A favorite trick of people who consider themselves friends of the environment is reframing luxury consumption preferences as gifts to humanity. A new car, a solar-powered swimming-pool heater, a 200-mile-an-hour train that makes intercity travel more pleasant and less expensive, better-tasting tomatoes—these are the sacrifices we're prepared to make for the future of the planet.

Our capacity for self-deception can be breathtaking. In 2010, a forward-thinking friend of mine took me for a ride in a Ford Fusion, a gas-electric hybrid that gets more miles per gallon than comparable cars with conventional engines. His dashboard fuel gauge filled with images of intertwining green foliage, a symbolic representation of the environmental benefits we were apparently dispensing from the tailpipe as we aimlessly drove around.

I felt a twinge of idiotic virtue while in that car, as I also do when I leave an especially large pile of cans, bottles and newspapers at the end of my driveway for the recycling truck. Like many concerned Americans, I'm susceptible to the Prius Fallacy: a belief that switching to an ostensibly more benign form of consumption turns consumption itself into a boon for the environment.

If only all big problems could be tackled with product substitution. We're consumers at heart, and our response to difficulties of all kinds usually involves consumption in one form or another. My car's a problem? Tell me what to drive instead. Wrong water heater? I'll switch. Kitchen counters not green? I'll replace them. The challenge arises when consumption itself is at issue. The world faces a long list of environmental challenges, yet most so-called solutions are either irrelevant or make the real problems worse. That's the conundrum facing anyone who yearns for "sustainability."

Energy efficiency—which has been called "the fifth fuel"—is especially problematic. In 2010, I flew from New York to Melbourne, Australia. My plane consumed a lot of energy and had a big carbon footprint; in fact, my proportional share of the jet fuel burned during my round trip was greater than the total amount of energy that the average resident of the Earth uses, for all purposes, in a year.