But now these schemes may be ready for their day in the sun. In a soon-to-be-released report, the National Research Council (NRC)–the operating arm of the prestigious National Academy of Sciences–endorses further study of geoengineering, granting the field a legitimacy it has so far lacked. Although the panel does not support even pilot programs, it calls geoengineering “technically feasible in terms of cooling effects and costs” and says it has “the potential to affect greenhouse warming on a substantial scale.”
The appeal of a techno-fix is simple: it promises to cure problems without requiring society to change the habits that caused them in the first place. The chief way to stave off the greenhouse effect is by reducing emissions of the gases that trap heat in the atmosphere: carbon dioxide (CO2), released when coal, oil and natural gas burn, and CFCs, the refrigerants, solvents and foam-blowing agents that also chomp the ozone layer. Greenhouse gases can be cut substantially without making people freeze in the dark or drink warm beer: a report last month by another NRC panel calculated that the United States could reduce emissions 10 to 40 percent at little to no cost. Some policies to reduce emissions, such as making building, machines and cars ,ore energy efficient, might even bring a net dollar benefit. Yet quite a few people, including many officials in the Bush administration, don’t believe that. They equate conservation not with efficiency but with sacrifice and limits to growth. If we could just bounce sunlight back to space, goes the argument, we could burn fossil fuels as profligately as ever without suffering the rising sea levels, droughts, heat waves and killer storms that a warmer world threatens.
So far, geoengineering to defuse the greenhouse amounts to little more than back-of-the-envelope calculations. The costs are mere guesstimates, the details fuzzy, but all of them give new meaning to the idea of bagging some rays:
Turn Boeing 747s into a special air force for the environment. A fleet could crisscross the skies releasing dust into the low stratosphere, blocking sunlight. Even simpler, the planes could fly with dirty engines that leave a contrail of soot, which also reflects sunlight. These options could wipe out the effects of 8 billion to 80 billion tons of CO2, estimates the NRC. (The United States emits 5 billion tons of CO2 a year.) Cost: up to $9 per ton of CO2 offset.
Use naval guns to shoot dust high into the stratosphere. Arthur Rosenfeld, a physicist at Lawrence Berkeley Laboratory, calculates that dust of the size spewed out by erupting volcanoes could offset the annual rise in CO2 emissions until the world adopts enough energy efficiencies or alternative energy sources to rein in emissions. One-ton naval shells, shot straight up, would release the payload of dust. (Alternatively, a Green army could periodically release special balloons filled with dust; they would rise into the stratosphere, pop and release their cargo.) the dust would remain aloft about two years; each shell would offset 100,000 tons of CO2 for that long. A dime’s worth of dust will counter the effects of burning 1.4 tons of coal, so the scheme could be financed with a $2 levy per ton of coal, now selling for $25. Call this the cheap-but-dirty fix.
Send billions of aluminized, hydrogen-filled balloons into the stratosphere, where they would reflect as much sunlight as needed. Cost: up to $99 per ton of CO2 offset–or as much as half a trillion dollars to deal with U.S. emissions alone, giving new meaning to the phrase ballooning deficits.
Orbit 50,000 mirrors, 39 miles square, to reflect sunlight. Cost: up to $99 per ton of CO2 offset. But this scheme, says the NRC panel, doesn’t deserve further study: no one knows how so many huge mirrors would be launched or maintained. Since they would dwarf the space shuttle, they would have to be ferried into orbit in pieces and assembled by space-walking astronauts. Given NASA’s unimpressive record on hauling hardware into space on time and without incident, the planet could be well on its way to a greenhouse disaster before the reflective armada was in place.
Even environmentalists have trouble dismissing geoengineering outright. Says Stephen Schneider, a climatologist at the National Center for Atmospheric Research and one of the most forceful advocates for reducing greenhouse emissions: “I cannot in good conscience oppose studies to find out what is possible and what is not.” He endorsed the NRC panel’s call for geoengineering research (which he says has brought him “a lot of heat form environmentalists”) because worst-case predictions about the greenhouse effect might come true. If the world warms a catastrophic 17 degrees Fahrenheit by the next century, Schneider says, the additional heat could induce what scientists call “positive feedbacks.” For instance, a warmer world might thaw arctic tundra, releasing methane–another greenhouse gas– and thus raise the thermostat even more. If that happened, it might be too late to implement emissions-reducing policies. “What would we do then?” Schneider asks. the vanishing ozone layer is fast approaching just such a worst-case scenario. Stratospheric ozone, which screens out the sun’s ultraviolet rays, is disappearing twice as fast as was predicted only two years ago; the Environmental Protection Agency has junked its forecast of 12 percent ozone loss over the next 20 years–and an accompanying 200,000 more skin-cancer deaths–as far too conservative. Although 90 nations have agreed to ban CFCs by 1989, CFCs already released will remain in the atmosphere an average of 75 years. clearly, the ozone layer will thin much more before it stabilizes, much less repair itself.
That frightening forecast prompted physicist Thomas Six of Princeton University to explore the idea of using lasers to destroy CFCs before more reach the ozone layer. He calculates that powerful infrared lasers, installed on 14,000-foot mountainsides and ricocheting between mirrors three miles apart, could destroy most of the CFCs that winds blow their way. About 150 such installations could process 10 percent of the atmosphere’s CFCs each year, shattering them into molecules that would dissolve in raindrops. Although it would be “a superherculean task,” Six says, and cost $10 billion a year in electricity alone, improving laser efficiency 10- to 20-fold would bring costs down.
Besides cost, the trouble with technological fixes is that they can leave a problem worse than before. Despite pervasive use of pesticides, for instance, more crops than ever are lost to fungus and insects, and the chemicals pollute ground water and leave residues on produce. No one knows the ecological effects of a constant veil of stratospheric dust, or of broken CFCs raining out of the sky. If sulfur droplets were the sunlight bouncers of choice, for instance, “there would be no more blue sky, and God knows what it would do to stratospheric chemistry,” says geophysicist Wallace Broecker of Lamont Doherty Geological Observatory in Palisades, N.Y. And technological fixes can be addicting. “We’d be hooked on it,” says Broecker. That’s because geoengineering could well induce a complacency about the root causes of the greenhouse effect and ozone depletion: with shiny balloons reflecting away sunshine, there would be little incentive to control CO2.
Trying to manage climate could also bring sticky political problems. Who would decide whether, and when, to launch a geoengineering scheme that would affect not merely the country lofting the balloons or releasing the soot, but the entire globe? How would the world resolve a claim by, say, Florida citrus growers that a ruinous February freeze was caused by space mirrors reflecting sunlight? Might not the Soviet Union be concerned that a perpetual cloud of sulfur froze its northern ports? “Geoengineering could be limited more by politics than by science,” says Schneider.
The real question is whether mere mortals can fine-tune the climate. The history of weather modification–one big step down from climate control–offers little reason for optimism. Whether seeding clouds above the Ho Chi Minh Trail during the Vietnam War or above the parched fields of South Dakota in the 1970s, would-be rainmakers have never proved that they can produce showers when, where and in the quantity they want. Geoengineering schemes might work too well: our knowledge of climate is too imperfect to know precisely how many dust-filled balloons to loft or how many dirty 747s to fly to counter the oil and coal we burn. A few too many balloons, or a dust cloud a little too thick, and the geoengineers might push the planet into a deep freeze.
NRC panelists who endorse more study of geoengineering nonetheless insist that the real answer is to not release pollutants in the first place. “We got into this mess by changing the planetary metabolism in ways we didn’t understand or intend,” says Jessica Tuchman Mathews of World Resources Institute. “Technological fixes can turn around and bite you.” That’s a lesson that Americans who believe in the magic want of technology have trouble learning.
