Seven floors below, the streets of Manhattan's Morningside Heights have taken on the look of a maze, with walls of white channeling the scurrying pedestrians into precise paths. It snowed last night, and for a while it showed no inclination to stop. Even Rulers won't do; to measure the accumulation, yardsticks are in order. So if this seems like an odd moment to turn one's thoughts to the warming of the world's climate, well, James E. Hansen begs to differ. "No, this is the perfect time!" the director of NASA's Goddard Institute for Space Studies in New York says in his crammed office. "As you get more global warming, you should see an increase in the extremes of the hydrologic cycle--droughts and floods and heavy precipitation."
Hansen, 54, is back where he's most comfortable: out on a climatological limb. It hasn't been sawed off from under him yet. In 1981 this weatherman to the world bucked the scientific consensus that the planet was getting cooler. He argued that, to the contrary, the globe had warmed 1 degree Fahrenheit in the last century--because industrial gases were trapping heat in the atmosphere: He was right, it turns out, and "that was the first thing that got us in trouble," he says with a faint smile. In the spring of 1990 he bet a colleague that at least one year from 1990 to 1992 would be the warmest on record. When 1990 topped the charts, Hansen pocketed $100. Then he nailed his prediction that the 1991 eruption of Mount Pinatubo in the Philippines would put a lid on the warming trend until the 20 megatons of heat-reflecting volcanic dust had settled. And four days after 1995 was history, Hansen announced that it had been the hottest year ever, an average 59.7 degrees. It wasn't a quirk: Pinatubo had lowered the average global temperature so significantly that "it would be very unlikely" for chance alone to push the mercury to a new record.
It's even less likely that chance alone could explain weather that, in 1995, gave new meaning to "capricious." In Antarctica, a 'berg the size of Rhode Island broke off, and flowers bloomed on the ice shelves (map, page 26). Seas warmed off southern California, decimating populations of zooplankton that sustain fish; Northern Europe bared out from under spring floods. Eleven hurricanes--the most since 1933--pummeled the Caribbean. More than 800 people died in the Midwest's summer heat wave, and London had its hottest, driest summer in 200 years. Northeast Brazil suffered its worst drought of the century and now its south is underwater: Rio has already had three times as much rain in eight days this month as it usually gets in all of January. Siberia was a full 5 degrees hotter than normal last year. Alaska has had almost no snow this season--but Memphis, Tenn., would love to ship it some. "The more rapidly we force changes in the [climate] system," says Stephen Schneider of Stanford University, "the more likely it is to exhibit inscrutable behavior."
"Inscrutability" to a scientist is like a vacuum to nature: theories rush in at the speed of sound. The theory in this case is that the word is caught in the grip of a "greenhouse effect." Gases such as carbon dioxide, released when fossil fuels like coal and oil burn, trap infrared (heat) radiation in the atmosphere much as panes of greenhouse glass do. Since the atmosphere's load of these gases keeps rising, the world will almost certainly get warmer. The Intergovernmental Panel on Climate Change, sponsored by the United Nations, last month forecast a rise of 1.8 to 6.3 degrees by 2100. Since the IPCC can hardly agree on what to order for lunch, that unanimous prediction was a milestone. Even representatives from Kuwait and China were on board: the two countries resist the idea that the world is warming because greenhouse panic could bring restrictions on oil and coal.
But consensus ends right about there. Not even researchers who agree that the world is warming, and will keep warming. agree on what happens next. On the one hand, Panglossians foresee milder winters and bumper crops from Kansas to Siberia. Despite the recent weather, they expect fewer severe storms in the future: temperature differences between the poles and the equator will even out, and the fury of storms will therefore diminish. Cassandras, on the other hand, warn that in a warmer world agricultural zones will shift, causing a mismatch between climate, soil and rainfall that could empty many of the world's bread-baskets. Sea levels will rise between 6 and 38 inches, obliterating islands, robbing coastal New Jersey and Louisiana of congressional districts and forcing Kevin Costner to rebuild his ark. Up to two thirds of the world's forests could turn to grasslands. The Mideast and northern Africa can expect widespread droughts. A balmier North Pole could alter ocean currents that now warm Western Europe; there will always be an England, but it might not be able to cultivate buttercups.
Meaner storms: It's too soon to tell which side knows what it's talking about. But one alarming prediction seems to be coming true: the expectation that, in a warmer world, extremes of wet and dry will intensify. As Earth's surface warms, more moisture evaporates. Over arid regions, where there's little to evaporate, turning up the thermostat would exacerbate droughts. Rainfall would thus increase over moist areas, like the coasts, and be rarer in the interiors of continents. "The odds of getting drought years will increase markedly," says Jerry Mahlman, director of the Geophysical Fluid Dynamics Laboratory, part of the National Oceanic and Atmospheric Administration (NOAA). Hurricanes, too, should get more intense. "The warmer the ocean gets, the meaner the tropical storm," says A. E. (Sandy) MacDonald of NOAA's lab in Boulder, Colo.
Last week's blizzard can't be blamed on the warming world. No storm or drought or heat wave ever can be so neatly diagnosed. "You can't connect a given weather event on a particular day in a particular place with long-term climate change," says physicist Michael Oppenheimer of the Environmental Defense Fund. The snows of yesteryear prove that. The record Northeast blizzards of 1888 and 1947, after all, hit when the only greenhouse effect anyone cared about was the one that forces lilies to bloom for Easter. Extreme weather is connected to global warming more subtly. "All that long-term climate change can do is affect the probabilities," Hansen explains. Instead of equal chances that any one storm will be heavier or lighter than normal, or any one day hotter or colder than normal, the climate dice are now loaded. The greenhouse effect, says Hansen, "has changed the odds" on extreme weather.
Whatever its pro, mate cause, the blizzard of '96 is just what a greenhouse world would whip up. The storm was born when cold air blew down from Canada. The arctic air happened to smack into a warm, moist air mass hovering over the Atlantic Ocean. In a warmer world, those chance circumstances could be more common. "Global warming has made the Atlantic an even greater source of moisture" from evaporation, Hansen says. And when water vapor condenses, becoming liquid again, the process releases heat. So warm moist air that feeds blizzards is more likely to be parked over the Atlantic, just waiting for the delivery of a cold mass. "The greenhouse effect alters the probabilities [of having the ingredients of a massive snowstorm]," says Hansen. "In that sense the greenhouse effect is changing our climate now."
Hot Venus: Hansen was not always a greenhouse cultivator. In 1965, he was casting about for a dissertation for his Ph.D. in physics at the University of Iowa. His mentor, James Van Allen (discoverer of the radiation belts that girdle Earth), suggested that Hansen tackle the question of why the surface of Venus is hot enough to melt lead. The catch was that the explanation had to be wholly original. The best theory for Venus's heat--that it was the victim of a runaway greenhouse effect-had already been claimed by some young Harvard professor named Carl Sagan, Hansen wasn't deterred. "I decided to say that Venus was so hot because a dusty atmosphere was trapping internal heat," he recalls. That was good enough for the doctoral committee (even though it turns out that Sagan was right about Venus). Hansen received his degree and landed a fellowship at Goddard, which has lately become as well known for its location as for its science: Tom's Restaurant, where the "Seinfeld" characters chow down, is on the ground floor. Now Hansen can't escape climate change even on his birthday. For his 50th, he got a clear plastic bank filled with coins from around the world--and labeled GLOBAL CHANGE.
Some researchers resent Hansen's bravado. One June day in 1988, as drought and record heat fried the Midwest, Hansen res-titled before a Senate committee that he was "99 percent" certain that greenhouse warming had gone from theory to reality. The senators paid attention--it was 100 degrees in Washington that day-- and Hansen became famous overnight as the government scientist who said the world was warming. Looking back on Hansen's testimony, says Kerry Emanuel of MIT, "I don't think it was good for scientific research. It was such an outlandish view that it sparked a counterrevolution. We found ourselves in the middle of the Chicken Littles on the one hand, and the reactionaries on the other." But there is little debate that, as Van Allen puts it, "Hansen's work is really the standard of reference in the field."
And lately the weather has been on his side. Downpours are one of those "extreme hydrologic events" that Hansen expects from the greenhouse. Higher temperatures mean more evaporation, which means more water vapor in the air. That does not portend more frequent rainfalls--whether or not a storm forms depends on circulation patterns that are not expected to shift much. But storms that do form will have more moisture-laden air to wring out. Since 1970, reports Thomas Karl of the National Climatic Data Center in Asheville, N.C., more rain in the United States has been falling in big sloppy storms, with less arriving in showers. In other words, when it rains it pours. "We were flabbergasted, to be honest with you," Karl says. "Our best information is that global warming is having an impact [on rainfall] now." It also seems to be affecting the infamous Pacific Ocean warming known as El Nino. El Nino brings torrential rain to the Southeastern United States and unusual heat to the Pacific Northwest. And global warming, says Kevin Trenberth of the National Center for Atmospheric Research, makes El Nino effects stronger and more frequent.
To scientists who remain skeptical about greenhouse warming, wacky weather and a balmier world reflect no more than normal variability. Weather is so sensitive to tiny changes, after all, that a butterfly flapping its wings in Beijing can make it rain in Pittsburgh (and if we ever find that butterfly we're going to make it stop). Need evidence that the science underlying climate models is unsettled? The IPCC now predicts that the world will warm only half as much as it forecast in 1990. The 1990 report neglected the cooling effect of sulfates, which are released into the air when dirty, high-sulfur coal and other fuels are burned; 1995's took account of sulfates. The Global Climate Coalition, an industry-sponsored group fighting efforts to require cuts in the emissions of carbon dioxide, argues that this "trend [toward lower warming estimates] could continue . . . and is a very good reason why continued research is a wise strategy." The coalition suggests that the world has 40 to 240 years to stabilize greenhouse gases before the heat gets turned up uncomfortably high.
Several reputable scientists agree. There are huge uncertainties in the computerized climate models. For one, the increased evaporation in a warmer world might produce more clouds, which have a cooling effect. For another, oceans might absorb most of the increased heat, leaving little to change the climate. "I don't believe the climate system is messed up," says climatologist Robert Balling of Arizona State University. "[Neither] circulation patterns [nor] precipitation records are showing any cataclysmic problem."
The Global Climate Coalition describes its views as "business and industry's," but one player has broken ranks. Insurers have concluded that a greenhouse world could "bankrupt the industry," as the president of the Reinsurance Association of America said last year. Hurricane Andrew, the kind of storm a warmer world could see more of, produced $16.5 billion in damage claims. In Europe, reinsurers Swiss Re and Munich Re have lobbied governments to regulate greenhouse gases, and Swiss Re suggested that global warming might force people to abandon major cities. "This hazard has to be contained," says a Swiss Re statement. "We have to rethink, correct our mistakes and win time." Insurers are also meeting with Greenpeace, which is exhorting them to take on energy companies in a battle that would be straight out of a Japanese monster movie.
At the 1992 Earth Summit in Rio de Janeiro, developed nations pledged to cut their releases of greenhouse gases so that emissions in the year 2000 would not exceed 1990's. About the only country that has a chance of living up to its promise is Sweden. The United States is relying on industry to voluntarily reduce emissions-by using less energy and making more fuel-efficient cars, for instance. Rather than adopting tough measures like an energy tax, which would cut energy use but also end political careers, the United States and other countries are hoping that technology will ride to the rescue. Maybe solar power and hydrogen will replace coal and oil before greenhouse warming gets bothersome. But Hansen thinks there's less time than governments are counting on. "The climate system is being pushed hard enough that change will become obvious to the man in the street in the next decade," he says. To many people trudging along streets lined with urban Himalayas last week, it already was.
GRAPH: Getting Warmer. The average surface temperature of the earth has risen more than 1.5 degrees in the last 135 years.
SOURCE: CLIMATIC RESEARCH UNIT, UNIVERSITY OF EAST ANGLIA
PHOTO (COLOR): Hansen: A smile and an umbrella
The weather is always capricious, but last year gave new meaning to the term. Floods, hurricanes, droughts --the only plague missing was frogs. The pattern of extremes fit scientists' forecasts of what a warmer world would be like.
California: Heavy rains in March led to flooding throughout the state, causing 15 deaths and $2 billion in damage.
Mexico: Northern parts of the country are experiencing the coldest weather in 25 years. On New Year's Day, Mexico City saw its first real snowfall in two decades.
Midwest: 1,011 tornadoes were reported, the second most active season on record.
Northeast and Midwest: July's heat wave killed more than 800 people, including hundreds in Chicago alone.
East Coast: Hot and dry summer; then the blizzard of '96 buries the Northeast.
Caribbean: Eight tropical storms and 11 hurricanes made this the worst season since 1933.
Rio de Jeneiro: The March rains have come early this year already bringing more rainfall than January's monthly average.
Argentina: The plains region experienced its worst drought in history. The Patagonia forest is having one of its most active fire seasons in memory.
Antarctica: A 48-by-22-mile piece of the Larsen Ice Shelf fell off.
British Isles: Severe summer heat wave and drought. London had its hottest summer since 1659.
Southwest Europe, Northwest Africa: Protracted drought through first six months of '95
West Africa: Prolonged drought.
Northeast Brazil: Suffered its worst drought of the century last year, with only 40% of normal rainfall.
Central and Northern Europe: Above-normal rainfall early last year caused flooding in France and the Netherlands.
Austria: Record highs now being set. World Cup ski events canceled for lack of snow.
Ghana: July saw its heaviest rainfall in 30 years, with 20 deaths from flooding
South Africa: The '95 wet season was late, then caused widespread flooding.
Siberia: A five-degree increase in average temperature for '95 was the largest in the world.
Russia: Moscow's May 31 temperature hit 91 degrees F, breaking the previous record.
India, Bangladesh and Nepal: June monsoons caused massive flooding, stranding nearly 2 million people and killing more than 100.
NE China, Korean Peninsula: Summer rain and flooding led to famine in some regions.
Japan: With unprecedented snowfall in the north, the city of Sapporo last week asked for military assistance in removing snow.
Philippines: Typhoon Angela, the area's most powerful storm since 1984, hit in November, killing more than 600 people.
Australia: The weather has been wet in the west, with record-high levels of rainfall. In the east, Sydney had its first rainless August ever recorded.