The Hot Zone

Global warming isn't just a theory anymore. Now the arguments are about how dire the changes in world climate will be, how soon they'll come--and what, if anything, can be done to moderate them.

Out on the sand plains about 50 miles north of Minneapolis, there's a cluster of broken-down farmsteads that belong to the University of Minnesota. It's flat, unremarkable land, dotted with clusters of oak and pine, crossed by weedy, dead-end roads. Near a tin shed by the side of one of the trails, three circles of bare earth have been carved neatly into the stubbled grass. Each is divided into a grid of 6-by-6 plots that will soon be seeded with various sets of prairie plants--purple bush clover, butterfly weed, green coneflower, Indian grass.

By the time the plants come up next spring, a tanker truck will pull up here once a week, bearing pure carbon dioxide from a brewery. Researchers will fill a tank and pump high concentrations of CO2 over two of the three circles, using a sensor to make sure the level stays constant at about 150 percent of what it is now. The third circle will be left alone for comparison. The point is to find out how the plants grow in the enriched air, and whether diverse plots do any better than monocultures. It's a neat little study.

It is also an experiment inside an experiment. For a century and a half, humanity has been adjusting carbon dioxide in the atmosphere upward about 25 percent, bringing it to a level higher than it's been any time in the last 150,000 years. Now the results are starting to come in.

Over the past century the globe has warmed up about 1 degree, and the oceans have risen an inch. Ice is melting at the poles and atop mountain ranges. Droughts and floods are becoming more common. The very timing of the seasons has shifted; spring now comes a week earlier to the Northern Hemisphere than it did in the 1950s. Plankton has been dying in the ocean off California; bugs and plants are moving north or uphill; the Arctic permafrost is thawing; and strange things are happening with the El Niño system of ocean currents.

Global climate change, global warming, the greenhouse effect, whatever you name it, is no longer a controversial theory or even a worrisome prediction. With little fanfare, and considerable reluctance on the part of many researchers, it's become expert consensus. How much further to push the global experiment is a matter politicians from around the world are supposed to decide later this year. But the change already set in motion will continue at least until the children of children born now are old. What this means for the planet--20 years, 50 years down the road--is the question researchers at the UM's prairie site and elsewhere are trying to answer now.

You've heard the basic greenhouse explanation. It's like leaving your car out in the sun. Light comes through the windows at a certain wavelength; bounces off the interior; and can't get back out because of its new wavelength. Similarly the stratosphere--the layer of air some nine to 31 miles up from where we live--is less "transparent" to radiation bouncing off the globe's surface than to that coming in from the sun. Without this natural greenhouse, Earth's average temperature would be around 18 below.

The substances chiefly responsible for the greenhouse effect are water vapor, methane, and carbon dioxide. And since humans began vaporizing the world's coal mines and oil deposits around the mid-1800s, they've added billions of tons of CO2 to the atmosphere.

This much is basic physics. What was disputed, until recently, was whether those additions enhanced the natural greenhouse effect or simply blended in without further consequence. (One caveat: Though often confused, the greenhouse effect is not the same as the ozone-hole problem. In fact, they work somewhat at cross-purposes. Ozone deterioration, caused by chemicals until recently found in air conditioners, spray bottles, and styrofoam, allows more ultraviolet radiation to hit the surface of the earth, causing skin cancer and other problems. But thinning ozone makes little difference in terms of temperature; it could even help cool the globe, much as a fraying blanket would send you shivering at night. Just to make things more complicated, the chemicals that destroy ozone do also serve as greenhouse gases, probably canceling out the cooling effect right there.)

The jury appointed to answer the global-warming question was the Intergovernmental Panel on Climate Change, a body of 2,400 scientists set up by a United Nations conference in 1987. Its membership was drawn from the world's most illustrious research institutions; the U.S. delegation alone hails from places like the Lawrence Livermore National Labs, Harvard, MIT, and the Woods Hole Oceanographic Institute. The IPCC has released two "global climate assessments"; each ran thousands of pages, with footnotes enough to fill another volume. But if the first report was comparatively inconclusive, the second, published in 1995, was a bombshell.

First, the IPCC said in the 1995 report, its earlier findings (the 1-degree increase in global temperatures over the last century-plus, the 1-inch sea-level rise, and many other slight, but increasingly noticeable trends) had been confirmed by additional research. But, it added as it did in 1990, such trends in themselves didn't mean much: Global temperatures have fluctuated up to 10 degrees over geologic time, usually triggered by shifts in the earth's orbit around the sun. And though the most recent warming started right after fossil-fuel burning took off, that didn't prove a causal relationship. What led the IPCC to conclude that such a relationship did exist was a scientific breakthrough no one had expected for at least another decade or two: The computer models had fallen into place.

When it came to the greenhouse effect, the models climatologists use as stand-ins for the real world had always confounded researchers. If you enriched a model's hypothetical air with the amount of CO2 humans have been pumping out, you got a much warmer climate; but it was much warmer than what we actually have. Which meant that either some other force was moderating the human influence, or the climate was simply doing its own thing independent of human inputs.

Then some enterprising graduate students plugged another key real-world variable into their model: sulfates, the acid-rain chemicals that are a major by-product of fossil-fuel burning. If CO2 acts to reinforce Earth's greenhouse layer, sulfates are thought to create a "parasol effect." Like veils draped through the air high above, they reflect radiation back into space before it can warm Earth.

As soon as sulfates were accounted for, the models' warming curves snapped into position, overlapping the actual record with eerie accuracy. The globe would warm more at night than during the day, they predicted (and it has); it would stay cooler in places downwind from most coal burning, such as the Northeastern U.S. (right again); the stratosphere would get colder while the air further down heated up (likewise).

It looked, for all intents and purposes, like a climatic "fingerprint": No other force--solar cycles, volcanoes, and the like--could produce as good a match to the real-world record as the CO2-plus-sulfate model. And so the 2,400 IPCC scientists finally put their signatures to a statement as bland as it was remarkable: "The balance of evidence suggests that there is a discernible human influence on global climate."

A predictable firestorm followed. Critics called the IPCC a political body, beholden to world governments--which, apparently, couldn't wait to have their energy policies indicted. There were rumors about key statements being inserted, or removed, surreptitiously. Congress even held hearings to debunk global warming.

And it's true that much remains uncertain about the IPCC report. Some unknown force could be playing hide-and-seek, changing the climate in a way that only looks like human interference. This is a standard scientific disclaimer: Similarly, researchers don't know that gravity exists, they just know the planet behaves as if it did. "There's not a single experiment that proves human emissions cause climate change," says John Pastor, a University of Minnesota-Duluth researcher who has studied the response of forests to climate change. "For a long time, it also wasn't proven that smoking causes cancer. But there is such a thing as the cumulative weight of evidence."

And new evidence keeps emerging, with crucial studies published almost monthly since the release of the IPCC report. Perhaps the most interesting was the National Oceanic and Atmospheric Administration's disclosure that over the past 80 years, "extreme weather" has become more common around the world--and that the change has occurred in just the way the global-warming models predict. Precipitation, for example, now happens less frequently, in bigger downpours, and in winter more than summer.

The NOAA extreme-weather study team was headed by Robert Quayle, a fairly prominent "climate agnostic." In 1991, he said that it would take at least another four decades to validate the theory of human-induced greenhouse warming. Last year, Quayle told the magazine International Wildlife he had revised that estimate: Chances were 19 out of 20, he said, that what was being observed was indeed global warming. "I'm not particularly agnostic anymore," he said. "There is such a convergence of data it gets to be a little spooky."

Why should we care? That people have changed the climate may be philosophically crucial--you can't, if you let the fact sink in, look at storms or other "acts of God" the same way again--but so far, it doesn't seem to have made much of a tangible difference.

Or has it? That's the trouble with the law of averages. The researchers can tell you that somewhere, there's a river that wouldn't have overflowed without global warming, a drought that would have ended sooner, a storm that wouldn't have been so severe. But they can't and won't say whether it was the Red River of '97 or the Mississippi of '95, the storm that blacked out South Minneapolis last week or the heat wave that killed 500 in Chicago two years ago. Nor will they ever: Climate, it's been said, is what you predict. Weather is what you get.

Every prediction needs a starting point; right now, most of the forecasts assume that between 2050 and 2100, CO2 in the atmosphere will reach a level twice as great as before the Industrial Revolution. This, the IPCC estimates, will send average global temperatures up an additional 2.5 to 6.5 degrees. Most forecasters split the difference and estimate an increase of 4 to 5 degrees, with the warming distributed unevenly around the world. On the models' crude regional scale, the Twin Cities look to get right about the average increase, becoming 4 degrees warmer and somewhat drier. It would, in effect, look more like Omaha around here.

If that seems unremarkable, consider the historical precedent. Through all of the time humans have been recording their stories, there is not a single instance of warming even approaching the level predicted now, and far lesser climate ripples have split societies apart. Egypt's Old Kingdom ended when the Sahara's freshwater lakes dried up after the winds shifted slightly south. The "Little Ice Age," a mere 1-degree cooling from circa 1400 to 1850, sent Europe into a cycle of war, famine, pestilence and mass migration to the New World.

Granted, the people of those times may have been more susceptible to climate change than we (at least those with air conditioners and food supplies carted in from thousands of miles away) are now. But from what's known so far, average temperature is just the start of global climate change--or, as many researchers prefer to call it, just plain "global change."

To start with, there is a nasty rule that says a slight increase in the average means an exponential rise in extremes. If Minneapolis/St. Paul get only a little warmer, days with a "heat index" of 95 degrees or more--the kind that can kill the old, the young, and the sick--could come four times to 10 times as often.

If flooding becomes just a little more common, extreme floods increase that much more; a 100-year-flood plain can become a 10-year-flood plain. The same goes for 100-year droughts, and so on.

One of the reasons why researchers now speak of "global climate change" rather than "global warming" is that warmer temperatures change the way air and precipitation move. Minnesota, as it happens, sits at the intersection of three major climate forces--warm, moist air from the Gulf, winds from the West, and the Alberta clippers. A slight shift in one or all of them could bring anything from a little extra snowfall to a new tornado alley. Stanford University climatologist Stephen Schneider calls the region "ground zero of climate change" for precisely that reason.

As climate shifts, so do the boundaries within which plants and animals can live. University of Minnesota researchers have been studying samples drilled from deep lakes and forest floors for traces (plant pollen, fossilized fly wings, ash from prairie fires) of eras long gone. They've found that through geologic time, trees like spruce and oak have pulsed back and forth across the region, crossing vast territories in pursuit of favorable climate; in fact, the forests growing here now may have evolved precisely in response to constant climate change at the glacial boundary.

But those changes were gentle compared to what's down the road. Margaret Davis, a University of Minnesota regents' professor in ecology, says even at their fastest rate, the trees she studied moved no more than two-thirds of a mile per year. Under current climate projections, "we're asking them to go about ten times that fast. And I fear that a lot of species won't be able to keep up."

How exactly the landscape will change is hard to forecast. UMD's John Pastor has run calculations which suggest that at the IPCC's projected rate of warming, spruce, maple, birch, oak and pine could all but disappear from sandy soils in northern Minnesota. There's nothing unduly apocalyptic, the data indicates, in envisioning parts of Voyageurs National Park and the Boundary Waters, which now make up the southern edge of the "northern boreal forest," as landscapes of stumps.

Dying forests, of course, would be at much greater risk of burning. The Canadian Forest Service has found that forest fires were up almost fourfold in the mid-1990s from a decade earlier; Minnesota, too, has seen a record number of blazes. Fires, in turn, release carbon the trees have heretofore been storing--more greenhouse-enhancing CO2.

And don't forget the peat bogs that cover much of the Arctic and chunks of northern Minnesota. They contain, says UM regents' professor Eville Gorham, about one-third again as much carbon as there is in the world's atmosphere now. Even a slight warming could cause many peat bogs to dry up and release CO2; or the permafrost below some of them could thaw and release another potent greenhouse gas, methane. In a worst-case scenario, vast tracts of peat could catch fire, smoldering for years at a time in what Gorham calls the "Kuwait of the North."

But the plants of most immediate concern in global-warming scenarios are agricultural crops. There are those who argue that there's nothing to worry about. Avowed "climate skeptic" Sherwood Idso notes that CO2, besides warming the atmosphere, serves as an airborne fertilizer. Thus, humans should celebrate fossil-fuel burning--because it heralds a "rebirth of the biosphere," the return to a "paradise lost" of lush growth.

Most ag researchers are not so sure. Aside from the matter of how long crops could sustain a CO2-induced growth spurt, changed weather patterns are almost guaranteed to affect production. Crop failures are likely in portions of the world's corn belts as rains fail to show or heat spikes wilt crops. As far back as 1988, the U.S. Environmental Protection Agency calculated that crop acreage in the Midwest could decline by 25 percent under the global-warming projections of the time. In one scenario, a string of severe droughts could turn Kansas into a desert in as little as a decade. What's more, warmer temperatures bring better conditions for pests, from grasshoppers to corn borers.

There is an easy answer: Farming will just have to move north. It looks a lot less attractive when you consider the upheaval involved (ask any small town in southern Minnesota). Nor is it clear that the sandy soils of, say, northern Minnesota and Alberta could perform the way the Central Plains' deep-down black dirt has. And even if it all works out, a transition period of dicey harvests could be bad news at a time when the world's food supply looks increasingly uncertain.

And that's just the story of the North--which, according to the models, is in for a much better time of it than the Southern Hemisphere. For much of Africa and Latin America, the models forecast average temperature increases up to twice as high as those of North America, Europe, and much of Asia. That means more droughts for parts of the world that already suffer from chronic water shortages. A mild shift in monsoon patterns could wipe out entire regions where farmers barely get by now. This is known as the "green north-brown south" pattern; the consequences for migration alone are staggering.

There are, however, two great equalizers: the oceans and the bugs. Both have ways of evading containment, and neither is very well understood. Ocean waters are slower to react to atmospheric changes than the air. But they have, the IPCC reported, been getting warmer. That may have caused the 70-percent die-off California researchers discovered two years ago among the tiny sea organisms called plankton. And if plankton is in trouble, so are the fish that eat it--as well as the 30 percent of humanity that rely on fish for food and agricultural fertilizer. (Closer to home, a University of Minnesota biologist estimates that at the predicted rate of warming, something like 40 percent of the walleye and northerns could disappear from the lake country.)

Tropical storms--hurricanes, typhoons, cyclones--by contrast, like warm water. They don't even form in places where the surface temperature isn't at least 78 degrees. Researchers aren't far enough along with the models to say for sure that global warming will bring more storms, but the insurance industry has been taking notice.

Meanwhile, on mountain ranges from the Rockies to the Alps, glaciers have been pulling back, in some places as fast as 100 feet or more each year. In Austria, the retreating ice exposed the body of a man who'd tried to cross the mountains the last time the glacier was this small--before the Roman Empire. Melting ice, along with the fact that warm water expands, is the most likely explanation for the last 100 years' ocean-level rise. And there's more to come: The IPCC projects that if current trends continue, the seas will rise 12 inches by 2050, flooding most of the East Coast's beaches and up to one-fifth of countries like Bangladesh and the Netherlands.

As for the bugs, first the good news: Researchers expect that as climate warms, fewer people in North America and Europe will die of cold-season illnesses, including flu. Most of the rest of humanity's predators, however, stand to see global warming as a boon. Right now, about 45 percent of the world is suitable habitat for the mosquito that carries malaria. With a 5-degree average warming, the insect could expand its range to 60 percent of the globe, reaching upland mega-cities like Nairobi, Kenya and Harare, Zimbabwe, as well as to a good part of the central United States. In the past few years, the mosquito has been found 1,700 feet up on Latin American mountains where it never used to climb above 1,000 feet.

Similar projections apply for the bug that carries dengue hemorrhagic fever, an illness that starts with headaches and ends with fatal internal bleeding. It, too, has been moving north and uphill, bringing an epidemic that began in Argentina to much of Mexico and into the States. Hantavirus, which has killed 60 people in the United States since it appeared in the Southwest four years ago, was handed outbreak conditions by a series of odd-weather years in which mice multiplied.

The world's lead killers, waterborne microbes, also thrive in warmer waters, and they love to be sloshed around by floods. The Third World, where 6 million children already die each year for lack of clean water, will feel the consequences first. But Los Angeles, Phoenix, and Miami also know what it means to be water-starved; even Minneapolis has reason to consider the effects of pollution and microbes in the Mississippi River water it drinks.

And that's only the devil we know. It doesn't take much to figure out that as weather conditions push plants and animals to their limit, new diseases are likely to be carried out of the interiors of forests; or that climate stress, like any other kind, can weaken the immune systems of humans, plants, and animals, making them more susceptible to disease just when they can least afford to be. Perhaps, some public-health researchers figure, it will be disease that finally puts global warming front and center.

Beyond all the predictions, though, one more great unknown lingers. Wily as it seems, climate is actually an astonishingly balanced system. Winds work to even out air temperatures between the poles and the tropics. Plants and tiny mollusks store carbon that would otherwise float in the atmosphere. The oceans swallow massive amounts of heat and move it around, with pachydermal speed, in currents larger than all the world's rivers put together.

But just as those forces balance each other, they can also feed on each other. Feedback crescendos, researchers believe, are what caused past climate "flips," in which the globe switched from one state of relative equilibrium to another--not, as it used to be thought, in millions or even thousands of years, but in as little as a few decades. That's what happened some 11,000 years ago, during an event called the Younger Dryas--a kind of climatic hiccup at the end of the last Ice Age. Meltwater from the shrinking glaciers diluted salty ocean waters and set off a chain reaction in the way warm and cold water masses moved around. In a nutshell, the Gulf Stream that keeps northern Europe comfortable took an unpredictable turn, and glaciers returned to much of the continent. And in Minnesota, mammoth and mastodon disappeared as the forests they roamed became deep freezes.

What the coming climate has in store by way of climate flips is unclear. But there are scenarios pointing just about any possible direction--one, by UM associate professor Robert Johnson, suggests that global warming could actually send the glaciers that once covered Minnesota creeping back from the Arctic. "Climate is an angry beast," Wallace Broecker of Columbia University's Lamond-Doherty Earth Observatory has said, "and we are poking it with sticks."

One thing researchers know for sure is that carbon dioxide is a remarkably long-lived gas. Almost all the CO2 humans have been sending into the atmosphere for the past century is still up there (minus, that is, the 50 percent or so plants have obligingly extracted), and will affect climate for another century or more. Children born now may see the rate of climate change slow down, if they live long lives and if most fossil-fuel burning stops immediately.

Which, of course, will not happen. But coal and oil consumption could come down--drastically if desired, slowly otherwise. This is something the IPCC considered. One of the most interesting graphics in its 1995 report shows just how much warming is likely, both for this generation and the next few, under various "emissions scenarios."

Under the most benevolent of those scenarios, humans would put the brakes on fossil-fuel burning to the point where CO2 emissions would increase just a little for the next 25 years, and then begin declining. By about 2100 they'd be back to where they were in 1960 and keep going down. This is what the science panel called the "safe trajectory"--not because it would avoid global warming, but because average temperatures would rise a mere 2.5 degrees over the next 100 years. The commission figured that was the upper range to which humans and ecosystems could more or less adjust.

For a moment, it looked as if the world's politicians were listening. In a 1992 convention signed by, among others, George Bush, the governments of 157 nations promised to "achieve... stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference in the climate system." As a first step, by 2000 they would all rein in their carbon emissions to 1990 rates. And by 1997, they would get together to determine "legally binding" targets for the next century. A meeting to do just that is set for December in Kyoto, Japan.

Judging from the performance of the first five years, the signatories aren't doing too well. Worldwide, carbon emissions are up some 6 percent over the 1990 level, and rising; the U.S. is in the lead, set to overshoot the target by as much as 11 percent. (It's also the world's biggest carbon user, period: The average American is responsible for some five tons of CO2 each year, compared to 2.5 for the average Japanese and a mere 0.25 tons for the average East Indian.) Bill Clinton came into office promising to get serious about emissions reduction; yet when international negotiations turn to how much and how fast, the American delegation has a reputation for blocking any firm targets. It's thus earned itself the designation of "chief of the carbon club."

It's not until you start reading the international press that you realize just how far out of step that position is. Not that the U.S. is alone in wanting to keep burning fossil fuels; everyone does, with varying degrees of hypocrisy. But no other industrialized nation seems to cling to the notion that climate change is just a theory. Which, in turn, reveals the depth of the public-relations war that has shaped debate here.

One recent effort was particularly instructive: In 1994, a group called the Information Council on the Environment (ICE) launched a campaign aimed explicitly at "repositioning global warming as theory rather than fact." It included, according to internal memos, locating and funding scientists who would question global warming; getting them interviewed by the press; and producing ads that asked things like "If the earth is getting warmer, why is Minneapolis getting colder?" Those spots, a campaign memo noted, should be aired on shows appealing to "older and less educated men" and "young, low-income women" in districts that got their electricity from coal plants and, if possible, had a representative on one of Congress's energy committees.

ICE was sponsored by coal-industry trade groups, who called off the whole endeavor after its existence became known. But kindred efforts have continued, chiefly by way of funding and publicizing a small but vocal group of researchers known as the "climate skeptics." The best-known are Patrick Michaels of the University of Virginia, Richard Lindzen of MIT, and "rebirth of the biosphere" theorist Idso.

Contrary to what some greenhouse activists like to claim, these are not uncredentialed kooks. Their research, when it appears in scientific journals, is subjected to the same scrutiny as anyone else's, and in many cases it opens interesting questions about the climate puzzle. What it does not do is balance the weight of evidence on the other side--unless, that is, the voices of the skeptics are amplified beyond what their number would warrant.

Other key bits of information, by contrast, haven't been nearly as well publicized. A number of economists calculate that industrialized countries could cut their CO2 emissions by up to 30 percent at no net cost. Even further reductions are feasible with technology allowing cars and power plants to run on "fuel cells" in which natural gas is converted to energy without being burned. As the IPCC noted, each factory, power plant, and office building will be replaced at least once within the next century anyway, "offering opportunities to change the energy system without premature retirement of capital stock."

So far, though, advocates of what author Russ Gelbspan (The Heat is On) calls "a Manhattan Project to rewire the world's energy system" have been less than successful. Oil and coal firms have little sympathy for obvious reasons. Utilities, still smarting from their underperforming nuclear investments, are leery of taking chances. Some European countries have adopted "carbon taxes" to give business a little extra push. But in the U.S., the Clinton administration's faint attempt at such a tax failed miserably in 1993. (A carbon-tax proposal in Minnesota, developed by the advocacy group ME3, could come to the Legislature next year.)

Lately, though, advocates of climate action have found an unexpected and ironic ally: natural disasters. According to the Federal Emergency Management Association, federally insured catastrophes are up fourfold from a decade ago; and while the politics of disaster relief may play into that figure, the trend in floods, droughts, and storms is also up elsewhere. Worldwide, insurers shelled out $57 billion worth of weather-related disaster claims in the first half of the 1990s. That was three times as much as they paid over the entire preceding decade--giving rise to statements like that of Franklin Nutter, president of the Reinsurance Association of America, to a trade group last year. "The insurance industry is first in line to be affected by climate change," Nutter said. "[It] could bankrupt the industry." Other executives have been talking similarly tough, raising the specter of a whole new battle on the climate scene: Big Oil vs. Big Insurance.

There is, of course, another possibility: If politics doesn't get a hold on climate change, climate might get a hold on politics. How long, Gelbspan asked a St. Paul audience this spring, until the U.S. political system feels the effects of "more Hurricane Andrews, more Ohio River flooding, more Red Rivers and more crop-destroying droughts?

"This is not the kind of climate in which democracy flourishes. This is the kind of climate that could easily lead to food rationing with its associated black-market crime. It could lead to a military takeover of relief operations [like the Federal Emergency Management Agency] to maintain order in the face of natural disruptions. Social unrest arising from a series of natural disasters could easily lead to a significant expansion of our internal security forces."

William Ruckelshaus, the first administrator of the Environmental Protection Agency and now the CEO of garbage giant Browning-Ferris Industries, said as much some time ago. "Long before the systems of the planets collapse," he told Gelbspan once, "the processes of democracy will buckle under the weight of the series of ecological emergencies."

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