The UK business secretary, Kwasi Kwarteng, is considering a “full vegan diet” to help tackle climate change, saying people will need to make lifestyle changes if the government is to meet its new emissions target of a 78% reduction on 1990 levels by 2035.
But how much difference would it make if everyone turned to a plant-based diet? Experts say changing the way we eat is necessary for the future of the planet but that government policy is needed alongside this. If politicians are serious about wanting dietary changes, they also need to incentivise it, scientists and writers add.
The literature on the impact of reducing or cutting out meat from your diet varies. Some studies show that choosing vegetarian options would only reduce greenhouse gas emissions per person by 3%. Others show a reduction in emissions per person of 20-30% for halving meat consumption.
“Probably the most important thing to point out is that emissions are often viewed as the only metric of sustainability: they are not. Impacts of farming systems on carbon sequestration, soil acidification, water quality, and broader ecosystem services also need to be well considered,” said Matthew Harrison, systems modelling team leader at the Tasmanian Institute of Agriculture.
“There is also a need to account for farming systems that may replace livestock,” he said.
The writer and environmental campaigner George Monbiot says the numbers on the impact of going vegan are different because of what scientists measure. “There are two completely different ways look at the carbon impact of diet: one is carbon released by producing this or that food – that is ‘carbon current account’. But another one is ‘carbon capital account’, which is the carbon opportunity cost of producing this food rather than another one,” he said.
“If you are producing meat, for example, what might land be used for if you took meat away? If you are growing forests there instead or peat bog there.”
Monbiot says what we eat is a “huge issue”, alongside our transport habits. “Most of what you can do at an individual level is weak by comparison to what governments need to do … but changing diet does not. That has a major impact,” he said.
“It is easier done if the government acts to change the food system but in the absence of that, we should still try and change our diets.”
In 2018, scientists behind the most comprehensive analysis to date of the damage of farming to the planet found avoiding meat and dairy products was the single biggest way to reduce your environmental impact on the planet. The research showed that without meat and dairy consumption, global farmland use could be reduced by more than 75% – an area equivalent to the US, China, European Union and Australia combined – and still feed the world.
“There are lots of different sectors that have an impact on emissions and the food system is surely one of the most important ones as it is globally responsible for about a third of all greenhouse gas emissions,” said Dr Marco Springmann, senior researcher on environmental sustainability and public health at the University of Oxford.
He added that the overwhelming majority of emissions were due to foods such as beef and dairy, which “means that without changing emissions associated with those products it is hard to make progress”. He said there were no good technical solutions for the fact that “cows emit methane emissions”.
“You can change feed composition but that does not change the animal and the need to feed the animal a lot of feed product,” he said. He believes the government needs to offer price incentives for sustainable products, making beef and dairy more expensive.
Frank Mitloehner, professor and air quality extension specialist at the University of California and Davis, said putting the onus on the individual was a distraction from policy changes that are needed. He said literature suggests “going vegan for two years has the same saving impact as one flight Europe to the US would generate.”
“If we really want to make a difference in carbon emissions we need to change policy. We need to have a cost for carbon that is appropriate. We need to incentivise those who can reduce greenhouse gas emissions to do so,” he said.
He believes the most important individual choice someone can make is to “go and vote … That is number one.”
Martin Heller, a research specialist at the University of Michigan, said: “There are no silver bullets for climate change. Nothing in isolation will be ‘enough’.”
He added that studies showed that even with gracious assumptions in improvements in agricultural production, feeding an anticipated population at anticipated growing demand for animal-based foods by 2050 would occupy “all of the allowable emissions if we are to stay below a 2C temperature rise”.
“We have to change the way we eat,” he said. “That certainly isn’t saying that diet change – or even becoming vegan – will ‘save the planet’. It’s more of a necessary but not sufficient kind of thing.” He added that “these diet shifts need to come with government, corporate and every other kind of action”.
“It’s also probably naive to assume that people will just change these behaviours because it’s good for the planet. It will require directed policy, changes in the restaurant and foodservice industries,” he said.