Ask SciMoms: What Does Meat Have To Do With Climate Change?

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This piece has been updated.

A few years ago, the SciMoms received an email asking us about a 2017 video from Vox that states “what you eat matters: 24 percent of greenhouse gas emissions can be attributed to simple dietary choices, or about two times as much as all the cars on the planet combined.” We were asked if this was accurate, and to explain the impact of between meat consumption on climate change. Here’s what we found:

Global food systems are indeed responsible for now over a quarter or 26 percent of all greenhouse gas emissions. The source for that figure is a 2018 study on food and climate change published in Science, a meta-analysis based on lifecycle analyses from 38,000 farms located around the world. Hannah Ritchie took that study and translated it into a series of incredibly helpful infographics for Our World in Data, which can be found here:

Isn’t meat only 4 percent of US climate emissions?

In the US, agriculture is responsible for around 10 percent of emissions, with four percent coming from livestock. But agriculture is global. Meat, dairy, soy and corn are global commodities that are imported and exported to consumers around the world.

As you can see from the graphic of global figures below, beef has a major environmental impact. 


Two other things to keep in mind. First, the EPA’s figures don’t include carbon opportunity costs, which we explain below, and the reason US agriculture contributes a relatively small percentage share is because our overall emissions are massive: “The same emissions per capita would be 24% of an average European’s total emissions and roughly all per capita emissions in sub-Saharan Africa.” 

Two big reasons for beef’s climate emissions: methane and land use

Cattle are responsible for higher greenhouse gas emissions than chicken or hogs or any plant-based protein at all, for that matter, because (1) they are ruminant animals that belch more methane and (2) feeding them requires large amounts of land

Ok, what’s a ruminant?

Ruminants are animals with four stomach compartments, one of which is called the “rumen.” Cows digest their food by fermenting it in the rumen through enteric fermentation. It’s an amazing process that gives cows the ability to eat all sorts of food that humans won’t eat, including food waste and leftover crops. 

The downside is enteric fermentation also causes cows to emit high amounts of methane into the atmosphere, mostly in the form of belches. Globally, enteric fermentation from meat is responsible for around 40 percent of all the methane produced each year. In the US, the percentage is 25 percent.  

The way methane is measured is somewhat tricky to communicate (see this Twitter thread for more discussion). It’s a far more potent greenhouse gas than carbon — either 25 times or 84 times more potent depending on whether you measure “global warming potential” or GWP on a 100 year or 20 year scale. But unlike carbon, it’s a short-lived pollutant, lasting only around ten years in the atmosphere. The problem is that while it’s here, methane traps heat more effectively than carbon, which means methane causes more damage while it’s in the atmosphere

The other important impact to keep in mind is land. Beef has a high climate emissions cost because of the massive amount of land required to raise and feed cattle. And the reason that matters is because of what happens when you deforest wild land and convert it into farmland.

Meat and climate change explained: Deforestation

Here’s the basic idea: forests and grasslands start out as sinks for storing carbon. When you deforest land and convert it into farmland, you lose the opportunity to store carbon there. That loss comes with an environmental cost, a cost that we can measure in carbon emissions. 

Because raising cattle requires a whole lot more land than, say, lentils or poultry, the carbon opportunity cost for beef is much higher than any other protein other than lamb, which is also a ruminant. 

The bottom line: our global population is growing. If everyone continues to eat as much meat as we do now or more, beef production will continue to go up, which would have a devastating climate impact. Increasing global beef production means increasing the number of cows on the planet. More cows on the planet means more deforestation and more methane emissions. 

What should we do about it? 

There is no single fix to climate change, even if we’re just looking at the role food plays. But the good news is there are a number of evidence-based solutions we can implement right now and, yes, reducing red meat consumption is one of them. 

I’m just one person. How does the meat I eat affect climate change?

The suite of evidence-based solutions recommended by research organizations like World Resources Institute and Project Drawdown include both individual and systemic change. 

Here’s what we recommend:

  • Support organizations that advocate for climate action. 
  • Vote for leaders that have committed to pass strong climate policies. 

What individual change looks like won’t be exactly the same for every single person. We recognize it’s a lot easier to make sweeping dietary changes when you have privilege—money, time and support to try out and adopt new habits. 

  • But whatever you can do to cut food waste and beef consumption helps. Researchers know it’s unlikely everyone will stop eating beef entirely. Do what you can to be part of the solution.

Draft Beef Enviro Impacts

What does this mean for cattle ranchers? 

The recommendation to eat less beef isn’t a ban on burgers nor will it put the beef industry out of business. In fact, WRI’s model for food-climate solutions assumes beef eating will go up in some countries while US consumption would decrease, according to their recommendations.

As is frequently pointed out by US cattle ranchers, many ranchers in this country are raising cattle on land that wouldn’t be best for growing crops anyway. The best thing those cattle ranchers can do is to raise their beef in the most sustainable way they can. Some farmers in areas that border the Amazon in Brazil are using agroforestry, a type of farming that combines trees and crops rather than cutting down trees for farming. In some regions with drained peatlands, it might make more sense to rewild these areas because of how well peatlands mitigate climate emissions. There are many different agricultural solutions to consider depending on the local context, far more than we’re going to touch on in this blog post. The takeaway here, however, is that eating a little less meat can be compatible with a number of different approaches to farming. 

Taking action to reduce our dietary impacts: Layla’s Story

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 (Jenny is now vegan). 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. However, there are many delicious recipes that we’ve enjoyed (my husband makes a killer coconut spinach and chickpea).

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