SUVs owners are often castigated by treehuggers for their Earth-unfriendly lifestyle. A new book argues that pets are just as bad.

New Zealand authors Robert and Brenda Vale's book, "Time to Eat the Dog: The Real Guide to Sustainable Living" is an exhaustive analysis of the environmental impact of common pets such as cats and dogs. The authors studied the carbon emissions created by pets, including the ingredients in their food and the land required to grow it. And the results don't bode well for Fido, who compares poorly to that SUV.

The Values noted that a medium dog consumes 90 grams of meat and 156 grams of cereals daily in its recommended 300-gram portion of dried dog food. They then determined that Fido wolfs down about 164 kilograms of meat and 95 kilograms of cereals per year.

It takes 43.3 square meters of land to generate 1 kilogram of chicken per year — far more for beef and lamb — and 13.4 square meters to generate a kilogram of cereals. So that gives him a footprint of 0.84 hectares. For a big dog such as a German shepherd, the figure is 1.1 hectares.

Meanwhile, a Toyota Land Cruiser driven a modest 10,000 kilometers a year, uses 55.1 gigajoules, which includes the energy required both to fuel and to build it. One hectare of land can produce approximately 135 gigajoules of energy per year, so the Land Cruiser's eco-footprint is about 0.41 hectares — less than half that of a medium-sized dog.

The authors aren't really arguing that we should eat our pets of course, merely that we need to think more about the ecological impact of the things we do on a daily basis, and how we choose to use land.

"Owning a dog really is quite an extravagance, mainly because of the carbon footprint of meat," Vale told New Scientist magazine. So what's the "eco-pawprint" of your pet?

  • German shepherds: 1.1 hectares, compared with 0.41ha for a large SUV

  • Cats: 0.15ha (slightly less than a Volkswagen Golf).

  • Hamsters: 0.014ha (two of them equate to a medium-sized plasma TV).

  • Goldfish: 0.00034ha (an eco-finprint equal to two cellphones).

For more information, read the full article on New Scientist.