THE SKY-is-falling greenies are getting progressively batty. It's not enough that we shut down our oil, gas and coal industries, bike to work, switch lightbulbs, take cloth bags to the supermarket, smash our clunkers, take lukewarm low-water showers, and turn our thermostats down and sit in our mittens and tassel caps.

Now they want us to cook our dogs.

Not hot dogs. Real dogs - the furry ones that live in our homes.

According to authors of a new book, "Time to Eat the Dog: The Real Guide to Sustainable Living," it takes 0.84 hectares of land to feed a medium-sized dog.

A hectare is 2.471 acres, so they're saying it takes more than two acres of the planet's limited surface just to keep one midsized dog fed at any one time.

Bad as cars are alleged to be for global warming, that single dog is about twice the environmental burden of a Toyota Land Cruiser, according to New Zealand writers Brenda and Robert Vale, husband-wife professors at Victoria University, who are specialists in sustainable architecture and co-authors of "Time to Eat the Dog."

Driving a 4.6-liter Toyota Land Cruiser 10,000 kilometers a year (6,214 miles) requires 0.41 hectares, they claim, slightly less than half the 0.84 hectares that's eaten up by each midsized dog. And that supposedly includes all the energy needed to build the car.

Dump the Earth-burdening dog and get a midsized cat and the eco-footprint falls to "slightly less than a Volkswagen Golf," say the Vales. (The downside is that there's no one to fetch the morning newspaper, and you end up with a pet that acts like a paranoiac, instead of your best buddy.)

Downsize further from the cat to two hamsters and the eco-burden becomes "the same as owning a plasma TV" - still negative, according to the eco-profs.

A bug as a pet is probably the only guilt-free answer to satisfy the more hysterical element of the global warming activists.

Just pick up a log and find a nice thousand-legger to bring inside as a companion. Even with all those feet, it's gotta have a smaller eco-footprint than a single M&M.

The Vales recommend that our pets be "usefully recycled" either by us eating them or turning them into pet food when they expire.

"A lot of people worry about having SUVs, but they don't worry about having Alsatians . . . What we are saying is, well, maybe you should be because the environmental impact is comparable," explains Brenda Vale.

Adds co-author Robert: "Once you see where cats and dogs fit in your overall balance of things, you might decide to have the cat but not also to have the two cars and the three bathrooms and be a meat eater yourself."

Get a cat, in short, and go down to one car. Get two St. Bernards and walk to work. Get a Great Pyrenees and some supersized parrots and go directly to jail.

Like the sharing of wealth that steadily appeals to the redistributionist left, Robert Vale advocates the sharing of pets, the collectivization of Fido, like Stalin with the farms, thereby eliminating man's pesky desire for individualism, personal sovereignty and private ownership. "Shared pets are the best - the theater cat or the temple dogs," he says.

A temple dog? Shared? It's all starting to look like a watermelon - green on the outside, red on the inside.

Ralph R. Reiland is an associate professor of economics at Robert Morris University in Pittsburgh.