Today, Niman believes, and argues, that cattle are good to have around for many reasons. They can improve biodiversity on a landscape and increase the biomass of an ecosystem. These improvements, she writes, can lead to the removal of carbon dioxide from the atmosphere. Raising cattle can also be good for many human societies, in part, she argues, because beef is a healthy form of protein. And while still a vegetarian herself, Niman told me it’s because meat doesn’t taste good to her anymore. Her children love their beef, and she gladly feeds it to them.
Obviously, there are some red flags when a rancher chimes in on a debate over whether ranching is good or evil. But the book is full of citations in scientific journals in support of her claims, and she makes some compelling arguments.
To those concerned about global warming, the methane issue is one the most concerning threat posed by beef. Niman’s read on the evidence is that improved landscapes created by properly raised cattle will absorb enough carbon dioxide to offset the methane they emit. She also discusses research into different ways that cattle methane emissions can be reduced — such as by adding nutrients to salt licks. But many in the scientific and environmental advocacy communities don’t buy the argument that cattle could be climate friendly.
Emily Cassidy, a research analyst at the Environmental Working Group, acknowledged via email that cattle can have beneficial impacts on the soil. But, she writes, “There are a lot of scientific leaps to be assumed from [improved] soil fertility to offsetting the methane emissions from cattle.”
The main problem with grass-fed beef, she wrote, is the cows, “…take at least twice as long to reach slaughter weight [than grain-fed beef], and during this time beef cattle continue to emit methane, a greenhouse gas ~30 times as potent as carbon dioxide.”
That’s why Cassidy and many other environmentalists believe, somewhat counterintuitively, that feeding grain to cattle can be better for the climate than grazing them.
Niman isn’t against any and all supplemental feeding of grain, providing most of a cow’s life is on pasture, where they can do the most good.
Many of the Earth’s ecosystems were once covered by enormous populations of large grazing animals, Niman explained by phone.
The question, she says, is do you need those animals for proper function of ecosystems?
Her read on the evidence is that we do, that the health of some ecosystems can improve under properly managed cattle. But even if this is true, the meat of the methane debate comes down to how much carbon sequestration these ecological improvements might facilitate, and how this compares to the amount of methane emitted by those cattle.
“If you’re making a claim that something benefits the climate, the onus is on you to demonstrate that it does,” Cassidy said.
But if this debate has demonstrated anything to me, it’s that the methane question hasn’t been settled either way.
According to a 2011 study published by the Union of Concerned Scientists, “Raising the Steaks,” the amounts of carbon sequestration by pasture, and methane emissions by cows, are not set in stone. The report concludes that managing forage crops to improve their nutritional quality could reduce methane emissions by as much as 30 percent, and that improvements in forage species could help cattle reach marketable weight sooner, resulting in shorter cow life spans, and less methane.
Corn is a very efficient feed, the study’s author Doug Gurian-Sherman explained to me. This is why many studies show that CAFO (Concentrated Animal Feeding Operation) beef produces less methane. But some forage plants are more efficient than corn, he said, and there is a huge amount of untapped potential in this field.
“Corn efficiency has gone up tremendously after receiving decades of serious investment. We’ve done almost no research in improving forage crops,” Gurian-Sherman told me. “I’ve no doubt that we could improve forage crops if we put some effort into it.”
Thus, he believes it’s plausible pastured beef could outperform feedlot beef in the climate department, while in terms of other impacts, such as on animal welfare, water quality, various human society impacts, and nutritional content of the meet, grass fed beef is a slam-dunk winner over feedlot beef.
Whether or not grass fed beef can actually be climate-friendly isn’t settled. But beef consumption is going up, no matter what a bunch of environmentalists have to say about it. This reality makes Niman’s prescriptions for how to maximize the upsides of cattle on the land, while reducing their harm, worth exploring, whatever the exact carbon cost of cattle may be.