Here in the US, the Obama administration has been reluctant to encourage people to eat less meat for health and environmental reasons. The 2015 US Dietary Guidelines, for instance, remained fairly muted on the topic after fierce lobbying by the meat industry.

But in China, where livestock emissions are soaring and obesity is on the rise, officials are being far less circumspect. The Chinese Nutrition Society (CNS) is now enlisting celebrities like Arnold Schwarzenegger, director James Cameron, and actress Li Bingbing in a nationwide campaign urging people to cut their meat consumption in half — in line with new dietary recommendations.

The campaign, taglined "Less Meat, Less Heat, More Life," will tout the climate benefits of lower meat consumption and feature PSAs on billboards and televisions across China. Here’s Schwarzenegger (who has long been encouraging people to go part-time vegetarian for eco reasons) and Cameron (an outspoken vegan) talking about it:

We'll see how it goes, but even a partway successful "less meat" campaign could have a surprisingly large impact on global warming. A new report from WildAid, which is partnering with the campaign, crunches some numbers. Right now the average Chinese person eats about 170 grams of beef, pork, poultry, and lamb a day. China's latest health guidelines, crafted by CNS and the Ministry of Health, advise cutting back to 75 grams a day.

If all 1.3 billion people in China were to follow this advice — a big "if," but just to illustrate — global agricultural emissions would drop 12 percent. That, in turn, would cause total greenhouse gas emissions to fall roughly 1.5 percent, more than the entire annual output of France and Belgium combined. And the savings would get bigger and bigger over the next few decades. We’d get about one-twelfth of the emission cuts needed to stay below 2°C, the report calculates.

Now, obviously getting people to eat less meat will take more than the Terminator on a few glitzy billboards. But it does show how outsize an impact diets can have on climate emissions, something I’ve written about before. It doesn’t have to entail going full vegetarian — even just whittling down portions can make a dent.

China’s meat consumption is expected to soar in the coming decades

The average Chinese person eats half as much meat as the average American each year. But because there are 1.3 billion people in China, total meat consumption is enormous — and growing fast. China already consumes twice as much meat as the United States. By 2030, it’s expected to be triple:

The livestock needed to support those diets have a considerable climate footprint. Cows and sheep release lots of methane through "enteric fermentation" — burps, mostly — and their manure. Plus, there’s land use, the energy needed for farming, and so on. All told, emissions from livestock are estimated to be some 14.5 percent of the global total.

As a 2015 report from Chatham House points out, the type of animal makes a big difference. Beef and lamb produce the most greenhouse gases per kilogram of meat produced. Chickens, which convert feed more efficiently and use less land, produce just a fraction of the amount:

Now, there are some ways to curtail livestock emissions without actually reducing meat production. This Nature Climate Change paper gets into possible strategies: lessening enteric fermentation from cows by adding certain chemicals to feed; better manure management; or even switching to fewer but better-fed animals. If everyone adopted these techniques (plus others), livestock emissions could fall by one-sixth or so.

Those strategies shouldn't get overlooked. But countries could get even bigger reductions on top of that by shifting their diets.

China’s new dietary guidelines suggest cutting back on meat

As China gets richer, the country has also seen a rise in obesity, diabetes, hypertension, and so on. So health officials have been pushing healthier diets: more fruits and veggies, less meat, etc.

In May 2016, the Chinese Nutritional Society, in partnership with the government’s Ministry of Health, unveiled its newest "food diet pagoda" (China's version of the food pyramid):

This is in Chinese, but it advises people to keep to 40 to 75 grams of seafood a day, 40 to 75 grams of beef, pork, and chicken, and 40 to 50 grams' worth of eggs. That’s a small reduction from the 2007 guidelines, which advised 50 to 100 grams of meat per day.

Currently, people in China eat much, much more than this — around 170 grams of beef, pork, chicken, and lamb each day, CNS estimates. And, again, that number is currently projected to rise significantly in the coming decade as China gets richer and more people join the middle class. (Case in point: McDonald’s is eyeing China as a major cheeseburger growth market in the years ahead.)

Here’s a final chart from WildAid, showing the potential impacts of the guidelines. The first column shows greenhouse gas emissions in 2015 related to China’s meat consumption — and how much they would fall if everyone followed the guidelines. The second shows the same values for 2030:

Compared with current projections, having everyone stick to the guidelines would cut China’s emissions in 2030 by a whopping 9.5 percent. Granted, that’s probably unrealistic — humans are very good at not following dietary guidelines — but it at least gives a sense of what’s possible.

Read more: Our bodies don’t need meat. So why can’t we give it up?