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104 • Billions and Billions cuticle of your little finger if you're not fastidiously manicured. It's not very much ozone. But that ozone is all that stands between us and the fierce and searing long-wave UV from the Sun. The UV danger we often hear about is skin cancer. Light-skinned people are especially vulnerable; dark-skinned people have a generous supply of melanin to protect them. (Suntanning is an adaptation whereby whites develop more protective melanin when exposed to UV.) There seems to be some remote cosmic justice in light-skinned people inventing CFCs, which then give skin cancer preferentially to light-skinned people, while dark-skinned people, having had little to do with this wonderful invention, are naturally protected. There are ten times more malignant skin cancers reported today than in the 1950s. While part of this increase may be due to better reporting, ozone loss and increased UV exposure seem implicated. If things were to get much worse, light-skinned people might be required to use special protective clothing during routine excursions out-of-doors, at least at highish altitudes and latitudes. But increased skin cancer, while a direct consequence of enhanced UV, and threatening millions of deaths, is not the worst of it. Nor is the increased rate of eye cataracts. More serious is the fact that UV injures the immune system—the body's machinery for fighting disease—but, again, only for people who go out unprotected into the sunlight. Yet, as serious as this seems, the real danger lies elsewhere. When exposed to ultraviolet light, the organic molecules that constitute all life on Earth fall apart or make unhealthy chemical attachments. The most prevalent beings that inhabit the oceans are tiny one-celled plants that float near the surface of the water—the phytoplankton. They can't hide from the UV by diving deep because they make a living through harvesting A Piece of the Sky Is Missing • 105

sunlight. They live from hand to mouth (a metaphor only—they have neither hands nor mouths). Experiments show that even a moderate increase in UV harms the one-celled plants common in the Antarctic Ocean and elsewhere. Larger increases can be expected to cause profound distress and, eventually, massive deaths.

Preliminary measurements of populations of these microscopic plants in Antarctic waters show that there has recently been a striking decline—up to 25 percent—near the ocean's surface. Phytoplankton, because they're so small, lack the tough UV-absorbing skins of animals and higher plants. (In addition to a set of cascading consequences in the oceanic food chain, the deaths of phytoplankton eliminates their ability to extract carbon dioxide from the atmosphere—and thereby adds to global warming. This is one of several ways in which the thinning of the ozone layer and the heating of the Earth are connected— even though they are fundamentally very different questions. The main action for ozone depletion occurs in the ultraviolet; for global warming, in the visible and infrared.)

But if increasing UV falls on the oceans, the damage is not restricted to these little plants—because they are the food of one-celled animals (the zooplankton), who are eaten in turn by little shrimplike crustaceans (like those in my glass world number 4210—the krill), who are eaten by small fish, who are eaten by large fish, who are eaten by dolphins, whales, and people. The destruction of the little plants at the base of the food chain causes the entire chain to collapse. There are many such food chains, on land as in water, and all seem vulnerable to disruption by UV For example, the bacteria in the roots of rice plants that grab nitrogen from the air are UV-sensitive. Increasing UV may threaten crops and possibly even compromise the human food supply. Laboratory studies of crops at midlatitudes show that 106 • Billions and Billions many are injured by increases in the near-ultraviolet light that is let through as the ozone layer thins. In permitting the ozone layer to be destroyed and the intensity of UV at the Earth's surface to increase, we are posing challenges of unknown but worrisome severity to the fabric of life on our planet. We are ignorant about the complex mutual dependencies of the beings on Earth, and what the sequential consequences will be if we wipe out some especially vulnerable microbes on which larger organisms depend. We are tugging at a planetwide biological tapestry and do not know whether one thread only will come out in our hands, or whether the whole tapestry will unravel before us.

No one believes that the entire ozone layer is in imminent danger of disappearing. We will not—even if we remain wholly obdurate about acknowledging our danger—be reduced to the antiseptic circumstance of the Martian surface, pummeled by unfiltered solar UV But even a worldwide reduction in the amount of ozone by 10 percent—and many scientists think that's what the present dose of CFCs in the atmosphere will eventually bring about—looks to be very dangerous.

In 1974, F. Sherwood Rowland and Mario Molina of the Irvine campus of the University of California first warned that CFCs—some million tons per year were being injected into the stratosphere—might seriously damage the ozone layer. Subsequent experiments and calculations by scientists all over the world have supported their findings. At first certain confirmatory calculations suggested the effect was there, but would be less serious than Rowland and Molina proposed; other calculations suggested it would be more serious. This is a common circumstance for a new scientific finding, as other scientists try to

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find out how robust the new discovery is. But the calculations settled down more or less where Rowland and Molina said they would. (And in 1995 they would share the Nobel Prize in Chemistry for this work.) DuPont, which sold CFCs to the tune of $600 million a year, took out ads in newspapers and scientific journalsAnd testified before Congressional committees that the danger of CFCs to the ozone layer was unproved, had been greatly exaggerated, or was based on faulty scientific reasoning. Its ads compared "theorists and some legislators," who were for banning CFCs in aerosols, with "researchers and the aerosol industry," who were for temporizing. It argued that "other chemicals ... are primarily responsible" and warned about "businesses destroyed by premature legislative action." It claimed a "lack of evidence" on the issue and promised to begin three years of research, after which they might do something. A powerful and profitable corporation was not about to risk hundreds of millions of dollars a year on the mere say-so of a few photochemists. When the theory was proven beyond the shadow of a doubt, they in effect said, that would be soon enough to consider making changes. Sometimes they seemed to be arguing that CFC manufacture would be halted as soon as the ozone layer was irretrievably damaged. But by then there might be no customers.

Once CFCs are in the atmosphere, there is no way to scrub them out (or to pump ozone from down here, where it's a pollutant, to up there, where it's needed). The effects of CFCs, once introduced into the air, will persist for about a century. Thus Sherwood Rowland, other scientists, and the Washington-based Natural Resources Defense Council urged the banning of CFCs. By 1978, CFC propellants in aerosol spray cans were made illegal in the United States, Canada, Norway, and Sweden. But most world CFC production did not go into spray cans. 108 • Billions and Billions

Public concern was temporarily mollified, attention drifted elsewhere, and the CFC content of the air continued to rise. The amount of chlorine in the atmosphere reached twice what it was when Rowland and Molina sounded the alarm and five times what it was in 1950.

For years, the British Antarctic Survey, a team of scientists stationed at Halley Bay in the southernmost continent, had been measuring the ozone layer high overhead. In 1985 they announced the disconcerting news that the springtime ozone had diminished to nearly half what they had measured a few years before. The discovery was confirmed by a NASA satellite. Two-thirds of the springtime ozone over Antarctica is now missing. There's a hole in the Antarctic ozone layer. It has shown up every spring since the late 1970s. While it heals itself in winter, the hole seems to last longer each spring. No scientist had predicted it.

Naturally, the hole led to more calls for a ban on CFCs (as did the discovery that CFCs add to the global warming caused by the carbon dioxide greenhouse effect). But industry officials seemed to have difficulty focusing on the nature of the problem. Richard C. Barnett, chairman of the Alliance for a Responsible CFC Policy—formed by CFC manufacturers—complained: "The rapid, complete shutdown of CFCs that some people are calling for would have horrendous consequences. Some industries would have to shut down because they cannot get alternative products—the cure could kill the patient." But the patient is not "some industries"; the patient might be life on Earth.

The Chemical Manufacturers Association believed that the Antarctic hole "is highly unlikely to have global significance. . . . Even in the other most similar region of the world, the Arctic, the meteorology effectively precludes a similar situation."

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More recently, enhanced levels of reactive chlorine have been found in the ozone hole, helping to establish the CFC connection. And measurements near the North Pole suggest that an ozone hole is developing over the Arctic as well. A 1996 study called "Satellite confirmation of the dominance of chlo-rofluorocarbons in the global stratospheric chlorine budget" draws the unusually strong conclusion (for a scientific paper) that CFCs are implicated in ozone depletion "beyond reasonable doubt." The role of chlorine from volcanos and sea spray— advocated by some right-wing radio commentators—accounts at most for 5 percent of the destroyed ozone.

At northern midlatitudes, where most people on Earth live, the amount of ozone seems to have been steadily declining at least since 1969. There are fluctuations, of course, and volcanic aerosols in the stratosphere work to decrease ozone levels for a year or two before they settle out. But to find (according to the World Meteorological Organization) 30 percent relative depletions over northern midlatitudes for some months of each year, and 45 percent in some areas, is cause for alarm. You don't need many consecutive years like that before it's likely that the life underneath the thinning ozone layer is getting into trouble.

Berkeley, California, banned the white CFC-blown-foani insulation used to keep fast foods warm. McDonald's pledged replacement of the most damaging CFCs in its packaging. Facing the threat of government regulations and consumer boycotts, DuPont finally announced in 1988, 14 years after the CFC danger had been identified, that it would phase out the manufacture of CFCs—but not to be completed until the year 2000. Other American manufacturers did not then promise even that. The United States, though, accounted for only 30 percent of worldwide CFC production. Clearly, since the long-110 • Billions and Billions term threat to the ozone layer is global, the solution would have to be global as well. In September 1987, many of the nations that produce and use CFCs met in Montreal to consider a possible agreement to limit CFC use. At first, Britain, Italy, and France, influenced by their powerful chemical industries (and France by its perfume industry), participated in the discussions only reluctantly. (They feared that DuPont had a substitute up its sleeve that it had been preparing all the time it was stonewalling about CFCs. The United States was pushing a ban on CFCs, they worried, in order to increase the global competitiveness of one of its major corporations.) Such nations as South Korea were altogether absent. The Chinese delegation did not sign the treaty. Interior Secretary Donald Hodel, a conservative Reagan appointee averse to government controls, reportedly suggested that, instead of limiting CFC production, we all wear sunglasses and hats. This option is unavailable to the microorganisms at the base of the food chains that sustain life on Earth. The United States signed the Montreal Protocol despite this advice. That this occurred during the antienvironmental spasm of the late Reagan Administration was truly unexpected (unless, of course, the fear of DuPont's European competitors is true). In the United States alone, 90 million vehicle air conditioners and 100 million refrigerators would have to be replaced. This represented a considerable sacrifice to preserve the environment. Substantial credit must be given to Ambassador Richard Benedick, who led the U.S. delegation to Montreal, and to British Prime Minister Margaret Thatcher, who, trained in chemistry, understood the issue.

The Montreal Protocol has now been strengthened still further by amendment agreements signed in London and Copenhagen. As of this writing, 156 nations, including the republics of the former Soviet Union, China, South Korea, and India have A Piece of the Sky Is Missing • Hi signed the treaty. (Although some nations ask why, when Japan and the West have benefitted from CFCs, they must forgo refrigerators and air conditioners, just when their industries are hitting stride. It is a fair question, but a very narrow one.) A total phaseout of CFCs was agreed to by the year 2000, and then amended to 1996. China, whose CFC consumptioH*\vas rising by 20 percent per year through the 1980s, agreed to cut its reliance on CFCs and not avail itself of a ten-year grace period that the agreement permitted. DuPont has become a leader in cutting back on CFCs, and has committed itself to a faster phaseout than many nations have. The amount of CFCs in the atmosphere is measurably declining. The trouble is, we will have to stop producing all CFCs and then wait a century before the atmosphere cleans itself up. The longer we dawdle, the more nations that hold out, the greater the danger. Clearly, the problem is solved if a cheaper and more effective CFC substitute can be found that does not injure us or the environment. But what if there is no such substitute? What if the best substitute is more expensive than CFCs? Who pays for the research, and who makes up the price difference—the consumer, the government, or the chemical industry that got us into (and profited by) this mess? Do the industrialized nations who benefited from CFC technology give significant aid to the emerging industrialized states who have not? What if we need 20 years to be sure the substitute doesn't cause cancer? What about the UV now pouring down on the Antarctic Ocean? What about all the newly manufactured CFCs rising toward the ozone layer between now and whenever the stuff is completely banned?

A substitute—or better, a stopgap measure—has been found. CFCs are temporarily being replaced by HCFCs, similar molecules but involving hydrogen atoms. For example:

They still cause some damage to the ozone layer, but much less; they are, like CFCs, a significant contributor to global warming; and, especially during start-up, they are more expensive. But they do address the most immediate need, protecting the ozone layer. HCFCs were developed by DuPont, but— the company swears—only after the discoveries at Halley Bay.

Bromine is, atom-for-atom, at least 40 times more effective than chlorine in destroying stratospheric ozone. Fortunately, it is much rarer than chlorine. Bromine is released to the air in halons used in fire extinguishers, and methyl bromide, H H — C — H Br used to fumigate soil and stored grain. In 1994-96, the industrial nations agreed to phase out the production of these materials, capping them by 1996, but not totally phasing them out until 2030. Because there are as yet no replacements for some halons, there may be a temptation to keep on using them—ban or no ban. Meanwhile, a major technological issue is finding a superior long-term solution to overtake HCFCs. This might involve another brilliant synthesis of a new molecule, but perhaps will go in other directions—for example, acoustic refrigerators that have no circulating fluid carrying subtle dangers. Here A Piece of the Sky Is Missing -113

is an opportunity for creative invention. Both the financial rewards and the long-term benefit for the species and the planet are high. I'd like to see the enormous technical skill at the nuclear weapons laboratories, now increasingly moribund because of the end of the Cold War, turned to such worthy pursuits. I'd like to see generous grants and irresistiblsAprizes offered to invent effective, convenient, safe, and reasonably inexpensive new modes for air conditioners and refrigerators—that are appropriate for local manufacture in developing nations.

The Montreal Protocol is important for the magnitude of the changes agreed to but especially for their direction. Perhaps most surprising, a ban on CFCs was agreed to when it was unclear that there would be a feasible alternative. The Montreal conference was sponsored by the United Nations Environment Programme, whose director, Mostafa K. Tolba, described it as "the first truly global treaty that offers protection to every single human being."

It is an encouragement that we can recognize new and unexpected dangers, that the human species can come together working on behalf of all of us on such an issue, that rich nations might be willing to bear a fair share of the cost, and that corporations with much to lose can be made not only to change their minds, but to see in such a crisis new entrepreneurial opportunities. The CFC ban provides what in mathematics is known as an existence theorem—a demonstration that something that might, for all you know, be impossible can actually be accomplished. It is a reason for cautious optimism. Chlorine seems to have peaked at about four chlorine atoms for every billion other molecules in the stratosphere. The amount is now decreasing. But at least partly because of bromine, the ozone layer is not predicted to heal itself soon.

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