Text by Robert H. Boyle

and so is the earth. James Hansen warns that in the next 100 years our planet could get as hot as it was 65 million years ago, when the dinosaurs disappeared.

 Busloads of excited tourists disembark every day outside Tom's Restaurant at 2880 Broadway in Manhattan. They have come to render homage to the greasy spoon of Seinfeld sitcom fame, and they are absolutely unaware of an infinitely more important program under way upstairs on the seventh floor. There, James E. Hansen, chief of NASA's Goddard Institute for Space Studies and adjunct professor of geological sciences at Columbia University, leads a team of scientists assessing the climatic-and possibly climactic-fate of this planet as it spins into the third millennium.

 Aside from the receding threat of nuclear war, no issue is more vital than the one occupying Jim Hansen and his Goddard group: climate change, popularly known as the greenhouse effect, with its potentially devastating impacts on nature and civilization. At the current rate of global warming, and as envisioned by climatologists, life on earth is hurtling toward conditions never before experienced.

 By the year 2050-only as far in the future, after all, as 1950 is in the past-the global temperature could be 3 degrees Fahrenheit warmer than it is now. It has not been that hot for 200,000 years, a time well before modern humans evolved. By 2075 a 5-degree jump would make the planet its hottest in 4 million years, and by the end of the coming century the earth could be as hot as it was 65 million years ago, when the dinosaurs disappeared. 

Rapid heating on this scale will change the very face of the planet and cause chaos for the global environment, the economy, and politics. Glaciers will melt, and as seas heat and expand, the ocean will rise, drowning low-lying island nations and coastlines. Say sayonara to the Maldives, the Pacific atolls, Bangladesh, the Nile River delta, and much of the East and Gulf coasts of the United States. Tens of millions of people will be forced to move, and move again, in a kind of endless caravan, bearing conflict and disease. Adapted to specific climate zones, plants and animals will be hard pressed to move north; climate zones could shift 400 miles north by the end of the next century-far faster than trees and other plants spread after the retreat of the last glacier-and many species will become extinct. Old forests will burn, farmland will succumb to drought, and floods will increase. 

As Wallace Broecker, a geochemist at Columbia University's Lamont-Doherty Earth Observatory, warned in the late 1980s, "Earth's climate does not respond in a smooth and gradual way; rather, it responds in sharp jumps. These jumps appear to involve large-scale reorganizations of the Earth system. If this reading of the natural record is correct, then we must consider the possibility that the major responses of the system to our greenhouse provocation will come in jumps whose timing and magnitude are unpredictable. Coping with this type of change is clearly a far more serious matter than coping with a gradual warming." 
 

Jim hansen, now 58 years old, is a lanky six feet, with receding, light-brown hair. He occupies a relatively neat 15- by 20-foot office at the Goddard Institute for Space Studies, his desktop filled with orderly stacks of research papers. He still has the soft-spoken, aw-shucks manner of someone from small-town Iowa-a manner that seems somewhat at odds with the dire environmental forecast he has been making for more than a decade. In 1988 Hansen made the greenhouse effect world news when he told a Senate committee, "The greenhouse effect has been detected, and it is changing our climate now." In the uproar that followed, Hansen got tremendous, well, heat from industry, anti-enviro talk show hosts, and politicians, as well as from many fellow scientists. But not only was Hansen right then, he has been right so many times since that he has assumed a prophetic stature rare in history. Michael Oppenheimer, chief scientist for the Environmental Defense Fund and an author of a major United Nations report on climate change, says of Hansen's work, "His science is impeccable, and his prescience is unparalleled." In other words, Nostradamus, get lost.

 First proposed more than 100 years ago, the greenhouse effect theory postulates that manmade emissions of carbon dioxide and other trace gases act like glass in a greenhouse surrounding the earth. (The term greenhouse effect is really a misnomer; the carbon dioxide and water vapor naturally present in the atmosphere already function like greenhouse glass. In popular usage, greenhouse effect refers to the problem that comes with adding manmade gases.) Although greenhouse gases allow sunlight to pass through to the earth, they trap heat being carried back off into space and radiate some of it back down here. Thus, the more gases emitted through human activity, the more the planet warms.

 Essential to life, carbon is found in everything alive or that ever lived. In 1800, before the Industrial Revolution began in earnest, the atmosphere naturally contained 280 parts per million (ppm) of carbon dioxide. Then, with the eventual large-scale burning of coal, oil, and gas-literally fossil fuels, the entombed remains of plants and animals that lived millions of years ago-atmospheric levels of carbon dioxide accelerated. Ice-core samples from 1910 show that the atmosphere contained 295 ppm of carbon dioxide, and in 1958, when C. Douglas Keeling of the Scripps Institute of Oceanography began his landmark annual measurements at Hawaii's Mauna Loa Observatory, the reading was 315 ppm. By 1998 the reading had climbed to 365 ppm.

 Hansen grew up in Denison, Iowa, where signs on highways leading into town proclaim IT'S A WONDERFUL LIFE, HOME OF DONNA REED. Hansen's father was a tenant farmer who moved into town to become a bartender when Jim was four; his mother worked as a waitress. All told, they had seven children: five girls and two boys, with Jim third from the youngest.

 A smart youngster who seldom saw the need to crack the books, Hansen played second base in Babe Ruth ball. Unlike the other kids, who rooted for the Cubs or the Cards, he was and is a Yankees fan, and on occasion he'll use a baseball statistic to illustrate a point about climate change. With a scholarship and money saved from his paper route, he went to the University of Iowa, graduating with distinction in 1963 after majoring in math and physics "because that's what I could do well." He went on to get a master's degree in astronomy in the physics department. "It was a very stimulating research environment," he says. The department even had its own satellite, and the chairman was James Van Allen, the discoverer of the radiation belts around the earth that bear his name. In 1967 Hansen got his Ph.D. with a dissertation on the atmosphere of Venus, which he wrote while serving as a graduate assistant at the Institute for Astrophysics in Kyoto and in the astronomy department at the University of Tokyo.
 

After earning his doctorate, Hansen received a job offer from the Goddard Institute for Space Studies (GISS) and was so excited that he immediately drove to New York without sleeping. Except for one year, 1969-70, spent at the Leiden Observatory in the Netherlands, where he met his wife, Anniek, he has been at Goddard ever since. In 1976 he was happily working as the principal investigator on the Pioneer Venus Orbiter experiment when a Harvard postdoctoral researcher asked his help in calculating the greenhouse effect of manmade gases in the earth's atmosphere. "It didn't take long until I was captivated by this greenhouse problem," Hansen says. He resigned from the Venus project to work on the earth, "because I thought it was even more exciting to study a planetary atmosphere that was changing-scientifically exciting and also of practical importance."

 Hansen says the contrasting atmospheres on Venus and Mars "provided the best proof at the time of the reality of the greenhouse effect [on the earth]. Mars, which has only a thin atmosphere of greenhouse gases, is only a few degrees warmer than it would be if it had no atmosphere. Venus, on the other extreme, has a thick atmosphere of carbon dioxide and such a strong greenhouse effect that you could bake pizza on its surface. In fact, the pizza would burn, because the temperature is about 800 degrees Fahrenheit. The earth has an intermediate amount of greenhouse gases, which keeps the surface a comfortable 60 degrees warmer than it would be without these gases. For each of these planets, the amount of warming is in good agreement with what we calculate for the greenhouse effect."

 Hansen put together a team to build the GISS 1-D (one-dimensional) computer climate model, later superseded by a 3-D model. A climate model, designed to simulate the earth's climate, is a set of equations with numerical values allotted to such processes as absorption of solar energy, radiation of heat energy, ocean currents, and transfer of heat and moisture by winds. 

Greenhouse skeptics, including critics ideologically hostile to the very concept of global warming, question the validity of models. "Sometimes the media, and global-warming critics, leave the impression that predictions of climate change are based mainly on such models, but that conclusion is naive and misleading," Hansen says. "In reality, expectations of climate change are based on an understanding of the climate system, which derives mainly from observational data. Climate models are just one of our tools." 

In 1981 hansen, newly named chief of the Goddard Institute for Spaces Studies, and seven colleagues published a paper in Science in which they predicted, "The combined warming of carbon dioxide and trace gases should exceed natural temperature variability in the 1980s and cause the mean global temperature to rise above the maximum of the late 1930s." This ran counter to the scientific wisdom of the time; climatologists generally believed that the earth, which had been cooling since 1940, would continue to do so. But the GISS team's prediction would prove correct: Global cooling not only stopped, but the decade of the 1980s was the hottest ever recorded up to that time.

 The New York Times ran a front-page story about the GISS study, and along with The Washington Post used it in a lead editorial about U.S. energy policy, then heavily committed to the greater use of coal and other carbon-based fuels. The Times stated, "The greenhouse effect is too uncertain to warrant total alteration of energy policy. But this latest study offers fair warning; that such a change may yet be required is no longer unimaginable."

 In the first of the "don't listen to the message, shoot the messenger" reactions that Hansen was to experience, angry officials in the Department of Energy reneged on their promise to add to the GISS research budget and also warned an independent researcher that he would lose funding if he used results from the GISS model. Hansen had to cut both staff and research until he was able to scrounge money from the Environmental Protection Agency a year later.

 As a result of the 1981 study, Rafe Pomerance, who was then president of the group Friends of the Earth, arranged for Hansen to testify about the greenhouse effect at congressional hearings during the late 1980s. Although Pomerance was "never the person in the news," Hansen says, "he is the one who deserves most of the credit-if you consider the results positive-for the attention generated."

 Even so, the greenhouse effect did not generate all that much attention until 1988, and then only after Hansen told Pomerance that he was opposed to testifying in November because the weather was too cool to get public attention. "Moreover, I had decided to testify as a private citizen in 1987 because I could not agree with all the changes which the Office of Management and Budget had instructed me to include in my testimony," Hansen says. "That sort of bickering with management takes a lot of psychic energy, because it's hard to say what damage it causes to our research and institutional support."

 On June 23, 1988, with the temperature reaching a record 101 degrees in Washington, D.C., and much of the country suffering from a searing drought, Hansen made three main points to the Senate Committee on Energy and Natural Resources: "First, that the world was getting warmer on decadal time scales, which I said could be stated with 99 percent confidence. Second, that with a high degree of confidence I believed there was a causal relationship with an increased greenhouse effect. And third, that in our climate model there was a tendency for an increase in the frequency and the severity of heat waves and droughts with global warming." Besieged by the media afterward, he said, "It's time to stop waffling so much and say that the greenhouse effect is here and affecting our climate now." Suddenly global warming-and Hansen-became world news. 

The Bush White House complained to NASA. Also, many scientists, even some who privately agreed with Hansen, accused him of stretching the facts. Science ran an article called "Hansen vs. the World on the Greenhouse Threat," and the business magazine Barron's quoted the climatologist Reid Bryson of the University of Wisconsin as calling Hansen's testimony a "phenomenal snow job"-an odd metaphor given that the subject was global warming. Faced with this criticism and serious personal problems (his father died, and his wife had breast cancer, though she survived), Hansen did not back down. Scientifically, he was again ahead of his time-by seven years, in this case. In 1995 the hundreds of scientists on the United Nations Intergovernmental Panel on Climate Change concluded that "the balance of evidence suggests that there is a discernible human influence on global climate." 

When Hansen went to testify again in 1989, an official in the White House Office of Management and Budget changed his testimony so as to negate the conclusion that global warming would cause the hydrologic cycle to intensify, resulting in periods of excessive precipitation and severe drought. The upshot: a rerun of Mr. Smith Goes to Washington, with Hansen, in the role of Jimmy Stewart, protesting publicly, and Senator Al Gore lambasting the Bush administration for "science by fraud." An editorial cartoon in The Des Moines Register showed President George Bush muffling Hansen's mouth with a handkerchief that was labeled "The Whitehouse Effect," and a Seattle Post-Intelligencer cartoon compared an official in the Office of Management and Budget to an inquisitor of Galileo. 
 

The year 1990 set a new record for the global temperature, and a year later, when Mount Pinatubo, the Philippine volcano, erupted, it gave Hansen the opportunity to make "a nice check on climate models" for skeptics. The eruption, the greatest in this century, injected 20 megatons of sulfur dioxide into the stratosphere, where winds formed it into a global blanket of fine sulfuric-acid droplets. Accordingly, Hansen predicted that the global temperature would cool temporarily before the aerosols returned to the earth. He was right again, and in 1995 the rewarming earth had a higher annual record temperature than it had had in 1990. 

Regarding the heat and drought that plagued much of the United States this past summer-last July was the hottest on record-Hansen says, "Droughts and heat waves have a high degree of natural fluctuation, so you can't blame a given cause for a particular drought, and that's what I said in 1988. But the frequency is likely to increase with global warming. Whether it's a modest increase or a large change, like back in the 1930s, or more extreme than that, is hard to say until we can exactly understand these patterns."

 Hansen notes that most previous annual global record temperatures were only a few hundredths of a degree warmer than the previous record, "but in 1998 the temperature was three-tenths of a degree warmer." He adds, "It has become very difficult for anyone to argue that observed global warming is natural variability. We have good reason for being able to say that the world will be warmer by about a quarter of a degree in the next decade. It's the same reason we had 10 years ago when we said that the 1990s would be warmer than the 1980s: The planet is out of equilibrium." 
 
 

A 20-inch rise in sea level, predicted by 2100, could inundate 5,000 square miles of dry land and drown 15 to 60 percent of our coastal wetlands. Most regions would have a net loss of wetlands (wetlands gained are subtracted from wetlands lost), the anomaly being the West Coast. If no action is taken, Louisiana could lose as much as 3,500 square miles of dry and wet land. By some estimates, a one-foot rise in sea level along the Gulf and Atlantic coasts is likely by 2050 and could even occur by 2025. A two-foot rise is likely in the next century, and a four-foot rise is possible. Source: Environmental Protection Agency
 
 

Although the report is cautious about predicting the future, it says that two basic consequences are "probably inevitable" in the region: more warming and a further increase in sea level. For New York City itself, the report projects temperature increases of more than 4 degrees Fahrenheit for the 2050s and 6 to 10 degrees for the 2090s. As early as the 2010s, the average number of days that top 90 degrees in the city is projected to more than double, from 13 a year to 27 a year. By 2050 the city could swelter through 47 days of 90-degree weather, and 80 such days by the 2090s.

 The report also predicts an increase in the frequency of unusually warm nights and notes, "The combination of extremely hot days and unusually warm nights can be deadly. . . . The most recent results suggest that by the year 2050, New York's heat-related mortality will increase by between 50 percent and 200 percent" over current levels.

 There are other health impacts to consider. An increase of 5 to 9 degrees could bring "a significant northern shift in outbreaks of two mosquito-borne diseases, western equine encephalomyelitis and St. Louis encephalitis." Indeed, late this summer, for the first time ever, another mosquito-borne disease, the rare West Nile virus, was discovered in the city. By early September it had killed several people in Queens and Brooklyn and sickened dozens more. While weather conditions in the Baked Apple-mild winter, wet spring, and hot, dry summer-favored the spread of the virus, Duane J. Gubler, M.D., of the federal Centers for Disease Control told The New York Times that global warming had "nothing to do" with the outbreak. 

In addition, says the report, high temperatures and temperature inversions would increase concentrations of ground-level ozone, putting anyone with chronic respiratory illness, and even healthy children and adults, at risk. In high concentrations, ozone "irritates and injures cells lining the respiratory system, causing eye and nose irritation, coughing, and generally impaired lung function."

 Ever since the last Ice Age peaked 18,000 years ago, and the glaciers retreated from New York, sea level has generally been rising as the ocean warms and expands. Although much of the local rise is due to land subsidence-the result of geological processes-sea level is rising at the rate of 0.11 inches a year in New York City. 

Nor'easters are far more common than hurricanes in New York, and in December 1992 a nor'easter flooded parts of lower Manhattan, shutting down the city's subways and the underground trains to New Jersey and drowning stretches of the FDR Drive along the East River. Flooding also closed LaGuardia Airport, cut commuter-railroad service, forced the evacuation of seaside communities in New Jersey and on Long Island, washed away beaches, and destroyed more than 150 houses.

 Consider that a gentle preview, because higher sea levels will cause storm surges to intrude farther inland. In lower Manhattan, storm surges coming from the harbor or the Hudson River would submerge the foundations of Battery Park City and the World Trade Center, while the East River would do a number on the FDR Drive, Bellevue Medical Center, and East Harlem. 

Warming causes an intensification of the hydrologic cycle. "Extremely heavy precipitation events"-more than 2 inches of rain or equivalent snow in 24 hours-have increased in number as the United States has grown warmer. But contrary to what one might expect, warming also increases the likelihood of drought, because soil dries more quickly. With much higher temperatures and little change in precipitation, severe "100-year" droughts could begin to occur every 3 to 11 years sometime in the next century.

So what can be done? The report advocates a number of possible strategies, such as abandoning beaches and residential areas, like Brooklyn's Seagate, that require periodic rebuilding, and erecting a seawall around lower Manhattan, which is particularly vulnerable to storm surges. Additionally, a reduction in greenhouse-gas emissions "would improve air and water quality now" by reducing ground-level ozone, acid rain, and the eutrophication of waterways. But what is really needed nationally is for presidential and congressional candidates to begin taking global warming seriously. This, after all, is the only planet we have.