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Exactly how, then, does one reconstruct the climate of seven hundred million years ago or a billion years ago or two billion years ago? From work emerging over the past fifty years or so, but really coalescing over the past ten years and largely through the efforts and personality of one man, the idea of Snowball Earth has taken hold. It is science at its ugliest, when evidence is scarce and inconsistent, when speculation and ego and charisma mix with observations, when data are insufficient to unambiguously confirm or refute ideas. And for now, the speculation and ego and charisma of Paul Hoffman — backed up by a certain amount of hard-won data from remote locations in the Canadian Arctic, the Namib Desert, and Australia’s Flinders Ranges — has won the day. The earth of seven hundred million years ago, Hoffman believes, was frozen from pole to pole, one more or less continuous, frigid, blood-thickening, numbing ball of ice: Snowball Earth.
His evidence is in the geology of Precambrian rocks. It is the same sort of evidence left by the Pleistocene Ice Age, but the rocks are much older and occur at all latitudes. The tropics, seven hundred million years ago, were not so tropical. The oceans were frozen over. One could have ice-skated between tropical islands. Across much of the earth’s surface, a mercury thermometer would be of little use because the mercury would be frozen solid. Mean global temperature could have been something like minus sixty degrees. At the equator, temperatures would have hovered around negative ten, what Apsley Cherry-Garrard would have called forty-two degrees of frost. The planet would have been only slightly more hospitable than, say, Mars.
As early as the 1870s, people were finding scattered evidence of long-past ice ages, ice ages much older than Agassiz’s original Ice Age. There was, for example, a paper by H. Reusch published in 1891 with the title “Skuringmærker og Morængrus Eftervist i Finn-marken fra en Periode meget Aeldre end ‘Istiden’ ” — in English, “Glacial Striae and Boulder-Clay in Norwegian Lapponie from a Period Much Older Than the Last Ice Age.” In 1948, the Antarctic explorer Sir Douglas Mawson spotted signs of ancient ice ages in Australia. “Verily,” he told the Royal Geological Society of Australia, “glaciations of Precambrian time were probably the most severe of all in earth history; in fact, the world must have experienced its greatest ice age.”
Others slowly built on the idea of an ancient ice age, but it took the ambition, ego, and entrepreneurial maneuverings of Paul Hoffman to bring the idea home. He has been quoted as saying, “Everyone’s entitled to my opinion.” During a scientific debate, he once challenged a Snowball Earth naysayer to “try me out in the Boston Marathon some year.” And his own self-assessment, according to a biographer: “Gosh, I’m awful. I don’t know how I’d react to me.” But the history of science shows that new ideas take hold because they are pushed by strong personalities. In 1998, Hoffman, with a couple of coauthors, published “A Neoproterozoic Snowball Earth” in the prestigious academic journal Science. The idea and the people behind it were immediately attacked, both verbally and in print. The “Snowball” jargon had charisma, but it was a charisma that worked both ways. Opponents wrote papers with titles such as “The Snowball Earth Trip: A Neoproterozoic Snow Job?” and “Has Snowball Earth a Snowball’s Chance?” Some talked of a “Slushball Earth,” not quite as cold as Hoffman’s Snowball and with oceans that were not entirely frozen over. Others rejected the idea entirely. Still others have gone in the other direction, delving farther back in time, suggesting that an even colder Snowball Earth circled the sun some two billion years earlier than Hoffman’s did.
Hoffman has been awarded the Logan Medal by the Geological Association of Canada, the Miller Medal for outstanding research in earth science by the Royal Society of Canada, and the Alfred Wegener Medal by the European Union of Geosciences. He is a member of the National Academy of Sciences. He is a professor at Harvard. But he also has been accused of founding the Church of the Latter-day Snowballers. He stirs up bitter debate. It has been said that he sometimes alienates people who were once friends. He inspires passions, both positive and negative. He is, in short, a successful scientist. He has, if nothing else, made the world of science consider the possibility of a chilled earth, an icicle planet, one big ball-shaped skating rink in bad need of a tropical vacation.
It is September thirtieth. Last night, it dipped to thirty-six degrees in Anchorage, but by noon it is sunny and nearly fifty. There are eleven hours, thirty-two minutes, and one second of daylight today, sunrise to sunset. That is five minutes and forty-one seconds less than yesterday, and five minutes and forty-one seconds more than tomorrow. By December twenty-first, the shortest day of the year, we will be down to about five hours of daylight. The sun, when up, will drift low in the eastern sky, nowhere near overhead at high noon, but rather just above the mountains, angling in, its rays scattered and pasting long shadows on what will by then be thick snow. My son and I drive out to Eagle River with the top down. He complains about the cold. Soon the convertible will have to be parked for the winter.
It has been snowing in the mountains again. Above us, what had been termination dust is now a shroud of snow. On the trail, well below the snow, we pass a hunter lugging out a Dall sheep. Under his load, the hunter is hunched over but moving fast. He looks as though he has been sleeping on the ground for several days. Although he looks bad, his sheep, draped over a pack frame and strapped in place, looks far worse.
Dall sheep, smaller relatives of the bighorn sheep that live in the Rocky Mountains, roam the mountain slopes winter and summer. It would be fair to say that sheep seem uncomfortable on level ground. It would only be a slight exaggeration to claim that a Dall sheep can stand upright on a vertical cliff. The rams, with their long curling horns, live in bachelor bands. The ewes, with stubby billy-goat horns, give birth in May or June, and by the onset of winter the young have weaned. Both rams and ewes butt heads now and again to maintain social order. They live in what is sometimes called “escape terrain,” steep rugged slopes where they can elude predators. In summer, they eat the green fuzzy stuff growing between the rocks. In winter, they eat frozen grasses and lichens and moss where the wind has whipped away the snow on exposed ridges. They lose weight.
Just north of here, students at Wasilla High School are raising funds to help pay the hospital bills of their basketball coach, Jake Collins. In August, Jake and his fifty-three-year-old father had been sheep hunting in the Wrangell Mountains. They had driven a four-wheeler eighteen miles down a mud trail and then hiked in another six miles. Doing the steep terrain work of sheep hunting, they were at something like four thousand feet. The mountains were alive with ewes and lambs and, higher up, rams with full-curl horns. Jake went after one of the rams. His father watched from below. “There was some really gnarly stuff that had me nervous,” his father later told a reporter, “but he got through the gnarly stuff.” He watched his son shoot a ram. The ram dropped. Jake moved toward it but was thwarted by the terrain. He tried a different route. He was above the ram and tried to work down toward it but was stopped by a cliff. He went back up. “I think that third time was when he fell,” his father said. When his father reached him, Jake was lying in a creek, bloody and unconscious, one eye swollen shut. Jake’s father dragged him from the creek, took off his wet clothes, and redressed him in some of his own gear. Night fell. Freezing conditions are not unusual in the Wrangells even in the middle of summer. The wind blew. By morning, Jake’s father decided he had to go for help. There were the six miles to the four-wheeler, then the eighteen miles of muddy four-wheeler trail, then twenty-five miles to help. It was night before a rescue helicopter was airborne. The pilot came in with night goggles. Thirty-five-mile-an-hour winds made the helicopter shiver. When they reached Jake, he was still breathing. It took some time to get him into the helicopter, and more time to get him to an Anchorage hospital. By then, his body temperature had dropped to eighty-eight degrees, the temperature at which shivering slows or stops, muscles stiffen, and the mind becomes cold stupid. Twenty days later, Jake came out of a coma.
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My son and I stick to the valley floor. We watch salmon fanning the sand just above a beaver dam. We walk along a flat trail, below the treeline and the snow, and well below sheep country. We bend over a small, weed-choked pool of water and scoop some mud into a plastic bottle. The water feels close to freezing, like that of Prudhoe Bay in June. I put the bottle in my day pack. Later, I will put it in the freezer with Fram and Bedford, next to the frozen vegetables and a slab of salmon, and in spring, we will thaw it and see what comes out.
When I look up from here, certain slopes look almost skiable. It is late in the afternoon. Shadows have dusted the mountainsides, and a breeze carries the cold air downward, into the valley, onto this trail. Despite the day’s sunshine, winter breathes down our necks.
OCTOBER
It is October third and forty-five degrees in Fairbanks. Patches of early-autumn snow lie scattered in the shadows of buildings and trees. On the University of Alaska campus, students wear jackets. There is a correlation here: when it is cold, people wear jackets. It seems momentarily plausible that the jackets cause the cold. People put on their jackets, and winter comes. They encourage winter, welcoming it as others would welcome sunshine.
Fairbanks is a cold-affected town. It was settled in 1901, when the skipper of the steamboat Lavelle Young decided that he could not go any farther upriver, toward the goldfields. He offloaded a man named E. T. Barnette near what would become the corner of Cushman Street and First Avenue. Barnette would become influential, but the place would have amounted to nothing had it not been for Felix Pedro. It was Pedro who found gold nearby just a few months after Barnette landed. For a short time, Fairbanks became the largest city in Alaska. And often it is the coldest. The average temperature in January is minus ten. The temperature has been known to go close to a week without breaking minus forty. Thermometers in Fairbanks know what it is to dip south of fifty below. And the people sometimes look weathered, too, pale and hardened. They are thicker than most people, more insulated for winter. With minus forty just around the corner, this is no place for anorexia. Beards are abundant and robust. Half of these people seem to live in cabins, which, by and large, does not mean a log cabin so much as a plywood shack. Having said that, when an Alaskan claims to live in a cabin, what is meant is never entirely clear. A cabin could have a dirt floor and log walls, or it could just as easily have five bedrooms, picture windows looking over a lake, and an alarm system tied to a remote response service that notifies the owner if the central heat fails. In Fairbanks, though, cabins tend to be on the shack side of things. Many do not have running water, in part because wells have to go deeper than empty pockets can afford, and in part because arsenic occurs naturally in the rock around Fairbanks.
The cold weathers more than just faces. Road surfaces are wavy from frost heave. Houses are slumped from thawing ground ice. Paint is dull and chipped, seemingly because of the cold but perhaps also because the summer is too short to be wasted on the business end of a paintbrush. But if the town and people are weathered, they do not seem to mind. “There’s hardly any wind,” they will tell you, looking on the bright side. For their health, they roll in the snow and jump into hot tubs. They make ice sculptures, including a life-size phone booth with a working pay phone. When cold fronts pass through, they pose in Bermuda shorts in front of thermometers. The frozen Chena River makes a perfectly good road.
Wandering around the university, I find a flyer advertising a bike for sale. The flyer is fringed with tear-off tabs offering a phone number. The bike comes with studded tires and thick Gore-Tex gauntlets on the handlebars, a far cry from the Draisine of Mary Shelley’s time. The gauntlets protect the hands and forearms almost to the elbows. “Perfect year-round commuter bike,” the flyer says. Almost anywhere else, this would be a joke. Here, all of the phone number tabs have been torn off. At forty below, it is easier to jump on a bike and go than to start and warm up an engine.
The university spreads out across a low hill overlooking Fairbanks. Stately buildings, most of them no older than the students themselves, hold lecture halls and laboratories. The International Arctic Research Center uses an entire building. It has a curved front and big dish antennas on its roof. Inside these walls, Russians and Japanese and Americans intermingle, talking about things such as frost deformation and shoreline erosion in a warming Arctic and construction of pipelines in frozen ground. The Japanese, though they have no Arctic of their own, helped pay for the center. The Russians are here because they know more about development in the Arctic than anyone else. First under the tsars and later under the Communists, they built gulags in the far north, and today they build pipelines and roads and operate a port above the Arctic Circle. In light of today’s warming climate and melting sea ice, they see the Arctic Ocean as an increasingly accessible frontier, a resource basin, and with their experience, they may be the first to cross the starting line in the inevitable race for fish and oil.
I am here at the invitation of a friend, a professor at the university. A graduate student shows me a time-lapse video clip of soil freezing in a test chamber with transparent walls. Horizontal bands of segregation ice appear. The water in the soil moves toward the bands, and the soil between the bands visibly dries. Vertical cracks form. The column of soil grows taller. With the right music and juxtaposed against the right scenes of cars bogged down in snow, men with icy beards, and musk oxen puffing hot breath against a frozen northern landscape, I feel certain that this could be a popular short film, something for the Sundance Film Festival. The student sees no humor in this prospect. She plays the video twice, pointing out the features of a freezing soil profile. A man interested in the engineering challenges of a gas pipeline explains how frost heave can bend a buried pipe, and another man shows me how the pipe will be squeezed and deformed as the ground freezes and thaws around it.
I have dinner with friends in a restaurant near Cushman and First, where E. T. Barnette was dumped with his goods in 1901. No one mentions Barnette. We are, for the most part, busy eating. We are busy fattening up for winter. Although it is not yet truly cold, we huddle together like miners around a woodstove or muskrats in a snow-covered lodge. If I lived in Fairbanks, I would put on fifty pounds and sleep until June.
Humans, as it turns out, cannot hibernate. Hibernation would kill us. NASA scientists, wanting to understand the effects of weightlessness, recently offered thousands of dollars to volunteers willing to lie in bed for up to several weeks at a stretch. The ideal job, perhaps, except for this: bone and muscle mass decreases, digestion slows, tissues become resistant to the effects of the body’s own insulin, and control of blood sugar levels deteriorates. And this: humans, despite what they may want to do, cannot sleep for days on end. They need a drink of water. They must urinate. They require a snack. They want to get up and walk around.
Hibernation, once thought simple, is complex. It is sometimes argued that bears do not hibernate at all. They merely sleep, the argument goes, without entering a deep stupor and without a dramatic drop in body temperature. Some call this “winter dormancy” instead of hibernation, to distinguish between a bear and, say, a ground squirrel. But the difference between hibernation and winter dormancy is not clear. One blends into the other. And different bears fall into different levels of hibernation. The heart rate for active bears hovers around a hundred beats per minute, but for hibernating bears it may drop to forty beats per minute, or in some cases as low as eight beats per minute. An expert working on black bears in the Carolinas claims that his bears always watch him as he approaches their winter dens. Another expert working on black bears in Minnesota talks of falling into a den. His fall scared a cub. It was crying, immediately next to its mother, but the mother took more than eight minutes to awaken.
Hibernation, in its broadest sense, is winter inactivity. It is a way of bypassing periods of food scarcity, of skipping those times when the calories needed to stay warm exceed the calories that can be reliably gathered. Black bears, preparing for hiber
nation in the late fall, can gain thirty pounds in a week while for the most part eating nothing but berries and foliage and maybe insects. Brown bears — grizzlies — can pick up eight inches of fat, becoming, according to official information published by the Alaska Department of Fish and Game, “waddling fat” just before hibernation. Then winter hits. Food availability diminishes, snow slows down movements of foraging animals, and cold burns calories. Animals preparing for hibernation stop eating. They repair to a den — maybe a hollow tree, a brush pile, a crack in the rocks, a corner in a cave, a pit dug into the side of a hill. A black bear was once found denning in a tree hollow ninety-six feet aboveground. Grizzlies have been known to tunnel nearly thirty feet into the earth. For polar bears, only pregnant females hibernate. In Alaska, the polar bear den is a snow cave, dug on land or on the sea ice, sealed over and invisible after the next real snow.
The bear curls into a ball, its head resting between its forepaws, its back to the cold. Heart rate drops. Breathing slows. The digestive tract shuts down for the winter. Blood concentrates in the head and upper body. Body temperature drops nine degrees. The bear lives off its summer fat. Cholesterol levels skyrocket, but without causing heart problems. The bear will not urinate for months. Urea, normally jettisoned in urine, is reabsorbed through the bladder wall and processed back to amino acids and proteins. Likewise, calcium leaking from bones into the blood is recycled.