In 2006 the UN’s Food and Agriculture Organization (FAO) reported that livestock account for 18% of the world’s greenhouse gas emissions (more than cars, planes and other forms of transportation combined). And most of those emissions are blamed on the world’s 1.5 billion cows. Cows are funny, but the idea of a farting cow is even funnier. The media had a field day (no pun intended) with the concept that farting cows are causing global warming and Youtubers took it upon themselves to educate the public about the danger of cow farts. The government of Estonia even slapped a ‘flatulence tax’ on farmers to pay for the estimated 25% of Estonia’s greenhouse gas emissions that Estonian cattle produce.

Technically, the greenhouse gases are coming out the other end—cow burping (not farting) is the problem. Scientists estimate that a single cow belches out 25 to 50 gallons of methane a day. And, according to the cover story in the June 2008 issue of Wired, an organic cow releases 16% more greenhouse gas emissions than a non-organic cow. To be organic, cows must eat organic food (grass and grain that has been grown without the use of pesticides), they must have access to pasture and they must not be treated with any hormones or antibiotics. Without the aid of extra hormones, organic cows produce less milk (about 8% less milk than industrial cows) so it takes more cows to make the same amount of milk—and of course, more cows means more emissions.

So what if organic cows burp more than their non-organic counterparts. Does that mean that organic cows are bad for the environment? Not quite.

Organic cows may be a huge contributor to greenhouse emissions (and thus to global climate change) but organic cows (and other organic livestock) as well as organic fruits and vegetables are much gentler on the environment than their conventional counterparts.

Conventional farming relies on the use of synthetic fertilizers (mostly nitrates) and pesticides. Heavy rains wash these chemicals into nearby waterways. They flow downstream from one waterway to the next, down the Mississippi, and all the way to the Gulf of Mexico. Along the way, the nitrates contaminate drinking water supplies. The city of Des Moines, Iowa issues “blue baby alerts” in the spring to warn parents of the potential for nitrates in the tap water—nitrates convert to nitrites which can suffocate a baby by reducing the ability of an infant’s blood to carry oxygen to the brain.

The influx of an estimated 210 million pounds of excess nitrates into the Gulf of Mexico turns a New Jersey-sized section of the northern Gulf into a Dead Zone every spring. The Dead Zone is an area with insanely low levels of oxygen. Marine animals need oxygen to survive, so they need to get out, and fast. Fish take off for more oxygen-rich waters, but some fish, along with less mobile bottom-dwellers like crabs, clams, sea stars, shrimp and worms, suffocate in the Dead Zone.

When the Mississippi dumps excess fertilizer into the Gulf, the fertilizer does what it’s supposed to do: it fertilizes. And tiny plants and algae (called phytoplankton) flourish. And when these massive blooms of phytoplankton die, they sink to the bottom and decompose. The bacteria that decompose the plankton bloom rob the surrounding water of oxygen, thereby creating the Dead Zone.

Over the last 40 years, conventional agriculture has intensified and the amount of nitrogen flowing down the Mississippi into the Gulf has tripled. Phytoplankton have become even more abundant, which means bigger blooms, more decomposition and even less oxygen.

Now, let’s ponder life’s important questions: which is more dangerous–a few burping cows or 210 million pounds of man-made agricultural run-off?