بخش 2 فصل 1

دوره: پایان طبیعت / درس 4

بخش 2 فصل 1

توضیح مختصر

  • زمان مطالعه 0 دقیقه
  • سطح خیلی سخت

دانلود اپلیکیشن «زیبوک»

این درس را می‌توانید به بهترین شکل و با امکانات عالی در اپلیکیشن «زیبوک» بخوانید

دانلود اپلیکیشن «زیبوک»

فایل صوتی

دانلود فایل صوتی

متن انگلیسی درس

Part II

The Near Future

A Promise Broken

A hurricane draws its might from the heat transferred to the atmosphere when ocean water evaporates. The warmer the ocean’s surface, and the farther beneath the surface the warm water runs, the more powerful the hurricane. If the sea turns cold a few meters beneath the top, the winds of the hurricane will soon churn up that frigid water and the storm will brake itself. But if the warm water runs deep—and in the tropics it may stretch down a hundred and fifty meters or more—the hurricane can build and build. Under present conditions—tropical ocean temperatures of about 80 degrees Fahrenheit—Hurricane Gilbert, which formed off the Windward Islands in the autumn of 1988, approached what Massachusetts Institute of Technology professor Kerry Emanuel has calculated as the upper bound of intensity for a hurricane. The atmospheric pressure at its center dropped to about 885 millibars, and so its winds reached two hundred miles per hour. It can’t get any worse than that—under present conditions.

But we switch now from the present to the future. Say the global temperature increased, and as one result the temperature of the ocean went up. A rise of 3 or 4 degrees Fahrenheit in tropical sea-surface temperatures would cause the upper limit of hurricane strength to grow. In the middle of these warmer storms, atmospheric pressure could fall to 800 millibars; as a result, the destructive potential of these superhurricanes would grow between 40 and 50 percent—a Gilbert and a half.

We have killed off nature—that world entirely independent of us which was here before we arrived and which encircled and supported our human society. There’s still something out there, though; in the place of the old nature rears up a new “nature” of our own devising. It is like the old nature in that it makes its points through what we think of as natural processes (rain, wind, heat), but it offers none of the consolations—the retreat from the human world, the sense of permanence, and even of eternity. Instead, each cubic yard of air, each square foot of soil, is stamped indelibly with our crude imprint, our X. A lot that has been written about the greenhouse effect has stressed the violence of this retuned nature—the withering heat waves, the drought, the sea rising to flood streets. It certainly makes dramatic sense to imagine this break with nature as one of those messy divorces where the ex-husband turns up drunk and waving a gun. But it may, on the other hand, be a nature of longer growing seasons and fewer harsh winters. We don’t know, can’t know.

Simply because it bears our mark doesn’t mean we can control it. This new “nature” may not be predictably violent. It won’t be predictably anything, and therefore it will take us a very long time to work out our relationship with it, if we ever do. The salient characteristic of this new nature is its unpredictability, just as the salient feature of the old nature was its utter dependability. That may sound strange, for we are used to thinking of the manifestations of nature—rain or sunshine, say—as devious, hard to predict. And over short time spans and for particular places they are; the most cheerful and boisterous weathermen are no more reliable in their forecasts than the cheerful and boisterous sportscasters seated next to them. But on any larger scale nature has been quite constant, and on a global scale it has been a model of reliability. In fact, it has been the model of reliability—“as sure as summer follows spring.” Where I live, it is safe to plant tomatoes after June 10, and foolish to plant them before May 20; the last frost is almost sure to fall in those three weeks. In the fall, the first frost nearly always shows up at the beginning of September, and there’s a killing freeze by month’s end. As a consequence there are no farms nearby. There were once—people tried to grow crops on the land for a generation or so after the initial settlement, but the farms failed, people gave up, and now you come across neat stone walls five miles through the forest from any road. And it’s the same in other places; virtually all settlement patterns testify to the dependability of nature. Every year during the late summer, the Nile overflows its banks (or did until the Aswan Dam was built). A pilot knows how the air will behave along his flight path—that a tropical air mass in summer over the American Southeast will breed thunderstorms. (“The details,” one meteorologist has said, “are as multifarious as geography itself, but much of it has by now been put into manuals.”) Even extreme events, weather emergencies, have been fairly predictable. Mary Austin, in one of her fine essays on the American desert, wrote that storms “have habits to be learned, appointed paths, seasons, and warnings, and they leave you in no doubt about their performances. One who builds his house on a water scar or the rubble of a steep slope must take his chances.” Engineers calculate every drainage and wall for the ability to withstand the “hundred-year storm.” Every developer who builds a resort along the coast, every underwriter who insures a ship or a plane, does so with a conscious dependence on the reliability of nature. And even more dependent are those of us who rely unconsciously on nature’s past performance. The farmer, it is true, has always watched for rain, and sometimes his crops have shriveled. But those of us who do our harvesting at the Price Chopper never doubt that enough rain will fall on enough farms, and it always has.

It is this very predictability that has allowed most of us in the Western world to forget about nature, or to assign it a new role—as a place for withdrawing from the cares of the human world. In some parts of the world, nature has been more capricious, withholding the rain one year or two, pouring it down by the lakeful the next. In these places people think about the weather, about nature, more than we do. But even in Bangladesh people have known that for the most part nature would support them—not richly, but support them.

In this unconscious assumption we mimic animals and plants; as Loren Eiseley says, the “inorganic world could and does really exist in a kind of chaos, but before life can pop forth, even as a flower, or a stick insect, or a beetle, it has to have some kind of unofficial assurance of nature’s stability, just as we read that stability in the ripple marks impressed in stone, or the rain-marks on a long-vanished beach, or the eye of a hundred-million-year-old trilobite.” Nineteenth-century biologists, he writes, were “amazed” when they discovered these fossils, “but wasps and migratory birds were not. They had an old contract, an old promise … that nature, in degree, is steadfast and continuous.” And this promise has enabled life to establish itself even in the places we think of as harsh, since they have been harsh in a fairly dependable way. Mary Austin, for instance, writes of the water trails of the desert—paths that lead to the old and trusty springs. “The crested quail that troop in the Ceriso are the happiest frequenters of these paths,” she writes. “Great floods pour down the trail with that peculiar melting motion of moving quail, twittering, shoving, and shouldering. They splatter into the shallows, drink daintily, shake out small showers over their perfect coats, and melt away into the scrub, preening and pranking, with soft contented noises.” There is change, says Eiseley, but it is change at “the slow pace of inorganic life,” and the seasons never “come and go too violently.” This is “nature’s promise—a guarantee that has not been broken in four billion years that the universe has a queer kind of rationality and expectedness about it.” That promise was long since broken for passenger pigeons, and for the salmon who ran into dams on the ancestral streams, and for peregrine falcons who found their eggshells so weakened by DDT that they couldn’t reproduce. But now it is broken for us, too—nature’s lifetime warranty has expired.

The measure of change has gone from the millennium to the decade; we are altering the climate, says Stephen Schneider of the National Center for Atmospheric Research, at a rate ten to sixty times its natural rate of change. The long-range climate forecasts for particular cities made by some researchers are, he says, “somewhat meaningless,” and the actual outcome of a general heating could be far different—“better,” “worse,” but mainly just different—from our educated guesses. “Unfortunately,” says Schneider, “there is no time over Earth’s history that we can turn to when the carbon dioxide amounts in the atmosphere were, say, twice what they are now, and at the same time examine instruments that tell us what the earth’s climate was then.… Instead we must base our estimates on natural analogs of large climatic change and climatic models.” One analog is the Arctic, which biologists, for climatological reasons, have long characterized as “stressed,” or “accident-prone,” less able to absorb disaster than the milder temperate and tropic zones. Barry Lopez offers an example of this in his Arctic Dreams: “In the fall of 1973 an October rainstorm created a layer of ground ice that, later, muskoxen could not break through to feed. Nearly 75 percent of the muskox population in the Canadian archipelago perished that winter.” Our climate is not likely ever to be as harsh as the weather currently found above the Arctic Circle, but it is not likely to be as forgiving as the “natural” weather we are used to.

IT MAY TURN OUT that we’re not much more suited by our genes to quick adaptation than the musk ox. “Large animals charging, rocks falling, children crying, fires starting—these are the sort of short-range changes that our ancestors had to react to,” the population specialist Paul Ehrlich has written. “But the world of 276,824 B.C. was much like that of 276,804 B.C.” Still, even if our knack for adaptation proves hardy—and, after all, boat people moving from Cambodia to Canada go through much more severe climatic shifts than anything the scientists forecast—the stress will be continuous, unrelenting, because no one knows how all this will turn out. “The only thing objectively good about the current atmosphere and climate is that they are the ones we are used to,” David Doniger of the Natural Resources Defense Council said a few years ago. “Life and civilization are adapted to this environment: change necessarily will be disruptive.” It will likely be worst, of course, for those already living on the edge, already subject to nature’s whim—out on the floodplains of Bangladesh. But it will affect, at the very least, the mind of each of us. We are not necessarily doomed to suffer some cataclysm. But we can’t count on not being so doomed. Professor Emanuel points out that there is no certainty that an increase in global warmth will push up tropical ocean temperatures and thus hurricane strength; neither is there any certainty that it won’t.

The uncertainty itself is the first cataclysm, and perhaps the most profound one. If we can’t count on enough snow falling to fill the reservoirs that feed our faucets, or if we have to worry that too much of that water will evaporate in the heat, then the weather report is suddenly going to be leading off the Dan Rather newscast. This tension has already begun to show in some places. In the summer of 1988 New York City burned beneath a terrific heat wave, but no relief was to be found in the nearby oceans where medical waste bobbed in the waves. Instead of the usual beach reports—water temperature, available space in the parking lot—the papers ran regular dispatches like this one from mid-July: “The beaches on the southeastern shore of Staten Island, including South and Midland beaches, which have been closed since Wednesday, remained closed yesterday, and officials said they would stay closed until the tides are free of syringes. No blood vials were found yesterday.… In New Jersey, Monmouth County health officials lifted a five-day-old ban on swimming at most of Asbury Park’s beaches, but left the ban in force for Ocean Grove. Water quality tests showed that fecal coliform bacteria levels were down, but contaminated water was moving south toward Ocean Grove.” Even for people who had no intention of swimming off Staten Island, there was something claustrophobic about those reports; even people who moved by air-conditioned cab from air-conditioned apartment to air-conditioned office tower found themselves thinking about the heat. By summer’s end, Time (no alarmist rag) was reporting that “on top of the usual chafing at day after day of hot, humid, and hazy” weather, Americans were suffering a “communal attack of the worries.” This “fretful mood,” in which the “soggy unremitting heat sometimes seemed a symptom of general ecological collapse,” the magazine’s editors dubbed “ecophobia.” People, they said, were asking, “Had the great breakdown begun?” THE FRETFULNESS can only grow, for it is the natural world that has always provided our chief images of stability, our necessary antidotes to the “fast-paced,” “dynamic” human society. Art is no longer eternal, if it ever was; it moves with fruitfly speed from one impulse to another. The tools we use each day are not familiar (I am writing this on a “third-generation” computer, now hopelessly outdated), nor are the foods we eat (once upon a time two eggs over was a “healthy breakfast”). We move physically (I was born in California and grew up on the other edge of the continent) and we move mentally (I was born in the Industrial Era and now live in the Information Age). Even our relationships to other people change—I was born before the sexual revolution and came of age in its wake. Such incredible freedom and creativity is stressful. We want our freedom, in the words of the Cape Cod essayist Robert Finch, “as children want it and need it—within safe bounds.” Nature has always provided the “deep, constant rhythms,” even if, in our turbocharged and jet-propelled arrogance, we have come to think that we are independent of the earth’s basic pulses. We still rely on the earth’s “basic integrity and equanimity” to give us a “safe and stable context,” Finch says, and, in particular, we rely on the seasons. “The recurring cycles of the year are not simply entertaining phenomena, to be noted at our convenience and for our enjoyment, but signs that the cosmos is still intact, that we remain in something larger and more reliable than our own short-lived enthusiasms. It is for this that we need to know the insects will hibernate, that turtles and warblers will migrate and return, that the tide will retreat, the ice let go, the earth tilt back toward the sun, and the grass reawaken.” Despite the dozens of new ways to look at the world—the genetic, the microscopic, the chemical—we are still very much the same people who built Stonehenge so that each year we could make sure the sun really did begin its retreat, the same people who trembled at eclipses. As I write this, it is early December. Yesterday, finally, we had our first real snowfall of the winter, and I could feel myself relaxing a little. I took a hike this afternoon, and the woods that had yesterday seemed too brown for the temperature now seemed right, and the squeak of the dry snow matched the cold, astringent air in my nostrils.

Around our small town, which is stuck out on the edge of a wilderness, people talk about the weather constantly—as people do, I assume, in every part of the world. This is not because people can’t think of anything else to say. It’s because the weather is important, physically and psychologically. Unless there’s a storm, the conversations are less about the weather that day than about the signs for the future. (“Did you get frost up your place last night? Time to start splitting wood.”) It is the oldest way of saying that deep down all is right with the world. It may have been an arrogant comfort (“What are we / The beast that walks upright with speaking lips / And little hair, to think we should always be fed, / sheltered, intact, and self-controlled?” asked Robinson Jeffers), but it was how we saw the earth. Edwin Way Teale, a twentieth-century American naturalist, devoted two decades to four large volumes chronicling spring, summer, fall, and winter across America. (The final volume alone, Wandering Through Winter, journeys from south of San Diego on the Mexican line, where the whales pass in their winter migration, to north of Caribou, on Maine’s border with Canada, where “we glimpsed one farmhouse in the moonlight buried to its eaves.”) He writes, “This we learned from our experience with the four seasons. We want them all. We want the rounded year.” And for more, much more, than variety—we want it for reassurance that the wheel still turns, so that we can worry about our human affairs secure in our knowledge of the eternal inhuman.

And it’s not merely the annual cycles of renewal that cheer and assure us but also the longer and more dramatic cycles. Thoreau wrote, “I love to see that Nature is so rife with life that myriads can afford to be sacrificed and suffered to prey on one another, that tender organizations can be so serenely squashed out of existence like pulp—tadpoles which herons gobble up, and tortoises and toads run over in the road.… With the liability to accident, we must see how little account is to be made of it.… Poison is not poisonous after all, nor are any wounds fatal.”

Some of our culture’s greatest images of reassurance come from religious sources—from the preacher in Ecclesiastes, for instance, who reminds us that for everything there is a season. In his words we discover the apparent meaninglessness and vanity of human life, since, for all our struggle, nothing ever really changes in the universe: “The wind blows to the south and goes round to the north; round and round goes the wind, and on its circuits the wind returns.” But if this dependable cycle is boring it is also comforting: “What has been is what will be, and what has been done is what will be done, and there is nothing new under the sun.” A more positive statement of this truth comes from the Sermon on the Mount. “Therefore I tell you,” Jesus declares, “do not be anxious about your life, what you shall eat or what you shall drink, nor about your body, what you shall put on. Is not life more than food, and the body more than clothing? Look at the birds of the air: they neither sow nor reap nor gather into barns, and yet your Heavenly Father feeds them.… And why are you anxious about clothing?” The certainty of nature—that God’s creation or Darwin’s or whoever’s will provide for us, bountifully, as it always has—is what frees us to be fully human, to be more than simply gatherers of food.

But what will happen—this summer or next summer or some summer soon—as that certainty falters? The birds of the air, returning each winter to South America, find less and less of the forest that is their home; as a result (and as a result of other human changes), there are fewer birds around us each year. Songbirds are a cause for exclamation now, and the spring grows more quiet than before. And we, I think, grow more nervous.

What happens as that certainty falters? “Adventure,” said Bob Marshall on the return from his Arctic jaunts, “is wonderful, but there is no doubt that one of its joys is its end.… Lying in bed, with no rising rivers, no straying horses, no morrow’s route to worry about, we enjoyed a delightful peacefulness.” What happens is that adventure ceases to be a joy and becomes a source of fear, for the end of the adventure is not so certain.

What happens as that certainty falters? What happens, I think, is that for those of us who on Sundays say the Lord’s Prayer, the vestigial and anachronistic phrase “Give us this day our daily bread,” which has in this nation been either a quaint reminder of an earlier time or a symbolic statement, acquires earthy new meaning, a panicky edge. (And that panicky edge is perhaps a little sharper because once upon a time most people lived near enough to nature to have some feeling they could cope with it. At the turn of the century, two-thirds of the American people lived in places with populations of five thousand or less, and most, I imagine, had some land and some idea or another about how to grow their daily bread—information that has not been passed along to most of us in the Information Age.) But the first thing that happens as that certainty falters, I think, is the replacement of one idea of the world with another. Instead of thinking of birds, for instance, as serene, independent, carefree, flitty creatures, we may soon develop a store of pictures like the remarkable one recorded by Mary Austin in The Land of Little Rain, her tribute to the California desert published in 1903. Usually, she notes, April, May, and early June are the blossoming, humming months in the desert, after the winter and before the long heat, but once in a while even benign, natural nature misfires, and the heat arrives too early: “The quick increase of suns at the end of spring sometimes overtakes birds in their nesting and effects a reversal of the ordinary manner of incubation.… One hot, stifling spring in the Little Antelope I had occasion to pass and repass frequently the nest of a pair of meadowlarks, located unhappily in the shelter of a very slender weed. I never caught them sitting except near night, but at midday they stood, or drooped above it, half fainting with pitifully parted bills, between their treasure and the sun.” Sometimes, she went on to say, both mother and father stood there together, their wings spread to keep that precious shade on the egg. It is a fitting image for the age we are heading into—for an age when The New York Times had above the fold on its front page one day last autumn stories about the Yellowstone fire, the threat to our homes from radon gas, and the rampage of Hurricane Gilbert. Mary Austin, by the way, eventually rigged up a piece of canvas to cast a shadow across the nest. But it is not clear what, if anything, will come to our aid.

THE SCALE OF THIS uncertainty is so enormous that there are even those who see the greenhouse atmosphere yielding an Ice Age. This theory, formulated by John Hamaker, a retired Midwest engineer, and fervently advanced by a number of California disciples, is dismissed by most professional atmospheric scientists, but it gives an interesting sense of the fragility of present arrangements.

Basically, Hamaker and his followers believe that the cycle of ice ages experienced by the planet in recent geologic times has been driven by changes in the concentration of carbon dioxide, which, in turn, are driven by the “mineralization” and “demineralization” of the soil. Over thousands of years the soil is stripped of its minerals—plants remove them as they grow, they leach out, and so on. When this reaches some critical point, the plant life begins to die out, and this causes, for reasons we’ve already discussed, a massive increase of carbon dioxide in the atmosphere. Then, as the greenhouse effect heats the equator, it causes large amounts of evaporation from tropical waters. The earth’s natural climatic currents push the water-laden clouds north, where they cool and lose their moisture as snow—so much snow that eventually some of it remains over the summer, and the huge glaciers of the next Ice Age form. The glaciers, as they move through the higher latitudes, grind the mountains to dust and “remineralize” the soil, at which point plants are once again able to prosper and the cycle begins again.

Now, it is true that the warm periods between ice ages have lasted for fairly regular ten-thousand-year intervals for a long time, and since the present warm period began about ten thousand years ago, there is reason to think we’re about due. Though we haven’t given it a thought, our climatic future has always been uncertain. But Hamaker and his following argue that the burst of carbon dioxide released by the Industrial Revolution has jump-started the change—in fact, Hamaker says, the worst effects of this new glaciation will become apparent between now and 1995. The worsening winters “we can stand for some time into the future,” he writes. “What we cannot stand is for the winters to carry over into the summers and to destroy crops and trees with frosts and freezes.” He says it is already too late “to prevent the deaths of hundreds of millions of people from famine,” but “there may still be time to prevent the extermination of civilization for another ninety thousand years of glaciation.” He recommends, besides an immediate end to the use of fossil fuels and a total halt to the burning of the rain forests, a crash program of “remineralization”—putting every available airplane into service to drop billions of pounds of crushed rock dust on the earth’s forests to spur their growth.

Though there is some scientific backing for the idea that ice ages can begin with startling speed (the National Academy of Sciences said in the 1970s that a period of glaciation could be underway within a century), almost all scientific attention has been focused in recent years on the warming. Hamaker dismisses this focus as a mistake and a cover-up. The government, he writes, would rather deal with a problem fifty years away than with one that will happen before the turn of the century. This I doubt—the scientists I talked to were hopelessly sincere. Anyway, most climatologists now attribute ice ages to the so-called Milankovitch cycles, when the earth’s wobble, its tilt, and the shape of its orbit varies its dose of solar radiation. “I’m not saying there’s no chance they’re right,” says Stephen Schneider of the Ice Age theorists, “but it’s down below the first decimal point of probability.” That it’s even a possibility, however, testifies to our poor understanding of the system we’ve knocked out of kilter, and to its immense power. Some people will undoubtedly find comfort in such uncertainty, just as some people still rely on those scientists in the pay of the tobacco companies who insist that there is no “proof” of the link between cigarettes and cancer. But it is a superficial comfort, a whistling in the heat. Uncertainty is often seen as nicer than grim certainty, because we, being human, tend to imagine that the happiest outcomes are likely. Maybe we don’t need to do anything! For more than a decade, no one did anything about acid rain because some scientists said that our understanding was incomplete, that we didn’t know all the chemical interactions and so we had better study some more before spending the sums necessary to clean the obvious sources of pollution. The increase in carbon dioxide has evoked, and will evoke, the same kind of reactions. But, powerful though the uncertainties are—and terrifying, too—they are uncertainties about horrors. How bad will the hurricanes get? Fire or ice? These are not comforting uncertainties—not the lady or the tiger. This is the lion or the tiger.

The uncertainties we are used to dealing with—political uncertainties, such as “Is the budget deficit a real problem?” and personal uncertainties, such as “Should I take this job?”—do not unduly alarm us only because they occur amid general political and personal stability. We live, in the Western world, amid abundance. Most of us have pensions and retirement accounts and certificates of deposit and plans for the future, all of them based on the world operating pretty much as it has always operated. It is in that context that our uncertainties occur. The world around us reassures us: if we don’t take this job or marry this woman, we will get another chance. But what happens when that context itself is a source of fear? When the world around us is going crazy? It will be a little like living in wartime, I think, when only the most basic reassurances—the belief, say, that one will go to heaven when one dies—will matter.

MOST OF THE EFFECTS that scientists are starting to predict stem from the heating of the earth, the 3- to 8-degree rise in average global temperature that is the consensus prediction for the near future. It doesn’t require great imagination to see that this will change our lives, but it takes powerful computers to give a hint of just how. And even the powerful computers often disagree. The three main American models of a global warming (Hansen’s NASA projections, a program devised at Oregon State University, and another at the National Oceanic and Atmospheric Administration) predict widely different results for the continental United States. The NASA model predicts increased summer precipitation in the Great Lakes region, for instance, while the NOAA program yields a decrease, and Oregon’s figures it won’t change at all. In the meantime, though, there are plenty of scenarios.

The single most-talked-about consequence is probably the expected rise in global sea level as a result of polar melting. For the last few thousand years, the sea level “has risen so slowly that for most practical purposes it has been constant,” says James Titus, of the Environmental Protection Agency. As a result, people have developed the coastlines extensively. Not just the beaches in Rio or the canals in Venice, but also the infrastructure of all major ports, around which have grown up most of the world’s great cities. And not just people: marine plants and animals have taken the opportunity provided by sea-level stability to build huge communities such as the one in Chesapeake Bay. But, despite all this confidence, the sea level is not a given. A hundred thousand years ago, during the last interglacial period, it was twenty feet above the current levels; at the height of the last Ice Age, when much of the world’s water was frozen at the poles, the sea level fell three hundred feet. Scientists estimate that the world’s remaining ice cover contains enough water so that if it should all melt the sea level would rise about 75 meters, or nearly 250 feet. This potential inundation is stored in the Greenland Ice Sheet (if it melts it will raise the world’s oceans twenty feet), the West Antarctic Ice Sheet (another twenty feet), and East Antarctica (nearly two hundred feet), with a smaller amount, perhaps one and a half feet, in all the planet’s alpine glaciers combined. (Melting the ice currently over water, such as the sea ice of the Arctic Ocean, won’t raise the sea level, any more than a melting ice cube overflows a gin and tonic.) As the East Antarctic is considered safe, the direst fears of a rising sea came as the result of a 1968 study that concluded that the Ross and Filchner-Ronne ice shelves supporting the West Antarctic Ice Sheet could disintegrate within forty years, swelling the oceans seven meters, or twenty-three feet. Subsequent investigations, however, seem to have demonstrated that such a disintegration would take at least two centuries, and probably more like five (though several investigators have speculated that such a deglaciation might become irreversible within the next century).

However, the salvation of the West Antarctic does not mean the salvation of Bangladesh, or even of East Hampton. A number of other factors seem ready to raise the sea level significantly. The alpine glaciers, while small compared with the ice caps, are not small. Glaciers bordering the Gulf of Alaska, for instance, have been melting for decades, and constitute a source of fresh water about the size of the entire Mississippi River system. And even if nothing melted at all, the increased heat alone would raise the sea level considerably. Warm water takes up more space than cold water—this thermal expansion, given a global temperature increase of 1.5 to 4.5 degrees Celsius, should raise sea levels a foot, according to Hansen. Two Canadian researchers announced in May 1989 that, according to their measurements of more than four hundred sites, sea level is already rising an inch a decade—it is by now widely accepted that sea level will rise significantly over the next decades. The EPA has estimated that it will increase 144 to 217 centimeters (4.7 to more than seven feet) by 2100, and speculated about worst-case scenarios that might lead to an eleven-foot-plus rise; the National Academy of Sciences has been more conservative, but other researchers have turned in even scarier numbers. Suffice it to say that the best guess of almost every panel and every individual scientist studying the problem includes within its range an increase in global sea level of better than one meter, or 3.3 feet.

That does not sound like so much, but it means that the sea would reach a height unprecedented in the history of civilization. The immediate effects of this swollen sea would be seen in a place like the Maldive Islands. By most accounts, this archipelago of 1,190 small islands about four hundred miles southwest of Sri Lanka sounds fairly paradisaical. Its 187,000 residents had never heard a gun fired in anger until a short-lived coup attempt mounted by foreign mercenaries in 1988. They survived the downturn in the coir business (coir is an elastic fiber made from coconut husks); breadfruit, citron, and fig trees are abundant. The worst criminals are banished to uninhabited outer islands. But most of this happy nation rises only two meters above the Indian Ocean. If the sea level were to rise one meter, storm surges would become an enormous, crippling danger; were it to rise two meters, a rise well within the range of possibilities predicted by many studies, the country would simply disappear. In October 1987 Maldive’s president Maumoon Abdul Gayoom went before the United Nations General Assembly. He described his country as “an endangered nation.” The Maldivians, he pointed out, “did not contribute to the impending catastrophe … and alone we cannot save ourselves.” A map drawn in a century may not show the Maldives, except as a danger to mariners.

Other nations, though not extinguished, would be horribly hurt. A two-meter rise in the sea level would flood 20 percent of the land in Bangladesh, much of which is built on the floodplains at the mouth of the Brahmaputra. In Egypt, such a rise would inundate only about 1 percent of the land, but that 1 percent includes much of the Nile delta, where most of the population live. All across Asia, farmers grow rice on low river deltas and floodplains. Because those farmers lack the resources to build dikes and seawalls (and in some places, such as Bangladesh, such defenses are practically impossible), harvests would almost certainly fall.

But it is not just the Third World. A couple of years ago, the United States Environmental Protection Agency issued a worksheet whereby local governments could calculate their future position vis-à-vis the salt water. (In Sandy Hook, New Jersey, for instance, add thirteen inches to account for local geologic subsidence to the projected increases in sea level, for a net ocean rise of four feet one inch.) Direct inundation of land would cause a certain number of problems; in Massachusetts, for instance, between three thousand and ten thousand acres of oceanfront land worth between $3 billion and $10 billion might disappear by 2025, and that figure does not include land lost to growing ponds and bogs as the rising sea lifts the water table. But storm surges would do the most dramatic damage. In Galveston, Texas, 98 percent of the land is within the plain that would be flooded by the worst storms. Such surges are the reason that Holland built its protective dikes. The most extensive barriers went up after the winter of 1953, when a surge breached the existing dikes in eighty-nine places along the central delta, killing nearly two thousand people and tens of thousands of cattle. Afterward the Dutch decided to spend more than $3 billion building new defenses.

As the Dutch effort indicates, much can be done to defend against increases in the sea level. The literature abounds with studies on how much it would cost to protect coastal areas. Researchers, for instance, have worked out three methods to save Long Beach Island, an eight-mile-long barrier island off the New Jersey coast: it could be encircled with a levee, or gradually raised by adding sand, or allowed to “migrate” landward by piling new sand on its inland edge as sand was eroded from the front. The levee would be the cheapest solution at only about $800 million, but the money would have to be spent all at once. (“Moreover,” commented one of the researchers, “a levee would eliminate the waterfront view.”) Allowing the island to migrate landward, on the other hand, would cost a staggering $7.7 billion, mainly because all the roads and utilities would have to be repeatedly ripped up and moved. So, with interest rates and the like figured in, the cheapest method would be to gradually raise the island by gradually adding sand—a bargain at $1,706,000,000.

The exactness of such figures provides a sense of comfort, but almost certainly a false one. Though each study is filled with footnotes on topics like “the sensitivity of sand costs to increasing scarcity,” the estimated cost of doing anything on a very large scale—even something like building a missile, which can be done under controlled conditions—is invariably off. Any numbers are at best a guess, useful only as a way of saying “big problem, very big problem.” The estimates of the cost of protecting the sheltered shoreline of America alone run as high as $80 billion; add barrier islands and so on and the cost of defending against a 6-foot rise in sea level might top $300 billion according to the experts. In Holland, nearly six cents of every dollar of the gross national product is already spent on holding back the sea.

Still, it’s only money, and it would probably be worth it to save our beaches, especially since the warmer greenhouse weather would increase the need for a day at the shore. (A study, of course, has quantified this relationship. Ocean City, Maryland, it found, might hold back a one-foot sea-level rise by spending about twenty-five cents per visitor, which would be well within its means, because the warm weather might increase its total tourist revenues 25 percent.) The trouble is, spending the money to protect the shoreline would lead to ecological costs harder to enumerate but easy to understand.

Coastal marshes or wetlands exist in a nearly unbroken chain along the Gulf and Atlantic coasts of the United States. Part land and part water, they are more “biologically productive” than either the ocean or the dry land. The tide flows in and out, spreading food and flushing out waste—a cycle that encourages quick growth and rapid decay. Protected from the waves of the ocean by barrier islands or sand dunes or peninsulas, these peaceful communities are used by an immense variety of birds, fish, shellfish, and plants. “All organic life is beautifully and variedly adjusted to the conditions of its environment,” wrote biologist James Morris, “but it is doubtful if in any other zone of the organic world the accommodations are more exquisitely ordered than in the marshes of the ocean shore.” This fact was not always appreciated; early settlers, with noble exceptions such as Bartram, thought these coastal marshes “miasmal” and drained or filled many of them. In recent years, though, federal and state authorities have grudgingly begun to protect them. In the fall of 1988, a panel of “governors, businessmen, and environmentalists” chaired by New Jersey governor Thomas Kean compared the continuing loss of wetlands to development to “the Texas chainsaw massacre” and proposed that the government in the future allow “no net loss” of the remaining wetlands. As King Canute demonstrated, however, the ocean disregards governments, and, presumably, even blue-ribbon commissions, and as its level rises the area of the wetlands will dwindle. This is not axiomatic: if the marsh has room and time enough to back up slowly, it will, and the drowned wetland will be replaced by a new one. But as a government report pointed out last July, “in most areas, the slope above the marsh is steeper than the marsh; so a rise in sea level causes a net loss of marsh acreage”—that is, in many cases the marsh will run into a cliff it can’t climb.

In some places—along the coast of Maine, say—the cliffs are natural. But in many other places they may be man made, like the levee proposed for Long Beach Island. If I have a house on Cape Cod, and my choice is to build a wall in front of it or to let a marsh come in and colonize my basement, I will likely build the wall. (There are a lot of houses like this. As Joseph Siry notes in a recent book about wetlands, the growth of the American population since the Depression has centered only generally on the states of the Sunbelt; more specifically, it has been along the coasts of those states.) What this wall building will mean if the sea level rises is truly staggering. Should the ocean go up a meter, at least half the nation’s coastal wetlands could be lost. But, said the EPA, “most of today’s wetland shorelines still would have wetlands; the strip would simply be narrower. By contrast, protecting all mainland areas would generally mean replacing natural shorelines with bulkheads and levees. “This distinction,” the relentlessly practical authors add, “is important because for many species of fish, the length of a wetland shoreline is more critical than the total area.” It is also important if you are used to the idea of the ocean meeting the land with ease and grace, not bumping into an endless cement wall.

THERE ARE OTHER REASONS, too, to fear a sea-level rise. A few years ago I spent a happy day with William Harkness, the rivermaster of the Delaware River. He has an office in Milford, Pennsylvania, and a little tower a few miles away on the river, right at a prime shad-fishing bend. Essentially, his job is to watch the Delaware to see how much water flows past each day. If the flow drops below a certain level, he orders the City of New York, which maintains several great reservoirs on the upper reaches of the river, to release water downstream instead of piping it east to the city. The rivermaster’s job results from several decades of litigation between New York City and the communities, especially Philadelphia, near the mouth of the Delaware. Under the agreement, New York must release enough water to keep the “salt front”—the ocean—from advancing up the river. In normal times the water pouring out of a river pushes the ocean back, but in a drought the reduced flow creates a vacuum, which the sea oozes in to fill. During the drought of the 1960s, said Harkness, the salt front nearly reached Philadelphia’s water intakes. “It didn’t, but that’s something you worry about,” he said. “Everyone in Philly turning on a tap and getting salt water.” The only problem with the present arrangement is that during a drought, when New York must release vast quantities of water down the Delaware to hold the salt front back, New Yorkers continue to take showers and wash their hands. During the last severe northeastern drought, in the summer of 1985, city officials made up for the diminished flow from the Delaware by pumping water straight from the Hudson. This worked well—the water turned out to be considerably cleaner than many had feared—but as the flow of the Hudson was reduced the salt front began to creep up that river, and the town fathers of Poughkeepsie became very worried about their supply getting salty. As the greenhouse warming kicks in, increased evaporation could steal 10 to 24 percent of the water in New York’s reservoirs, the EPA concluded; in addition, a one-meter sea-level rise could push the salt front up past the city’s water intakes on the Hudson. In all, says the government, “doubled carbon dioxide could produce a shortfall equal to twenty-eight to forty-two percent of planned supply in the Hudson River Basin.” Which, in turn, worries me, because the city’s water engineers have always looked covetously at the Adirondacks as a possible source of supply, even though they are more than two hundred miles distant. When the Catskill reservoirs were built early in this century, they drowned several small towns and miles of wild land; the same thing will happen if they build a set of reservoirs here. As I have been saying, complications pile upon complications—and pretty soon my vegetable garden is under forty feet of drinking water.

THE EXPECTED EFFECTS of a sea-level rise typify the many consequences of a global warming. On the one hand, they are so big we literally can’t understand them. If there is a significant polar melting, the earth’s center of gravity will shift, tipping the globe in such a way that the sea level might actually drop at Cape Horn and along the coast of Iceland—I read this in a recent EPA report and found that I didn’t really understand what it meant to tip the earth, though I was awed by the idea. On the other hand, the changes ultimately acquire a quite personal dimension: Should I put in a wall in front of my house? Does this taste salty to you? And, most telling of all, the human response to the problems, the utterly natural human attempt to preserve the old natural way of life in this postnatural world, creates entirely new consequences. The ocean rises; I build a wall; the marsh dies, and, with it, the fish.

What’s more, many of the various effects of the warming compound one another. If the weather grows hotter and I take more showers, more water must be diverted from the river, and the salt front moves upstream, and so on. The contradictions multiply almost endlessly (more air-conditioning means more power generated means more water sucked from the rivers to cool the generators means less water flowing downstream, et cetera ad infinitum). These aren’t the simple complications of, say, the summer of 1988, when the hot weather drove everyone on the East Coast to the beaches, only to discover the tide of syringes. These contradictions are the result of throwing every single system into an uproar at the same time, so that none of nature’s reliable compensations can be counted on.

For example, at the same time that the sea level is increasing and the warmer air can gather up more water vapor, and, presumably, the overall precipitation will be increasing, the temperature is also going up. The result, say the computer modelers, will be greatly increased levels of evaporation, and, in many parts of the world, a drier interior to match the sodden coasts.

It’s not simply a matter of heat. If the temperature rises, the number of days with snow cover will likely fall. When the snow-melting season ends, more of the sun’s energy is absorbed by the ground instead of being reflected back to space and as a result the soil begins to dry out. In the greenhouse world, however, this pattern of seasonal change happens earlier because the snow melts sooner. Along with such increases go changes in the weather, of course. In some parts of the world these may offset some of the evaporation—Roger Revelle, the Scripps climatologist, once estimated that flows along the Niger, the Senegal, the Volta, the Blue Nile, the Mekong, and the Brahmaputra would increase, probably with disastrous results in the latter two cases, while flows might diminish in the Hwang Ho in China, and the Amu Darya and Syr Darya (which run through Russia’s principal agricultural areas), the Tigris-Euphrates, and the Zambezi. The United States, as usual, has been most closely studied. America is blessed with ample water—on an average day 4,200 billion gallons of rain fall on the lower forty-eight states. Most of that evaporates, leaving only about 1,435 billion gallons a day, of which, in 1985, only about 340 billion gallons a day are withdrawn for human use. It seems like more than enough. However, as anyone who has ever flown across the nation (and looked out the window) can attest, the water is not spread evenly. Vast sections of the West are arid, though not necessarily unpopulated. Total water use exceeds average stream flow in twenty-four of fifty-three western water-resource regions, a difference made up by “mining” dwindling groundwater stocks and importing water. Much of the Colorado’s flow, for example, is dammed, diverted, and consumed upstream by irrigation and by the millions upon millions of people living (and insisting on green lawns) where it would otherwise be too dry.

And matters may get much worse. After studying the temperature and stream flow records, scientists have concluded that if a “conservative” 2-degree Celsius increase in temperature occurs, the virgin flow of the Colorado could fall by nearly a third. If, as some of the computer models suggest, this is accompanied by a 10 percent fall in precipitation in the Southwest as the result of new weather patterns, water supply in the upper Colorado could fall by 40 percent, but even if precipitation went up 10 percent, runoff would still drop nearly a fifth. Across the West, the picture is similar—in the Missouri, Arkansas, Texas Gulf, and California irrigation regions, runoff could fall by 40 percent or more. In the Missouri, Rio Grande, and Colorado basins, even current water needs could not be met by stream flows after the expected climatic changes. “One model we’re looking at,” says Texas agriculture commissioner Jim Hightower, “predicts a twenty-five percent increase in the demand for irrigation water” from the Ogallala aquifer, the great subterranean lake that irrigates the plains and is already badly depleted. “You can’t pump more water if the well has already gone dry.” Even areas that we’re used to thinking of as ruined may be ruined in new and interesting ways. Lake Erie and the Great Lakes in general became symbols of environmental decline in the 1970s. They have recovered somewhat, but a change in climate may subject them to unprecedented stresses (which is like subjecting the South Bronx to unprecedented decay). Under EPA models of doubled carbon dioxide levels the average level of Lake Superior could fall by a foot and a half—which doesn’t sound like so much, except that the fleet of ships working the Great Lakes are designed to pass within a foot of the bottom of the locks and channels. Ships will have to carry smaller loads and sail more frequently (burning more fuel, which will—you know). Shippers may be aided by a longer shipping season. The central basin of Lake Erie currently sees eighty-three days of ice, but if the temperatures rise, only areas near shore will freeze, and then for three weeks or less. But in that case the erosion along the shoreline, which has been protected by the ice, will increase, since the winter is the season of big storms. And if the ships do keep sailing, it may also increase the supply of sad folk songs—it was a winter gale in 1975 that sank the Edmund Fitzgerald with all twenty-nine hands.

Declining water levels can cause a variety of miscellaneous mischief. When droughts lowered Lake Michigan in the 1960s, dry rot set in along the piers and pilings of Chicago’s shoreline. Hydropower production may drop as flows along the Niagara River fall, pollutants in the lakes may become less diluted, and the warmer lake waters will almost certainly lead to algal blooms and a return of the oxygen deprivation that “killed” Lake Erie once before. That “increased eutrophication could make the Lake Erie Central Basin uninhabitable for finfish and shellfish during the summer,” concluded the EPA.

Across the country and across the world the usual endless list of multiplying dangers can be compiled. “Water quality appears to be vulnerable to deterioration because of increased use of agricultural pesticides as a response to climate change,” reported the EPA. There is an increased risk of forest fires like 1988’s Yellowstone blaze (“The biggest difference between this year and other years is no rain,” the park ecologist Donald Despain said after the fire). As usual, no one knows exactly what will happen. But, the computer model used by Syukuro Manabe, of the National Oceanic and Atmospheric Administration, insists there’s a greater than 90 percent chance that soil moisture across North America, western Europe, and Siberia will decrease.

A OBVIOUS QUESTION is what all this means for agriculture (or, since “agriculture” has become abstracted from everyday life in the same fashion as, say, “the military,” it might be better to ask what this will mean as regards dinner). The answer comes on several levels, the first that of the individual plant. Quite apart from heat and drought, the simple increase in the amount of carbon dioxide in the atmosphere affects plants. Ninety percent of the dry weight of a plant comes from the conversion of carbon dioxide to carbohydrates by photosynthesis. If nothing else limits a plant’s growth—if it has plenty of sunshine, water, and nutrients—then increased carbon dioxide should increase the yield. And in ideal laboratory conditions this is what happens; as a result, some journalists have rhapsodized about “supercucumbers,” and found other green linings to the cloud of greenhouse gases. But there are drawbacks. If some crops grow more quickly, farmers may need to buy more fertilizer. Leaves may become richer in carbon but poorer in nitrogen, reducing food quality not only for humans but for nitrogen-craving insects who may eat more leaf to get their fix. In the best case, direct effects of increased carbon dioxide on yield are expected to be small: annual harvests of well-tended corn crops might rise about 5 percent when carbon dioxide levels reach four hundred parts per million, all other things being equal.

But all other things, of course, won’t be equal. All other things—moisture, temperature, growing season—will be different. It is an obvious point, but one worth repeating: everything we eat, except fish and a few hothouse vegetables, spends its growing life in the open air, “exposed,” in the words of biologist Paul Waggoner, “to the annual lottery of the weather.” Today’s Lean Cuisine frozen entrée stood rooted in some Kansas field last year, where it survived attacks from insects and disease, and grew as fast as its supply of water and sunshine and nutrients allowed. About fifty million acres of America’s cropland and rangeland is irrigated, but even that depends on the weather over any long stretch. And we can’t just stick the wheat crop under glass.

It is a tricky business trying to predict what changes in the weather will do to crops. A longer growing season—the period between frosts—obviously helps; a lack of moisture obviously hurts. If temperatures stay warm, plants grow nicely. If temperatures get really hot, plants wither; a long stretch above 95 degrees Fahrenheit, for instance, means that corn won’t fertilize. The climate models are too crude to project with any precision what will happen in a given area, though that fact hasn’t stopped scientists from trying. As I write this, I have by my side two thick volumes from the United Nations Environmental Programme about climate change and agriculture. Seventy-six scientists from seventeen nations contributed to the report. Should a drought of the severity of the one in 1936 recur in Saskatchewan, farmers working dark brown soils would spend, provincewide, $28,000 less on lubricating oil. Carcass weight of Icelandic sheep falls 802 grams for every degree Celsius decrease in the mean annual temperature, at least in the Arneshreppur district. Should the temperature warm, Japan would suffer a “very severe rice surplus,” especially since most of the rest of the world prefers indica rice to japonica, limiting the export market. The town of Ouricuri will increase its cowpea yield more than five other towns in northeastern Brazil if precipitation should increase 10 percent and evaporation drop an identical amount. If late-winter absolute temperature minima were to increase by about .8 degree Celsius, thus decreasing the frost risk, the upper limit of cultivation on the slopes of the Ecuadoran sierra might rise two hundred meters to the four-thousand-meter mark.

Similar studies have been done for the United States. The potato leafhopper, a serious pest to soybeans, at present spends the winter in a narrow band along the Gulf of Mexico, but, says the EPA, the warmer temperatures in the computer models “suggest a doubling or tripling of the overwintering range,” and thus an increase in “the invasion populations in the northern states by similar factors.” Higher winter temperatures “may lower the incidence of respiratory diseases in livestock,” but hotter summers will almost certainly “increase the costs of air-conditioning in poultry housing.” The horn fly already causes annual losses of $730.3 million in the beef and dairy-cattle industries; if warm weather extended its season by eight or ten weeks, milk production could significantly decrease.

The uncertainty ahead, in other words, extends to the pastures and the fields—to our food supply. Too many unknowns and too many variables make even the broadest predictions difficult. Looking back at the severe droughts of the Dust Bowl years provides scant guidance: on the one hand, the technological revolution in agriculture has tripled yields since that time, but, on the other hand, as the EPA noted, “the economic robustness associated with general multiple-enterprise farms has long since passed from the scene on any significant scale,” and therefore, “the current vulnerability of our agricultural system to climate change may be greater in some ways than it was in the past.” Consequently, most of the experts have simply thrown up their hands. The guesses seem to be mostly that the northern reaches of the Soviet Union and Canada will be able to grow more food and the Great Plains of the United States less—not so little that America couldn’t feed itself but enough below present production that U.S. food exports, which earn the country between $35 billion and $40 billion in a good year, might fall by 70 percent. “It has been suggested,” Stephen Schneider, of the National Center for Atmospheric Research, told Congress last summer, “that a future with soil moisture change would translate to a loss of comparative advantage of U.S. agricultural products on the world market”—a phrase to make an economist shiver on an August day.

As USUAL, there is a strong temptation to clutch at every reassurance: if the models say there will be enough food to go around, whew! But when computers are modeling something as complex as all of agriculture, the potential for error is enormous (or the potential for accuracy is small). The effect of the heat and drought of 1988 made liars of most of the computer programs in just a few weeks. They had concluded that a doubling of carbon dioxide, which will not happen for several decades, might make the weather hot and dry enough to cut American corn and soybean yields as much as 27 percent. But in the summer of 1988, when the rains held off, the American corn crop fell over 35 percent, down 2.6 billion bushels. The summer of 1988 was like the Antarctic ozone hole: it showed up in none of the models.

Even if the heat wave had little to do with the greenhouse effect, we now have some idea of what it will feel like once it does kick in. By early this year, grain storage around the world amounted to only about 250 million metric tons, enough to last fifty-four days—the lowest level since 1973. Worldwide consumption of grain outpaced worldwide production by 152 million metric tons last year. One can run a budget deficit for quite a while, but when the food runs out there’s no central bank to mint some more. A second year of drought would be a “catastrophe,” the assistant secretary of agriculture said. “If we return to a normal situation in the weather, we’ll be okay,” said Nelson Denlinger, executive vice president of the United States Wheat Association.

But there is no normal situation in the weather to return to—that’s the point. The weather of the future cannot be predicted from the weather of the past, nor can its effects. Paul Waggoner, in a National Academy of Sciences report published in 1983, concluded that “the safest prediction of any we shall make is: farmers will adapt to a change in climate, exploiting it and making our preceding predictions too pessimistic.” But farmers depend on the past; that is the source of their skill. All of a sudden, they are like Ethiopian tribesmen hurling spears against Italian tanks. The chance for surprises grows as fast as the changes in the weather. Last fall, when American farmers finally harvested what corn crop there was and took it to the grain elevators, United States Department of Agriculture officials began to find new trouble: corn samples from at least seven states—including Iowa, Illinois, and Indiana, which grow close to half the nation’s crop—were found to be contaminated with aflatoxin, a fungus commonly found in topsoil. When overheated corn kernels crack, the mold rushes in. Aflatoxin is a potent carcinogen, known to cause liver cancer, and corn for human consumption can’t contain more than twenty parts per billion, while immature hogs are limited to a hundred parts per billion and mature cattle to three hundred. As federal inspectors examined harvests under ultraviolet light, an alarming percentage glowed with the fungus; as much as 70 percent of the fields in northeast Texas had aflatoxin levels above the highest acceptable level, reported The New York Times, and forty dairies there had to dump milk from cows fed infected grain. In some cases the corn could be mixed with uncontaminated grain and the aflatoxin levels thus reduced enough to be used as cattle feed; still, an FDA official said, it was a “severe problem.” And it had never occurred to me—or, I suspect, to anyone else who wasn’t a corn farmer—that it might happen.

The thing to remember, as I have said before, is that all these various changes may be happening at once: it’s hotter, and it’s drier, and the sea level is rising as fast as food prices, and the horn fly is spreading, and the hurricanes strengthening, and so on. And not the least of it is the simple fact of daily life in a hotter climate. The American summer of 1988, when no one talked about anything but the heat and when it would end, was, on average, only a degree or two warmer than what we were used to. But the models predict summer could soon be 5 or 6 or 7 degrees warmer than the old “normal.” Science has yet to devise a way of measuring what percentage of people feel like human beings on any given August afternoon, or counting the number of work hours lost to the third cold bath of the day—or, for that matter, reckoning the lost wit and civility in a population concerned mainly with keeping its shirts dry. These are important matters, and a future full of summers like that is a grim prospect. Summer will come to mean something different—not the carefree season anymore but a time to grit one’s teeth and survive. Summer will mean something new in Omaha if the temperature is above 95 degrees fifty days instead of the current thirteen, and in Memphis if it fails to fall below 75 degrees ninety nights a year instead of today’s twenty. We can air-condition, of course (though air conditioning pumps carbon into the atmosphere, and air conditioners often require the use of chlorofluorocarbons), and perhaps that will be the new nature’s greatest effect. Perhaps summer will become the season when no one goes outdoors. But to anyone who lived through the 1988 heat it seems unlikely we’ll simply get used to it.

A certain number of people who didn’t get used to that heat died of it. Public health researchers have correlated mortality and temperature tables. When the weather gets hot, they find, preterm births and perinatal deaths both rise. Heart-disease mortality goes up during heat waves and emphysema gets worse. The EPA notes that if “climate change encourages a transition from forest to grassland in some areas, grass pollens could increase,” worsening hay fever and asthma. If the number of days between 60 and 95 degrees increases, so will the mosquito population. To the EPA this means that malaria, encephalitis, and dengue fever (“severe pain in the joints,” often fatal) might break out in the continental United States, and that there is at least a slight risk of yellow fever and Rift Valley Fever. I find it hard to imagine malaria, but all too easy to conceive of new clouds of mosquitoes harassing me while I weed the garden, or droning by my ear at night. Mosquitoes are bad enough as a force of nature; if we have to blame ourselves for their presence, they may become an unbearable symbol of our folly—our many follies, for it was the desire to be rid of them altogether that led us to poison the world with DDT, of course, and now we may inadvertently enlarge their number.

“A variety of other U.S. diseases indicate a sensitivity to changes in weather,” the EPA reports. “Higher humidity may increase the incidence and severity of fungal skin diseases (such as ringworm and athlete’s foot) and yeast infections (candidiasis). Studies on soldiers stationed in Vietnam during the war indicated that outpatient visits for skin diseases (the largest single cause of outpatient visits) were directly correlated to increases in humidity.” The interesting thing about this last sentence, from the EPA’s official report to Congress on the effects of climate change, is less the fact than its source—that a useful place to look for information about the new American weather is Vietnam. There is nothing wrong with the Vietnamese climate—it is not “better” or “worse” than the various American climates, or the weather in Britain, or the cold of Canada. And people have been able to move back and forth between all these zones, adapting to conditions. In fact, we’ve all often wanted to; a change of climate is perhaps the single biggest inducement to travel. But now the climate is traveling. According to a United Nations study, “the climate of Finland is estimated to become similar to that of northern Germany, of southern Saskatchewan to northern Nebraska, of the Leningrad region to the western Ukraine, of the central Urals to central Norway, of Hokkaido to northern Honshu, and of Iceland to northeast Scotland.” If we felt like keeping the weather we’re accustomed to, it’s we who would have to move, traveling north ahead of the heat.

THE TEMPTATION to spend much time in the sun, reduced by the growing heat, will be further reduced by the erosion of the ozone layer, the health effects of which could be potentially greater than anything stemming from the change in the climate. Ultraviolet radiation is not uniformly dangerous. Ultraviolet A, with wavelengths above 320 nanometers, is necessary for the formation of vitamin D. But the energy in a UV-B photon is much higher than in UV-A; as a result, it can damage cells. In the sunlight we grew up with, ozone and oxygen in the stratosphere screened out much—not all—of the solar radiation with wavelengths between 290 and 320 nanometers. Even at present levels, the UV-B that reaches the earth’s surface ages the skin and can cause skin cancer. Since most of the ultraviolet is absorbed in the first few layers of cells, a creature the size of, say, a human being will feel the effects principally on exposed organs—the skin and the eye. It is the melanin pigment in the upper layer that absorbs most of the radiation; however, depending on the amount of melanin, radiation can penetrate to lower levels, exposing basal cells and squamous cells and causing the mutations in them that lead to cancer. One thing this means is that white people are seven to ten times more likely to contract malignant melanoma than blacks. Interestingly, according to studies quoted by the Environmental Policy Institute, this is a disease less of the field hand than of the office worker; it most often affects parts of the body not usually exposed to the sun (the torso, for instance), and seems to come from sunbathing on vacation. A 3 percent decrease in ozone, which is near what scientists have currently observed, would likely produce two hundred thousand additional cases of skin cancer, mostly in North America, Europe, the Soviet Union, Australia, New Zealand, and Japan.

Ultraviolet radiation can also easily damage the human eye. Eskimos have always worn slitted glasses, because snow reflects 80 to 90 percent of the UV-B that strikes it, while vegetation reflects very little; as a result of the snow glare, eyes often swell shut. (Sand reflects 40 percent, so vacationing in Aruba instead of Aspen may not help much.) Photokeratosis, the scientific name for what is more commonly known as snow blindness, is like a sunburn of the eye. It usually heals without permanent injury. But long-term ultraviolet exposure can result in cataracts and then blindness. Cataracts are already a serious problem in the United States. But here, at least, surgeons are available. The 3 percent decrease in ozone, according to the Environmental Policy Institute, would lead to approximately four hundred thousand new cataract cases a year. Many would go blind, especially in the Third World, where people work outside and where a surgeon is a rare thing. Again, as usual, there are a thousand tiny interactions. We have already seen that hot weather increases the number of premature births. And retinal damage leading to blindness in premature babies is believed by many to be connected with ultraviolet radiation. On a larger scale, the ability of farmers to cope with the changes in the weather may be limited if they have to worry about staying out of the sun. If the damage to the ozone turns out to be more severe than is now expected (and so far all the models have been too conservative), some analysts talk about cattle that could only graze at dusk for fear of eye damage, and farmers that might measure their exposure to the sun in minutes—like workers at a nuclear plant.

The increased ultraviolet radiation could also have direct effects on plants, exacerbating many of the problems caused by the warming. At least two hundred plant species have been tested at elevated levels of ultraviolet, and about two-thirds have shown some degree of sensitivity. The increased ultraviolet seems to limit leaf size, cutting the amount of energy the plants could capture from the sun. Peas, beans, squash, melons, and cabbage were found to be especially affected; one study of soybeans (the world’s fifth-largest crop) showed that a severe depletion of the ozone could cut yields by a quarter to a half. Ozone loss poses an even greater threat to the small marine animals (zooplankton) and marine plant life (phytoplankton). They are sensitive to ultraviolet because they are so tiny; our skin can absorb most or all of the increased radiation, but it penetrates right to the heart of these organisms. There are indications that many plankton species have already reached their maximum tolerance for ultraviolet radiation. “They are under very drastic ultraviolet stress right now,” Donat Haber, of the University of Marburg, in West Germany, told The New York Times last March. “Most of them are incredibly sensitive. When you expose a population of these organisms [to increased levels] they will die within a few hours.” In the case of zooplankton, those that do not die may sink lower in the water to avoid the increased ultraviolet, and this cuts the amount of sunlight they receive. A number of zooplankton, including shrimp, apparently tailor their breeding season to make sure they’re not on the surface in the summer, when ultraviolet levels are at their height; a 7.5 percent reduction of ozone might cut the shrimp breeding period in half.

Some scientists—notably James Lovelock—think that ozone was not necessary for life’s emergence, and argue that certain algae could survive a full dose of ultraviolet. Unfortunately, other studies show that the kinds of plankton that can cope with excess ultraviolet are not as nutritious as the kinds that die. All this is important because the little zooplankton grow into crabs and anchovies and the like, and the little phytoplankton get eaten by larger fish (and some whale species). About half the world’s protein comes from marine species, and in Third World countries the percentage is especially high. And—oh, yes—phytoplankton play a key part in the carbon cycle, sucking in vast amounts of carbon dioxide. If a large part of the world’s algae die, the greenhouse effect will speed up.

THE LIST of miscellaneous effects that will result from changes in the atmosphere is, literally, infinite: everything down to the proverbial (the price of tea in China, the water in the kitchen sink) changes when the world changes on this scale. Researchers have calculated, for instance, that paint will fade, transparent window glazings yellow, and polymer automobile roofs become “chalky” much more quickly if the ozone layer deteriorates. Ultraviolet radiation damages polyvinyl chloride, requiring that it be manufactured with more titanium oxide, a light stabilizer. By 2075, this could add $4.7 billion to the cost of siding and other PVC products. In New York City the 1988 summer heat increased the effects of leaks from underground steam pipes, softening asphalt and causing thousands of “hummocks,” potholes in reverse, in the streets. “When it’s over ninety degrees for a prolonged period, it becomes a minor disaster,” said Lucius Ricco, of the New York City Bureau of Highway Operations. Steel expansion joints bubbled along Interstate 66 around Washington, D.C., during the heat wave, and a hundred and sixty people were injured when a train derailed in Montana, apparently after the heat warped the rails.

Coupled with the physical predictions are endless political and financial conjectures. If the higher northern latitudes warm 8 degrees or more in winter, as some models project, “the fabled Northwest passage would be open,” according to one researcher. “You could sail from Tokyo to Europe in half the time.” Politics could change; Francis Bretherton, of the National Center for Atmospheric Research, told Time that if the Great Plains became a dust bowl and people followed the seasonable temperatures north, Canada might rival the Soviet Union as the world’s most powerful nation.

This game can go on forever, swinging from the absurdly specific to the madly speculative. There is no easy way to say that something can’t happen or is unlikely to happen; such forecasts are based on the past, and now there is no relevant past. In this case, gauging the future from the past is like predicting that a man can jump the same distance on the moon as on the earth. This uncertainty has very tangible effects: if engineers don’t know where the sea level will be, or how much water will flow down a river, they don’t know how much concrete to pour. A group of scientists meeting in Austria in 1985 concluded, “Many important economic and social decisions are being made today on major irrigation, hydropower, and other water projects; on drought and agricultural land use, on structural designs and coastal engineering projects; and on energy planning, all based on assumptions about climate a number of decades into the future. Most such decisions assume that past climatic data, without modification, are a reliable guide to the future. This is no longer a good assumption.” Jesse Ausubel, director of programs at the National Academy of Engineering, said it may become difficult “to find a site for a dam or an airport or a public transportation system or anything designed to last thirty to forty years. What do you do when the past is no longer a guide to the future?” The problem is, there are no good substitutes—even the men who make the general climate models admit that their projections are crude at the global level, wildly uncertain at any lower one. We are left with a vast collection of “mights,” and only one certainty: we have changed the world, and therefore some of the “mights” are inevitable.

OF COURSE, there has always been change, and the future has always been a collection of possibilities. But we have speeded up that change so much that it is really a difference in kind, not quantity. The typical projections of global warming over the next century—an increase of between 2 and 6 degrees Celsius in average temperature—amount to saying that the world’s climate will be changing at ten to sixty times its natural speed, Stephen Schneider, of the National Center for Atmospheric Research, has explained. “Ten times is the best possible case,” he said in a recent interview. But even ten times is an almost unimaginable acceleration; it’s as if we were driving down a highway at sixty miles an hour and suddenly the accelerator got stuck and the brake didn’t work and we were doing six hundred miles an hour. The sixty times as fast hardly matters—it probably wouldn’t be much more impossible to drive the car at 3,600 miles an hour. The difference would come earlier than that. I’ve driven a car a hundred miles an hour, maybe a little faster; on the autobahn I guess some cars hit 120, and Jackie Stewart can cruise at two hundred. But past that would be not faster, just different. You couldn’t turn or brake or even really see what was whipping past you. Your ability to handle a car at sixty does not prove anything about your ability to handle a car at six hundred miles an hour. A car can’t be handled at six hundred miles an hour except on the Bonneville Salt Flats. Similarly, our ability to survive the dust bowl years—our ability to survive the heat in the summer of 1988, though with a lowered water table, depleted grain reserves, and so on—is no proof of our ability to survive what’s coming.

Even the possible scenarios of future change—the melting ice caps, say—reassure us a little bit, because they let us at least begin to imagine living in that world. We can plan where we might move, and contemplate possible changes in our property values, and whether or not our jobs will still exist. But such reassurance is illusory. “Quite simply, the faster the climate is forced to change, the more likely there will be unexpected surprises lurking,” Schneider told Congress.

WHILE AMERICA SWELTERED last summer, scientists on the staff of the Environmental Protection Agency were finishing up the most comprehensive assessment yet made of the possible effects of the climate change. Congress had requested the study two years earlier, and the EPA did its work diligently, studying four regions in great detail and pulling together most of the available literature on the subject. Though the report’s authors were not timid in their conclusions, they did insert several caveats. “We have no experience with the rapid warming projected to occur over the next century. We cannot simulate in a laboratory what will happen over the entire North American continent,” they wrote. And, they added with ominous modesty, “The results are also inherently limited by our imaginations. Until a severe event occurs such as the drought of 1988, we fail to recognize the close links between our society, the environment, and climate. For example, in this report we did not analyze or anticipate the reductions in barge shipments due to lower river levels, the increases in forest fires due to dry conditions, or the impacts on ducks due to disappearing prairie potholes.” Let’s look at that last small item, “the impacts on ducks,” for it sums up many of the lessons of this new artificial nature. As everyone knows, the changes already wrought by man have hurt a lot of other species—this has been true since we built the first dam or plowed the first field. And as the changes have accelerated, so has the damage. Only 29 million birds flew up the midcontinental flyways in the spring of 1988, down from a high of 45 million thirty-three years ago when the Fish and Wildlife Service first started counting. But there have also been great efforts in recent years to save enough nature to accommodate at least some ducks (and bears and elk and eagles) and, at least to a certain degree, these efforts have succeeded. In the summer of 1988, however, as ducks flew north they found very little water. Parts of North Dakota were 90 percent dry, and one aerial survey of Canadian prairie, reported Penny Ward Moser in Sports Illustrated, showed only seven of 330 prairie potholes holding water. The potholes were a product of nature’s slow pace: when the glaciers retreated ten thousand years ago they left pockmarks on the plains. Over the last hundred years or so, men have drained many of them. And last summer the drought emptied most of the rest. “The strongest of the early arrivals staked a claim, mated, and tried to raise a clutch in rapidly dwindling waters, surrounded by predators who congregated nearby, anticipating a summer-long feast,” Moser wrote. Some ducks took one look and decided to forget about mating; they spent the summer floating unproductively on the larger lakes. Others flew farther north, arriving finally at suitable habitat but by then they were too protein-starved to produce eggs. Meanwhile, the ducks that had found potholes to nest in, and had so far survived the lurking predators, began to contract botulism; in the warm and shallow water it became an epidemic. Other ducks—many other ducks—died when the United States Department of Agriculture, attempting to aid drought-stricken farmers, released fifty million acres of “set-aside” and conservation land they had been paying the farmers not to touch. As the tractors roared through, they mowed and baled nests and ducks as well as hay. Millions of fish were dying, too, as temperatures soared in streams and lakes, and lowering water levels concentrated pesticides. Moser, on the farm in northern Illinois where she grew up, wrote: “We see no great blue herons in our streams this summer. There are barely any streams at all. The muskrats’ underwater tunnels are high in the banks above the water.… Hanging over a culvert along the road, we watch some minnows wriggle over mud shallows looking for a deeper pool. Then the minnows reverse direction, pushing over the mud again, back to where they had been. This is the deeper pool.” This is not one country’s sadness, nor is it the story of a single year. Animals and plants that live in refuges around the world may soon find their “sanctuaries” and “preserves” unendurable traps. If the forests indeed die as the weather warms, many animals will go with them; as the EPA report points out, the fig wasp is at a loss without the fig tree and vice versa. Millions of the tiny animals that constitute the coral reefs may already be dying as warmer water kills their main food source, a species of brown algae.

But even if the trees manage to migrate—if the ecosystem avoids a “crash”—wildlife will be in trouble. Animals don’t know they’re in refuges, and they aren’t as adaptable as people. As the temperature warms, the elk will move north out of Yellowstone, and so will the bison and the grizzly and the dozens of other plants and animals that find safety there. When a bison steps across the park line, he is, of course, fair game for hunters, who already line the boundaries at the proper season. The hunting laws can be changed, of course, but hunters are not the only danger the animals face. The way north is cut with roads and fences, crossed by cars, divided up into small chunks. Montana isn’t exactly crowded, but a couple of hundred miles (that is, a couple of degrees Celsius) north of Yellowstone Lake you’re in Great Falls, which is no place for a bison herd. In the Kalahari desert of Botswana, when a drought sent a quarter million wildebeest north in search of water, incalculable numbers of them died along a hundred-mile fence set up to protect cattle. We have confined nature to small parcels; the shifting climate “will find thousands of species blocked by farm fences and fields, four-lane highways, housing developments, and other man-made barriers as they try to escape to cool safety,” Robert L. Peters, of the World Wildlife Fund, writes. “There is reason to believe that the impact on the natural world would rival that of the last Ice Age.” I find myself thinking often of the birds in Mary Austin’s desert, or the purple martin chicks near Moser’s Illinois farm that “cooked to death” in last summer’s heat. They are actual events and also metaphors. The heat will cook the eggs of birds, and that destruction—and the hurricanes and the rising sea and the literally blinding sun—will rob us of our sense of security. There will be no reason to feel secure because there will be no reason to be secure. The old planet is a different planet. That the temperature had never reached 100 degrees at the airport in Glens Falls, the city nearest my home, made it a decent bet that it never would. And then, last summer, it did. There is no good reason anymore to say it won’t reach 110 degrees. We live in a different world; therefore, life feels different.

مشارکت کنندگان در این صفحه

تا کنون فردی در بازسازی این صفحه مشارکت نداشته است.

🖊 شما نیز می‌توانید برای مشارکت در ترجمه‌ی این صفحه یا اصلاح متن انگلیسی، به این لینک مراجعه بفرمایید.