CHAPTER ONE

Of Termites and Computer Models

In May 1995, following New Orleans's fifth consecutive winter without a killing frost, the city was overrun by mosquitoes, cockroaches, and termites. "Termites are everywhere. The city is totally, completely inundated with them,"said Ed Bordees, a New Orleans health official, who added that "the number of mosquitoes laying eggs has increased tenfold." Bordees attributed the infestation to the lack of frost, combined with unusually high levels of rainfall--it totaled 80 inches in the previous year.

Across the Atlantic, residents in the area around Cadiz, in southern Spain, were suffering through the fourth year of the worst drought in that country's recorded weather history. Until 1992 the region had had the highest amounts of rainfall in Spain--84 inches a year. Since then, it has dropped by more than half, to 37 inches. On June 2, 1995, Russian thermometers soared to 93 degrees, melting chunks of asphalt at Sheremetyevo airport. It was the hottest June 2 in Moscow since 1889. Just over a month earlier, snowflakes had covered the Russian capital during the coldest April in the previous 120 years of record-keeping. In China at the end of May, unseasonal torrential rainstorms in Sichuan province killed 62 people, left 25,000 homeless, and destroyed $30 million in property. Two weeks later, Lin Erda, director of China's Academy of Agricultural Sciences, warned his country to prepare for increasingly severe and prolonged droughts, intensified typhoons, and erratic rainfall. If China's climate trends continue, he added, much of the country will face shorter crop-growing periods and increased water deficits in the next century. In mid-June 1995 the death toll from a broiling heat wave in northern and central India reached 300. Temperatures topped 113 degrees Fahrenheit in Uttar Pradesh, Rajasthan, and other regions. Press accounts noted that Indian summer heat waves are normally broken by intermittent rainstorms. But that year there was no respite from the relentless heat.

Halfway around the globe, in the midwestern United States, a series of rainstorms triggered the second 100-year flood in the region in three years. A month later, a heat wave in Chicago killed about 500 people.

Although it has lurked in the dim margins of public attention for the last few years, global warming first emerged on the public stage during the brutally hot summer of 1988, when Dr. James Hansen of NASA's Goddard Institute for Space Studies warned a congressional panel that it was at hand.

Following Hansen's testimony, growing numbers of scientists raised more concerns about warming, predicting erratic and extreme weather events--early symptoms of a rise in the average global temperature. (Today the term climate change has emerged as the name of choice for the warming-driven destabilization of the planetary climate system.) An extreme possibility that many scientists fear is that, under increasing stress, the earth's climate could snap abruptly into a much warmer regime. But even in the absence of such an abrupt, catastrophic change, they fear that the heating could produce increases in severe floods that threaten coastlines, and a wave of droughts, hurricanes, and snowstorms. They foresee rising sea levels and the spread of infectious diseases unleashed by warmer temperatures. What ultimately troubles a consensus of scientists is the prospect of a dramatic rise in the average global temperature on the order of 3 to 4 degrees Celsius (6 to 8 degrees Fahrenheit) in the next century, if present trends continue. That change is roughly equal in magnitude to the difference between the last ice age and the climate today.

In 1988, in response to those concerns, the United Nations established the Intergovernmental Panel on Climate Change (IPCC) to assess the impacts of climate change. The assessments were to be used as the basis for strategies by which nations could curtail their [CO.sub.2] emissions. Comprising the leading 2,500 relevant scientists in the world, the IPCC issued a series of reports through its two primary working groups. Working Group I focused on the state of the science while the mission of Working Group II was designed to analyze the impacts of climate change. (A third IPCC panel, composed primarily of economists, was commissioned to examine primarily the costs of mitigating climate change.) The two IPCC scientific panels set up to report to the UN Framework Convention on Climate Change constitute one of the most authoritative bodies of scientists ever assembled around a single area of scientific concentration. In 1990, in the first of four reports the panel has issued, the IPCC concluded that a doubling of carbon dioxide near the middle of the next century will increase the average global temperature by as much as 4.5 degrees Celsius. (They subsequently revised that upper limit down to 3.5 degrees, not because of any scientific correction, but, ironically, because of estimated increases in emissions of low-level air pollutants. In the short term, these pollutants mask the warming of the larger atmosphere.) In 1994, the IPCC, citing new findings from ancient ice-core records, noted that the planet's temperature is demonstrably sensitive to changes in [CO.sub.2] concentrations in the atmosphere. The paleontological record, as interpreted by the scientists, shows that prehistoric changes in carbon dioxide concentrations correlate very closely with rapid, dramatic snaps in the climate.

You don't have to be a scientist to understand the basic workings of the greenhouse effect. Under normal conditions, when the sun's rays warm the earth, a percentage of that heat is reflected back into space. The rest of the heat is absorbed by the oceans and the soils and warms the surrounding areas to create the climate conditions we live in. But the recent buildup of carbon dioxide in the atmosphere traps in heat that otherwise would be reflected back into space. The resulting warmth expands ocean water, causing the sea level to rise--just as the level of water heated on a stove rises in its pan. The heating also accelerates the process of evaporation, even as it expands the air to be able to hold more water. The resulting airborne water vapor, in turn, traps more heat, perpetuating the cycle. The more heat that is trapped, the more intense the greenhouse effect.

On the planetary scale, the earth's carbon cycle is at the center of the evolution and continuation of life. Soon after the earth's formation, its atmosphere consisted of around 95 percent carbon dioxide. As plant life evolved, the spreading vegetation absorbed that carbon dioxide and, as it decomposed, stored it in the form of carbon-rich coal and oil deposits. Eventually the earth's plants and oceans absorbed and stored so much carbon dioxide that they reduced the atmospheric concentration of the gas to less than three-tenths of one percent--a level that made the earth's climate hospitable to oxygen-breathers, mammalian life, and human civilization. But the recent explosion in fossil fuel emissions has begun to increase that [CO.sub.2] concentration--in effect, reversing millions of years of the natural carbon cycle.

In terms of the carbon content of our atmosphere, "we are in uncharted waters relative to the last 400,000 years," according to Dr. James McCarthy, who is director of Harvard University's Museum of Comparative Zoology and a professor in Harvard's department of earth and planetary sciences.

In June 1995 more than 70 people died from flooding in Bangladesh, while countless others suffered from outbreaks of malaria as mosquitoes swarmed in following the heavy rains. Overall, the floods affected nearly 10 million people. "The area suffers flash floods almost every year, but they [normally] never last more than two or three days,"said a provincial official, who noted that this year's rainstorms lasted nearly two weeks. The following month, Ghana experienced its heaviest rainfall in thirty years. That same summer, according to the British Meteorological Office, Great Britain endured its hottest summer since 1659 and its driest summer since 1721. In July northeastern Brazil suffered its worst drought in this century, as rainfall in the region declined by 60 percent. Nine months later, mudslides there, triggered by torrential rainstorms, killed 26 residents. "In the last twelve hours, we have received 9.3 inches of rain when precipitation for the whole month averages fourteen inches," said the mayor of the provincial capital of Salvador. Despite the international scientific consensus, the small band of industry-sponsored "greenhouse skeptics" continue to maintain that the trend is too unproven to justify action. Until recently, their skepticism had some basis, given the black holes of uncertainty in our knowledge of the planet's complex and exquisitely interrelated climate system. The skeptics have repeatedly pointed out, for example, that although the world's output of carbon dioxide has essentially exploded since 1940, there has been no corresponding increase in the global temperature since that time. They argue, moreover, that scientists know too little about certain dynamics--ocean-atmosphere exchanges, the role of clouds, the mechanisms of the deep oceans' transfer of heat from equatorial to other latitudes--to predict accurately the behavior of the global climate. The naysayers also emphasize the inadequacy of a major climate research tool--a type of computer model known as the general circulation model. This model is technically unable, they argue, to perform the large numbers of calculations needed to completely simulate climate systems.

As defensible as these objections once were, today they are obsolete. For one thing, there is now little doubt that, in their gross and aggregate outcomes, the computer models are correct. Moreover, the delayed onset of detectable warming was explained by an important discovery that was made a couple of years ago. Scientists had already known that atmospheric warming is delayed because the surface waters of the oceans store heat at deeper levels before subsequently releasing it. But not until the beginning of this decade did they discover that the same fossil fuel emissions that contribute to global warming by emitting carbon dioxide simultaneously mask that warming by emitting sulfate particles as well. While the carbon dioxide high in the upper atmosphere acts to trap heat inside the global greenhouse, the lower-level umbrellas of sulfate particulates reflect the sunlight back into space, creating localized cooling effects that conceal the continuing warming. "If everyone in the world could magically [remove the sulfates from coal and oil], you would see the fingerprints of global warming in a very short time," says Harvard's McCarthy.

Unfortunately, the sulfate aerosols cannot be considered a long-term neutralizing agent against global warming. For one thing, they remain airborne for only several weeks and mostly in localized areas, while carbon dioxide remains in the atmosphere for one or two centuries. Since both by-products of fossil fuel burning are released simultaneously, the much-longer-lived carbon dioxide will eventually overwhelm the transient sulfates. The sulfates emitted by power plants, factories, automobiles, and volcanoes are regarded by scientists less as an offset than as a mask.

But there is a second reason not to regard sulfate aerosols as a remedy: They are a serious and persistent public and environmental health hazard. They cause low-level air pollution, which visits on us lung disease, crop destruction, and acid rain. A cure of such proven toxicity can scarcely be regarded as a cure at all. At bottom, sulfates are simply another airborne industrial poison generated by the combustion of fossil fuels.

A massive but short-lived pulse of sulfates masked the progression of atmospheric warming when Mount Pinatubo in the Philippines erupted in 1991. But since mid-1992, when the volcanic sulfate debris began to settle out, the planet's surface air temperature has increased by a half-degree Celsius--as much as it had warmed between 1900 and 1990, according to scientists from NASA's Goddard Institute for Space Studies and the National Oceanic and Atmospheric Administration's (NOAA) National Centers for Environmental Prediction.

Earlier generations of computer models were inadequate because their results did not always correspond to the known recorded climate history of the last century. But in the more recent models sulfate aerosols have been included as a significant factor. These models are all still too crude to forecast particular impacts in specific geographical locations--their resolution needs sharpening. But in large gauge they do match the historical record--and the types of impacts they project, I believe, are already beginning to happen.

By mid-June 1995, enormous fires burning in Canadian northern forests had spread into central Canada, expanding at a rate of about 240,000 acres a day. That year fires in Canada's boreal forests consumed more than 3 million acres, an area half the size of the Netherlands. A study by Canadian Forest Service scientists concluded that the northern forest has lost almost a fifth of its biomass over the last 20 years because of enormous increases in fires and insect outbreaks. Before 1970 the forest had absorbed 118 million tons of carbon each year, according to the study--more than counterbalancing Canadian fossil fuel emissions. But in the last decade that balance has shifted, and the forest has released on average 57 million tons of carbon each year. The Canadian Forest Service concluded that the reversal of the forests--from an absorber to an emitter of carbon dioxide--may be contributing to an accelerating buildup of greenhouse gases in the earths atmosphere.

Nor were the weather extremes confined to northern latitudes. While western portions of Australia experienced record rainfalls in the summer of 1995, the city of Sydney, in eastern Australia, recorded its first rainless August in history. Several months later, the island of St. Thomas was blasted to shambles by one of fifteen named hurricanes that ravaged the Caribbean that fall. Those devastating storms made 1995 the worst hurricane year since 1933.

In late 1995, after scientists had successfully integrated the cooling effects of sulfates into their climate models, the 2,500-member IPCC reported that it had detected the "fingerprint" of human activity as a contributor to the warming of the atmosphere. "A pattern of climatic response to human activities is identifiable in the climatological record," the IPCC found. In other words, global warming could no longer be attributed to natural climate variability. Furthermore, the scientists observed that the projected warming is due to the increasing quantities of carbon dioxide released by our burning of coal and oil.

The IPCC report was the scientific equivalent of a smoking gun. It should have laid to rest nearly a decade of squabbling over the verification of global warming.

James McCarthy commands a broad overview of the current research. Between 1987 and 1993 he chaired the Scientific Committee for the International Biosphere-Geosphere Programme, a research complement to the IPCC. There he oversaw the work of the leading climate scientists from sixty nations. Dr. Bert Bolin, the Swedish physicist who, until mid-1996, headed the IPCC, served as his vice-chair. In 1996 McCarthy became chair of the Advisory Committee on the Environment of the International Committee of Scientific Unions.

"There is no debate among any statured scientists of what is happening," says McCarthy. By "statured" scientists he means those who are currently engaged in relevant research and whose work has been published in the refereed scientific journals. "The only debate is the rate at which it's happening."

McCarthy echoes concerns that popular accounts of global warming have created a misconception in the public mind. "Questions about global warming--when will it happen, what is the threshold--are the wrong questions," he says. "The real question involves the instability of the climate system. If the world became, on average, ten degrees warmer in the winter and ten degrees cooler in the summer, the average global temperature would remain the same. But the economic and agricultural and ecological effects would be disastrous. The real question is how the planet will be affected by the extremes of a climatic instability that could put whole segments of, say, agriculture out of business at either end of its spectrum of extremes."

Noting that the recent phenomenon of five consecutive El Nino years (marked by a vast pool of warm water in the eastern equatorial Pacific Ocean) is unprecedented, McCarthy wonders whether "we have already tripped into a new climate regime where the old anomalies have become the new norm. And we have yet to appreciate the biological impacts of prolonged warming. The concern of many scientists is that by pushing the concentrations of atmospheric carbon dioxide to higher and higher levels, we are directing the system into a new state that may be considerably less stable than what we have enjoyed for the past several hundred thousand years."

El Nino is associated with intense storms in the Pacific Ocean, and it promotes severe droughts in continental interiors. Several scientists note that the current, extended El Nino may be followed by its opposite--a protracted La Nina, whose upwelling of cold waters from the ocean depths could actually cool the climate for the next several years. While that would add even more confusion to the public perception of global warming, it would nevertheless be consistent with the intensifying weather oscillations that mark the erratic and nonlinear processes of climate change.

In November 1995, following record rainfalls and extensive flooding in France and the Netherlands, Typhoon Angela--the most powerful storm in nearly two decades--killed more than 600 Filipino residents. At the end of the year frustrated officials were forced to cancel the World Cup ski tournament in Austria because record high temperatures and a lack of snow cover made skiing impossible.

At the same time northern portions of Mexico experienced the coldest winter in 25 years, and on New Years Day 1996, Mexico City saw its first snowfall in 20 years. That same month, when Sapporo, Japan was buried by unprecedented levels of snow, officials had to call in the military to help dig out the city.

A second smoking gun--proof of the increasing instability of the world's climate--was discovered in 1995, when a team of scientists at the NOAA's National Climatic Data Center verified an increase of extreme weather events in the United States, the former Soviet Union, and China (the only areas for which they examined the data). These areas, they found, are experiencing more extreme rain and snowfalls, more winter precipitation, more droughts and floods, and more extremely warm weather. The team of scientists, headed by Dr. Thomas Karl, compiled an index that showed elevated minimum nighttime and winter temperatures, higher-than-normal levels of precipitation during winter months, a higher-than-normal number of extreme one-day rain or snowfalls in the United States, and unusually severe droughts during summer.

The NOAA team's findings are extremely significant. The signature of the recent climate record, they found, is unlike natural variability. Rather, it resembles the kinds of changes that would be expected from escalating emissions generated by the burning of oil and coal. The scientists concluded that the growing weather extremes are due, by a probability of 90 percent, to rising levels of greenhouse gases. Specifically, they declared that the climate in the United States is becoming more "greenhouse-like." In scientific terms, they concluded that "the late-century changes recorded in U.S. climate are consistent with the general trends anticipated from a greenhouse-enhanced atmosphere."

The events they identified, in other words, are precisely what the corrected climate models project.

In February 1996 Texas residents shivered through ice, snow, and single-digit temperatures--the coldest weather to hit the region in almost a decade. But an extraordinary March brought with it record temperatures--in the mid-nineties. As a result, northwest of Forth Worth, grass and brush fires blackened a swath of land the size of Manhattan. The fires continued intermittently for a month, scorching more than 300,000 acres in one of the worst fire seasons in Texas history.

In March 1996 a deadly blizzard in the western Chinese highlands prompted appeals for international aid to avert famine. At least 60,000 ethnic Tibetan herders in Qinghai province and Tibet faced starvation from storms that drastically reduced their food supply, wiping out 750,000 head of livestock. The storms, accompanied by record-setting lows of minus 49 degrees, killed 48 herders in Sichuan, according to reports. According to Chinese officials, "This year's snowfall is four times greater than last year."

By March 1996, more than 20 percent of Laos's rice paddies had been decimated by five successive years of floods, droughts, and pest attacks, according to reports from Reuters. UN officials estimate the country faces a shortage of 132,577 tons of rice--which amounts to 75 percent of the caloric intake of the Laotian people. One official estimated that without immediate food aid, nearly 10 percent of Laotians are at risk for malnutrition and starvation. The official noted that the country's persistent and worsening food crisis was propelled into a pull-fledged disaster by last year's floods--the worst in Laos in 30 years.

The most striking aspect of the recent severe weather events is that virtually all of them set a new record. Are these events absolute proof of global warming? Not taken alone--anecdotal evidence never is. But in combination with the gathering weight of other evidence--both from scientific laboratories and from the world's oceans, glaciers, and forests--they present an urgent and compelling case. Nor was 1995 an aberration. The severe weather has continued into 1996. My own backyard became a snow-buried casualty of New England's 1995-96 winter from hell. As late as May 13, we experienced record low temperatures. Eight days later, the temperature set a new record high, for that date.

The naysayers have dubbed global warming "the mother of all environmental scares." Despite its sarcasm, that dismissal contains a recognition that potentially destabilizing social and economic and philosophical issues cluster around the phenomenon of climate change.

The threat of climate change challenges the capacities of our governments and imperils the basic processes of democracy. And it highlights with startling ferocity a basic shortcoming of our economic system: That system ignores the fact that the global economy is rooted in and bounded by the global environment. Our system of economic accounting counts as profit all the coal and oil the world consumes, but it fails to enter the resulting environmental damage anywhere on the global balance sheet.

It is not only the oil and coal spokesmen who deny the evidence of climate change. A number of economists, political commentators, and conservative ideologues downplay the urgency of the issue as well. Some say that if we simply allow the free market to flourish over the next several decades, we will accumulate enough capital to pay for remedial actions. Huge economic dislocations would be involved in switching to new sources of energy, they argue. Paying to remedy the damage later, they contend, will be no more costly and less disruptive than paying for preventive measures now.

Several years ago James Watkins, then secretary of energy in the Bush administration, expressed horror at the prospect of making an economic shift as extensive as global warming demands. "What if the science is wrong?" he asked me. "Can you imagine how much it would cost?" "What if it's right?" I responded. "What would the costs be then?" Watkins did not respond.

The "pay later" argument is absurd on its face. Numerous economists have shown that the longer we delay making an energy transition from fossil fuels to renewable energy, the costlier that transition will be, as the pressures of environmental deterioration reduce the time we have to plan and implement the transition.

Other naysayers point to estimates that certain agricultural areas may actually benefit from a slight warming and subsequent longer growing seasons. A little bit of warming isn't really so bad, they say, ignoring the fact that crops in the developing world would be decimated. But they fail to acknowledge how intricately the earth's climatic and ecological systems are interrelated. Scientists use the term feedbacks to refer to the complex and often unanticipated chains of events that can ripple through the ecosphere when one part of it is perturbed.

Take baby seals, for example.

Several springs ago, a large number of seal pups were found to be starving to death on the beaches and rocks of the northern California coast. Responding to the alarm, hordes of well-meaning volunteers--armed with baby bottles and diced fishing bait--converged on the area and eventually nursed many of the pups back to health. But the starving pups--like the proverbial canary in the coal mine--were an expression of a larger problem. Every spring seal pups feed on fish that inhabit the surface waters off northern California. That spring, however, the surface waters had warmed so much that the fish descended to colder, deeper levels to survive. Unfortunately, their new habitat was deeper than the seal pups could dive--leaving them stranded and malnourished until the sympathetic humans rescued them.

Some feedbacks may be induced by even a slight increase in average global temperatures. The most powerful "greenhouse gas"--and the one most responsible for global warming--is atmospheric water vapor. At a concentration thirty times greater than that of carbon dioxide, atmospheric water vapor cannot be directly affected by increasing or reducing oil and coal emissions, according to Dr. Michael Oppenheimer, a former researcher at the Harvard-Smithsonian Center for Astrophysics and now a senior scientist for the Environmental Defense Fund. Rather, its effect is indirect: Even the slight warming caused by the carbon dioxide buildup leads to more evaporation of ocean waters, which in turn causes a disproportionate increase in the amount of heat-trapping water vapor in the atmosphere.

A more dramatic feedback could accelerate the thawing of the Alaskan tundra. For thousands of years on the northern slope of Alaska, the plants of the tundra have been taking up carbon dioxide. When these plants die, before they can decay, they are frozen in deep layers of permafrost, where they store carbon dioxide. But in 1993 scientists discovered that this process has reversed itself and that the tundra has begun to thaw, releasing stored carbon dioxide into the atmosphere.

Dr. Walter Oechel, of San Diego State University, attributes this unanticipated thaw, which began sometime before 1981, to a marked warming trend in the high Arctic, where the mean summer temperature rose from 35 degrees Fahrenheit in 1971 to 41 degrees twenty years later. If the global temperature increases even slightly, it could accelerate the release of huge amounts of [CO.sub.2] (as well as methane, another potent greenhouse gas), which in turn could hasten the retreat of the Arctic ice pack, which could trigger a cascade of uncontrollable catastrophic reactions. The Arctic ice cover, at present, cools the ocean currents and reflects sunlight back into space. But when that ice cover melts and exposes the dark soil underneath, the Arctic landmass will absorb--rather than reflect--sunlight, thereby accelerating the warming of the oceans.

What most frightens scientists is this possibility of runaway feedbacks. To be sure, global warming is not likely to be a smooth, gradual, linear process. But scientists do not know at what threshold a slight increase in warming--accelerated by feedback effects--could abruptly catapult the planet into an entirely new climate regime.

The skeptics who say a little warming isn't so bad are betraying not only our scientific knowledge of natural systems but our firsthand recognition of their exquisitely complex intricacies. Their view insults our basic sense of reality.

If all our scientific endeavors--to understand the physical universe, the human body, and the planetary environment--share one lesson, it is this: Throughout human history, the complexities of nature have consistently surprised and outflanked the human mind. Did the last generation of pharmaceutical researchers anticipate that microbes would resist the cures they invented, generating new forms of immunity and, in some cases, increased virulence? Did their pharmaceutical forefathers foresee the side effects of the cures they invented? The casualties are in the literature.

Regardless of the pronouncements of climate scientists on both sides of the warming argument, this fact is inescapable: We are, through our industrial activities, tampering with immense planetary systems whose complexities and interactions we barely understand.

"The inhabitants of planet Earth are quietly conducting a gigantic environmental experiment," says Dr. Wallace S. Broecker of Columbia University's Lamont-Doherty Earth Observatory. "So vast and sweeping will the consequences be that, were it brought before any responsible council for approval, it would be firmly rejected."

A third important contribution to our understanding of the global climate appeared in the spring of 1995, when David J. Thomson, a signals analyst at AT&T Bell Labs, published his evaluation of a century of summer and winter temperature data. While some greenhouse skeptics had attributed this century's atmospheric warming to solar variations, Thomson discovered the opposite: The accumulation of greenhouse gases had overwhelmed the relatively weak effects of solar cycles on the climate. But Thomson also discovered something that may explain the unseasonal nature of some of today's extreme weather events. Around the beginning of World War II, accelerating industrialization led to a skyrocketing of carbon dioxide emissions. At that point, Thomson found, the timing of the seasons began to shift. After 1940, he wrote in the journal Science, the seasonal patterns "of the previous 300 years began to change and now appear to be changing at an unprecedented rate."

In the northern hemisphere spring is now arriving a week earlier than it did twenty years ago because of increased concentrations of carbon dioxide, according to Drs. Charles Keeling and T. P. Whorf of the Scripps Institution of Oceanography and J. F. S. Chin of the Mauna Loa Observatory in Hawaii. These researchers wrote in 1996 that the changes in seasonal timing "reflect increasing assimilation of carbon dioxide by land plants in response to climate changes accompanying recent rapid increases in temperature."

This point is important. One of the major arguments of the naysayers has been to contend that the planet did not warm significantly between 1940--when emissions of greenhouse gases began to skyrocket with the wartime industrial mobilization--and the mid-1970s, when temperatures took an upward course. Between 1940 and 1970, much of that newly generated carbon dioxide may have been absorbed by forests and oceans, and its effects may have been temporarily neutralized by the sulfate cover. But it is precisely since 1940 that the timing of the seasons has changed. This change could be a significant driving force behind some of the recent extreme weather events.

The worst possible consequences of global warming involve more than an alteration in the seasons or even a steady increase in global temperatures. The scientists' most cataclysmic, if improbable, scenario is based on paleontological records culled from ocean sediments and ice-core samples from glaciers. Until recently, scientists believed the transitions between ice ages and more moderate climatic periods had occurred gradually, over several centuries.

No longer.

Ancient ice cores are made of annual layers of frozen water, which hold natural records of our ancient atmosphere. Several years ago researchers examining them found that those ice age transitions, involving temperature changes of up to 10 degrees Celsius, occurred within the space of only ten years--a virtual millisecond in geological time. In the last 70,000 years, they learned, the earth's climate has snapped--abruptly and dramatically--into radically different temperature regimes. "Our results suggest that the present climate system is very delicately poised," said Scott Lehman, a researcher at the Woods Hole Oceanographic Institution, announcing findings in 1993. "The system could snap suddenly between very different conditions with an abruptness that is scary. It's a strongly non-linear response, meaning shifts could happen very rapidly if conditions are right, and we cannot predict when that will occur. Our studies tell us only that when a shift occurs, it could be very sudden." In an interview with The Boston Globe he added, "You don't want to push your luck by perturbing the system. A small effect might produce a major change."

Lehman's cautionary tone is underscored by findings that the end of the last ice age, some 10,000 years ago, was marked by a series of extreme oscillations between warming spikes and severe regional deep freezes. As the surface waters of the North Atlantic warmed, the Woods Hole team found, rising temperatures triggered snowmelts in the Arctic and increased rainfall in the northern latitudes. That infusion of fresh water diluted the salt content of the ocean, which in turn, changed the course of the deep-ocean warming current from a northeasterly direction to one that ran nearly due east. Should such an episode occur today, the researchers concluded, "the present climate of Britain and Norway would change suddenly to that of Greenland and Northern Canada."

The foremost researcher of deep-ocean-current dynamics, Wallace Broecker of Lamont-Doherty, observed in November 1995 that an ocean conveyor current "shutdown or comparable drastic change is unlikely, but were it to occur, the impact would be catastrophic. The likelihood of such an event will be highest between 50 and 150 years from now, at a time when the world will be bulging with people threatened by hunger and disease and struggling to maintain wildlife under escalating environmental pressure. It behooves us to take this possibility seriously. We should spare no effort in the attempt to understand better the chaotic behavior of the global climatic system."

The naysayers' rallying cry of last resort is uncertainty. We know too little about climate change to act, they assure us. Until the holes of scientific uncertainty are filled, they warn, it would be irresponsible to act--especially when action could be costly and, worse, so revolutionary as to disrupt the established order of things.

What they do not mention is that to avoid acting could be to compound, incalculably, the costs of addressing climate change and its disruptions to civilization. What they do not mention is that uncertainty cuts both ways.

At a recent meeting at Tufts University, Dr. Richard Lindzen of the Massachusetts Institute of Technology, arguably the most academically accomplished of the scientific skeptics, described at great length the various shortcomings of the climate models and their inability to resolve a number of significant uncertainties. When he had finished, Dr. Michael McElroy, chairman of Harvard University's department of earth and planetary sciences, recalled that in the early 1980s scientists had spent several years modeling projected ozone depletion. "When researchers finally conducted actual ozone measurements in the atmosphere, their findings were far worse than the worst case scenarios of the models," he said, adding, "Just because a situation is uncertain does not imply that the underlying reality is benign."

Our scientific knowledge, in other words may even be lagging behind nature. The momentum of globally disrupting climate change may be further advanced than earth science, with its areas of uncertainty, is currently able to prove.

What we do know is that the earth's systems are showing irrefutable signs of climate-related stress. The evidence goes beyond computer models and laboratory calculations. It lies in numerous research discoveries (examined later in this book) about the oceans, the forests, the glaciers, and the soils, and in the dramatic outbreaks of infectious diseases under the forces of climatic change.

Moments like these are what we make of them. They can swamp us with a paralyzing hopelessness, or they can inflame us with a new sense of purpose. What is needed, I think, is the social counterpart to a climate snap--a rapid, immense, worldwide gathering of political will.

When I was young, my father told me the countries of the world would make peace only when they were threatened by invaders from outer space. Today it is climate change that poses a common threat to all of humanity. Yet the situation also contains a hopeful potential within its grim prospect--a moment of extraordinary, thrilling opportunity.

Under all the political instability that marks the end of this millennium lurks the single message that the world we have created needs to be changed. Too many elements of our social and economic systems, far from serving human needs, are now frustrating our survival as a civilized species.

Finding solutions--given the fury with which the battle over climate change is being waged--will require a massive mobilization of our determination. It will mean putting aside, at least temporarily, many things that divide us. It will demand of us a huge leap in thinking--and mustering the collective will to force the changes our fevered atmosphere requires.

The resistance will be that strong. Necessity for change and the requirements for our survival are that great.

Introduction Climate Change is Here. Now	p. 1
of Termites and Computer Models	p. 15
the Battle for Control of Reality	p. 33
a Congressional Book Burning	p. 63
the Changing Climate of Business: Boom or Bankruptcy	p. 85
After Rio: the Swamp of Diplomacy	p. 107
Headlines from the Planet	p. 135
the Coming Permanent State of Emergency	p. 153
One Pathway to a Future	p. 171
Appendix a Scientific Critique of the Greenhouse Skeptics	p. 197
Notes	p. 239
Index	p. 259
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The Heat Is On The Climate Crisis, The Cover-up, The Prescription

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