For years (decades, even) I've derided radical vegetarians and animal rights activists. By way argument ad absurdum, many times I have sarcastically opined that, given a chance, they would mandate a vegetarian diet.

Well, thanks to the Global Warming hype, it looks like they may be getting the chance:

Livestock are responsible for 18 percent of greenhouse-gas emissions as measured in carbon dioxide equivalent, reports the FAO. This includes 9 percent of all CO2 emissions, 37 percent of methane, and 65 percent of nitrous oxide. Altogether, that's more than the emissions caused by transportation.

The latter two gases are particularly troubling - even though they represent far smaller concentrations in atmosphere than CO2, which remains the main global warming culprit. But methane has 23 times the global warming potential (GWP) of CO2 and nitrous oxide has 296 times the warming potential of carbon dioxide.

Animal-rights activists and those advocating vegetarianism have been quick to pick up on the implications of the FAO report.

"Arguably the best way to reduce global warming in our lifetimes is to reduce or eliminate our consumption of animal products," writes Noam Mohr in a report for EarthSave International.

Changing one's diet can lower greenhouse gas emissions quicker than shifts away from fossil fuel burning technologies, Mr. Mohr writes, because the turnover rate for farm animals is shorter than that for cars and power plants.

"Even if cheap, zero-emission fuel sources were available today, they would take many years to build and slowly replace the massive infrastructure our economy depends upon today," he writes. "Similarly, unlike carbon dioxide which can remain in the air for more than a century, methane cycles out of the atmosphere in just eight years, so that lower methane emissions quickly translate to cooling of the earth."

Researchers at the University of Chicago compared the global warming impact of meat eaters with that of vegetarians and found that the average American diet - including all food processing steps - results in the annual production of an extra 1.5 tons of CO2-equivalent (in the form of all greenhouse gases) compared to a no-meat diet. Researchers Gidon Eshel and Pamela Martin concluded that dietary changes could make more difference than trading in a standard sedan for a more efficient hybrid car, which reduces annual CO2 emissions by roughly one ton a year.

It occurs to me that making us all stop eating animals might not end methane emissions, though. I realize that animals emit methane, but aren't humans also part of the methane equation? Considering that there are 6.5 billion humans and no euthanasia plan in place to reduce their numbers, what would be the consequences of forcing them all to be vegetarians?

Why, more methane gas, of course:

Suffice it to say that flatulence is a common complaint among and about vegans, and for that matter vegetarians generally. (For those of you who don't know many vegetarians, they come in various flavors; vegans are the most hard-core, eschewing not only meat but animal products of any kind, including milk and eggs.) The problem is the body's inability to fully digest the complex carbohydrates so abundant in the vegetarian diet and the consequent excessive production of gases such as hydrogen, carbon dioxide, and methane.

Vegetarian nutritionists claim this phenomenon abates once the intestinal flora adapt to the new menu; perhaps your friend is an intransigent case. However, I suspect high gas production is inherent in any diet consisting predominantly of plant products. Cows and sheep, for example, are marvelously adapted to all-veggie fare, yet they generate such prodigious quantities of methane-laden flatulence that some authorities regard them as major contributors to the greenhouse effect and thus to global warming.

Isn't it time someone asked Al Gore about his diet?

According to Kathy Freston (a vegan who writes for the HuffPo), "Vegetarian is the new Prius." But as a commenter to one of her later posts observed,

Al Gore eats meat, and lots of it.

UPDATE: Commenter XWL has a great blog post on how to stem Global Warming, plus usher in a winter we've all been waiting for. As Final Solutions go, it's not bad.

Which means I was mistaken when I said there was "no euthanasia plan in place."

My bad.