20 percent of Americans responsible for almost half of US food-related greenhouse gas emissions

Credit: CC0 Public Domain

On any given day, 20 percent of Americans account for nearly half of U.S. diet-related greenhouse gas emissions, and high levels of beef consumption are largely responsible, according to a new study from researchers at the University of Michigan and Tulane University.

To estimate the impact of U.S. dietary choices on greenhouse gas emissions, the researchers built a database that assessed the environmental impacts involved in producing more than 300 types of foods. Then they linked the database to the findings of a nationally representative, one-day dietary recall survey involving more than 16,000 American adults.

They ranked the diets by their associated greenhouse gas emissions, from lowest to highest, then divided them into five equal groups, or quintiles. The researchers found that the 20 percent of U.S. diets with the highest carbon footprint accounted for 46 percent of total diet-related greenhouse emissions.

The highest-impact group was responsible for about eight times more emissions than the lowest quintile of diets. And beef consumption accounted for 72 percent of the emissions difference between the highest and lowest groups, according to the study.

"A big take home message for me is the fact that high-impact diets are such a large part of the overall contribution to food-related greenhouse gases," said U-M researcher Martin Heller, first author of a paper scheduled for publication March 20 in the journal Environmental Research Letters.

The study estimated the greenhouse gas emissions associated with food production only. Emissions related to the processing, packaging, distribution, refrigeration and cooking of those foods were not part of the study but would likely increase total emissions by 30 percent or more, Heller said.

"Reducing the impact of our diets—by eating fewer calories and less animal-based foods—could achieve significant reductions in greenhouse gas emissions in the United States. It's climate action that is accessible to everyone, because we all decide on a daily basis what we eat," said Heller, a researcher at the U-M Center for Sustainable Systems in the School for Environment and Sustainability.

If Americans in the highest-impact group shifted their diets to align with the U.S. average—by consuming fewer overall calories and relying less on meat—the one-day greenhouse-gas emissions reduction would be equivalent to eliminating 661 million passenger-vehicle miles, according to the researchers.

That hypothetical diet shift, if implemented every day of the year and accompanied by equivalent shifts in domestic food production, would achieve nearly 10 percent of the emissions reductions needed for the United States to meet its targets under the Paris climate accord, the authors wrote. Though President Trump announced his intention to withdraw the United States from the accord, many states and municipalities are still working to meet the emissions targets.

In the United States in 2010, food production was responsible for about 8 percent of the nation's heat-trapping greenhouse gas emissions. In general, animal-based foods are responsible for more greenhouse gas emissions per pound than plant-based foods. The production of both beef cattle and dairy cows is tied to especially high emissions levels.

For starters, cows don't efficiently convert plant-based feed into muscle or milk, so they must eat lots of feed. Growing that feed often involves the use of fertilizers and other substances manufactured through energy-intensive processes. And then there's the fuel used by farm equipment.

In addition, cows burp lots of methane, and their manure also releases this potent greenhouse gas.

"Previous studies of diet-related gas emissions have focused mainly on the average diet in a given country. This study is the first in the United States to look instead at self-reported dietary choices of a nationally representative sample of thousands of Americans," said Diego Rose, principal investigator on the project and a professor of nutrition and food security at Tulane University's School of Public Health and Tropical Medicine.

By linking their database of environmental impacts to the individual, self-reported diets in the National Health and Nutrition Examination Survey, the U-M and Tulane researchers were able to estimate the distribution of diet-related impacts across the entire U.S. population on a given day.

They found that Americans in the highest-impact quintile consumed more than twice as many calories on a given day—2,984 versus 1,323—than those in the bottom 20 percent. But even when the findings were adjusted for caloric intake, the highest-impact quintile was still responsible for five times more emissions than the lowest-impact group.

Meat accounted for 70 percent of the food-associated in the highest-impact group but only 27 percent in the lowest-impact group.

NHANES is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The survey, which combines interviews and physical examinations, is a major program of the National Center for Health Statistics, which is part of the U.S. Centers for Disease Control and Prevention.

Explore further

Dietary recommendations may be tied to increased greenhouse gas emissions

More information: Greenhouse gas emissions and energy use associated with production of individual self-selected U.S. diets, Environmental Research Letters (2018). DOI: 10.1088/1748-9326/aab0ac
Journal information: Environmental Research Letters

Citation: 20 percent of Americans responsible for almost half of US food-related greenhouse gas emissions (2018, March 20) retrieved 20 August 2019 from https://phys.org/news/2018-03-percent-americans-responsible-food-related-greenhouse.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Mar 20, 2018
There is a real and continuing effort to convince Americans to stop eating meat.

* It is not good for you.

* It is not good for the animals.

* It is destroying the climate.

* Etc.

Won't work, but I guess it funds these foolish studies.

Mar 20, 2018
It may not matter what the 20% do. The coming Trump tariff and trade war will hamper U.S. beef export growth relative to our competitors', say in Brazil, Canada or the E.U.

Mar 20, 2018
Soon farmers will be required to put carbon filter diapers on their cows. Environmentalists (and all other liberals) think with their emotions, not their brain.

Mar 20, 2018

Methane burps.

28 times as potent as carbon, with it comes to greenhouse effects.

GET AWAY from beef.

The destruction of the environment for feeding them, processing them, and eating them... is worse than fossil fuel issues. This is never illustrated to us. +50% of us land cultivation is directly tied to beef!

The Amazon is going missing ...over burgers! Double negative!! Fuck me!!

The most important thing you can do to help stop the world's temperature rise and the poles melting, is to simply stop eating BEEF. Today. Right now. No beef burger. chicken instead.

'Death to all beef based fast food outlets' -seriously!

Getting an electric car pales in comparison--it's a joke.

Cutting back on beef is an easy thing to do. No more fast food, or whatnot. Cut back on beef in the west .....and you'll actually be fixing the world in the immediate and now.

It does not get more direct than that. Do it yourself or have it legislated into existence.

Mar 20, 2018
Hold on - that looks like chinese take out to me. Everyone knows youre hungry again an hour after eating that stuff.

I think we've established causality.

Mar 20, 2018
Keep telling your children that they are unjustly privileged.
Keep telling your children that they are racist.
Keep telling your children that they are guilty of microaggressions.
Keep telling your children that they are killing the planet by their very existance.

Keep wondering why they are depressed and killing themselves with drugs.

Mar 20, 2018
Make sure that you replace all of your meats and animal fats with BIG servings of bread, pasta. potatoes and rice. You should have no problem gaining 50 pounds and raising your blood sugar levels to 200-300 without trying.

Mar 20, 2018
Sadly this is another fake science total crap article. Why obsess about diet related green-house gases, its like worrying about the carbonation in tonic water. The amount of gas is so small compared to other source as to meaningless. It is not true that the amount of methane in the farts of the American populace come anywhere close to the amount of CO2 exhaled. Moreover vegetarians eat a lot of beans, it is a primary source of protein without which they sicken. Beans are a major source of flatulence so, even if the researchers data were not completely pointless, it is dubious their claims claims are valid. Publicizing political drivel dressed up science is really getting tiresome. I implore you to stop doing it.

Mar 20, 2018
Beef - Real Food for Real People®

Mar 21, 2018
They won't let up until everyone (except for the elites, of course) are living like peasants of old.

Mar 21, 2018
This protein myth, in the so-called educationally advanced countries, needs to be debunked. A human can easily live all his/her life without even touching meat. A significant part of Indian population ( = population of US) have been living on strictly plant-based diet for tens of thousands of years and they still continue to do so (consider exceptions). They didn't die due to protein deficiency!

If people can't stop eating animals and thereby supporting meat industry, consider buying an animal and kill it and cook as per wish. Don't buy the meat, buy the living animal. We need STRICT laws on this. Control your palate!

Mar 21, 2018
The article dances beautifully around the bush to avoid giving any direct context and point of reference on any absolute scale of the issue.

if implemented every day of the year and accompanied by equivalent shifts in domestic food production, would achieve nearly 10 percent of the emissions reductions needed for the United States to meet its targets under the Paris climate accord

The paris agreement would put US greenhouse emissions 17% below in 2020 down to 26-28% below at 2025 from 2005 levels.

10% of that is a reduction of 1.7 - 2.7% in total emissions compared to 2005.

They didn't die due to protein deficiency!

Not dying doesn't mean you aren't suffering.
80% Indians Suffer from Protein Deficiency, Reveals Survey
Vegetarians showed a higher protein deficit (91%) as compared to non-vegetarians (85%).

Mar 21, 2018
The main issue in India is that people are eating "convenience foods" that are cheaper, mainly consisting of starches and simple sugars because with 1.3 billion people it's not possible to maintain adequate supply of meat to meet demand. Other sources of protein such as legumes and nuts aren't particularily rich in protein either, and contain plant toxins that harm nutrient absorption and are generally harder to digest without extensive and costly processing.

Protein deficient people experience a number of ailments, such as lethargy, weakness, excessive weight loss, water retention (edema), skin conditions, wounds that heal slowly, cognitive issues, hormonal issues, metabolic issues...

For example, diabetes is quickly becoming an epidemic in India despite the low levels of obesity.

Mar 21, 2018
"For example, diabetes is quickly becoming an epidemic in India despite the low levels of obesity."

Diabetes is a direct result eating high glycemic index carbs like breads, pasta, potatoes and rice. If you are a starving peasant you are protected by lack of available food. Once you can afford food these will kill you. Even whole grain breads and pastas are not safe to eat.

Mar 21, 2018
"20 percent of Americans responsible for almost half of US food-related greenhouse gas emissions"!

If that's the conclusion of this research, why would anyone criticise this article if their diet has never been significant to greenhouse emission in the first place except for the top 20%?!

If someone says your diet is destroying the planet, then cite this research! Tell them to attack the big guy, the hypocrites, not you!

Mar 21, 2018
You mean plant food?

Mar 21, 2018
That's not an argument against the findings, that's just you saying you find the conclusions inconvenient.

Mar 21, 2018
Reduce coal power and we've got more than Paris right there. This article is clickbait.

Mar 21, 2018
Indian descend can extract protein from plant more efficiently than Western descend does, so it is wrong to apply nutrient logic of Western population to another population because that'll cause metabolic diseases like Diabetes, for example; Eskimo descend are adapted to high-meat diet but you shouldn't apply Eskimo diet to Western population (just because Eskimo appear healthier) because you don't know what's going on in Eskimo's biology, for example; Native Canadian who live north near Alaska reported Cancer when their diet changes away from tradition to modern (although nobody knows if it's instead caused by Arsenic poisoning from the river water or pollution by oil refinery nearby). There's a real adaptation at biological level for different population living in different climates.

Mar 21, 2018
A sugar in red meat is not good for us: Neu5Gc
https://www.natur.../nrc3904 (paywall)

Mar 21, 2018
China is just as guilty, but the future is ours to craft:
It would be interesting to see which of those are anemic and/or on blood thinners, so they need the iron.
It is likely obesity. So here is a good recipe:

Mar 21, 2018
We also lead the world in food waste, so i wonder the other 50% and how much 'can' be changed.
Its easy to just so, oh the fat people did it. But that is wrong. Food is an easy escape, but I highly doubt it causes more then transportation or airplanes. The infrastructure is already in place. Blaming individuals does nothing. Change how things are done and staying open is the key.
Who knows maybe that Antarctic methane eating bacteria already saved the world.
ALSO water is a green house gas....

Mar 29, 2018
Indian descend can extract protein from plant more efficiently than Western descend does

You can't extract protein that doesn't exist. Getting enough protein from mainly carbohydrate diets would require you to eat enough to become obese, or shit partially undigested food which would show up as massive digestive problems.

If you are a starving peasant you are protected by lack of available food.

If you are a starving peasasnt, you're dying anyways due to the lack of available energy and nutrients. If you're trying to subsist on solely plant based diet with just enough energy to sustain you, you'll be deficient in B12, iron, and proteins for a healthy diet and you're most likely to live miserably and die young.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more