Ask SciMoms: What’s the environmental impact of beef?


This is the first post in a new segment we’re naming “Ask SciMoms”. Every month, we’ll pick a few questions we’ve received and answer them. If you have a submission, you can send it to us by our social media channels or by emailing In our first post, we answer a question related to the environmental impact of beef.

SciMoms recently received an email asking us about a Facebook video from that states “What you eat matters: 24% of greenhouse gas emissions can be attributed to simple dietary choices, or about 2x as much as all the cars on the planet combined.” We were asked whether this is accurate, and I (Layla) thought I’d look up a few references on the topic.

Is beef really so damaging to the environment?

According to the EPA, in the entire US, all of agriculture is responsible for 9% of US greenhouse gas emissions. In contrast, transportation accounts for 26.4%. Given those numbers, the claim that dietary choices account for 24% of GHG emissions or about 2X as much as all the cars on the planet, seems impossible. Even if we look at global numbers from the EPA, where agriculture, forestry and other land use account for 24% of emissions and transportation for 14%, this claim seems implausible. Furthermore, a recent paper calculated that even if every American went vegan, we would reduce GHG emissions by only 2.6%.

Cattle are significant contributors to  carbon emissions in the agricultural sector, not only due to the resources needed to feed them, but also due to the methane they emit. While it is well documented that reducing our meat consumption, particularly red meat, will decrease greenhouse gas emissions, there is nuance. For example, some ranchers raise their cows on lands that have limited utility, and consequently, the environmental impact is lower since land was not cleared for the ranch (I interviewed one such rancher in this blog post).

Despite the environmental impact of livestock, the adoption of a plant-based diet is likely not the most impactful action that one can take to reduce GHG emissions. Flying less frequently and getting rid of your car may be more impactful given the percentage of emissions due to transportation. This doesn’t mean reducing meat consumption does not help decrease your carbon footprint, merely that the numbers in the Vox video seem to be greatly exaggerated.

Taking action to reduce our dietary impacts

I discussed the topic of meat consumption with my fellow SciMoms early 2017. I was surprised to note that I was the individual with the highest intake of red meat, with 2-3 servings a week. Several SciMoms are vegetarians or nearly vegetarians. I made the decision to decrease the amount of red meat my family consumes for environmental and health reasons. During 2017, we increased our intake of seafood and we made more frequent vegetarian meals. It does require commitment: cooking a vegetarian dish isn’t as simple as just throwing a steak on the grill, and a pound of ground beef is much cheaper than a pound of salmon. And let’s face it: given the image that I selected for this blog post, it’s clear that I love steak. However, there are many delicious recipes that we’ve enjoyed (my husband makes a killer coconut spinach and chickpea).

Decreasing our carbon footprint cannot be about a single action. As an example, a vegetarian can have a larger carbon footprint than a meat-eater if the former takes frequent flights and drives a gas guzzler. We need to make a conscious commitment to decreasing our carbon footprint where we can, but this also means being realistic about the extent of the impact of our individual decisions. Reducing red meat consumption may be a small yet significant way in which individuals can lower their carbon footprint.

REVISED Jan 3 2018: Based on feedback received by readers, we have edited this post to more clearly answer the question posed to us. We have included more data, particularly from the EPA, to address these claims.

Learn More