TIME: Almanac 1993/TIME Almanac 1993.iso/time/021792/0217330.000

Text File | 1992-10-19 | 3.5 KB | 71 lines

                                                                                ENVIRONMENT, Page 68

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.