The Great White Bear (8 page)

A polar bear's buoyancy is considerably aided by a thick layer of blubber, which not only helps keep a bear warm, but also enables it to store huge reserves of fat for lean periods and metabolize them when needed, a response to an environment of uncertain and uneven productivity. Polar bears frequently eat seemingly to excess when food is available and then slow down their metabolism substantially while drawing on fat reserves, a state known as "walking hibernation," when pickings are thin and food is hard to find.

That layer of blubber can be as much as four and a half inches thick and is topped by skin that is, perhaps surprisingly, black. Equally surprisingly, a polar bear's fur is not actually white.

It is in fact unpigmented, but because it reflects visible light it appears white to the human eye when it is clean and in sunlight. During sunrise or sunset, the fur may actually appear to take on the orange-yellow hues of the rising or setting sun; later in the season, in spring or late winter, before the annual molt that begins in April or May, bears may appear to be "off-white" or even yellowish.

While sunlight is reflected off the pelt (contributing to its white appearance), the late Norwegian scientist Nils Øritsland found that some of it passes through and reaches the black skin, which naturally enough warms up.

"Warm surfaces, of course, emit long-wave infrared radiation, or heat," notes Øritsland's colleague David Lavigne. (This is the principle behind night-vision optics.) "So the skin emits long-wave infrared and it turns out that, when it hits the hairs on the way out, they trap the heat inside the pelt."

In other words, polar bear hairs let some of the sun's warming rays pass through, but they don't let the heat radiate back out. Not only that, but because the hairs are hollow, they contain air that is warmed by the heat trapped within the pelt, causing further warming.

It is the final line of defense against the polar bear's most constant and potentially dangerous enemy, the bitter chill of its Arctic domain, and perhaps the most effective. (Although not, of course, in the very dead of winter, when there is no daylight at all. For the mechanism to work, it needs sunlight.) It is also a line of defense that has been frequently misreported and misunderstood.

A polar bear hair does not, as Richard C. Davids writes, act as "a miniature light pipe that funnels only ultraviolet light down through its core to be absorbed by the black skin." That idea—that polar bear hairs not only trap heat from sunlight but actively channel the ultraviolet directly to the skin—is a myth, but a persistent one. Its origins lie in a misreading of both Øritsland's research on polar bear fur and another study he conducted with Lavigne.

In 1974, the two men were attempting to determine a means of counting seal pups from the air that was more effective than searching for white seals on white ice.

"We discovered that ultraviolet photography turns white seals black, and in the course of doing so, we discovered that ultraviolet photography turns most white animals black," Lavigne recalls. "We were in a hurry and wanted to photograph a white animal from the air, so we went to Churchill, Manitoba, and photographed a polar bear with three cubs, and they all showed up black. That led to a cover story in
Nature
called 'Black Polar Bears.'"

The reason seal pups and polar bears look black when photographed in ultraviolet is that their fur absorbs UV radiation; conversely, they appear white to us in normal conditions because the fur reflects visible light. There is no obvious benefit to the bears—or the seals—from absorbing UV radiation in this way; as Lavigne noted, it turns out that most white animals do so, and later he discovered that the Canadian military's equipment, painted white to provide camouflage in snowy Arctic environments, did as well.
^*

But subsequently, some American military researchers who had not been involved in either study conflated the two findings and, speaking to a reporter for
Time
magazine, described the process differently.

"Now the ultraviolet hits the polar bear, gets to the hollow pipe which acts as a fiber optic, transmits this high-energy ultraviolet radiation into the skin, and then heats up the bear," says Lavigne, describing the distorted version. "But the problem is that the ultraviolet never gets to travel down the hair because the whole point of what Nils and I described is that it is immediately
absorbed
by the hair."

Even so, what Lavigne describes as "the myth of the solar polar bear" endures. "Solar energy? Do polar bears hold the secret?" asked the
Washington Post
rhetorically in 1987. "Polar bears' fur holds clue to better lasers," insisted the London
Sunday Times
in 1995. Even the august
Scientific American
got in on the act, headlining a 1988 article simply and succinctly, "Solar Polar Bears."

It endures partly because distinctions among visible spectrum light, infrared, and ultraviolet, among absorption and reflection and transmission, can be subtle and confusing. It endures because it is hard to fact-check when so many sources have repeated the story as gospel. But it endures also because it seems like something that should be true, that a magnificent animal in an almost impossibly hostile environment should have developed an almost fantastic mechanism for keeping warm.

The pity of it is that the truth needs no elaboration. Every polar bear is so well insulated that not only does it boast a thick layer of blubber and a warm pelt, but that pelt warms the cold air that reaches its skin and traps it against its body, enveloping the bear in a thermal blanket. Polar bears, in effect, are mobile, furry greenhouses. That, by itself, is remarkable enough.

As Robert Bieder has observed, the polar bear is a creature of paradox. It is a white bear with translucent hair and black skin. It is an enormous predator that walks softly and almost silently across the ice. It is an Arctic resident whose major problem is not staying warm but keeping cool. And the winter, when other bears are generally hibernating, is for the polar bear among the most active times of the year, as it stalks the ice in search of seals.

To the members of a sixteenth-century voyage of exploration, it was a white bear "of a monstrous bigness." Eighteenth-century whalers dubbed it the "farmer," tending the ice fields across which it wandered. Scientists call it
Ursus maritimus,
the sea bear. But it is in Norwegian or German—where it is known as, respectively,
ijsbjorn
and
eisbär
—that the nomenclature most accurately describes the species.

For these land carnivores that are officially classified as marine mammals are, above all else, creatures of the ice.

We were moving.

It was morning, I was in my bunk, I had been asleep, and when I woke up I could feel the movement of the ship. I lay there, blinked a few times, rubbed my eyes, stretched, gathered my thoughts.

We weren't supposed to be going anywhere. The previous day we had arrived off Barrow, the northernmost town in the United States, on the Beaufort Sea coast of Alaska. We had dropped anchor that afternoon; we were not scheduled to weigh it for several days, time for new crew to arrive and existing crew to leave, and to change the on-board complement of scientists and journalists.

But we were unmistakably on the move. And yet, something about our motion didn't feel right. It was almost as if we were moving ... backward.

Frank Kamp, the chief mate, had been the first to spot the impending collision. He had been on anchor watch, alone in the wheelhouse early in the morning, plotting our upcoming course on the chart, keeping the bridge tidy, casting an occasional eye out the window.

The watch had been uneventful, as anchor watches often are. The Beaufort Sea current was strong, driving at several knots along the Alaska coast; but although there was some ice, it was not especially plentiful. Floes appeared sporadically, mostly passing harmlessly by; those that appeared to be on a collision course looked to be of little consequence, but even so, when necessary, Frank nudged the rudder just enough to lessen or avoid the blow. Not that the strengthened hull could not withstand the impact, but there was no point subjecting it to any more encounters with ice than absolutely necessary. Besides, a series of jarring, thumping impacts throughout the night and early morning would have done little to endear the first mate to his fellow mariners.

As early morning dawned—the transition from night to day barely perceptible at this latitude in summer—the fog descended. Peering through the binoculars, Frank scanned what passed for a horizon, then paused. He lowered the binoculars, raised them again, wondering if his mind was playing tricks on him and finally realizing that he truly was seeing what he thought he was seeing. There was indeed an enormous ice floe headed for the ship, one that no amount of rudder turning could avoid. This one was going to hit, and when it did it was going to do more than briefly rouse a few people from their sleep.

He rushed below to fetch the captain, but barely had the pair made it back to the wheelhouse than the floe struck. The force of a half-million tons, one billion pounds of frozen water, drove into the
Arctic Sunrise,
and after token resistance the ship acquiesced to its demands. Now we too were headed along the coast at several knots, powerless to deny the urgings of the enormous piece of ice that had made us its plaything.

The severity of the situation was not initially apparent to all on board. For many it was an opportunity to photograph sea ice up close, the dirty, gnarled mass stretching in every direction and providing grist for photographic mills. There was even the added bonus of a brief appearance of the anchor chain—which, as captain and mate deployed the ship's thrusters in a desperate battle to twist and turn the
Sunrise
free of its imprisonment, abruptly sped across the surface of the floe, anchor in tow, before disappearing anew beneath the surface. The cook, awakened by the brouhaha, stuck his head out of his cabin porthole, only to be rapidly reprimanded by those assembled on deck, fearful that the anchor and chain might make an unscheduled reappearance and ricochet into the unwary.

But if not all those present immediately grasped the gravity of the predicament, Captain Arne Sorensen was all too aware of the dangers, not only because his years of sailing in polar seas had made him acutely familiar with the risks posed by marauding ice floes, but also because he had firsthand experience of their power to entrap the unsuspecting in their suffocating embrace.

On October 27, 1985, Sorensen, then captain of the Australian research ship
Nella Dan,
was grinding northward through the sea ice surrounding Antarctica, threading his ship gently through a maze of open water that promised to provide safe passage to the relative sanctuary of the Southern Ocean. As he did so, an easterly wind arose as if from nowhere, pushing the floes into each other on all sides, compressing them around the hull and under the bow. Almost in a matter of moments, the ship lifted clear of the water and ground to a halt. Over the next few days, the broken ice froze into one enormous field, and the
Nella Dan
was completely beset. There it stayed, frozen in place, for seven weeks, until released on December 14 by the Japanese icebreaker
Shirase.
The severity of the
Nella Dan
's captivity was underlined by the fact that, having plowed without resistance through a seemingly endless landscape of ice on its way to perform the rescue, the
Shirase
was forced, upon arrival at the frozen Alcatraz that encased the hull of Sorensen's vessel, to back up and charge through ice that in one spot close to the Australian ship was measured at sixty feet thick.

No fate so dramatic befell the
Arctic Sunrise
off Barrow that July day. After two hours of frantic maneuvering, Sorensen extricated us from our encounter, albeit not before we had been pushed four miles along the Alaska coast. ("Farthest I've ever traveled on an anchor watch," quipped one of the mates.) We were fortunate. Seafarers' encounters with sea ice have all too often ended far less happily.

Even Sorensen's enforced sabbatical on board the
Nella Dan
was relatively mild compared to the punishment the polar sea ice has at times meted out to those who have dared to enter its domain. Indeed, a little over a month after the Australian vessel escaped its imprisonment, another ship, the
Southern Quest,
was trapped between ice floes in the Ross Sea; its hull ruptured, it sank within a matter of hours, forcing the crew onto the ice, from where it was rescued by military personnel from a nearby U.S. Antarctic base.

It need not always be thus. George Best, a member of a sixteenth-century voyage in search of the Northwest Passage (a path from Atlantic to Pacific across the top of North America) and one of the first Europeans to encounter sea ice, recorded a scene that was far more placid than that experienced by the
Nella Dan
or
Southern Quest,
or even by us that morning on the
Arctic Sunrise:

...many of our company lept out of the Shippe upon Ilands of Ise, and running there uppe and downe, did shoote at buttes upon the Ise, and with their Calivers did kill greate Ceales, which use to lye and sleepe upon the Ise, and this Ise melting above at the toppe by reflection of the Sunne, came downe in sundrye streames, whyche uniting together, made a prettie brooke able to drive a Mill.

Best's positive portrayal of the surroundings was doubtless influenced not only by the novelty of his experience and the incredulity he felt at witnessing such a scene, but also by the sunny conditions and the fact that the expedition departed the Arctic before the onset of winter. It is a sense of wonderment shared by innumerable mariners in the years since; on a summer's day, with the sun's rays reflecting brightly off scattered, flat chunks of sea ice, the polar sea is a sponge that magically soaks up time and slows it to a crawl, a place of blissful calm and quiet.