If you’re concerned about the effect your food choices have on the environment, you should reconsider cheeseburgers. A recent study published in shows that beef and milk products are the world’s most polluting foods.

Just in time for the Fourth of July, this indictment of the all-American cheeseburger may be taken by climate change skeptics as proof that global warming is a left-wing conspiracy. But burger lovers who fear global warming should expect angst at the grill this summer.

Meanwhile, in what has to be awkward news for localvores, the study also found that for the average consumer, eating locally offers negligible benefits in terms of greenhouse gas prevention.

Crunching numbers from the U.S. departments of Commerce, Agriculture, and Transportation, a Carnegie Mellon University research team calculated that shipping food between production and consumption creates only 4 percent of food-related greenhouse gas emissions. Food production accounts for 83 percent, and transport activities production dwarfs post-production shipping to market by a ratio of three to one.

But before anyone gives up riding his or her bike to the farmers market, the study’s true take-home message is that if you’re serious about combating climate change with your eating habits, to make your decisions where they count. Locally purchased veggies, for example, have a larger impact on greenhouse emissions than the local purchase of any other type of food.

Given how most cattle are raised today, on the other hand, the delivery from meat packer to consumer is barely a footnote in the cow’s contribution to greenhouse gas emissions. A lot of carbon gets burned in the raising and shipping of cattle feed, and in moving cows around during production. And even the grass-fed cow next door produces methane– one of the worst greenhouse gases– as a metabolic byproduct.

To better understand the impact of eating locally, meanwhile, the researchers created a hypothetical scenario called “total localization,” in which an average household eats its average diet completely locally– with zero greenhouse gas emissions associated with food delivery. They found that the drop in greenhouse gas emissions created by this totally localized average household diet equals the emissions generated by one-seventh of the average household beef consumption. Thus, total localization would save roughly the equivalent of a cheeseburger worth of greenhouse gas emissions per week.

Meanwhile, the people who are developing, using, and supporting less destructive farming practices aren’t statistically significant enough to be included in this study, acknowledged lead researcher Chris Weber. “The subset that gardens or buys food at farmers markets is too small,” he told me.

If localvores and their ilk are too few to be statistically significant, it suggests that all your conscious eating won’t do a lick of global good as long as everybody else is popping cheeseburgers like Prozac. Nonetheless, I prefer local, sustainable farming. Nobody has come close to proving it can’t make a difference, and I think that aiming for a carbon-neutral diet has plenty of perks.

The drive-thru isn’t exactly the health food store, and reducing your intake of “average” cheeseburgers can’t hurt your survival odds. Meanwhile, the above-average food that’s being produced with care by your local farmer offers, in my experience, above-average flavor and fun.

At the farmers market last week, for example, a rancher named Ernie told me about a blind steer he couldn’t herd into his corral for slaughter, so the inspector and the butcher had to go into the pasture to inspect and kill it.

I bought a rib-eye steak off of Ernie’s blind steer. Then Ernie got going about how yellow his butter is these days, thanks to the dandelion-rich diet of his dairy cows. I’m a sucker for stories like this. Then I noticed Ernie’s feta, which reminded me that I have a patch of spinach that needs to be harvested.

Ernie’s blind cow, thinly sliced and fried with yellow onions, Philly-style– and accompanied by a glass of California red wine poured from an eco-friendly cardboard box– was spectacular. Ernie’s yellow butter was so good I ate it plain, like cheese. And my spinach/feta salad, with red onions, was perfect.

The world has too many cows, no doubt about it. But maybe, for special occasions, it’s OK to have a few of our tasty bovine friends around– especially if you’re a fan of organic agriculture, which uses manure as fertilizer. As my farmer friend Steve once pointed out: “Somebody has to make that shit.”

If we reduce the quantity but increase the quality of the beef and milk products we eat, then we’ll eat better and perhaps live longer, while having more fun. And we’ll probably leave a better planet behind us.