At the intersection of cattle and climate change, two rival visions for the future have emerged: One with more cows, one with fewer.
The test-tube burger that debuted last week inspired visions of a future in which meat is readily available without livestock's nasty byproducts—manure and methane. Mark Post, the Dutch physiologist behind the petri patty, said reduced methane emissions—and thus less cooking of the climate—was one desirable aspect of his pursuit.
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But earlier this year, one Zimbabwean scientist-farmer made a big stir—his TED Talk YouTube video just passed the half-million mark—with quite the opposite vision: Allan Savory suggests a world in which more herds of animals graze, fertilize and rejuvenate land turned barren by desertification. Such revitalized land can absorb a lot of carbon dioxide, the primary greenhouse gas.
So can cows nurture and sustain the land in symbiotic harmony while also providing an important source of protein, or have they become a modern plague whose waste pollutes and whose flatulence heats up the globe?
Both, It turns out. "It's a matter of how they're managed," said Ray Weil, a leading agriculture research scientist with the University of Maryland and Columbia University's Earth Institute. "But the way we manage cattle today makes very little ecological sense," he said, citing corn diets and concrete feedlots.
He said Savory's proposal to mimic herds of bison—tightly packed to protect from predators, ranging across the land—makes a lot of sense. The process, he said, is fairly simple: Crowd cattle onto one piece of land so they thoroughly graze, fertilize and trample it, move them quickly off to the next targeted field, then leave the cow-plowed land alone for awhile.
"It's brief periods of grazing and long periods of rest" that make for thriving soil and grass that can absorb large amounts of carbon, Weil said, especially in the semi-arid regions where Savory's ideas are most applicable. That's a large portion of the planet's land surface, and much of it is unsuitable for growing many crops but is a staunch host to grass. Cows' capacity to turn that cellulose into nutritious protein is what has made them so important to humans, he said.
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However, Savory also has his detractors. Historian James McWilliams, author of the 2010 book "Just Food: Where Locavores Get It Wrong and How We Can Truly Eat Responsibly," criticized Savory in Slate for a lack of scientific rigor in his research and for failing to distinguish between genuinely degraded landscapes and ecologically thriving deserts that are better left alone.
McWilliams concludes, "There's no such thing as a beef-eating environmentalist." That echoes one of PETA's refrains: "There's no such thing as humane meat." Interestingly, the animal rights advocacy group came out in favor of the development of lab-grown "victimless meat."
Chet Chaffee, an ecologist with Irvine, Calif.-based consultancy FirstCarbon Solutions, agrees with Weil that improved land management can "significantly reduce the amount of carbon going into the atmosphere," but he's also "intrigued" by the lab meat and the idea of reducing the number of methane-emitting cows.
Chaffee maintains that it's far too early to dismiss either managed grazing or "shmeat"—a coinage derived from "sheet of lab-grown meat." "Both approaches have merit," he said. "The trouble is nobody's done an apples-to-apples comparison."
Chaffee imagines that both strategies could develop in unison and even compete, though the development of cost-effective meat factories—or "carneries"—could takes decades while "holisitic planned grazing," as Savory calls his method, can begin at once; indeed, it is already under way in a few places.
Weil and Chaffee agreed that Savory's techniques offer no instant solutions for climate change, but could play an important role in combination with others strategies such as reform of the energy paradigm. They also cautioned against assuming that meat from a lab is more climate-friendly than that from a cow: "What are the energy inputs in this laboratory?" asked Weil. "Is it powered by coal?" asked Chaffee.
Weil further warned that cows are essential to keeping grasslands healthy, citing experiments carried out by the field research station Konza Prairie in Kansas. Without cattle's grazing, it turns to brush, he said.
A separate question for in vitro meat is whether it would be accepted by the public. Historian Maureen Ogle, whose book "In Meat We Trust: An Unexpected History of Carnivore America" hits bookstores this fall, pointed out that the idea of fabricated flesh is hardly a new one. She found writings as far back as 1894 suggesting it.
What's different is that back then people saw the prospect of such innovations in a positive light.
"But now we live in an age when there's a tremendous fear of science," she said. "There's no difference between that lab burger and a Twinkie—both were created in laboratories." But because of irrational rejection of scientifically developed food, she said, cultured chuck may face tough resistance, just as GMOs do in some quarters.
For her part, Ogle said, "I would've loved to have tried it!"
—By CNBC's Matt Twomey. Follow him on Twitter @Matt_Twomey