Tesco will soon carry carbon labels on its meat products. These will show that beef and cheese are vastly more costly in terms of carbon emissions than alternatives such as lentils and chicken. It would appear that Tesco knows how to sell things to the public — even climate-change induced dietary shifts — rather better than hairshirt-wearing environmentalists.

The furious response to Lord Stern of Brentford’s comments about meat consumption suggests that many believe he was calling for a Soviet-style imposition of strict vegetarianism on the entire population. He wasn’t. He was simply reiterating the point he has been making since the 2006 Stern report: that it would be much cheaper and more beneficial to address climate change now, rather than waiting for global warming to wreak havoc.

When it comes to food production, Lord Stern points out that people must pay for the true cost of their choices. Take the world’s remaining tropical forests. They are valuable habitat for innumerable species of plants and animals, and they store billions of tonnes of carbon, which if released, would harm everyone. And yet, millions of acres of forest are cleared every year, largely to produce soy and grassland to satisfy the soaring global demand for meat and dairy products.

Deforestation and forest degradation is costing the world’s economy €1.3 to €3.4 trillion every year. But no one is paying this bill. Although these costs are real, and constantly rising, the world economy currently has no mechanism for billing those responsible for them.

Lord Stern’s view is that we should put a price on these costs. This would mean that those who wished to buy the most polluting items would be free to do so: but they should pay for it. It is inequitable to expect others — including our descendants — to pay that bill for us.

Promoting vegetarianism to save the climate would be a tactical error. For the carnivorous majority it is an alienating concept and, more to the point, it is by no means necessary to save the planet. The V-word was invented in the 1840s to provide a label for those who wished to build a barrier between their own pure diet and the meaty meals of the majority. Society responded by pigeon-holing vegetarians as sandal-wearing faddists and then ignoring most of what they said.

There has been a turnaround in attitudes in the past two or three years. Rajendra Pachauri, chair of the UN Intergovernmental Panel on Climate Change, suggested last year that cutting down on meat was “the most attractive opportunity” for making simple and swift reductions in emissions. Jonathon Porritt, founder of Forum for the Future, has long put his name to the “eat less meat” campaign. Now Nicholas Stern has joined his voice to theirs.

These initiatives have largely been in response to the mounting evidence about the harmful effects of modern meat production. In 2006 the UN concluded that the livestock sector produces 18 per cent of all greenhouse gas emissions, from a noxious combination of methane emissions, fossil fuel consumption, nitrogen fertilisers and deforestation.

About 40 per cent of the world’s cereals are used to feed farm animals, mainly for the satisfaction of the world’s richest consumers. This seems greedy when there are nearly a billion people in the world who can’t get enough food for themselves. Of the 700 million tonnes or so of wheat, rice and maize fed to livestock, only a third of the calories in the feed ends up being converted into useful meat or dairy products. The rest is turned by the animals into faeces, heat and inedible tissues. In the US, livestock give back only 20 per cent of the food they consume. About a third of the meat and dairy products produced is then wasted, so only around 13 per cent of the calories in the original arable harvest is actually consumed by people.

This level of profligacy is also reflected by the amount of water used in meat production. It takes 500–4,000 litres of water to grow a kilogram of wheat. But a kilo of meat takes 5,000–100,000 litres. Meanwhile, water scarcity is one of the most serious threats to human survival in parts of Asia and sub-Saharan Africa.

There is enormous scope for reducing emissions by changing the way animals are reared. When humans first domesticated livestock they did so because they could contribute to the food supply. Sheep and cattle ate grasses and shrubs that were otherwise useless to humans; pigs and chickens foraged for leftovers. It is only in the past several decades that livestock have been turned into consumers of vast quantities of grains.

Some meat is still produced in the industrialised world without this inordinate reliance on feed concentrates: British hill-sheep farming relies on extensive grazing.

One big obstacle to producing meat sustainably is the EU ban on feeding food waste to livestock. Since the foot-and-mouth outbreak of 2001 it has been illegal to feed swill to pigs, even though swill can be rendered safe simply by heat-treating it. The UN has calculated that if we fed livestock with food waste and agricultural residues, we could feed three billion additional people. Feeding food waste to pigs could also save millions of tonnes of carbon emissions by avoiding the need to produce conventional feed.

Lord Stern was brave to confront the dramatic changes we will all have to accept if catastrophic climate change is to be averted. It may seem unfeasible to expect rich countries to forgo their meaty, dairy-lubricated diets any time soon. But is it any more realistic to expect global meat production to burgeon without causing irreversible damage to the environment?

Tristram Stuart is author of Waste: Uncovering the Global Food Scandal (Penguin)

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