NEW YORK - Next time you are out for lunch, try playing a little game: Without looking it up, can you find the most and least climate-friendly options on the menu? 

Unlike a meal’s price, the greenhouse gas footprint of food is not typically spelt out. But you do not need to ask a climate scientist to find out, either. There is one simple trick for identifying the highest impact item on almost any menu: If there is beef, that is probably it.

Of course, maybe that is not enough to change your order – sometimes you just want a good steak taco. Maybe you do not think the climate impact of any given meal matters in the grand scheme of things.

Here, too, there is a simple rule of thumb: Cutting back on beef makes a big difference. One 2022 study in the American Journal of Clinical Nutrition found that swopping out beef for a single meal can reduce a person’s carbon footprint for that day by almost half.

The more people who embrace such swops, the bigger the dent in food-related emissions. There may even be health benefits, too.

“You don’t have to become a vegan to have a big impact on your carbon footprint,” says Dr Diego Rose, a professor and director of the nutrition programme at Tulane University. “You just have to swop out beef.”

Food systems are responsible for roughly 30 per cent of human-caused emissions globally, according to a 2021 study in Nature Food.

Other research suggests that nearly 60 per cent of that comes from animal-based products, which is largely a result of the land used for livestock – clearing forests and vegetation has a huge emissions impact – and the land and fertiliser needed to grow animal feed. 

“All animal foods have a higher footprint than plant foods,” says Dr Rose, because “you have to produce plant foods first and then feed it to the animals”.

Beef’s footprint is especially outsized. For one, there are roughly 1.5 billion cows on the planet. About 13 million sq km of land is used to raise all that cattle, along with buffalo, and their food – one-quarter of all land used for agriculture, according to a 2017 paper in Global Food Security.

Then there is the methane. Cows and other ruminants have a unique digestive system that allows them to turn grass into fuel, but in the process their special gut bacteria releases methane, a greenhouse gas 80 times more potent than carbon dioxide in the short term.

There is no universal figure for beef’s emissions impact, which varies by region, type of farm, grazing habits and other factors.

But dozens of studies identify beef as among the most egregious emitters. 

Emissions from beef herd production alone typically range from about 79kg to 101kg of carbon dioxide equivalent (CO2e) per kg of edible weight, according to one paper.

That compares with 3kg to 21kg of CO2e for the full supply chain of chickens, including production. (Dairy cows’ emissions from production come in at 8kg to 75kg of CO2e, lower because they are shared across both meat and dairy products.)

Globally, “ruminant meats produce about seven times as much emissions and use about seven times as much land as chicken and pork to consume the same amount of protein”, says Ms Raychel Santo, a food and climate research associate at the non-profit organisation World Resources Institute. “They use about 20 times as much land and produce about 20 times as much emissions as lentils and beans.”

It does not help that humans eat a lot of beef. Back in 1961, some 28 million tonnes of cattle and buffalo meat was produced globally, according to the United Nations’ Food and Agriculture Organisation (FAO).

By 2022, that had more than doubled to about 76 million tonnes.

It is projected to grow further as the world’s population swells.

The United States has historically led that charge. Americans consumed roughly 485g of beef per person each week in 2023, according to the US Department of Agriculture.

US dietary guidelines do not include specific recommendations for red meat, despite a number of studies linking higher consumption levels with an increased risk of Type 2 diabetes, heart disease and certain cancers. But health and climate experts at the EAT Lancet Commission recommend people consume no more than 98g of red meat per week.

“In the US, most of us eat more beef than what’s considered healthy for us,” says Dr Stephanie Roe, a climate and energy lead scientist at the non-profit organisation World Wildlife Fund. “So that’s low-hanging fruit because then we can improve our health outcomes in addition to environmental ones.”

Per capita beef consumption is starting to slow in some places, including the US and the European Union.

It is also projected to decline in many parts of the world over the next decade, according to a 2023 outlook from the Organisation for Economic Cooperation and Development and the FAO.

In the Asia-Pacific region, though, beef consumption is projected to keep climbing. 

One response to the beef conundrum is to tinker with the cows. There is a growing field of research geared at reducing ruminants’ methane output, whether by including seaweed, biochar and other additives in their feed or designing masks to capture their burps.

Other solutions focus on improving breeding for cows that release less methane or reducing the amount of land being cleared for ruminant production.

Another option is to cut meat out of diets entirely. There is no question that vegans and vegetarians have a smaller food-related carbon footprint than people who consume meat and dairy.

But that is a hard sell in many countries – in the US, only 5 per cent of people identify as vegan or vegetarian – and policymakers often avoid prescriptive guidance for fear of framing climate action as sacrifice.

The lack of US policy in particular is what inspired Dr Rose at Tulane to start digging into diets. “(Sometimes) people do want to act,” he says, “and sometimes by people acting, that pushes governments to actually realise there’s a problem.” 

Dr Rose and his colleagues started by looking at records of what nearly 17,000 adults across the US recalled eating in the previous 24 hours, collected by the Centres for Disease Control and Prevention (CDC) between 2005 and 2010.

They calculated the emissions associated with producing and manufacturing each item – the bulk of a food’s carbon footprint – and then tallied up the emissions from each recorded daily diet. 

The findings were clear: What differentiated people whose diets had a higher carbon footprint was “one or two items of beef on a given day” Dr Rose says. The highest-impact foods “were all beef items”.

The study also set out to determine the impact of swopping out meat, and in particular beef, for an alternative. The researchers identified less climate-intensive food equivalents – pork spare ribs instead of beef short ribs, for example – and calculated the change in daily food-related emissions. They found that even small reductions in meat consumption, especially beef, added up quickly. 

In follow-up research published in Nature Food in 2023, Dr Rose and others took the swop concept a step further by looking at other high-impact swops across food groups, broken down into four categories: proteins, mixed foods, non-alcoholic beverages and dairy. The researchers used 2015 and 2016 dietary recall data reported by almost 8,000 adults and children to the CDC.

“If you have a choice between red meat and chicken or vegetarian, the chicken or vegetarian is going to have a lower carbon footprint and, on average, will also be healthier,” says Dr Anna Grummon, director of the Stanford Food Policy Lab and a co-author on the Nature Food study. 

Other meaningful swops include switching out juice for whole fruit, and replacing dairy milk with non-dairy alternatives like soy or almond milk. (The data pre-dated the rise of oat milk.)

The study did not account for every aspect of a food’s carbon footprint: It stopped short of including transportation, or emissions from food waste. To truly understand the environmental impact of swops, it is important to also consider what they mean for water use, land use, biodiversity loss and other environmental issues. (Almond milk, for example, uses more water than cow’s milk.)

But the study does do one thing incredibly well, Dr Rose says: It makes “a good argument for how small and incremental dietary changes through substitution can make a large overall impact”. BLOOMBERG