Previous researchers have argued that cows and sheep are big threats to the climate, but a recent analysis by two New Zealand architects has concluded that Fido and Fluffy, besides being warm and cuddly, are also warming the planet. As the Dominion Post explains:

Victoria University professors Brenda and Robert Vale, architects who specialise in sustainable living, say pet owners should swap cats and dogs for creatures they can eat, such as chickens or rabbits, in their provocative new book Time to Eat the Dog: The real guide to sustainable living.

The couple have assessed the carbon emissions created by popular pets, taking into account the ingredients of pet food and the land needed to create them.

"If you have a German shepherd or similar-sized dog, for example, its impact every year is exactly the same as driving a large car around," Brenda Vale said. "A lot of people worry about having SUVs but they don't worry about having Alsatians and what we are saying is, well, maybe you should be because the environmental impact ... is comparable."

In a study published in New Scientist, they calculated a medium dog eats 164 kilograms of meat and 95kg of cereals every year. It takes 43.3 square metres of land to produce 1kg of chicken a year. This means it takes 0.84 hectares to feed Fido.

They compared this with the footprint of a Toyota Land Cruiser, driven 10,000km a year, which uses 55.1 gigajoules (the energy used to build and fuel it). One hectare of land can produce 135 gigajoules a year, which means the vehicle's eco-footprint is 0.41ha – less than half of the dog's.

They found cats have an eco-footprint of 0.15ha – slightly less than a Volkswagen Golf. Hamsters have a footprint of 0.014ha – keeping two of them is equivalent to owning a plasma TV.

Their solution: Fido fricassee. The Post continues:

Professor Vale says the title of the book is meant to shock, but the couple, who do not have a cat or dog, believe the reintroduction of non-carnivorous pets into urban areas would help slow down global warming.

"The title of the book is a little bit of a shock tactic, I think, but though we are not advocating eating anyone's pet cat or dog there is certainly some truth in the fact that if we have edible pets like chickens for their eggs and meat, and rabbits and pigs, we will be compensating for the impact of other things on our environment."

Considering that there are about 72 million dogs and 82 million cats in the U.S., that would mean that their ecological pawprints are roughly comparable to that of the entire U.S. passenger vehicle fleet.

Carbon credits for pets?