You'd never guess that the lovable mutt sleeping at your feet is actually an inveterate carbon emitter--but that's what some have concluded.

As New Scientist reports, Robert and Brenda Vale--two New Zealand architects who specialize in sustainable building--calculated the carbon cost involved in feeding your dog. Even if it's dry dogfood, that means meat. And meat is very bad for the environment: Animal feed is often corn-based, and corn is a resource guzzling crop (thanks to nitrogen fertilizer and mechanical tilling). In addition, cows in particular emit copious amounts of methane, which is one of he worst greenhouse gases we product.

When you crunch the numbers, the yearly totals for feeding a dog are worse than driving around an SUV. Crazy right?! Too bad the figures smell like bullshit.

The dogfood exercise is a prime example of why carbon footprints are so difficult to calculate. The Vales appear to have assumed that fresh meat goes into dog food--and that feeding the dog requires more cows/sheep/chickens than we'd ordinarily consume.

It's not that simple. Dogs don't have dedicated livestock; their food mostly consists of byproducts that would otherwise be thrown away. In other words, the carbon involved in making their food gets burned whether or not we feed a dog. Owning a dog doesn't necessarily imply emitting more carbon.

The Vales would probably counter that they've done this calculation with chickens--and chickens are more likely to be produced specifically for dog food. But the chicken that goes into dog food is usually the stuff deemed unfit for human consumption--you're talking beaks and spleens.

Now, there's probably some room for more complexity here: For example, some of those byproducts that go into dog food might be used in other places, rather than dog food. Thus, dog food demand really might have some indirect relationship with the number of cows we're raising. But it's specious to assume that every pound of protein eaten by Fido is a pound we wouldn't have otherwise produced.

And another thing rotten about the New Scientist story: To tally the carbon footprint of an SUV, the Vales assumed that you'd only drive 6,200 miles a year. Seriously? The actual average in the U.S. is more than double that. (And the figures they actually used for gas mileage aren't in the story.)

[Via GOOD]