In Search of a Magic Bullet

Why can't technology rescue the world from the mess that technology created? Isn't there a quick fix? Scientists know there isn't, but that doesn't stop them from musing about fanciful schemes for mechanically or chemically refurbishing the ozone layer in short order. By discussing and critiquing these ideas, researchers hope to educate the public about the dangers of climate engineering as well as learn for themselves the feasibility of various solutions.

"One of the common suggestions is, 'Why don't we just ship L.A.'s ozone up?' " says chemist Sherwood Rowland. "Well, 30% of the ozone is in the stratosphere, and it drifts down from there to the lower atmosphere rather than the other way around. The energy that would be needed to move the ozone up is about 2 1/2 times all of our current global power use. If you could take every power plant in the world, every piece of coal and every oil tanker, the energy would be insufficient -- and then you'd still have the problem of how to get the ozone up there."

Considering that there are 350 million tons of ozone in the stratosphere, it would take 350,000 trips by specially outfitted 747 freighters, which can carry 100 tons of cargo, to replace even a tenth of the protective gas. Alternatively, climate engineers could shoot multi-ton bullets made up of frozen ozone into the upper reaches of atmosphere. But the technology for designing and building the tens of thousands of big guns that would be required does not yet exist -- not to mention the fact that compressed ozone is dangerously explosive. Furthermore, neither of these solutions attacks the heart of the problem, those long-lived CFCs, which would break down any replacement ozone as well.

As a result, some researchers are focusing their attention on the culprit molecules rather than the victims. Atmospheric scientists Richard Turco of UCLA and Ralph Cicerone of U.C. Irvine are exploring the idea of injecting into the stratosphere two chemicals -- propane and ethane -- that would combine with CFCs to produce an extremely weak, and therefore environmentally safe, solution of hydrochloric acid. That strategy would interrupt the CFCs' 100-year destruction cycle, and has the further advantage of requiring only 1,000 jumbo-jet flights over a single, critical 30-day period every year for the next several decades. The products involved are readily available. However, in order for the process to work efficiently, these chemicals must reach from 15 km to 25 km (9 miles to 15 miles) above the earth, and airplanes cannot fly through that entire range. Moreover, the researchers calculate, there is a chance the plan could backfire and accelerate ozone depletion.

At Princeton University, physicist Thomas Stix has suggested using lasers to blast the CFCs out of the air before they can reach the stratosphere and attack the ozone. His idea is to tune the lasers to a series of wavelengths so that only the offensive molecules would be destroyed. Admittedly, the energy requirement would still be exorbitant, but Stix believes that a 20-fold improvement in the overall efficiency of this approach could make it feasible. Even so, tens of thousands of lasers would have to be designed, tested and built before the first CFC molecule could get zapped. If this is the best idea for reviving the ozone layer, an ounce of prevention is worth more than many tons of cure.