Popular “wisdom” claims cattle produce more greenhouse gas emissions than cars, courtesy of the United Nations’ long-discredited “Livestock’s Long Shadow” report. But rigorous data consistently shows cattle produce a tiny fraction of the U.S.’ emissions.
A new analysis—perhaps the most comprehensive to date on the topic—puts that number at 3.3 percent. By comparison, transportation and electrical generation in the U.S. makes up 56 percent of the U.S.’ total greenhouse gas (GHG) emissions, according to the USDA’s Agricultural Research Service.
“We found that the greenhouse gas emissions in our analysis were not all that different from what other credible studies had shown and were not a significant contributor to long-term global warming,” summarized Dr. Alan Rotz, agricultural engineer at USDA’s Agricultural Research Service (ARS), who led the analysis.
Methods and models
“What makes this unique is it is the most comprehensive in that it was a regionalized analysis,” Dr. Sara Place explained to WLJ.
Place, senior director, Sustainable Beef Production Research for National Cattlemen’s Beef Association, was part of the analysis and an author on the resulting scientific article, “Environmental footprints of beef cattle production in the United States,” released Monday, March 11.
“We know that beef production differs pretty tremendously east to west, north to south. It’s not about comparing those regions, but about capturing reality in a more comprehensive way. The fact that we collected actual information from real, live producers to base our models off of makes it really unique and likely more accurate at reflecting reality than past assessments.”
The analysis collected data from 2,270 cattle operations across the country via surveys and farm visits. The participating operations ran the gamut of beef cattle operation types, including cow-calf, backgrounder, feedlot, and cow-calf-to-finish. It also included operations focused on dairy-sourced fed cattle and cull dairy cows, as well as beef-breed animals.
Surveyed operations came in all sizes—from one to 28,500 animals—and from all across the country, broken into seven geographic regions. The seven regions were the Northwest, Southwest, Northern Plains, Southern Plains, Midwest, Northeast, and Southeast.
This real-world data—combined with publicly-available production data for beef, resource use, and emissions—was used with the Integrated Farm System Model (IFSM) modeling system to estimate the environmental impact of regionally representative beef operations.
Though many members of the public are wary of information derived from models, Place explained that modeling is necessary.
“Pretty much all of our emission estimates for beef and agriculture—or, quite frankly, for most things when it comes to greenhouse gas emission inventories—are based on modeling because we can’t put a big bubble over all cattle operations and actually measure everything. That would be the best situation, but we can’t do it. So essentially, models are a useful way to understand the complexity of the world around us.”
She also said the IFSM system—which she described a long-running work of Rotz’ career—is unique as a predictive simulation tool for beef operations.
“It actually simulates most of the processes on the farm. So, for example, with the growing of alfalfa, it actually simulates the growth of the plant itself and how much nitrogen is taken up,” Place said.
“What’s super critical with any model is evaluating it with real world data. Even though we can’t put a bubble over every beef cattle operation, what Dr. Rotz has done with his model is refine it and change it when and if necessary to better capture reality.”
Other outcomes, opportunity
In the sustainability discussion, GHG emissions get all the attention. However, there’s much more to sustainability besides carbon.
The analysis was a farm-gate lifecycle assessment that looked at the GHG emissions (including CO2 and methane), fossil-based energy use, blue water (surface or groundwater resources) use, the release of reactive nitrogen (including nitrous oxide and ammonia), and the use of human-edible feed in cattle production. All of these are part of the growing public conversation on sustainability.
The analysis’ report highlighted two areas for potential sustainability improvement for the U.S. cattle industry: water use and reactive nitrogen losses. Much of the water use involved with cattle production is actually used for feed production, however, and most of the reactive nitrogen loss comes from ammonia emissions. Ammonia can come from fertilizing cropland, cattle urination and manure, and natural decomposition.
In both cases, there is little that can be directly controlled by cattle producers. Regarding ammonia emissions specifically, the report said, “economically feasible practices are not currently available.”
Though not directly discussed in the analysis, the data collection did involve feed usage. The use of foodstuffs that humans could eat as feed for livestock has received growing attention from sustainability-minded consumers. The ARS announcement of the analysis noted that cattle consumed “2.6 pounds of grain per pound of beef cut weight, which is comparable to pork and poultry.”
Place told WLJ that the real-world specificity that this analysis adds to the sustainability conversation is a valuable one.
“Studies like this will help us benchmark progress but also highlight where the real issues are, and where there are the issues that get a lot of attention but perhaps are … not as big of an issue from a sustainability perspective.” — Kerry Halladay, WLJ editor
