everyday economics: How the dismal science applies to your life.  from Slate.com

No Parking Anytime Why parking your car is more environmentally destructive than driving it.

By Steven E. Landsburg
Posted Thursday, April 19, 2007, at 12:48 PM ET

This piece is adapted from Steven E. Landsburg's new book, More Sex Is Safer Sex: The Unconventional Wisdom of Economics, which is being published this month.

Feeling guilty about your car's contribution to global warming? The good and bad news is that you and your car have got something far bigger to feel guilty about. My CO₂ emissions cause about $50 worth of damage each year. But my parking—on public streets where I take up valuable real estate—imposes far greater costs.

Apparently it took until 2006 for someone to notice that the social cost of mandated free and underpriced parking is nothing short of phenomenal, the implied subsidy being comparable to what we spend on Medicare or national defense. The someone who noticed is professor Donald Shoup of UCLA, who wrote a deeply thoughtful book on the matter called The High Cost of Free Parking.

Urban on-street parking is almost always underpriced, which is why you can almost never find a spot. In many cases, it would be better to have no on-street parking at all, freeing up that real estate for expanded homes, shops and cafes or additional driving lanes. Of course then it would be even harder to find a spot, but a lot of people would switch to public transportation, which would be all to the good.

It's crazy to feel guilty about dirtying the atmosphere without feeling even guiltier about clogging city streets. You might argue that global warming is a bigger problem than urban congestion, and you might be right. But that's not the issue. The issue is your contribution to global warming versus your contribution to urban congestion. And if you're a typical urban driver, the latter probably dwarfs the former.

Even if you never drive into the city, you're (at least indirectly) still part of the problem. Suburban shopping malls almost everywhere are required to have vastly oversized parking lots that are never close to full. You might not realize this because you tend to search for spots in the close-in areas that are full. But the outlying areas sit idle, precluding the use of that land for anything of social value. And for every shopper who arrives by car, the mandated size of those lots gets bigger yet.

Resources (in this case, parking spots) are overused when they're underpriced, and the solution is to price them appropriately. As professor Shoup points out, we already pay a high price for parking; it's just that we pay it indirectly "in our roles as consumers, investors, workers, residents and taxpayers." If instead we paid directly in our role as motorists, we'd have an incentive to conserve the underlying scarce resource. Surely anybody who's concerned about the environment can see the nobility of that goal.

There's a general principle here: We get bad outcomes when damaging the environment carries no penalty. That's why the world has too much pollution and too many cars on the street. It's also why, whenever something exciting happens at the ballpark, everyone stands up to see better and nobody succeeds. We all jump up out of exquisite concern for our own interests and none at all for the damage we inflict on our neighbors.

The same principle works in reverse: We get bad outcomes when improving the environment carries no reward. Just as there's too much pollution, there are too few volunteers for community cleanups. Just as there are too many cars, there are too few buses. And the principle is ubiquitous: In my very first Slate column, I observed that the pool of casual sex partners is polluted by the recklessly promiscuous and cleansed by the cautiously meticulous. It follows that the pickup bars are haunted by too many of the former and too few of the latter.

It's a fine thing to care whether you're damaging the environment, but it's also a fine thing to remember that our environment consists of more than just the air we breathe. It consists too of crowded sidewalks, vast empty parking lots, and much else that can't be measured in parts per million. Something for the environmentally conscious to consider.