The subject is the politics of global warming, and Benjamin Santer is pissed: "I've been accused of political tampering, scientific cleansing, abuse of the peer review system..." The Lawrence Livermore National Laboratory atmospheric scientist exhales a breath of frustration, then adds calmly, "Quite frankly, it's appalling." Appalling, indeed. As perhaps the greatest ecological challenge facing the international community, global warming would seem an ideal forum for objective research and collaborative goodwill. Instead, it's fast becoming a scientific mosh pit hotwired to political agendas. Just ask Santer. As lead author of a key chapter in a recently released report by the Intergovernmental Panel on Climate Change -- a U.N. working group that includes 2,500 scientists -- he is at the helm of the global warming debate's most fateful assertion: "The balance of evidence suggests that there is a discernible human influence on global climate." Those words may seem benign, even apologetic. But they have managed to light global warming's special interest fuse, detonating a torrent of environmental justification, public confusion and industrial outrage. "I'm not in the business of suggesting what motivates people," says Jeffrey Salmon, executive director of the Washington, D.C.-based George C. Marshall Institute, a science and public policy research group. "But the evidence shows that they (Santer and his colleagues) did what we contend they did: they changed the science to conform to the politics." So does the IPCC's conclusion represent a sound scientific consensus, or is it the progeny of an alleged courtship between Santer, his colleagues and political pandering? Clearly, Santer's predicament is not just another incident of remote academic infighting. Rather, it's a metaphor for a high-stakes global warming dogfight that promises to rock international energy policy and shape world ecology well into the next century.***A 500-square-mile slab of the Larsen Ice Shelf collapses into shards while ever-widening Antarctic cracks threaten to implode another few thousand frozen miles. Warmer winters taunt and decimate penguin populations while NASA researchers confirm that 1995 was the hottest year on record. A rash of violent weather systems plagues the United States over the past several years, cutting multibillion-dollar swaths of destruction. And disease-riddled vermin and insects ride a warming tide into uncharted territories, importing dengue fever to Texas and malaria into the northeastern United States.According to some, these developments are foreshocks to a very real and almost apocalyptic global warming trend. According to others, they merely constitute independent events that fall within the realm of natural climate fluctuation. Is global warming a disturbing reality or an overwrought scientific hallucination?"Catastrophic warming hasn't started," says John Shlaes, executive director of the Global Climate Coalition, an association of business trade associations and private companies. "Warming hasn't started. Right now, science cannot distinguish between natural variability and possible human influence."Santer, however, maintains that the best available research suggests that human greenhouse gas production has contributed to a warming trend over the past century and will continue to exert climatological influence. "No one hopes more than I do that we're wrong about this," he says. "But if we're not, and the next century brings climatic changes of a size and rate that we haven't experienced in the last 10,000 years, then that's something people should worry about." The implication of long-term global warming is clear: meteorological chaos that could unleash famine, pestilence and economic dysfunction. The IPCC report states that a doubling of atmospheric carbon dioxide concentrations -- a very real possibility at current emissions rates -- could push global mean temperatures between 1.8 and 6.3 degrees Fahrenheit over the next century. These are daunting figures: the planet is only about 6 degrees removed from the Ice Age, and a lurch of that magnitude would pry open a Pandora's Box of environmental and societal disruption.While no one disputes the havoc that a severe global warming could wreak, some contend that there isn't yet a legitimate or significant scientific connection between industrialized greenhouse gas emissions and the recent warming trend -- 1 degree over the past century -- upon which global warming predictions are partially based. "Nobody's made a direct link between emissions and global warming," Shlaes says.Santer disagrees: "There are some who would say that unless you can explain every little bump and wiggle in the observed temperature curve, then they're not going to believe anything you say. And that's patently ridiculous. The evidence in support of a human effect on climate comes from many individual areas. There's no smoking gun out there. But it's a strong circumstantial case coming from all sorts of independent lines of information."Adds Daniel Becker, director of the Sierra Club's Global Warming and Energy Program, "The scientists who have been studying this at the request of the World Meteorological Organization and the U.N. have reached a consensus, which is very unusual in the scientific community. So you've got the vast bulk of scientists agreeing that the earth has warmed, that the changes we've made to the atmosphere are at least partly responsible." Salmon, however, says that the IPCC's observation of a "discernible" human influence on climate is "so vague and so hedged" that it falls short of being meaningful. He adds that the warming prediction's figures are too broad to constitute a consensus. "You're getting a consensus that human action could have no impact on the climate, or human action could have some impact on the climate," he says. "So it's a distortion to say that the consensus of scientific opinion says that human action is going to cause serious global warming." Says Santer, "If you interpret consensus to mean total unanimity of all scientists in the world, then there wasn't consensus. But when the vast majority of knowledgeable scientists believe that there are now identifiable human effects on climate, and when 100 countries with divergent interests endorse such a statement, I'd say that constitutes a consensus."If global warming is indeed a burgeoning reality, it promises to work its twisted magic in mysterious ways. In the event of a long-term warming trend, many scientists expect to see a complex climate dynamic resulting in prolonged droughts, nastier floods, meaner blizzards and general meteorological disturbance.Some contend that such a pattern has already emerged over the past decade, causing an unusually chaotic dose of disruptive weather. Establishing a conclusive connection between global warming and localized weather events, however, is no simple task, and would require at least another decade of intensive research and data accumulation. And therein lies global warming's integral conundrum: by the time an enhanced greenhouse problem's worst effects could be conclusively traced, they might have already established a destructive foothold. Ultimately, Santer says, "We don't have access to a convenient parallel earth where we can study how climate might have behaved without human intervention...We're performing an uncontrolled experiment by increasing the levels of greenhouse gases and aerosol particles in the atmosphere."***While industrialists maintain that the global warming experiment is a little too uncontrolled to justify major economic shifts, environmentalists suggest that continued greenhouse procrastination is going to unleash dire economic consequences. It's a central struggle that promises to impact virtually every person who drives a car, heats their home or uses industrialized products.According to Shlaes, the United States is poised to enter into long-term global warming policy negotiations without a clear economic plan. It is, he says, a potential case of too much, too fast: "We're not saying don't do anything. We're saying that the kind of agreement we need is one that would be based on enhancing our investment in scientific and economic research...The Administration has developed some models to evaluate the economic impacts, but we have not had a discussion or debate in the United States about what they're going to recommend and what the impacts are going to be. That has to come before anything." The Clinton administration recently backpedaled from its call for short-term aggressive and binding emissions reduction targets. An international global warming summit is scheduled for next December in Kyoto, and the outcome promises to shape both short-term and long-term national energy policies.In 1992, 160 countries endorsed the Framework Convention on Climate Change and pledged to voluntarily reduce greenhouse gas emissions to 1990 levels by 2000. But the United States and others have fallen wide of the mark, and international talks later this year could forge binding reduction agreements. "There's still talk about a five to 10 percent reduction by 2005, 15 to 20 percent by 2010," says Shlaes. "And several major independent economic firms and universities have said that this would essentially be very harmful to the United States economy." He cites studies that suggest a 3 to 4 percent drop in the Gross Domestic Product and job losses approaching 600,000 per year. William O'Keefe, executive vice president of the American Petroleum Institute, has said that a 20-percent reduction in greenhouse gas emissions over the next two decades "would bring on a full-scale economic depression."But according to Becker, such predictions are just more scaremongering grease for industry's self-interested propaganda machine. "The coal, oil, utility and automobile industries are trying to confuse the American people so that they can continue raking in profits while not doing their fair share to prevent pollution...Waiting 10 years is going to be a big problem. When you've got a cumulative pollutant that lasts for a hundred years in the atmosphere, you can't afford to wait." Atmospheric levels of carbon dioxide -- the most problematic greenhouse gas -- have seen a 30 percent increase since the turn of the century. Carbon dioxide has a 100-year lifetime in the atmosphere, so continued emissions create a cumulative effect that implies an increasingly heightened global warming pace.Although curbing industrial emissions would prove costly, some economists maintain that a do-nothing approach would be even more expensive in the wake of warming-induced drought, disease and disruption. While January's floods in California cannot be linked to a burgeoning warming trend, they do provide an economic context in which to gauge a future increasingly plagued by heavy weather: $1.5 billion in damages. Indeed, it's the kind of context that has some insurers claiming that global warming could "bankrupt" the insurance industry. Another point of contention observed by the Global Climate Coalition is a potentially inequitable framework for global greenhouse gas mitigation. "We haven't found a way to meaningfully involve all countries of the world," Shlaes says. He says that current emissions negotiations target only developed countries, an arrangement that could competitively cripple the United States while not mitigating the greenhouse gas situation. "The point is, it's a global issue," Shlaes says. "It's immaterial to the atmosphere where the emissions come from, and the fact remains that if you add up China, India, Brazil, South Korea and all these other countries, they're going to have 70 percent of all the world's emissions on a yearly basis by 2025. You've got to get them involved in the process."Counters Becker, "Three-quarters of global warming pollution comes out of the industrialized countries of the United States, Europe, Japan and Australia. The United States and the developed countries are also the ones that have the technology for energy efficiency and renewables that we can export to the rest of the world. So we are in a position of having polluted the planet, and the companies that make the pollution are now saying we should do nothing to curb that pollution until developing countries are ready to act. It's a penny wise, pound foolish approach that industry is promoting here, and they're essentially lying about where the emissions are coming from."***The loudest volley in the report-and-retort global warming crossfire was fired by Frederick Seitz, a scientist and chairman of the George C. Marshall Institute. In a Wall Street Journal editorial, Seitz charged Santer with making substantive and unethical changes in the IPCC draft report after it had been reviewed and approved by the contributing scientists. Noting that several passages expressing uncertainty about both detection and attribution of global climate change had been excised from the draft, Seitz concluded that the revisions constituted the most "disturbing corruption of the peer-review process" he had seen in his 60 years as a scientist.By suggesting that the IPCC lacks the credibility upon which sound global warming policy decisions can be made, Seitz's accusation invokes a scenario in which tainted science "will have a major and almost certainly destructive impact on the economies of the world." Replies Santer, "Professor Seitz was in no position to assess the scientific reasons for the changes made to the chapter. He wasn't there, he wasn't privy to the comments that we received, he wasn't privy to the science and he's not a climate scientist." According to Salmon, Santer and others who were involved in the revisions are guilty of violating both IPCC procedure and the spirit of scientific objectivity. "We think the rules clearly state that once the draft text had been agreed to, that only minor technical changes were appropriate. But they went way beyond that, and they changed the substance of the text...They felt the science was not supportive of the policymakers' summary, so they went in and they changed the science." Not at all, says Santer. The revisions "had nothing to do with policy," he says, "and claims that they were engineered to conform to policy considerations are absolutely ridiculous...My job as convening lead author was to listen to all the scientific comments that were made during extensive discussions of our chapter, and then to incorporate in a revised version those comments that I and others judged to be scientifically valid."Have any of the contributing IPCC scientists expressed concerns to him about the validity of the revision? "Not a single one," Santer says. He adds, "The conclusion that the balance of evidence suggests a discernible human influence on global climate was certainly not based on my research alone, as others have alleged. Chapter eight cites 133 scientific papers, and it draws on a wide body of evidence...It's an attempt to make the best possible assessment of a complex scientific issue, and there's no unique set of words out there that would keep everyone happy." Right now, no one's happy. And while the global warming debate promises to get a lot uglier before it gets any prettier, the public's best interests cannot be served if greenhouse science is downgraded and oversimplified into special interest oblivion. "There are excesses both sides of the debate," Santer says. "Most of the scientists involved are interested in the science, not the political implications. What people need to know is what does the science show us, what does it tell us. I'm not here to make any suggestion to what should be done about it. I'm here to provide the best scientific information. And it sure doesn't help to have people try to distort the science for their own ends."Sidebar: GLOBAL WARMING PRIMER:Global warming is an extrapolation of a natural phenomenon called the "greenhouse effect." For more than a billion years, the greenhouse effect has encouraged and sustained life as we know it. It occurs today when about 60 percent of ultraviolet solar radiation evades atmospheric and surface reflection. This energy is absorbed by the planet and then jettisoned back toward space in the form of a lower-intensity infrared radiation; some of this "heat" energy, however, is trapped by a layer of gases, a process that mimics the effect of a greenhouse. The result is a generally hospitable average earth temperature of about 60 degrees Fahrenheit.The natural gases that comprise earth's 12-mile-deep atmospheric greenhouse layer include water vapor, carbon dioxide, nitrous oxide, methane and ozone.The term "global warming" suggests an "enhanced" greenhouse effect in which an accelerated and prolonged rise in global temperatures is directly related to human activities, most notably fossil fuel combustion. "We are essentially throwing a thermal blanket around the planet and slowly warming it," says the Sierra Club's Daniel Becker. Although some maintain that a significant human effect on climate has yet to be proven, the Intergovernmental Panel on Climate Change concludes that a 30 percent increase in atmospheric carbon dioxide levels has contributed to an overall warming trend over the past century. Other industrial pollutants, such as sulfate aerosols, can temporarily offset localized warming by increasing solar reflectivity. Therefore, an enhanced greenhouse effect caused by pollution would be manifest as a mosaic of complex interactions within an even more complex natural weather dynamic. Warming would not occur at a steady global pace, but rather as an uneven amalgam of generally increasing regional temperatures.While global warming popularly connotes droughts and heat waves, researchers note that ice melting and heightened evaporation would as well create schizophrenic climates conducive to floods and violent weather systems.