By Jonathan Fahey
يونيو 19, 2009
Link to article at Forbes.com هنا
Cows are getting much greener, thanks to not-so-green methods. How do we know what’s best?
You’ve got to feel for the cows lately–the poor things must be mortified. The details of some of their most personal behaviors are being analyzed in public, and it isn’t pretty.
The products of bovine digestion, which happen to emerge from both ends of the animal, include lots of methane and methane-releasing material. Methane, also known as natural gas (for good reason), is a greenhouse gas 25 times more potent than carbon dioxide.
But if you gave carbon credits to dairy farmers and cows, there would be some celebrations out in the verdant pastures: a study published by researchers working at Cornell University suggests dairy cows have actually come a long, long way in reducing their overall carbon footprints in the last 50 سنوات.
Yet before you give Bessie a green ribbon and ask her to do even better next time, you might want to take a close look at just what it takes to make green cheese.
Much of the shrinkage in the carbon footprint of cows can be attributed to methods that, when you get your nose into it, don’t seem very green. At the top of the list: the industrialization of dairy farming, improved genetic techniques and growth hormones.
"If you ask people whether they want lower greenhouse gases, they say yes," says Jude Capper, a dairy science professor and co-author of the study, now at Washington State University. "But when you talk about genetically modified foods or hormones, they say they don’t want that. So we have a problem."
وبالتالي, green cow or brown cow? Which do you want?
لسوء الحظ, this kind of dilemma is only becoming more and more common as the world tries to figure out how to feed and fuel more people with the least possible damage to land, air, humans and other organisms. The classic problems are uncomfortably familiar: Is it worse to fill up landfills with disposable diapers or to waste water and energy to wash cloth ones? A more recent and pressing question: If we make more fuel from crops to reduce oil consumption, might we end up worse off by using up too much land, مبيدات حشرية, fertilizer and tractor fuel in the process?
Capper’s cow numbers, published in the June edition of the Journal of Animal Science, are staggering. في 1944, الولايات المتحدة. dairy industry produced 117 billion pounds of milk from 25.6 million cows. في 2007, it produced 186 billion pounds of milk from 9.2 million cows.
Dairy produced in 2007 required just 21% of the cows, 23% of the food, 35% of the water and 10% of the land required to produce dairy in 1944. Cows apparently have better table manners these days, جدا: the volume of burped and passed gas–or if you prefer, methane and nitrous oxide emissions–was about half in 2007 what it was in 1944. Manure output was down 24%. That means the total carbon footprint for dairy production shrunk by about 41%.
Improving those scores will come with a cost. A study Capper published last year concluded that using the growth hormone recombinant bovine somatotropin (rBST) on a million cows would further reduce carbon emissions–so much so that it would be the equivalent of planting 300 million trees or taking 400,000 cars off the road. But consumers worry about drinking milk laced with rBST, even though studies have failed to show milk made with cows given the hormone is harmful–or even different–than conventional milk. The European Union, a leader in the effort to curb climate change, bans the hormone.
Another way to reduce methane from cows is to feed them fish oil. بالطبع بكل تأكيد, fish oil is derived mostly from anchovies and other so-called "forage fish," which are now being threatened by overfishing to satisfy the aquaculture market (See: "Fishing Expedition.") Fish oil also reduces the fat content of milk, meaning you need more cows to produce the same amount of cheese–ergo, more methane.
So pick your poison: Is it healthier for the land and for people to eat food grown in new ways, with new chemicals, drugs and pesticides which could be dangerous to people or the environment? Or is it better to eat food that is grown on a lot more land, that uses up more water, that emits more carbon, in ways that could be dangerous to people or the environment?
Jonathan Weiner, a professor of law and environmental policy at Duke Law School and author of the book Risk v. خطر, Tradeoffs in Protecting Health and the Environment, proposes trying to reduce "overall risk." But to calculate overall risk, there must be some way of creating a common metric–of comparing apples to apples. لسوء الحظ, the possible health risks of hormones vs. the health risks from say, global warming, seem more like comparing apples to arthritis.
"Ideally, in some sort of ‘green eyeshade’ ideal, you’d be able to compare everything on one metric," he says. "But it’s hard to do that, because there are different kinds of outcomes that people don’t always find commensurate."
Benjamin Franklin, in a letter in 1772, offered a technique he dubbed "Prudential Algebra." (See "Advice From A Founding Father.") It amounts to taking plenty of time to think about all the possible trade-offs and weighing them before deciding what is most beneficial and least harmful.
Legislators need to do that too, says Weiner, and then write regulations broad enough to shoot for a desired outcome (such as reducing greenhouse gas) without advocating a specific method (say, using biofuels).
Capper agrees–which is why she isn’t exactly petitioning for more ways to cut cow gas. "We have to look at things not just per cow or per tractor, but from a whole-system basis," تقول. "Not how much methane per cow, but how much methane per pound of cheese."
And that is the only recipe for real green cheese.