According to this article here, dogs have a larger carbon footprint than an SUV, largely due to their diet. Now, one of the many arguments that people use to argue for vegetarianism, is that it is less taxing to the environment. Michael Pollen says that a vegetarian in a Hummer has a smaller carbon footprint than a meat eater in a Prius. I think the research is pretty conclusive about the heaviness of meat in a diet.
However, since dogs and cats are obligate carnivores, they will consequently have a larger carbon footprint on the earth, than say myself, a vegetarian. Should I get rid of my two cats?
There's some scoffing in the article where Williams-Derry says that a dog would have to eat twice as much as a human does.... But I'm not sure if the math works out, since most people don't eat mostly meat, whereas most dogs do eat mostly meat. Compare a person on atkins to a dog, sure the person will have the bigger footprint. But the average american with all of the carbs included, I think would be equal to a dog's carbon footprint solely in food consumption (assuming a relatively large dog not those things that people try to pass as dogs that resemble more like rodents).
Whats keeping me from getting rid of my cats, besides that they're abnoxiously cute and lovable, is that the carbon argument is only one piece of a larger argument against meat. I'm primarily concerned with the cruelty that is involved in factory farming. I'm also concerned about the carbon cost of meat, as well as my vegetables, but I think in the grand scheme of things, the carbon cost is secondary to many other important concerns (only begrudgingly secondary).
Dogs also help people appreciate the environment more, I think. When people have fun with their dogs, its often at a park, in nature, etc, and at the very least helps us feel empathetic with other animals, which is lacking in the other spheres of animal interaction.
But it does give me serious pause. Maybe I shouldn't get a replacement cat when my cats inevitably die.