Is it true that cow, sheep, and termite flatulence does more damage to the ozone layer than fluorocarbons? How much damage do human farts do? --Mojo, Washington, D.C.
I'm glad you wrote, mon ami, because it gives me a chance to rail once again on my favorite topic, namely the unbelievable feebleness of the daily press. You were no doubt inspired to write by a story that appeared last December in the Washington Post headlined "Feed, Animal Flatulence and Atmosphere." It described the work of one Donald Johnson, an animal-nutrition specialist at Colorado State University, who supposedly has been studying cow flatulence. According to the story, animal flatulence "contributes in a large way to the potentially catastrophic warming of the globe, the 'greenhouse effect.'" Each cow emits 200 to 400 quarts of methane gas per day, or 50 million metric tons per year.
News of the cow-fart menace spread like wildfire--amazing how even the most innocuous cliches become dangerous in a story like this--throughout the media. For example, columnist Dave Barry, noting that methane is highly flammable, speculated that cows might become a favored weapon of international terrorists, since they can be sneaked past airport metal snoopers without fear of detection. Imagine the scenario, Barry mused: you're sitting there on the plane when suddenly somebody shouts, "Look out, he's got a cow!"
Only trouble is, cows don't emit 400 quarts of gas--at least in the common sense of "malodorous emanations from the posterior." According to Professor Johnson, they emit 400 quarts' worth of burps, known in polite circles as eructation. The Post, in other words, doesn't know one end of a cow from the other. And these guys broke the Watergate scandal?
That little detail aside, animal methane does present a definite threat to the biota. It's believed 18 percent of the greenhouse effect is caused by methane, which probably ranks third on the list of offending gases behind carbon dioxide and chlorofluorocarbons. Methane breaks down in the atmosphere to form carbon dioxide, ozone, and water, all of which absorb heat. The temperature of the atmosphere rises, and next thing you know the ice caps melt.
There are several major sources of methane: rice paddies (methane-producing bacteria thrive in the underwater environment), swamps and wetlands (ditto), mining and oil drilling, landfills, termites (although there's still some controversy on this one), "biomass burning" (notably in the Amazon rain forest), and animals. Ninety percent of animal methane is produced by ruminants (i.e., cud-chewers). These include sheep, goats, camels, water buffalo, and so on, but most of all cattle, of which the world has an estimated 1.2 billion. Ruminants eat hay and grass and stuff containing cellulose, which can be digested only by special microbes that, conveniently enough, live in the ruminants' guts. Unfortunately, the microbes tend to make a mess, and about 6 or 7 percent of what they eat winds up as methane. Thus the problem.
Now, you're probably saying, what the foo, cows have been around forever, how come all of a sudden they're a threat? All we know is this: atmospheric methane has been increasing at the alarming rate of 1 percent a year, and something's got to be causing it. The world cattle population is thought to have increased in the last decade, and Lord knows the Brazilians don't feel like taking any more crap for burning the Amazon, so hey, let's blame the cows.
Is there hope? Barely. Professor Johnson thinks a timely application of antibiotics in cattle feed could retard the microbes' methane production. But by and large antibiotics are already in use in the U.S., while in many third-world countries cattle forage out in the fields, making antibiotics difficult to administer. In other words, we've got still another largely insoluble problem that threatens to end life as we know it. Sometimes I wish one of those the-end-is-near predictions would come true, just to end the suspense.
Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.