Superfreakonomics_ global cooling, patri - Steven D. Levitt [78]
There’s a certain thrill to tracking a LoJack-equipped car, as if the hounds have just been released. The police spring into action, follow the radio signal, and nab the car thief before he knows what’s happening. If you’re lucky, he may even have filled up the gas tank for you.
Most stolen cars end up in chop shops, clandestine mini-factories that remove the car’s most valuable parts and scrap the remains. The police have a hard time rooting out these operations—until, that is, LoJack comes around. Now the police simply follow the radio signal and, often, find the chop shop.
The people who run chop shops aren’t stupid, of course. Once they realize what’s happening, they change their procedure. The thief, rather than driving the car straight to the shop, will leave it in a parking lot for a few days. If the car is gone when he returns, he knows it had LoJack. If not, he assumes it’s safe to deliver it to the chop shop.
But the police aren’t stupid either. When they find a stolen car in a parking lot, they may choose not to reclaim it right away. Instead, they watch the vehicle until the thief returns and let him lead them to the chop shop.
Just how difficult has LoJack made life for auto thieves?
For every additional percentage point of cars that have LoJack in a given city, overall thefts fall by as much as 20 percent. Since a thief can’t tell which cars have LoJack, he’s less willing to take a chance on any car. LoJack is relatively expensive, about $700, which means it isn’t all that popular, installed in fewer than 2 percent of new cars. Even so, those cars create a rare and wonderful thing—a positive externality—for all the drivers who are too cheap to buy LoJack, because it protects their cars too.
That’s right: not all externalities are negative. Good public schools create positive externalities because we all benefit from a society of well-educated people. (They also drive up property values.) Fruit farmers and beekeepers create positive externalities for each other: the trees provide free pollen for the bees and the bees pollinate the fruit trees, also at no charge. That’s why beekeepers and fruit farmers often set up shop next to each other.
One of the unlikeliest positive externalities on record came cloaked in a natural disaster.
In 1991, an eroded, wooded mountain on the Philippine island of Luzon began to rumble and spew sulfuric ash. It turned out that beloved old Mount Pinatubo was a dormant volcano. The nearby farmers and townspeople were reluctant to evacuate, but the geologists, seismologists, and volcanologists who rushed in ultimately persuaded most of them to leave.
Good thing, too: on June 15, Pinatubo erupted for nine furious hours. The explosions were so massive that the top of the mountain caved in on itself, forming what is known as a caldera, a huge bowl-shaped crater, its new peak 850 feet lower than the original mountaintop. Worse yet, the region was simultaneously being lashed by a typhoon. According to one account, the sky poured down “heavy rain and ash with pumice lumps the size of golf balls.” Around 250 people died, mainly from collapsed roofs, and more died in the following days from mudslides. Still, thanks to the scientists’ warnings, the death toll was relatively small.
Mount Pinatubo was the most powerful volcanic eruption in nearly one hundred years. Within two hours of the main blast, sulfuric ash had reached twenty-two miles into the sky. By the time it was done, Pinatubo had discharged more than 20 million tons of sulfur dioxide into the stratosphere. What effect did that have on the environment?
As it turned out, the stratospheric haze of sulfur dioxide acted like a layer of sunscreen, reducing the amount of solar radiation reaching the earth. For the next two years, as the haze was settling out, the earth cooled off by an average of nearly 1 degree Fahrenheit, or .5 degrees Celsius. A single volcanic eruption practically reversed,