Superfreakonomics_ global cooling, patri - Steven D. Levitt [90]
And what does he think of geoengineering?
“In a word,” Gore says, “I think it’s nuts.”
If the garden-hose-to-the-sky idea doesn’t fly, IV has another proposal that relies on the same science but is perhaps slightly less repugnant. As it turns out, the amount of stratospheric sulfur necessary to cool the planet is equal to the amount that just a handful of coal-burning power plants already belch out. This second plan calls for simply extending the smokestacks at a few strategically located plants. So instead of spewing their sulfur-laden smoke several hundred feet into the air, these smokestacks would release it some eighteen miles high, into the stratosphere, where it would have the same net cooling effect as the garden-hose scheme.
This plan is appealing because it simply repurposes existing pollution without adding any more. Although an eighteen-mile-high smokestack might sound like a hard thing to build, IV has figured out how—essentially by attaching a long, skinny hot-air balloon to an existing power-plant smokestack, creating a channel that lets the hot sulfur gases rise by their own buoyancy into the stratosphere. This project is dubbed, naturally, “chimney to the sky.”
And if even that plan is too repugnant, IV has something entirely different, a plan that is practically heavenly: a sky full of puffy white clouds.
This is the brainchild of John Latham, a British climate scientist who recently joined the IV stable of inventors. Latham is a gentle, soft-spoken man in his late sixties who is also a rather serious poet. So it caught his ear when, long ago, he stood on a mountaintop in North Wales with his eight-year-old son Mike, gazing down at a sunset, and the boy, pointing out how shiny the clouds were, called them “soggy mirrors.”
Precisely!
“On balance, the role of clouds is to produce a cooling,” says Latham. “If clouds didn’t exist in the atmosphere, the earth would be a lot hotter than it is now.”
Even man-made clouds—the contrails from a jet plane, for instance—have a cooling effect. After the September 11 terrorist attacks, all commercial flights in the United States were grounded for three days. Using data from more than four thousand weather stations across the country, scientists found that the sudden absence of contrails accounted for a subsequent rise in ground temperature of nearly 2 degrees Fahrenheit, or 1.1 degrees Celsius.
There are at least three essential ingredients for the formation of clouds: ascending air, water vapor, and solid particles known as cloud condensation nuclei. When planes fly, particles in the exhaust plume serve as the nuclei. Over landmasses, dust particles do the job. But there are far fewer cloud-friendly nuclei over the world’s oceans, Latham explains, so the clouds contain fewer droplets and are therefore less reflective. As a result, more sunlight reaches the earth’s surface. The ocean, because it is dark, is particularly good at absorbing the sun’s heat.
By Latham’s calculations, an increase of just 10 or 12 percent of the reflectivity of oceanic clouds would cool the earth enough to counteract even a doubling of current greenhouse gas levels. His solution: use the ocean itself to make more clouds.
As it happens, the salt-rich spray from seawater creates excellent nuclei for cloud formation. All you have to do is get the spray into the air several yards above the ocean’s surface. From there, it naturally lofts upward to the altitude where clouds form.
IV has considered a variety of ways to make this happen. At the moment, the favorite idea is a fleet of wind-powered fiberglass boats, designed by Stephen Salter, with underwater turbines that produce enough thrust to kick up a steady stream of spray. Because there is no engine,