From the dawn of human existence, the drive for shelter from blowing winds, driving rain, heavy snow, baking heat or bone-chilling cold has been an enduring daily theme. The spark of human ingenuity has seemingly blunted nature's force. Modern life has been ushered from the not-too-distant cradle of caves, teepees and sod huts into the climate-controlled world of central air and heat, high-rises, expansive enclosed malls and arenas for the pursuit of leisure and recreation.Despite this reshaping of personal climate to meet desired comfort levels, "the weather" remains a common conversational thread. Now a growing chorus of scientists is trying to raise the level of discussion above the mundane. They are warning that human activities are dramatically altering the global climate.Some scientists even think the spasm of extreme weather over the past few years -- more hurricanes and mega blizzards, floods across California and the Mississippi River Valley and incredible torrential downpours like last spring's Dane County soaking -- are evidence of fundamental climatic change."I say we are marching into the unknown," declares Francis Bretherton, a professor with the UW-Madison department of atmospheric and oceanic sciences. During the 1980s, Bretherton chaired a NASA advisory committee on global climate change. "There are going to be changes," he predicts. "Some of them will be bad, some may be good."Variability is an essential aspect of weather and climate, so attempts to finger humanity for climatic changes will always be subject to reasonable doubt. But Bretherton agrees with atmospheric scientists who believe a drastic climatic shift is under way.In December 1995, 2,000 of these scientists from around the world issued a joint proclamation declaring "the balance of evidence suggests that there is a discernible human influence on global climate change."The scientists, part of the United Nation's Intergovernmental Panel on Climate Change (IPCC), warned of a rapid rise in ocean levels, flooding island nations and coastal areas; shifts in annual and global rainfall patterns; agricultural disruptions; outbreaks of infectious disease; and tremendous stress on plant and animal communities."Potentially serious changes have been identified, including an increase in some regions in the incidence of extreme-high-temperature events, floods and droughts, with resultant consequences for fires, pest outbreaks and ecosystem composition, structure and functioning." SOME LIKE IT HOT Climatic records indicate that the earth is, on the average, 1 to 2 degrees Fahrenheit warmer than 100 years ago. Three of this decade's first five years, notes Bretherton, "have beaten all global records" for warmth. (The volcanic ash spewed by Mount Pinatubo's spectacular eruption temporarily clouded this trend and likely accounts for these two lagging years.) Even locally, the wintry ice sheet covering Lake Mendota now lasts about two weeks less than it used to, according to 140 years of data.In what is truly a long-range weather forecast, the IPCC scientists predict, given current trends, another 3.6 F rise in the earth's average temperature during the next 100 years. It's been 10,000 years since the planet experienced a rapid temperature rise of this magnitude.This long-range warming trend has been dubbed "global warming." But perhaps the most surprising result of climatic change is the potential for wide geographic variations in heating and cooling. The subtle dynamics of climate -- influenced by meandering jet streams, oceans and their currents, polar and mountain ice packs -- may spawn wildly uneven regional effects.John Kutzbach, also a professor in the UW's department of atmospheric and oceanic sciences, says it's entirely possible that some parts of the planet could get cooler, others a little warmer, and still others a lot warmer. Observational evidence already suggests that some parts of the planet have warmed up considerably more than other areas.Kutzbach's specialty is computer modeling, a discipline at the core of climatic forecasting. To better foretell the future, Kutzbach says, "we are looking at past climates." The models he works with try to simulate the earth's climatic changes over hundreds or thousands of years. The results are compared to evidence culled from fossils, archeological digs and glacial ice cores to provide a baseline for defining historical weather patterns. If the results are accurate, the models can be trusted. Kutzbach says these efforts to turn back the clock are finding "a fair amount of accuracy."Most scientists blame the bulk of climate change on increasing atmospheric levels of carbon dioxide (CO2), a clear and odorless gas. Created when coal, gas and oil -- the primary fuels powering the industrial age -- are burned, CO2 makes up only a tiny sliver of the earth's atmosphere. During the past 100 years, the amount of CO2 in the air has grown from .028% to .034%.Life on earth as we know it is only possible because of carbon dioxide's unique quality. The gas traps the sun's energy, warming the planet's surface. It works much like a car's windshield that collects solar energy and heats the interior on a sunny day."There is no doubt in my mind that if the CO2 level of the atmosphere increases, the climate will get warmer," says Kutzbach. His models confirm the pivotal role played by CO2 in determining the earth's climate. High levels of the gas trigger warmer epochs, and lower atmospheric levels parallel ice ages.Given the world's love affair with fossil fuels, economists and scientists expect a doubling or tripling of atmospheric CO2 levels by the end of the next century. "We're just on the beginning of the upward ramp," says Kutzbach.The United States leads the world in CO2 generation. The average American adds five tons of carbon to the air each year, with each car annually belching skyward its own weight in CO2. By comparison, Japanese or European citizens produce about half as much CO2 as Americans, and someone living in India creates only .2 tons of CO2 a year.Bretherton thinks another pollutant from fossil fuel burning -- sulfur dioxide, or SO2 -- may mask the true appearance of global warming. Little droplets of SO2, floating in the lower levels of the atmosphere, act as a reflective cloud and mirror sunlight back into space. This could account for why the eastern U.S. and western Europe -- heavily populated and industrialized areas -- are the two parts of the world that have experienced the least amount of warming during the past 100 years.Sulfur dioxide is also the key ingredient in acid rain, the killing and life-stunting precipitation plaguing the lakes and forests of North America and Europe. Many governments have taken steps to curb SO2 emissions, and Bretherton suggests climate change "will become more apparent" as the air clears atop the SO2-fouled regions of the globe.Two other gases spawned by modern society -- methane and ozone-destroying chlorofluorocarbons -- are also thought to contribute to global warming. To further complicate the issue, the planetary heat wave is expected to elevate the amount of water vapor in the atmosphere. The extra steam acts like a greenhouse gas, but how this will influence climatic change remains a matter of contention. THE SKY IS FALLING! One of the most controversial consequences of global warming has been raised by Thomas Karl, the senior scientist at the National Climate Data Center. Karl, whose academic credentials include study at the UW- Madison, has found a 20% increase during this century in the number of extreme precipitation events such as blizzards and downpours.The onslaught of blizzards pounding the Northern Great Plains this year and California's surge of flooding provide fodder for Karl's theory. Likewise, blizzards socked the Northeast in 1996, while the Southwest thirsted through a protracted drought. More frequent and powerful hurricanes are another consequence suggested by climate change. The 1995 barrage of Atlantic windstorms threatened to deplete the letters in the alphabet used for naming the violent storms.Kutzbach and Bretherton are cautious in their assessment of Karl's data. While not rejecting the possibility of more extreme weather, Kutzbach believes Karl is "on thin ice, statistically." Bretherton thinks the spate of tumultuous weather could be due to chance. "The only hard evidence," he adds, "is that as it gets warmer, the intensity of the most extreme hurricanes should go up."In some corporate circles, the economic destruction borne by recent wild weather is evidence enough. Alarm bells are ringing for insurance executives. Prior to 1989, weather-related losses from a single event in the U.S. had never exceeded $1 billion. Since then, losses have skyrocketed. Hurricane Hugo wreaked $5.4 billion in damage in 1989, Hurricane Andrew flattened property worth $16.5 billion in 1992, and Hurricane Opal's 1995 Gulf Coast party cost $2.1 billion. The great summer floods of 1993 took insurers for another $10 billion. And the prospect of a three-foot rise in sea levels during the next 100 years has even the most solvent of insurers issuing fearful forecasts.Last year's drought in Texas destroyed $1 billion worth of food. Kate Fish, speaking for agri-giant Monsanto, recently expressed her company's concern when she told The Washington Post, "We depend on farmers to a large part, and farmers depend on things like stable weather patterns and soil moisture content. Extreme weather patterns are daunting." PREORDAINED PLAN? While scientists and insurers sound an alarm, powerful economic interests are circling their wagons. Oil, gas and coal producers are blanketing the Internet with materials refuting global warming. Their lobbying group, the Global Climate Coalition, seeks to discredit the IPCC scientists. They argue that the scientific evidence is inconclusive and that natural patterns -- not human activities -- are causing any climatic shifts.A top priority for the fossil-fuel vendors is blocking or slowing national and international limits on CO2 production. They charge that CO2curbs will threaten jobs and may force Americans into "a second-class lifestyle."Another industry front group, the Western Fuels Association, has purchased full-page ads arguing for repeal of voluntary CO2 restraints adopted at the 1992 international environmental summit in Rio de Janeiro. Resurrecting choice rhetoric from the early days of the Reagan administration, the head of Western Fuels recently spoke of a divine plan for fossil fuels."It's easy to conclude," said Frederic Palmer, "that, under a preordained plan, coal and oil lay in wait for exploitation by humans to permit our creation of an environment on Earth conducive to the spectacular success of our species."As the debate swirls among the powerful, some scientists ponder the potential impact of global climate change on nonhuman life. Following the last ice age some 10,000 years ago, the earth experienced a rapid warming over a brief 100-year period similar to what is projected for the coming century. One significant difference, notes University of Minnesota ecologist Margaret Davis, was that this earlier swing went from "cool to warm, rather than from warm to warmer." In addition, plant communities were able to spread onto unoccupied fresh soils left by the retreating glaciers.Davis' study of forest migration rates suggests tree ranges, via seeds, can travel 20-40 kilometers during a century. Given the fragmentation of landscape by roads, cities and other human interventions, she wonders how quickly a plant community, especially one under stress, can adapt. "It's difficult, she says, "for me to see how you can create a whole new plant community on a new place."Creatures like migratory birds may be especially at risk. What happens if coastal feeding sites are under water, or prairie potholes are baked dry, or the emergence of hatchlings no longer coincides with insect breeding cycles?One winner in the looming climate change equation might be disease-causing microscopic bugs. Ancient human plagues like malaria, yellow fever and dengue fever could feed over a wider global range. According to the World Health Organization, 30 new infectious diseases have emerged during the last 20 years. Other bugs may await a warmer, distressed environment. THE NEED TO ADAPT Bretherton, a self-described "scientific activist," vows to seek out more and better information on climatic trends, if only "so our children and grandchildren will be able to act intelligently." He thinks there's still a little time -- perhaps a few decades -- to figure out how to adapt to coming changes.For southern Wisconsin, he foresees hotter and drier summers with warmer, wetter winters. Agriculture would probably change, as growing corn might not be possible. The "heat" might destroy the crop, he speculates.It's important, says Bretherton, "to find out what a new agricultural economy might be." He suggests farmers learn how to capture and store some of the excess winter moisture for use during hotter months.More immediately, Bretherton supports energy-conservation practices in buildings, on the road and with appliances. "Save fuel wherever it makes sense," he reasons.For all our heated and air-conditioned buildings, weather remains a fundamental quality-of-life issue. Says Bretherton, "I want to pass on to my grandchildren a world like I've had, with the full richness of opportunity. I don't want to hand on to them something I am ashamed of."Still, pessimism seeps into his thoughts: "Most likely we will continue to do nothing until nature has another unpleasant surprise for us. Nature is going to make it obvious." n [rule] Check the Document Feed section of Isthmus' Web page, www.thedailypage.com, for links to the IPCC and other climate-related Web sites. SIDEBAR: Forecasting far into the future [drop] Skeptics may question how accurate 100-year climatic-change forecasts can be when TV meteorologists still force school closings with predictions of blizzards that fail to materialize. The two forecasts, however, are different animals.Predicting next week's weather with any degree of precision is immensely more complex, according to John Kutzbach of the UW-Madison. Day-to-day weather forecasting is an attempt to measure the specific movement of many variables in a fluid or changing system. He compares it to canoeing in a pond. The little whirlpools left by the canoe paddle resemble weather patterns, and trying to predict where they will go and how long they will last is exceedingly difficult due to all the other water movement occurring elsewhere in the pond at the same time.In contrast, it's relatively easier to predict general changes to the pond's overall system. The pond's size, depth and other dimensions can be accurately measured. With this knowledge, it's possible to forecast how warm the water will get should someone drop 10 tons of molten lead into the middle of the pond.It's worth noting that the dizzying array of factors affecting the earth's climate, coupled with their counterbalancing effects, still makes broad climatic forecasting perplexing work.
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