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, albeit temporarily, the cumulative global warming of the previous hundred years.
Pinatubo created some other positive externalities too. Forests around the world grew more vigorously because trees prefer their sunlight a bit diffused. And all that sulfur dioxide in the stratosphere created some of the prettiest sunsets that people had ever seen.
Of course it was the global cooling that got scientists' attention. A paper in Science concluded that a Pinatubo- size eruption every few years would "offset much of the anthropogenic warming expected over the next century."
Even James Lovelock conceded the point: "[W]e might be saved," he wrote, "by an unexpected event such as a series of volcanic eruptions severe enough to block out sunlight and so cool the Earth. But only losers would bet their lives on such poor odds."
True, it probably would take a loser, or at least a fool, to believe a volcano could be persuaded to spew its protective effluvia into the sky at the proper intervals. But what if some foolish people thought Pinatubo could perhaps serve as a blueprint to stop global warming? The same sort of fools who, for instance, once believed that diseases like polio could actually be conquered, that worldwide famine was not foreordained?
While they're at it, could they also make their solution cheap and simple?
And if so, where might such fools be found?
Excerpt from "SuperFreakonomics," provided and reprinted by permission by William Morrow/ An Imprint of HarperCollins Publishers.