The world’s richest countries account for an overly large portion of food-related greenhouse gas emissions and need to radically overhaul their diets to meet global health and climate targets, researchers say.

In two new reports published Wednesday researchers analyzed countries’ diets—and their government’s dietary recommendations—finding that consumption patterns, especially in rich countries including the U.S., far exceed the greenhouse gas “budget” that countries need to maintain to stave off the worst effects of climate change.

“The world’s biggest contributors to the climate crisis can’t continue to ignore the environmental cost of what we eat,” said Stephanie Feldstein, a director at the Center for Biological Diversity, who was not involved in either study. “Integrating sustainability into national dietary guidelines is an important way to recognize that food policy is climate policy.”

A growing body of research has found that shifting to more plant-based diets and away from emissions-intensive livestock and dairy consumption is critical to slowing climate-warming emissions. Overall, the global food system accounts for about one-quarter of greenhouse gas emissions.

Roughly a dozen countries have dietary guidelines that include environmental considerations and recommend shifting to more plant-based diets. But more countries need to embed climate impacts into their guidelines, the researchers said. The U.S. Dietary Guidelines, for example, don’t include environmental considerations, nor do they contain explicit instructions to eat less livestock-heavy diets.

“You have to integrate both human health and environmental health. You can’t just focus on one or the other,” said Brent Loken, a food scientist with the World Wildlife Fund. “Leaving environmental considerations out of dietary guidelines is like being stuck in the dark ages.”

One of the reports, authored by Loken and released by the EAT Forum, a Norway-based think tank that last year released an influential report on sustainable diets in collaboration with The Lancet, looked at the climate effects of diets and dietary advice in the world’s biggest economies.   

It finds that the diets of the G20 countries account for 75 percent of the greenhouse gas emissions that the world’s countries can emit producing food while still staying within the targets of the Paris Climate Agreement. In theory, that leaves only 25 percent for the rest of the world, which includes countries where millions are malnourished.

“When we’re thinking about meeting the goals of the Paris agreement, we know that we have to decarbonize other sectors, like energy and transport. That’s pretty clear-cut,” Loken explained. “But for food it’s going to be different, because no matter what, we’ll have livestock, and fertilizer and we’ll till the soil. No matter what, we’ll generate emissions.”

The EAT researchers found that if top economies shifted to plant-based diets beyond the levels that those nations currently advise, they could lower their “food prints” to about 40 percent of the total planetary carbon budget for food, which they estimate at about 5 gigatons of greenhouse gasses in 2050.

Some countries, on a per capita basis, are particularly bad offenders. Countries in the EU, the US, Australia and Argentina emit more greenhouse gasses in connection with their diets and should pursue more ambitious reductions in greenhouse-gas intensive foods, the authors said. Others, including India and Indonesia, will need a slight increase to meet the food needs of their populations.

“If everyone ate like Argentina, we’d need 7.42 more earths, and if everyone ate like someone from the U.S., we’d need 5.55 more earths,” Loken said. “And if every country adopted their national dietary guidance, we’d need about 4.6 more earths. So clearly the national dietary guidelines are not going to get us there. Clearly, some of these countries aren’t ambitious enough.”

A second report published Wednesday, from researchers at Oxford, Harvard, Tufts and Adelaide universities and published in the BMJ (formerly the British Medical Journal) makes a similar case, but looks across the globe. It considers both the health and environmental impacts of dietary guidelines and how these align with global greenhouse gas reduction and development targets.

It found that at least two-thirds of countries’ dietary guidelines were not on track to meet the greenhouse gas reduction goals of the Paris agreement.

If the U.S., for example, were to adopt more ambitious dietary guidance, it could cut food-related emissions by 74 percent. The current guidelines put the nation on track to reduce emissions by only 38 percent. If the world adopted those U.S. guidelines, it would exceed the food-related emissions budget more than three times over.

“Most national food based dietary guidelines shy away from providing clear recommendations on limiting the consumption of animal source foods, despite their exceptionally high emissions and resource use, and, in the case of red and processed meat, their clear association with diet-related diseases, such as heart disease and cancer,” said the report’s lead author, Marco Springmann, of Oxford University, in a press release.

The reports were published the same day the U.S. departments of Agriculture and Health and Human Services released a review of dietary evidence that will undergird the upcoming version of the U.S. guidelines. Those form the cornerstone of U.S. dietary policy and are renewed every five years.

The process for the new review of the U.S. guidelines has been criticized by advocacy groups, in part because it failed to consider the climate and environmental factors and is subject to growing industry influence.

“The Trump administration predetermined the scientific topics and questions that the advisory committee was allowed to look at,” Feldstein said. “So even before the committees were chosen to determine the key questions, the administration predetermined the topics—and, of course, sustainability was not among them.”

Under the Obama administration, the dietary guidelines advisory committee considered the topic of sustainability and ultimately suggested limiting the consumption of carbon-intensive foods.  But under pressure from the meat and dairy industry, those suggestions were stripped out of the final version of the guidelines.

Industry influence continues during the current review. A recent report found that two-thirds of the advisory committee members have direct ties to the food and beverage industry. 

“While we are still working to comb through over 800 pages of recommendations released today, the inherent conflict of interest—Big Food’s overwhelming presence on the Dietary Guidelines Advisory Committee (DGAC)—remains,” said Ashka Naik, director of research for the watchdog group, Corporate Accountability.

Our neighbors to the north, on the other hand, have what many experts believe is a superior approach. 

“If you want to look at a good process, you should look at Canada,” Loken said, noting that Canada’s recent guidelines explicitly considered environmental sustainability. “What the Canada guidelines show is what happens when industry doesn’t influence the process. If you look at the U.S. guidelines—that’s what happens when industry has a seat at the table.”