You've heard the over-simplified message from vegetable-positive environmental groups: eating animal products is a big cause of global warming. Indeed, 7% of the greenhouse gas emissions produced from U.S. sources are from agriculture. The dairy industry is ripe for change, with only 2% of the farmers whose operations are suited for methane capture currently making use of it.
A Drop In the (Milk) Bucket
Just how bad a problem are dairy emissions? Well, it's a greatly increasing problem -- up 40% in the past decade. But compared, say, to the driving a car or even a tractor, dairy pollution is pretty insignificant. Of the 6.7% of overall U.S. greenhouse gas emissions in 2007 attributed to agriculture, 10.7% were from the methane of "manure management," mostly from pork and dairy farms.
According to the U.S. Environmental Protection Agency, the growth comes from a general trend in manure management to use liquid systems, which tends to produce greater methane emissions. "The increase in liquid systems is the combined result of a shift to larger facilities, and to facilities in the West and Southwest, all of which tend to use liquid systems," the EPA says.
Reducing dairy industry emissions by 25% over the next decade would reduce overall emissions by something less than one-quarter of 0.71%, or about one-tenth of 1%, in 10 years. That wouldn't do much as it would only get us back to what would be about 10% more greenhouse gas emissions from manure management than we generated in 2000.
Vilsack calls his agreement with the dairy industry a move that "will help us achieve the ambitious goal of drastically reducing greenhouse gas emissions while benefiting dairy farmers." He goes on to say that the harnessed emissions from one farm could power 200 homes.
Treating Symptoms, Not The Disease
I have many words for this reduction, but "drastic" is not one of them. I must leave aside the pie chart of U.S. greenhouse gas emissions that is now incinerated on my brain in which burning fossil fuels for electricity (coal) and transportation (cars) is responsible for 59.9% of 2007's total pollution.
But the moves being made to capture methane are neither an effective way to avert climate change nor a sensible way to address the problem of methane production. It's addressing the symptoms, not the disease.
Changing the way farms work would be a far more sensible manner to reduce methane production. In the bargain, this would eliminate the many other destructive side effects of the so-called liquid systems of manure management. At issue is not the poop itself, but the volume, concentration and makeup of the poop.
Over the past half-century, more animals have been forced onto smaller grazing areas. Cow food has been switched to corn and soy from the traditional range feed (grass, alfalfa, clover and the like). And meat cows have grown in size. All this has contributed to the precipitous rise in greenhouse gas emissions from dairy farms and pork and beef producers.
Worry About Farms, Not Cow Poop
The answer to this problem is simple, really, and is there between the lines in the reports from the USDA over the years. One, from 1995, promises to reduce greenhouse emissions by 50% by 2000. That didn't happen, obviously.
But if animals are getting bigger, farms are more concentrated and specialized and the nutrient content of the manure is changing, well, by Jove, farms should become smaller. They should also become more diverse and adopt a wider variety of species of animals that grow more slowly and end up smaller.
Turning dairy cow poop into electricity -- and the pitifully small greenhouse gas reductions that result -- may make a nice (also funny) headline. But it's a cartoon-character Band-Aid approach to the festering, infected wound beneath. Vilsack should stay focused on his patient's long-term health; not this week's media appearance.
b) "manure management" isn't the biggest source of methane from livestock, enteric fermentation (the actual farts themselves, not the manure byproduct) is, 3 times as much.