The heat on meat consumption keeps rising.
For decades, environmentalists have insisted that vegetables and other plant foods are the way to go.
The latest lob comes from the Environmental Working Group, which adds new number-crunching to the debate. The national nonprofit commissioned a life-cycle analysis of 20 common foods - meat, fish, dairy, and vegetables.
In a report released last week, "Meat Eater's Guide to Climate Change and Health," the group ranked them according to the amount of greenhouse gas emissions per kilogram - roughly four ounces - of the food.
Beef actually wasn't at the top - surprise! Lamb edged it out. But only because a lamb produces less edible meat relative to the animal's overall weight. So the emissions are concentrated in those little chops.
Generally, beef and lamb are the Humvees of food because the animals' digestive functions make a lot of methane, a greenhouse gas with 20 times the potency of carbon dioxide.
They also are fed a lot of corn that is often heavily fertilized and spritzed with pesticide, which adds to the emission load.
Need I mention manure?
These studies make me wince because environmentalists may have an ax - or a butcher's knife - to grind.
Still, it made me wonder. What's the best way to lower the impact of food?
To be sure, agriculture accounts for only about 7 percent of the nation's greenhouse gas emissions, according to the U.S. Environmental Protection Agency. Even though report author Kari Hamerschlag said that number counts only production and not the full life cycle, far more comes from transportation and electricity use.
But it's hard for many to change transportation overnight. Household energy use is easier, albeit still a tweak - adjust the thermostat, turn out some lights, and unplug devices.
But food? This part of your life you can change with one trip to the store or the farmer's market.
At the low end of the new report's emissions scale are tofu, dry beans, 2 percent milk, tomatoes, and lentils.
The food with the third-highest emissions was a disappointment: cheese. As a devoted cheese-lover, I object.
But since it comes from beef, sheep, or goats - all with similar methane-making digestive systems - perhaps I shouldn't be surprised.
Fortunately, Hamerschlag, an EWG senior analyst, softened when we talked about the cheese.
"If you looked at it from a serving-size situation, cheese would be much lower," she said. Most people don't sit down and eat four ounces of cheese at one sitting."
Even when it's brie?
The report had other surprises, too.
Farmed salmon ranked high - fifth - because the fish have diets of energy-intensive food that must either be caught or grown itself.
Fished salmon wasn't part of the study, but Hamerschlag said it wasn't so good either because most of it is flown in from Alaska, and any time food gets on a plane, as opposed to a ship, the footprint swells. Indeed, much of our food increasingly comes from far away - think apples from New Zealand this time of year.
But transportation isn't such a defining factor for meat. Its footprint was so large that switching to local didn't change the outcome much. A 2008 study by two Carnegie Mellon University researchers found that shifting one day's worth of calories per week from red meat and dairy products to chicken, fish, eggs, or vegetables can have a bigger impact than buying all locally sourced food.
Buying local, however, can reduce the overall footprint by as much as 20 percent for broccoli and 25 percent for tomatoes, the EWG report found.
Analyzing U.S. Department of Agriculture data, the scientists also found that consumers throw away 40 percent of the fish they buy. We throw away 12 percent of our chicken, 16 percent of beef, 25 percent of pork and 31 percent of turkey. We leave it behind at restaurants. We let it go bad in the fridge.
And so everything that went into producing the wasted meat is wasted, and we've upped our emissions for nothing.
But if the EWG study found that meat waste is high, the waste of vegetables, fruits, and dairy items is higher still - 32 percent for each, a 2010 University of Texas study showed.
The EWG report concludes that if everyone in the United States ate no meat or cheese just one day a week - along the lines of the Meatless Monday campaign - over the course of a year it would be like taking 7.6 million cars off the road.
High-powered foodies have endorsed the EWG report, from chef Mario Batali to The Ominvore's Dilemma author Michael Pollan, who suggests treating meat as a flavoring rather than the main event.
Nevertheless, when you mess with people's meat, a ruckus often ensues.
The American Meat Institute hit back, saying the report "appears to be an effort to throw a long list of concerns at the American public in hopes that some will stick."
It said the meat industry is making big progress. Emissions have remained steady, while protein production has increased dramatically.
The dairy industry likewise has made sustainability advances, said Lafayette Hill dietitian Althea Zanecosky, a spokeswoman for the Mid-Atlantic Dairy Association.
She noted that cheese is a concentrated source of calcium and that sometimes it can make those very vegetables we should eat more of taste better. "You have to look at the big picture," she said.
Mother Jones magazine held a smackdown - bacon lovers vs. soy huggers - that generated some heated back-and-forth.
One guy claimed that beef from a local lot where a small herd eats mostly grass has got to be better than asparagus from Chile.
So maybe the detail-laden report isn't so much a dictate as it is fodder for chewing over while you chew.
After all, I know of several local farms that produce great cheese. Do I get credit if I eat tomatoes from my garden at the same time?
Contact staff writer Sandy Bauers at 215-854-5147, firstname.lastname@example.org, or @sbauers on Twitter. Visit her blog at philly.com/greenspace