DAILY SCIENCE

In carbon terms, grass-feed beef is not the greenest choice

When researchers factored in land use, they found pasture-finished beef was significantly more carbon-intensive than the grain-finished alternative.
January 26, 2024

The idea of a free-ranging cow grazing on lush, grassy hills has elevated the status of pasture-fed beef in consumers’ minds. But now researchers say that this product actually comes with a substantial additional climate cost, compared to meat sourced from grain-fed cows.

Broadly, cattle can be split into two dietary camps: those that are fed grass most of their lives but then are moved into pens where they receive a diet of grain in the final stages before slaughter; and those that are kept on a straight diet of grass from pastures throughout their lives. Respectively, these two groups are known as ‘grain-finished’ and ‘pasture-finished’. 

Pasture-finished cattle make up a striking 33% of global beef production, and research has already shown that these grass-fed animals carry a higher carbon footprint. But, the new PLOS One paper is the first to show how surprisingly large that figure is, and why. 

The key difference in the new work is that its authors looked beyond emissions from feed production, cow burp methane, and other aspects of direct production. They also considered the emissions from the conversion of natural habitat into pastureland, which features more prominently in the life cycle of pasture-finished cows.

The researchers called this the ‘carbon opportunity cost’: the lost potential carbon storage that comes with converting native habitat into pasture to feed grass-hungry cows. 

To make these calculations, they looked at data from a mix of 100 pasture-finished and grain-finished cattle farms, spread across 16 countries, and tallied up the carbon footprints of each. This estimate was the collective sum of direct production emissions, the amount of carbon sequestered in the soil of pastureland (which varied according to how pastures were managed), and the aforementioned carbon opportunity cost. 

 

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What this international comparison revealed was that pasture-finished cattle farms had 20% higher production emissions than grain-finished farms, a figure that matched those from previous research. But the most novel part of the finding was that when both the soil sequestration and the carbon opportunity cost of the converted pastureland use was factored in, that carbon footprint figure rose to a striking 42%. In fact, the impact of land-use is so substantial, that on average it generates more emissions than the direct production of beef. 

“I was surprised to see how large the carbon cost is of beef’s land use,” says Daniel Blaustein-Rejto, director of Food & Agriculture at the Breakthrough Institute, which led the research. “We estimated that the carbon footprint from land use is more than twice as large as that from cow burps, growing feed, manure, and other farm activities.”

He and his colleagues found that the farming systems with the highest emissions were pasture-finished cattle raised on degraded fields with little to no pasture management—for example, where manure wasn’t properly handled. Further calculations also showed a clear connection between higher land-use intensity, and greater carbon emissions.  

The key takeaway in all of this is that pasture-finished beef is significantly more carbon-intensive than the grain-finished alternative, which may actually be the better environmental choice. 

But that challenges the elite status of that pasture-fed meat. “I don’t want to encourage carbon tunnel vision,” Blaustein-Rejto cautions. “People opt for grain- or grass-fed beef based on a variety of personal preferences, values, and beliefs such as a perception that grass-fed cattle have better welfare. Our study doesn’t address these. But it does provide more comprehensive data on the carbon benefits and costs of different types of beef, enabling more informed decision-making.”

So how can we put this information to good use? Blaustein-Rejto hopes to see people thinking more holistically about the real lifecycle costs of producing beef, which has excluded the land-use impacts for too long. 

And on the flipside, perhaps the study’s revelations can inspire better ways of farming, as beef production grows worldwide. “Producing beef more efficiently, with a smaller land footprint, has enormous carbon benefits, larger than typically thought,” he says.

Blaustein-Rejto et. al. “Carbon opportunity cost increases carbon footprint advantage of grain-finished beef.” PLOS One. 2023

Photo by Hennie Stander on Unsplash

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