So, you do know where this is leading, don’t you? Everyone required by international law to wear their Al Gore Signature Fart Collection device. They’ll come in a range of designer colors, of course.

In the future, America will harness cow farts to curb pollution and power the grid. What? It sounds like a joke, but it’s actually a real promise. By 2020, dairy industry emissions will be reduced by 25%, largely by persuading dairy farmers to capture methane gas, U.S. Agriculture Secretary Tom Vilsack announced at the Copenhagen climate change summit this week. Farmers will be able to buy anaerobic digesters that convert cow, errr, emissions into electricity.

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.

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.