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Carbon Footprints of Pets

While at the supermarket, I mentioned to a worker at the fish counter that frozen salmon has a lower carbon footprint than fresh salmon (which apparently needs to be flown in cold storage to arrive on time). That seemed odd, because the cost of fresh salmon was actually cheaper than frozen salmon. But the man said, “did you know your pet leaves as much a carbon footprint as your SUV?

I was flummoxed because I was planning to obtain a dog very soon. So I went googling around and found the article that made this claim (with some authority, if I might add). Then I found the thorough analysis of this claim by Clark-Williams Derry that finds the claim to be exaggerated and overblown (it assumed that SUVs drove a lot fewer miles than they assumed and that dogs were larger than normal. He writes:

Yet when you look at pet food from a macro-economic perspective—that is, from the top down, rather than the bottom up —dog food is little more than a rounding error.  Total retail food sales in the US topped $1.1 trillion in the US in 2008 (see table 36 from the USDA’s Agricultural Outlook statistics.)  But according to the pet food industry, retail dog food sales totaled just $11 billion in 2008.  By that measure, dog food represents about one percent of the total food economy.

Looking more narrowly at the economics of meat byproducts, I found these USDA estimates of meat “price spreads”, which show that meat byproducts are worth somewhere between 4 and 15 percent of the total value of livestock, depending on the year and the kind of animal.  And obviously, dog food is only one of many uses of those byproducts—there’s also food for other pets, and a variety of industrial uses as well. So based on the economics, there’s just no way to attribute much of the impact of agriculture on our dogs.

In short, whether you go by the macro-economics, or by the actual constituent parts of dog food, there’s simply no principled way to say that the dog food has the same impact as human food.  I’d be very surprised if ANY principled life-cycle assessment found that dog food has more than a small fraction of the overall environmental impact of US agriculture. My guess is that dog food accounts for a maximum of 5 percent of all US crop production, and possibly as little as 1 percent.  That’s a far cry from the one-third that the authors imply.

Of course, dogs have indirect environmental impacts, just as SUVs do:  veterinarians, energy for heating and cooling, the food calories that humans use while walking their dogs, etc.  I won’t even try to tally them up, because there’s no real point.  Just looking at the numbers so far—combining the underestimates of SUV impacts with the overestimates of dog food impacts—the anti-doggites are off by a factor of at least 18, and probably more.

That said, I made a decision to remove beef from my diet (because of its carbon footprint). It’s too bad that there isn’t a low-carbon alternative that doesn’t use beef.

Here’s Tara Parker-Pope on how having a dog increases the amount of physical exercise an older person does.

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