COLUMN ONE : An Early Warning of Warming : If the ‘greenhouse effect’ exists, the Arctic will be the first to experience it. Scientists are studying 100,000-year-old icecaps in an often-frustrating effort to predict the future.
White-knuckle fliers plying the trans-polar commercial routes might be comforted to know about Eureka: This tiny Arctic scientific station and military outpost, perched on the shore of an ice-choked fiord in Canada’s Northwest Territories, has a special “safety runway,” long and strong enough to handle an emergency landing if a passenger jet ever got into trouble over these desolate wastes.
But the skittish air traveler might be somewhat less reassured had he witnessed a Eureka scene from the summer of 1988.
A Canadian Hercules transport plane, heavily laden with supplies for the secret military post farther north at Alert, came in for a routine refueling stop at Eureka. The gravel runway looked dry, but when the Hercules touched down, it sank up to its undercarriage in mud that appeared out of nowhere.
It turned out that the Arctic summer of 1988 was a relative scorcher, and the unusual heat had melted hidden ice deep within Eureka’s soil. That left the seemingly dry “safety runway” floating precariously on an underground lake.
Unpleasant enough for the people who had to dig the huge air force plane out of the mud--but the freakish incident suggests even worse things to come.
“This sort of behavior could become more common if we have a number of summers like 1988,” said Sylvia Edlund, a research scientist with the Geological Survey of Canada who happened to be studying the links between vegetation, soil dynamics and the climate near Eureka the day the plane made its belly-flop.
Many climate experts are convinced that the world is warming up, probably because of increased atmospheric levels of “greenhouse gases” given off by the burning of fossil fuels. The gases--carbon dioxide is the leading offender--trap heat close to the Earth’s surface, much as windowpanes hold in a greenhouse’s warmth.
If predictions of a “greenhouse effect” prove out, then global warming will hit the Arctic faster and harder than anywhere else on Earth. While the planet is widely expected to warm by about 3 to 5.5 degrees Fahrenheit by the year 2050, the Arctic is expected to warm by as much as 18 degrees Fahrenheit, particularly during the winter.
Such an Arctic thaw could devastate the fragile and little-understood ecosystems of the Far North. The undermining of gravel runways would be just one small piece of the picture. While no one can say with certainty just what an Arctic thaw would look like, scientists say it could involve anything from the demise of the mighty polar bear to a rise in sea levels and the inundation of dozens of Inuit, or Eskimo, villages that now cling to the Arctic coast.
Some climatologists predict that if large areas of peat-rich Arctic permafrost melt, the thawing soil will release even more greenhouse gases into the atmosphere, accelerating the warming of the rest of the globe.
Still other scholars suggest, paradoxically, that by increasing Arctic seawater evaporation and creating prime conditions for more snow, an Arctic warming could eventually produce a new Ice Age.
It will be decades before anyone is sure whether a greenhouse effect has taken hold, either here or elsewhere. But already, soil specialists, botanists, wildlife biologists and others are wading into frigid Arctic creeks, setting transmitters on lonely ice floes, measuring tiny tundra plants, stalking wildlife by helicopter and otherwise combing the North for the earliest signs of trouble.
“Canada has a large Arctic, and the first signals of global warming will probably be detected in the high Arctic,” Edlund said. “I personally feel that Canada has an international responsibility to monitor what’s going on up there. It’s imperative for us to develop an early warning system.”
Each spring, Edlund’s Geological Survey colleague, glaciologist Roy Koerner, skis onto an icecap northeast of Eureka, makes camp and, with special equipment, drills down into the ice until he hits bedrock. Koerner has thus been collecting core samples from four Canadian icecaps for 31 years.
Icecaps are the cousins of glaciers; they form in places where the winter snowfall is greater than the amount of snowmelt in the summer. But unlike glaciers, which flow like slow-moving rivers, icecaps stand their ground. Thus, their accumulations of old snow, layered like the growth rings of ancient trees, provide an excellent record of weather conditions over time. The ice at the bottom of the Canadian Arctic icecaps dates back 100,000 years.
Once he has drilled his core samples, Koerner carries them, still frozen, back to the Geological Survey offices in Ottawa, where he and colleagues subject them to a variety of tests. Volcanic eruptions, new industrial processes, nuclear weapons test blasts--under scrutiny, the layered snow offers evidence of all of these.
And so do the workings of weather patterns. By compiling the data from his ice cores, Koerner has been able to construct a 100,000-year history of the world’s climate.
Such a weather log will be of tremendous help to the many scientists who are trying to find out whether the current warming trend is merely part of the natural variation in climate--or whether it is the more worrisome result of runaway fossil-fuel consumption. For those caught up in the global-warming debate, this is the threshold question.
The evidence so far is inconclusive. Scientists agree that the levels of carbon dioxide in the atmosphere have increased by about 25% over the past century. And credible statistics support a finding that not only is the Earth warming but that the past decade was, on average, the warmest since record-keeping began in the latter part of the 19th Century.
Individual studies have shown that:
* The part of the Northern Hemisphere covered by snow has been shrinking in recent years.
* Sea ice in the Arctic Ocean is receding toward the North Pole.
* Huge expanses of the sea ice north of Greenland have thinned by about 15% over the past decade.
* The Alaskan spring thaw came, on average, two weeks earlier in the 1980s than in the 1940s.
* Canadian and Alaskan permafrost has warmed by about 3 to 7 degrees Fahrenheit over the past century.
But is there a clear connection between the rise in carbon dioxide concentrations and the warming temperature? That’s where many competent researchers admit they are stumped. They point out that the Earth has gone through other warm spells down through the eons, none of them brought on through human deeds. Today’s rising temperatures, they say, may just be another one of those natural fluctuations.
“The question is, when can we firmly ascribe the change to something other than the normal variability?” asked David A. Robinson, a climate expert at Rutgers University who has documented a reduction in the snow cover of the Northern Hemisphere. Finding the answer, he said, “involves building long enough records to understand the climate’s natural variability.”
That’s where Koerner’s Canadian icecap samples come in. On the one hand, they show that for the past 150 years or so--since the spread of the Industrial Revolution across Europe--the Earth has been warming up.
But on the other hand, the ice shows that since the 1950s, the warming trend has dropped off.
What to conclude? While Koerner says that the ice offers no proof that the greenhouse effect is for real, he remains intrigued by one tantalizing possibility: The ice, he says, may be saying that greenhouse gases are indeed warming the Earth but that the trend could be masked by a simultaneous buildup of smog that began in the 1950s. The smog, he theorizes, may be blocking the sun’s rays and holding the temperature down.
The ice cores offer preliminary evidence of this. They show a rapid increase in smog levels since the 1950s.
To learn whether his hunch is sound, Koerner is now conducting more tests, fine-tuning his global-climate profile to yield even more information--facts about precipitation levels, for instance, and about season-to-season weather patterns.
“The (climate) models aren’t just saying it’s getting warmer,” he said. “They’re also saying that it’s going to get much warmer in the winter. And they’re saying that there’s going to be more precipitation. So we’re trying to separate this out. We want to see whether the way it’s going to warm up is the way the models predict.”
In trying to sort this out, Koerner has come up against another of the key problems facing the scientists who are trying to identify an Arctic thaw: The telltale warming itself is almost hopelessly mixed with, and obscured by, other signals.
Although the Arctic ecosystem is relatively simple, with far fewer forms of plant and animal life than are found in the more temperate zones, it nevertheless features a wide array of key natural processes, which are poorly understood and which often seem to interact with the temperature in confusing, contradictory ways.
Consider precipitation. “It sounds strange, but we’re still trying to figure out how snow fits into the whole picture of the climate system,” said Rutgers’ Robinson.
As Koerner points out, most climate modelers suspect that as the Arctic warms, there will be more snow and rain. This is because the ice covering much of the Arctic Ocean is expected to melt, exposing more of the ocean’s surface to the sun. That, in turn, would lead to greater evaporation and more moisture in the air, which would return to Earth in the form of precipitation.
Informed of all this, a reasonable layman might conclude that the chain reaction would continue, with global warming ultimately irrigating the arid Arctic soil, promoting a flowering of lush northern plant life and creating a rich new environment for such Arctic herbivores as the caribou and the musk ox.
But scientists are finding that it isn’t likely to be so. Walter Oechel, a biologist at San Diego State University who has done extensive fieldwork in Alaska, says that, alas for the caribou and the musk ox, the warming trend of recent years has in fact dried out the tundra--not moistened it.
“The Arctic is a strange situation,” he said. “Even if rainfall goes up, that doesn’t necessarily mean there’s going to be more water available to plants. In fact, the opposite may be true.” As precipitation levels go up, scientists say, other little-understood factors--soil dynamics, for instance, or the behavior of underground ice bodies and the wind--may offset their effects.
More unsettling still, Oechel has noticed that as the peaty tundra has dried out, it has been releasing its wealth of stored carbon into the atmosphere.
“This worries me,” he said. “It could be a very strong ‘feedback’ effect,” or an outcome that accelerates the very warming process that triggered it in the first place.
“The Arctic is a system that has a very strong potential for feedback,” Oechel added. “And its importance is much greater than just in the North. If this carbon (in the tundra) is released into the atmosphere, it’s going to affect broccoli and a lot of other things in Southern California.”
Given the Arctic’s propensity to feedbacks, scientists are trying to learn about the complex interactions between the Arctic’s frigid atmosphere and the much-warmer ocean; about how the sun’s energy behaves when it bounces off bare land versus snow; about the effects of cloud cover and wind, and about the timing of the seasons and how it may affect the life cycles of plants.
Some ongoing studies look at such seeming arcana as Arctic-silt dynamics, or the way ice cracks under pressure. Much of this work is close to pure research, with few obvious immediate practical implications.
But ultimately, an understanding of these complex and obscure interactions should answer pressing questions about the fate of Arctic pipelines, roads and seaside villages--and about some of the Arctic creatures dear to the hearts of nature-lovers.
The leading example is the polar bear, an animal that lives on the sea ice the way a fish lives in water: It has nowhere else to get its food. The average polar bear relies on seals for 95% of its nourishment, and it catches them by lying next to their breathing holes in the ice and nabbing them when they surface for air.
“Basically, the bears’ whole life is oriented around making a living on the ice,” said Ian Stirling of the Canadian Wildlife Service, one of the world’s leading authorities on the polar bear. “If the sea ice melts, they’ll simply disappear.”
There is a chance that this is already starting to happen.
Stirling’s work has focused on a polar-bear population that lives on the western shores of Hudson Bay. He has been studying it for the past 20 years, stalking the great predators by helicopter, darting them with tranquilizers, weighing and measuring them, taking tissue samples and releasing the animals back into the wild with radio collars for further tracking. The work has given him a more comprehensive database on the Hudson Bay polar bears than exists for any other polar-bear population in the Arctic.
And now, the database is telling Stirling that for the past 10 to 15 years, the polar bears of Hudson Bay have been in decline.
The bears aren’t as fat as they used to be, Stirling said. They have fewer cubs, and the cubs they do have are less likely to survive their first year.
There could be a variety of reasons for this, Stirling said, ranging from pollution in the food chain to a natural population “crash.” But, he said, “one of the possibilities is that we’re seeing some effect of climate warming, which is affecting the sea ice. If we are going to see (a melting of the sea ice), the first place we would see it is Hudson Bay. It’s already ice-free three or four months out of the year.”
During those difficult ice-free months, Stirling has observed, the Hudson Bay polar bears are forced to venture onto land, where they can’t hunt seals and must thus live mainly off their stored body fat. By the time their icy sealing platform returns in the fall, he said, the bears are lean, hungry and exhausted.
“The bears are already at the limit of what they can endure,” he said. “If we do get some warming of the climate, it probably won’t take too much before they have to lengthen their on-land fast more than they could endure.”
Climate modelers say a temperature increase of just 2 degrees Fahrenheit would be enough to advance the spring breakup in Hudson Bay by one to two weeks. That may sound like a small change, but Stirling said its effect on the half-starved bears could prove “devastating.”
So now studies are being conducted on the ice cover in Hudson Bay to see whether it is, in fact, shrinking. The findings so far have been inconclusive. But Stirling fears that if people wait for ironclad proof of a greenhouse effect before changing their behavior, it will be too late for the polar bear--and probably other Arctic species as well.
“If (global warming) is happening, the rate of change is very likely to accelerate,” he said, pointing out that even if fossil-fuel emissions were strictly regulated tomorrow, atmospheric levels of the greenhouse gases would continue to rise for some time. “Unless we realize that we’ve got to start reducing our influence on the ecology of the planet, we’ll wait until we’re so far behind the eight ball that we’ll never catch up.”
* A Symbol in Danger
The polar bear is perhaps the most recognizable symbol of the Arctic. Yet something is going wrong with Canada’s best-studied polar bear population, and wildlife biologists worry that the problems may be connected with global warming.
Polar bears living on the ice of the western Hudson Bay are markedly thinner than they were 15 years ago. They are bearing fewer young, and more of their cubs are dying.
The reasons are unknown, but one suspected explanation is a climate-related reduction of the ice covering the frigid Hudson Bay. The bears need the ice as a platform for hunting seals, their main source of food.
Evidence suggests that an average warming of just 2 degrees Fahrenheit could melt enough of the Hudson Bay ice to wipe out the local polar bear population.
* The Great Meltdown? Northern Canada is expected to be hard-hit if global warming melts ice packs. There is evidence that snow cover has already been reduced.
