Scientists Dream Up Bold Remedies for Ailing Atmosphere
By WILLIAM J. BROAD
Published: August 16, 1988
AS scientists and public officials urge painful, expensive measures to prevent climate change -reducing energy use, developing alternative sources of power, curbing production of destructive pollutants - a breed of visionaries is dreaming of more direct, if seemingly fantastic, countermeasures.
These experts are exploring extraordinary ways to combat pollution in the earth's atmosphere and its threat of climatic upheaval. They envision environmental wars fought with lasers that blast apart harmful chemicals, satellites that beam safe energy to earth, microoorganisms that soak up pollutants and chemical-releasing airships that replace critical elements being removed from the earth's atmosphere.
One aim is to counter the gases that produce the greenhouse effect, which is thought to be gradually warming the earth, threatening to raise oceans and damage agricultural production. Another is to halt the breakdown of the ozone layer, which blocks the sun's ultraviolet rays.
Work on futuristic cures for these pollution problems started in the 1970's and has accelerated in the 1980's as concern has grown about potential damage to the atmosphere. Experts involved in the research stress that the ideas are often untested and in some cases could be risky. Most experts agree that for now, preventing the release of harmful gases into the sky deserves far higher priority than efforts to fix a damaged atmosphere.
Yet the surge of creative thinking, they add, could ultimately play an important role in the battle to stabilize the earth's changing weather, especially if conditions take a dramatic turn for the worse.
''Some of this is mighty speculative,'' said Thomas H. Stix, a Princeton University physicist. ''But if we have a couple of summers like we just had, people are going to get pretty panicky over what we should do about it.''
Key questions are whether the techniques are safe and feasible, and, if so, whether the potentially huge cost of carrying them out would be economically justified. In addition, some experts warn that large-scale intervention in the earth's delicate and poorly understood cycles of climatic chemistry could trigger unwanted side effects.
Backers of the research say its value often lies not so much in sparking concrete plans as in inspiring thought about how, ultimately, to deal with climate problems.
''This area has been given little thought,'' said Wallace S. Broecker, professor of geochemistry at Columbia University. ''At a minimum, a rational society needs some sort of insurance policy on how to maintain a habitable planet.''
One futuristic idea is to use giant lasers atop mountains to scrub harmful chemicals from the earth's atmosphere, a concept pioneered by Dr. Stix at Princeton. He calls it ''atmospheric processing.'' His lasers would be aimed at industrial chemicals known as chlorofluorocarbons, or CFC's, which are used mainly in refrigerants and in the manufacture of plastic foams. Once released in the air, they rise high into the stratosphere where they destroy protective ozone. Stratospheric ozone helps block ultraviolet light, which can cause skin cancer and eye damage and harm natural systems. Array of Infrared Lasers
The laser system would break apart CFC's in the lower atmosphere before they had a chance to damage the ozone layer. The concentrated light would be tuned to a frequency most easily absorbed by CFC's, which is in the infrared part of the electromagnetic spectrum. Dr. Stix calculates that an array of infrared lasers around the world could blast apart as one million tons of CFC a year, equal to the current annual flow into the atmosphere.
In terms of feasibility, Dr. Stix said: ''Some of the answers are known. Many aren't. A major question is whether you can get the laser's energy absorbed by CFC's and not other molecules, such as water vapor or carbon dioxide.''
Another issue, he added, is to what extent the general atmosphere would absorb laser energy, limiting propagation of the beam. Plans to Replace Ozone
A less exotic cure for ozone depletion would be to simply replace it. Experts have proposed that bulk ozone be produced on earth and lofted into the stratosphere in rockets, aircraft or balloons. Other ideas include firing aloft ''bullets'' of frozen ozone, or placing solar-powered ozone generators in high-altitude balloons. Since ozone consists of three oxygen atoms, and atmospheric oxygen has two such atoms, raw material would be plentiful.
Leon Y. Sadler, a chemical engineer at the University of Alabama, writing recently in Chemical and Engineering News, proposed using a fleet of jets to dispense ozone. His calculations showed that the number of planes needed to replenish of the ozone would be equivalent to less than 2 percent of the aircraft that haul freight in the United States.
But other scientists have calculated that the job would be many times larger. ''Ozone replacement would be a really massive, massive thing to do,'' said Michael C. MacCracken, head of atmospheric sciences at the Lawrence Livermore National Laboratory in California For now, all scientists stress the importance of reducing emission of ozone-destroying chemicals, as called for in a recent treaty.