The Surprisingly Unpredictable Environmental Cost of Your Meals

What you eat and where you buy it from can have hugely different consequences for the environment.

A new study in the science journal “Nature” that looks at the climate impact of food production reveals some things you may have guessed — a diet higher in plants and lower in meat results in significantly less CO2 gas release — and some things that may come as a surprise, namely that the producer you buy from really, really matters.

It turns out the worst (what the study calls “high-impact”) producers of everything from chocolate to beef might be responsible for five-times as much greenhouse gas pollution as the most efficient producers of that same product, hence the title of the study, “Reducing food’s environmental impacts through producers and consumers”. As consumers we can simultaneously reduce our own impact by being thoughtful about our grocery purchases while pushing producers and suppliers to do better.

Interestingly, the climate impact was shown to vary from item to item. Plants tend to have a lower environmental cost than meat, and this makes sense. I teach my tenth-grade students about trophic levels in the food web, and the general rule is that energy is lost for every additional step you are removed from the original source: the sun. It requires more energy to raise one million calories worth of meat, as you have to first raise ten million calories worth of plant material (say corn, in the case of factory-farm beef), to produce that much cow meat. The other nine million calories? Burned up by the cows themselves.

But that’s only part of the story. The way we raise that corn matters. Do we overproduce, increasing the yield beyond naturally-sustainable levels through the use of industrially-produced artificial fertilizers? Do we ship corn and beef all over the country, or internationally, as part of this entire agricultural network that is sometimes more industrial than agrarian? This can all have extra impact on the environment.

You may wonder how all of factors impacts grocery prices. The answer is, not enough. The complex relationship of subsidies, trade deals, and taxes means the consumer cost in the United States is very much out of whack with the actual expense of producing different kinds of food, not to mention the environmental cost going forward. Meat, especially, is extremely affordable in the United States relative to other countries. Yet the foods we should be encouraging people to eat more of are often less economical in individual grocery budgets. As consumers, it’s often more affordable to have a high-meat, high-sugar, and highly-processed diet, and that’s bad for public health and the environment as well.

When we combine the data from the just-released study with typical grocery prices (I went through a few flyers for this), here’s what we see. You can take in 100g of protein from peas or nuts, and anywhere from below one kilogram to up to several kilograms of CO2 gas may have been released in order to provide that food for you. That level of variation, which means the worst producers release 500 percent as much pollution as the best producers, is itself astounding. It’s something I would like to see on food labels alongside the nutritional information — but that seems a pipedream right now.

More astounding is when you compare this to animal protein sources. Eggs and chicken range from a few kilograms of CO2 to maybe 15 kg per 100g of protein for chicken. Beef, on the other hand, produces at least 20kg and sometimes more than 100kg. If we take, say, 8kg of pollution for chicken as average, we can compare that to 65kg for beef (and these are just middle values for their respective data ranges).

So beef is eight times worse from the standpoint of environmental cost. Yet the consumer cost of beef compared to chicken is only about double when it comes to similar cuts, while ground beef is actually cheaper. Similarly, pork, which can also be highly energy-intensive and has additional issues related to groundwater contamination, can be significantly cheaper than either chicken or beef in some markets (including my own), again thanks to lobbying groups and the subsidies they have garnered.

The lead author of this study actually gave up meat as a result of these findings, and the study offers a number of options for the environmentally-conscious. Reducing your meat consumption would be a positive change, and choosing low-impact meats is another. One of the most difficult findings to implement might be finding the most low-impact producers for a given type of food, be it plant or animal-based. It might be more practical to lobby our elected representatives to end or reduce subsidies for high-impact agricultural items, support carbon taxes for all industries, including agriculture, and let the free market do its work.

Of course, some politicians are all about the free market until their lobbyist buddies want special treatment.

Photo credit: Thinkstock.


Kathy G
Kathy G2 days ago

Thank you

Naomi B
Naomi B7 days ago

Thanks for sharing

Karen Martinez
Karen Martinez8 days ago

This is interesting. Even though I live in a predominantly agrarian part of the country, the food at my local grocery store and even farmer's markets are imported. Yes, I can grow my own, except during the summer when it is just too darn hot, but there is only so much one can grow in a yard. We have altered our eating habits significantly, but according to this article we just need to curl up and die because we don't have any control over where our grocery stores procure the foods they sell.

Gino C
Gino C10 days ago


Barbara M
Barbara M12 days ago

thank you for posting

Dr. Jan Hill
Dr. Jan Hill15 days ago

Thanks - I guess I need to stop eating.

Cindy S
Cindy S18 days ago


Ben O
Ben O20 days ago

I don't think so, not my meals...

Janis K
Janis K23 days ago

Thanks for sharing.

Amanda M
Amanda M23 days ago

Thanks for sharing