Second-guessing the conventional environmental wisdom.

There seems to be a surge lately in counterintuitive stories about green living. First the London Times claimed that taking the train in England may burn more oil than busting out the family car. Soon after, another Times piece declared that merely walking to the grocery store uses up more energy than driving. (This one cited the work of Chris Goodall, "the latest serious thinker to turn popular myths about the environment on their head.") Then The New York Times and Boston Globe followed suit with articles suggesting that eating locally, the holy grail of crunchy types the world over, isn't all it's cracked up to be. Is everything we've been told about saving the planet totally wrong?

Well, not exactly. Much of this green contrarianism is either misleading or in dire need of caveats. Yes, diesel trains in England can sometimes give off more emissions per passenger-mile than cars do, but that's largely because they run well below capacity--the obvious fix is for more people to ride them, not fewer. Likewise, walking to the supermarket only contributes more toward global warming than driving does if you assume, among other things, that the walker gets all of his calories from beef. And while it's true that growing lettuce in a Vermont greenhouse during winter can use more energy than importing heads from Chile, on the whole, eating locally still makes plenty of environmental sense, especially if you stick to seasonal produce. No need to toss out the conventional wisdom just yet.

It's not hard to guess why these stories are cropping up all over: Contrarianism always makes for good headlines (The New Republic can hardly plead innocent on this score). No one wants to read a story titled "WALKING: STILL ECO-FRIENDLY." And, in the case of the London Times, which is owned by Rupert Murdoch, one could try to see something more sinister at play. (Though Murdoch recently had a come-to-Jesus moment on climate change, you never can tell what he's up to.) But set that all aside. More important than the why is what these contrarian stories tell us about environmental policy.

After all, most counterintuitive environmental pieces do offer useful insights--they just need to be read carefully. In the case of trains, the lesson isn't that people should drive more, it's that many diesel trains are dirty and inefficient, unable to keep pace with the better mileage cars are getting (in Europe, at least). And while it's nonsensical to argue that walking emits more carbon than driving does, Goodall's argument does highlight the fact that our industrial agriculture system uses an absurd amount of energy, especially for meat. (One recent Japanese study found that producing one kilogram of beef creates more greenhouse gases than puttering around in your car for three hours while leaving all the lights on at home.) Meanwhile, the eating-locally naysayers have a point: The much-hyped concept of "food miles" doesn't always capture the full carbon impact of a given product at the grocery store.

But this just means that voluntarily trying to reduce one's carbon footprint is hard. And not just hard in the sense that unplugging your television instead of keeping it on standby is a pain. Hard in the sense that it's not always clear where the most eco-friendly course of action lies. Is it better to put your dryer on the energy-saving setting and then run it twice if your clothes still aren't dry, or should you crank up the heat the first go-round? Is George Will onto something when he claims that Priuses harm the environment more than Hummers, on account of their shorter lifespans and all the zinc mining involved in their production? (Almost certainly not, but it's easy to wonder.) Will anyone ever settle the paper-or-plastic debate? (OK, that one's easy: Bring your own.)

In theory, if the United States ever got serious about tackling climate change and put a price on carbon--through either a cap-and-trade system or a simple carbon tax--we could put an end to much of this anguished contrarianism. Shoppers concerned about melting icecaps wouldn't have to scratch their heads and wonder how many food miles a tomato has traveled, or fret about whether a tightly packed ship full of produce from Chile emits more carbon than having everyone haul groceries in their SUVs from the local farm. The climate impact would be reflected in the price, and markets could work their magic. Simple enough.

OK, so it wouldn't be that simple. Carbon pricing and markets alone won't, for instance, produce better public transportation. Nor will they put an end to the vast array of government policies that subsidize suburban sprawl--which include, among other things, easy financing for roads, tax deductions for large McMansions, and various zoning regulations that can prevent mixed-use living and disfavor walkable town centers. Nor, for that matter, will they get rid of the federal subsidies that prop up the nation's agricultural system. (On the other hand, a carbon tax might convince voters that these policies should be altered.)

Carbon pricing can even generate some counterintuitive problems of its own. Take those carbon-offset programs that focus on planting trees. The local IKEA in Virginia now charges five cents for every plastic bag you grab, with the proceeds going to help seed forests around the world. Sounds good, right? Sure, except that scientists have recently learned that planting trees in certain high-latitude regions may actually cause more global warming, because forest covers are darker than the grasslands they often replace, and hence absorb more heat. This "albedo effect" outweighs the fact that the trees suck up carbon dioxide. Oops. Meanwhile, another recent study in Science found that various bio-fuels often cause more carbon pollution than the fossil fuels they replace, on account of all the rainforests that need to be cut down to clear land for, say, sugar crops. Another oops.

So for those who enjoy counterintuitive studies that fly in the face of everything environmentalists have been lecturing us about, no need to fear. Even if the world does get its act together and put a price on carbon, there will still be plenty of room for green contrarianism. There will just, mercifully, be a great deal less of it.

The New Republic