A boy eating a burger. (Bigstock)

Each week, In Theory takes on a big idea in the news and explores it from a range of perspectives. This week we’re talking about meat consumption. Need a primer? Catch up here.

Laura Wellesley is a research associate in the Energy, Environment and Resources department at Chatham House, where she focuses on issues relating to climate change and food security.

Meat consumption in the United States — and across much of the Western world — has reached a level that is unsustainable, both for our planet and for our health. We owe it to ourselves to make a change. Our politicians owe it to us to enable that change.

The average American eats three times as much meat as experts deem healthy, the average European around twice as much. And the emerging economies are quickly catching up: by 2050, global consumption is expected to rise a further 76 percent.

Excessive meat-eating is partly responsible for an epidemic of obesity — now one of the most costly social burdens, according to the consultancy McKinsey. Over-consumption of red and processed meat is contributing to the rising incidence of non-communicable diseases such as heart disease, type-2 diabetes and certain cancers.

What’s more, this pattern of excess is a key driver of environmental damage and a serious drain on water and land. The livestock sector accounts for 14.5 percent of global greenhouse gas emissions, roughly the same share as every car, truck, plane, train and ship put together. Unless we significantly reduce our meat consumption — by about half across the West, by up to two-thirds across much of the United States — it will be virtually impossible to keep global temperature rise below the danger threshold of 2 degrees.

Does this mean we all need to become vegetarian? No. Does it mean we need to forgo a burger — or 10 — every month? Undoubtedly.

Last month, the world’s most populous country, China, took an important step in addressing the population’s increasingly unhealthy meat-eating habits, introducing national dietary guidelines that recommend a daily meat intake half that of current consumption levels.

The move was designed to avert a public-health crisis, but it was also good news from an environmental perspective. Governments around the world should take note: National dietary guidelines are a good starting point for tackling unsustainable meat-eating habits, and they could help curb the climate-change-inducing impacts of our diets.

Dietary guidelines inform public policy, guiding menu choices in public institutions such as schools, universities and hospitals. They provide direction to industry, prompting supply-side changes and innovation in response to an anticipated rise in demand for non-meat products. And they indicate that the government is serious about public health, the environment and the climate.

This last point is key when it comes to shifting attitudes. Our research indicates that consumers take their prompts from official agencies when deciding which issues matter and what changes need to be made.

A government that is silent on excessive, unsustainable meat eating is sending a message to carry on as normal. But a government that introduces a forward-looking policy of reduced consumption — promoting a healthier and more sustainable eating pattern — signals that overconsumption is something we should all really care about.

Last year, Chatham House, the Royal Institute of International Affairs, published research on public attitudes toward meat eating in four of the most meat-obsessed countries: the United States, Britain, China and Brazil. Our focus group participants expected governments to educate, guide and help them make necessary changes in the interests of our health and our planet. Indeed, many of the Americans interviewed believed that their government had a duty to act.

Dietary guidelines are an example of the kind of win-win strategies that should excite policymakers. In one fell swoop, they respond to two of the most pressing issues of our time — rising public-health costs and a warming planet.

But there is no one silver bullet to prompting the behavior change that is so sorely needed if we are to avoid dangerous climate change. Dietary guidelines alone will not be enough. Climate change and environmental sustainability tend not to inform our food choices in the store. Health concerns do, but so, too, do prices. Taste, convenience and the habits of our friends and families also play major roles.

As our focus group interviewees freely admitted, our choices are guided to a large extent by the retail environment around us. If we’re to swap our bacon sandwich for a bean taco, the environment in which we eat and shop must change as well.

Foods that are good for our health and the climate — vegetables, fruits, pulses, nuts, legumes — should be more freely available, more appealing, more visible and, ultimately, cheaper. A broad package of policies will be needed to arrive at this goal — industry innovation, awareness-raising campaigns, nutrition education, cooking skills and, however contentious, a tax on the most environmentally damaging products.

We consumers can make a huge difference on the future of the planet, and to our own well-beings, through simple changes to our eating habits. But, truth be told, we will need more than a little nudge from our governments to do so.

Other perspectives:

Brian Kateman: We can save the earth without giving up bacon. Here’s how.

Blake Hurst: The latest threat to the American cowboy: Environmentalists