Lose weight. Exercise daily. Save more. It’s that time of year when holiday to-do lists morph into new year’s resolutions. Self-improvement goals are worthy, but it’s time to think bigger.

Fortunately, there’s a resolution offering better personal and planetary health that takes only modest effort. (Psychologists remind us that we stand the best chance of maintaining resolutions if we start with small steps.)

Greenhouse gas emissions from all of the world’s cars, trucks, planes, boats and trains together don’t quite match the contribution from a single agricultural sector: livestock. That industry, according to the UN Food and Agriculture Organization, accounts for nearly 15 percent of human-generated global greenhouse gas emissions.

A recent British study found that meat eaters contribute roughly 50 percent more food-related greenhouse gas emissions than vegetarians and about 100 percent more than vegans.

Food choices offer an expedient path to lower-carbon living. Two geophysicists, Gidon Eshel and Pamela A. Martin, have estimated that if Americans cut their meat consumption by just 20 percent, the resulting savings in greenhouse gas emissions would be like the nation’s car owners switching from midsized sedans to hybrid cars.

Why is the impact of livestock so large? The UN Food and Agriculture Organization breaks out the emissions this way:

 45 percent from feed production and processing (which includes fossil fuels burned in raising soy and corn feed, and clearcutting forests to create pasture land);

39 percent from ruminants’ enteric fermentation (better known as burps and farts from cows, sheep and goats);

10 percent from manure storage and processing (with the remaining 6 percent from meat processing and transportation).

What’s generated from any given farm depends on many factors, with reduced emissions possible through practices such as no-till farming, rotational grazing with high-quality forage, locally sourced feeds and use of anaerobic digesters (see the Source article on Stonyvale Farm in Exeter).

The UN study found that beef cattle produce the most emissions (41 percent), followed by dairy cows (20 percent), with pigs, buffalo, chickens, sheep and goats all contributing less than 10 percent each.

Although U.S. meat consumption has declined slightly in recent years, Americans still eat more meat per person than nearly any other country’s residents – downing, on average, 200 pounds per year.

Globally, meat-eating is still trending upward due to population growth and a marked rise in meat consumption among countries like Brazil and China. If developing nations rise to U.S. levels of meat consumption, ecologist Vaclav Smil predicts in the journal Global Food Security, “there is no realistic possibility of … moderating the rate of global climate change.”

Industrial beef production, which relies heavily on feedlots, generates large volumes of methane – a potent greenhouse gas – and mountains of manure that can contaminate waters. Habitat loss due to conversion of lands to livestock production could greatly accelerate global species extinction, a recent study found.

By reducing or eliminating consumption of feedlot meats, Americans could set a global example and be rewarded with better health. Doctors and nutritionists have long recommended that patients cut back on saturated fats from animal foods. And this fall, an agency of the World Health Organization classified processed meats (like hot dogs, ham, and bacon) as carcinogens and red meat as a probable carcinogen, suggesting that people cut consumption of these products to reduce their risk of cancer.

A panel of scientists and doctors recently prepared an advisory report for the U.S. Department of Agriculture in which members concluded that a diet “higher in plant-based foods, such as vegetables, fruits, whole grains, legumes, nuts and seeds, and lower in animal-based foods, is more health-promoting and is associated with less environmental impact (greenhouse gas emissions and energy, land and water use) than is the current average U.S. diet.”

So can we expect to see clear USDA guidance helping us choose foods that benefit both personal and planetary well-being? Not anytime soon. Succumbing to pressure from the meat industry, the agency chose to exclude all mention in its new guidelines of how our dietary choices affect the natural world.

This governmental failure is a reminder of the economics underlying the corporate food system. The meat industry represents a powerful lobby and has succeeded in getting federal subsidies that make industrial-scale meats artificially cheap. That skewed pricing, along with heavy marketing and a fast-food culture, fuels our collective meat intake.

But the choice at each meal remains ours. Must we resolve to become vegan? No. That’s not the only ecologically responsible choice. (And if vegan foods are highly processed or air-freighted, they can still have a large carbon footprint.)

We simply need to focus our meat consumption on quality over quantity: spending more on local, sustainably raised meat and – for our budgets and our health – buying less of it. Treat meat, as Michael Pollan writes, like a condiment rather than a centerpiece of meals.

For an even lower-carbon diet, consider eating more regional produce and dairy – eliminating the fossil fuels burned in long-distance food transport, and supporting small-scale farmers using sustainable practices.

Each year, it gets easier to find wholesome local food choices. Maine is blessed with an abundance of farmers markets, some of which operate through the winter, and the Maine Organic Farmers and Gardeners Association has a free seasonal foods guide.

This year, stretch the season of giving into the new year by choosing more foods close to their source.

Marina Schauffler, Ph.D., is a writer who runs Natural Choices (naturalchoices.com).