one-third of the food we produce is wasted. In the UK, 15 million tonnes of food are thrown away every year and food and drink accounts for one-fifth of our greenhouse gas emissions. When we throw away food, we effectively waste all the resources and effort that went into producing that food in the first place. None of this makes sense at all.

It’s not surprising that most people feel that wasting food is wrong. There’s a moral as well as a practical dimension. The United Nations estimates that if farmers around the world fed their livestock – just like those East Yorkshire piglets in the 1970s – on agricultural by-products and the food we currently waste, enough grain would be liberated to feed an extra three billion people, more than the additional number expected to be sharing our planet by 2050. It would also lessen the pressure on forests in tropical areas, great swathes of which are being cut down to create farmland to grow soya and other grains for livestock consumption.

Our appreciation of the relationship between food and climate change is relatively new. The Food Climate Research Network, set up by the pioneering Dr Tara Garnett and now hosted by Oxford University, celebrated its 11th anniversary this year. The Network brings together the research community to help understand the ways in which agricultural production and consumption patterns give rise to gigantic amounts of pollution, waste and greenhouse gas emissions and – importantly – how these can be tackled.

My reading of Tara Garnett’s insightful analyses over the years points to well-evidenced priorities for decarbonising our food system. To feed ourselves well and sustainably while significantly reducing greenhouse gas emissions, we must plan our food production and consumption to achieve:

– Better farming: supporting the right kind of agricultural production and more horticulture.

– Zero food waste: radically reducing food waste, and using all unavoidable food waste for good purposes.

– Energy efficiency: greatly improving energy efficiency in food production.

– Less but better meat: reducing livestock production and consumption.

– Healthier diets: engaging consumers through promotion of inherently healthier, low-carbon and low-waste diets and shopping.

It’s good to have a relatively simple shopping list of priorities for decarbonising our food system. It makes me want to roll up my sleeves and get cracking, recognising that these issues will require action at both practical and policy levels and the engagement of many sectors.

There is also something appealing about working on this at a city level, where policy and practice feel somehow closer to each other and more accessible, supported by a sense of civic pride. Good sense in food can be embedded in local authorities, in a city’s business practices and in London’s can-do, entrepreneurial culture.

The Mayor’s Healthy and Sustainable Food Strategy has made the capital a shining light in the growing movement of cities trying to secure a better food system. The Sustainable Fish City campaign, which started here in 2009, has secured pledges to buy and serve only verifiably sustainable fish from businesses that together serve over half a billion meals a year. The Capital Growth campaign, supported by the Mayor, saw the establishment of 2,012 new community food gardens across the capital, greening our city and providing more space for people to meet and grow their own fresh fruit and vegetables (see page 58). And the Good Food for London league table of London’s 33 boroughs and local authorities, now in its fifth year, has recorded impressive improvements in the healthiness and sustainability of the food and food-related services that local authorities buy or otherwise affect.

London’s wider influence is also worth considering. The UK’s Sustainable Food Cities network was established just three years ago, but already over 40 UK cities are participating: setting up food partnerships involving local authorities, businesses, third-sector and community organisations, and implementing action plans. They are sharing good practice, policies, campaigns, practical interventions and inspiration, some of it based on work first piloted in London. So what follows here is how I think London could play its part, not only in reducing its own food carbon footprint, but also in inspiring other cities across the UK and Europe in a beneficial ‘race to the top’. To do so would have benefits for city dwellers and food businesses, farmers, farm animals and the natural environment.

Better farming

We need to support the right kind of agricultural production and more horticulture. Farming with regard for environmental impact makes wise use of soil, water and other critically important natural resources and retains landscapes, particularly grasslands, which can sequester very large amounts of carbon. Farming may sometimes feel as if it is beyond the scope of city policies to influence. Yet nothing could be further from the truth. Farming is an embattled profession characterised by uncertain, often unfair trading conditions; unpredictable weather (and hence yields); and very poor income, often below the cost of production. Farmers have very little money or market incentive to invest in the necessary changes to achieve low-carbon farming. Yet we all rely on farmers to produce the food we need – and in a way that conserves rather than damages the environment.

London can play a leading role in supporting better farming by using its enormous buying power to incentivise change. Progress has been made, with 23 out of 33 London boroughs having adopted the Food for Life Catering Mark standards – specifying fresh, local and seasonal food, sustainable fish, higher-welfare and fairtrade products. Eleven of these have gone further, starting to demand better meat and dairy standards and environmental standards of farming, with two including organic food on their menus. The London Borough of Havering has helped other boroughs achieve impressive improvements by running a collaborative food procurement contract with ethical and environmental specifications built in, pooling the buying power of local authorities to make good food more affordable. All of this work has been helped by support from specialist organisations in the third sector and the Greater London Authority food team, proving we can achieve a lot when we get together and take concerted action.

At a national level, the UK alliance for better food and farming, Sustain, is also campaigning for the subsidy system to support climate-friendly and biodiversity-friendly farming. And more and more food businesses, including leading supermarkets, are understanding the importance of helping farmers to move towards better ways of managing the water, soil and emissions.

Zero food waste

London could become a zero food waste city. Why not? While this would require changes in policy and practice at both national and city level, good progress has already been made. Local authorities are setting up separated food waste collections, diverting household food waste to composting and energy recovery and promoting the Love Food, Hate Waste campaign to improve people’s wasteful shopping and cooking habits. There are impressive schemes in the pipeline to collect cooking oil to be reused as transport fuel. However, other food business waste remains a gaping hole in policy and practice – or perhaps a steaming pile.

There are growing numbers of innovative approaches to reducing food waste around the world. Some cities are setting up food collection networks to help divert legally permissible food manufacturing surpluses (such as bread or whey) to local pig farmers, enabling the breeding of more contented and well-fed piglets, which aren’t munching through soya grown on deforested tropical land. (In this country, the food waste campaign Feedback is championing the feeding of food waste to pigs through its initiative The Pig Idea.)

Some countries, such as France, have introduced new laws requiring supermarkets to divert all edible surplus food to good purposes such as charities. Others, such as Japan, have introduced modern treatment techniques for most food waste to make it suitable for use as animal feed. Japanese pigs fed on food waste are known as eco-pigs, and their meat commands a premium. Let’s get together to help London follow suit, to identify the entrepreneurs who could make the necessary changes and to show what can be done when we set ourselves an ambitious goal of zero food waste.

Energy efficiency

Energy efficiency is a large and important jigsaw piece in decarbonising our food system. Good work is underway, and already covered by many other organisations. But it’s worth noting that Government Buying Standards for food and catering services contain extensive specifications for energy-efficient equipment and fuel use. These are mandatory for government organisations, prisons and the armed forces, are required for hospitals under the NHS standard contract and encouraged for all state schools and new academies. There is much that cities can do to support implementation of these standards.

Less but better meat

Livestock is one of the most significant sources of greenhouse gas emissions in the food system. There are direct emissions from ruminant animals – famously, cows burping and from slurry – but also indirect emissions, most notably from production of the millions of tonnes of animal feed to supply our pork and chicken. It’s important to recognise that a blinkered approach to ‘sustainable intensification’, crowding animals into more and more cramped and ‘efficient’ conditions, might seem to have benefits when considering carbon alone. But such intensive livestock farming is predicated on animal feed from deforested tropical land and overuse of farm antibiotics that is, in turn, contributing to the growing crisis in antibiotic-resistant bacteria worldwide. We really must plan our livestock production and consumption more wisely.

There is a growing consensus that the best way to deal with these issues is to promote ‘less but better meat’, as championed by the Eating Better Alliance, deterring unsustainable livestock production. We can all do this by eating more meat-free meals; using traditional recipes that use the whole animal; eating meat in smaller portion sizes; using small quantities of meat to add flavour; or reserving meat for special occasions. We can also choose ‘better’ meat that is naturally fed. For example, grass-fed beef has a known provenance and is produced to high animal welfare, environmental and quality standards. A ‘less but better’ approach to meat eating can help support farmers without being more expensive for consumers.

Cities like London are in a good position to support such action through the buying power of businesses and institutions and through innovative chefs and communicators who can appeal to an increasingly health-conscious population. The work of the Sustainable Restaurant Association and the Food for Life Catering Mark are commendable for what they have achieved in starting to raise awareness and promote better practice.

Healthier diets

The good news is that climate-friendly food is also healthier food. Eating more fresh, local, and seasonal fruit and vegetables together with less junk food and fewer meat-based products has good health and environmental outcomes. This beneficial collision of environmental and health objectives also offers an opportunity to bring together a broad range of policymakers and organisations to bring about change. Our work through the UK’s Sustainable Food Cities Network and with the London Food Board shows that influential and highly creative local alliances can attract investment and lead to change.

To change consumption patterns we have to change food culture, which can feel like something we have little power to influence. But my experience over many years in the food movement suggests that this is precisely what we can do, and that it can be the most joyful and hopeful part of tackling climate change. And where else would you find tackling climate change described in terms of joy and hope?

People don’t generally eat climate-friendly food, or reduce food waste, to tot up the numbers and measure the carbon they’ve saved. They do so because they feel an emotional or moral connection with the stories that lie behind their food. They want to support better farming livelihoods; fair trading; animal welfare; wildlife; marine ecosystems; to reduce waste; to raise healthier children. Farmers’ markets, farm shops and pick-your-own farms have bucked the trend through the austerity years, continuing to attract customers keen to reconnect with their food. With the support of the Mayor of London, Sustain have also helped to set up over 2,000 community food-growing spaces, where Londoners can engage in healthy exercise and food-growing while also securing the future for hundreds of biodiverse green spaces.

I firmly believe that cities like London can play a very significant role in achieving a decarbonised food system. At home and at work, we are buyers, consumers, makers, investors, communicators, educators and inspirers. And when we get together and take concerted action, we can and do achieve great things.