Cold (7 page)
Warmth can hurt plants and animals accustomed to the cold. On sunny winter days, pine needles absorb heat from the sun. This
may, at first glance, seem like a good thing, a chance for a bit of midwinter photosynthesis. But as the needles warm, the
water vapor inside them warms, too. The warmed water vapor leaks out of the needles. The pine tree suffers from what is sometimes
called winter desiccation.
And from the world of well-meaning animal conservation: too much warmth in winter kills bats. Indiana bats spend the summer
spread out across the eastern United States, but in winter most of them flock to a handful of caves. Half of the world’s Indiana
bats overwinter in two caves. In 1967, Indiana bats were protected by law because of continuous population decline. What happened?
Cave entrances had been modified to prevent cavers from disturbing the bats. The new entrances — now too small for humans
but big enough for bats — restricted airflow. Caves breathe: as the temperature changes outside, air moves in or out of the
caves. It is not unusual to feel a strong breeze well underground. When the entrances were modified, the caves became asthmatic.
Winter temperatures in the caves rose. At Kentucky’s Hundred Dome Cave, temperatures rose almost twenty degrees. Hibernating
Indiana bats maintain a temperature close to that of the air. At lower temperatures, their hibernating metabolism is very
slow. They survive the winter by slowly burning through limited fat reserves. When the temperature increases, their metabolic
rate increases. Slowly, during their winter sleep, warm Indiana bats starve to death.
It is August fifteenth. It is around sixty degrees. I sit in the rain outside a yurt thirty miles north of my home in Anchorage,
Alaska. A yurt is a round, semipermanent tent modeled after those used by nomadic Mongolians. But this yurt is here in Alaska
rather than there in Mongolia, and it is furnished with a woodstove, bunk beds, and folding chairs. Beneath me, I can see
and hear the Eagle River, which flows from Eagle Glacier, out of sight some fifteen miles upstream. I look periodically for
a grizzly sow and her cub, which were seen by hikers just yesterday feeding on salmon in the river. Now the grizzlies are
as invisible as a North Slope caterpillar.
The Eagle River valley is U shaped, scraped out by a glacier, without the steep-cut angles of valleys cut by flowing water.
Higher up in the mountains around us, other valleys end in waterfalls that stream down the sides of mountains. These hanging
valleys mark the surface of the old ice, hundreds of feet up. In the past, the big glacier, the thick one, flowed through
this valley, extending up beyond what today are the high mountain passes, and the glaciers in the higher mountain passes intercepted
the glacier that flowed through this valley. The glaciers in the high mountain passes flowed into the larger valley glaciers
like shallow streams flowing into a deep river, leaving their beds perched well above the bottom of the deep river, but these
were streams and rivers of ice, moving with leisurely, mountain-grinding power. Boulders carried by the glaciers litter the
valley floor. My son climbs the boulders while I stare at the mountains, imagining this place buried under hundreds of feet
of ice. This makes me imagine Manhattan under ice. Fifty thousand years ago, the Wisconsin Glacier overran what would become
New York. Somewhat famously, it ground grooves into the rocks at Central Park. What would become New York has been overrun
by many glaciers, a complicated coming and going of glaciers that advanced and retreated over thousands of years, a cosmopolitan
mingling of ice and the effects of ice that make the modern world seem inconsequential. The glaciers in New York are gone
now, as is most of the glacier here in the Eagle River valley. All that is left is a pathetic remnant near the head of the
valley. The world has warmed. In national parks, there are signposts marking the extent of certain glaciers in 1959, in 1965,
in 1970, and so on to the present day. Trees grow around these signs. The glacier itself might not be visible until you are
standing next to a sign that says 1959. In ten years, it might not be visible from beyond a sign dated 1970. In twenty years,
it might be gone altogether. People say the glaciers in Alaska have retreated. In fact, they have melted, withered, and in
some cases disappeared, warmed and thawed into miniatures of their former selves or warmed further until nothing is left but
a ghostly memory running over ground rock.
Tired of the rain, I wander back into the yurt. The park management has left a guest book. Last January, someone wrote, “When
we got here yesterday it was three degrees out and not much warmer inside. We got the stove going and got it to seventy inside.”
Last February, someone wrote, “I hope that the next person that stays in this yurt will have a better experience than we did.
P.S. It was minus fourteen Fahrenheit when we got in. We brought my dog with us. Her name is Biscuit.”
Also in February, someone wrote, “The worst part however had to be the outhouse so cold on the bum.”
I write nothing. Instead, I stoke the fire in the woodstove. I listen to the rain hitting the tent, audible over the river’s
rushing. The next morning, although it is August in a warming climate, there is new snow on the tops of the mountains. It
is termination dust, early this year, a dusting of snow marking the end of summer.
On the prairies, hypothermic and frostbitten children were carried into tiny houses. When times were good, these houses might
have been heated with coal or wood. Some families burned dried buffalo bones. Some, when they had to, burned what they called
poor man’s coal or prairie coal — little bundles of hay, manually twisted together and fed into a hay burner. The trouble
with prairie coal was that it burned quickly and did not put out as much heat as wood or coal or bones. Hay burners had to
be fed almost constantly, which meant that someone was almost constantly twisting together handfuls of hay.
Richard Byrd, in his 1933 solo adventure in Antarctica, would strip off his mask and diving-suit apparel inside his hut in
early May — autumn on the southern continent. He wrote of “the small sounds of the hut”: ticking clocks, chattering instruments,
and, importantly, the hiss of his oil-burning stove. The stove, unbeknownst to Byrd, was leaking carbon monoxide, slowly poisoning
him. It left him weak and confused. “I was at least three hours getting fuel,” he wrote, “heating the engine, sweating it
into the shack and out, and completing the other preparations. I moved feebly like a very old man. Once I leaned against the
tunnel wall, too far gone to push the engine another inch. You’re mad, I whispered to myself. It would be better to stay in
the bunk and cut out paper dolls than keep up this damnable nonsense.” He became despondent. He ignored an overturned chair.
He could not bring himself to read his books. He could not get warm, inside or outside. “What baffles me,” he wrote, “is that
I have no reserve strength whatever.” Eventually, he radioed his support team. He did not want anyone to know how his condition
had deteriorated, so he asked a question, by his own accounting, in “an offhand manner.” His request was simple: “Have Dr.
Poulter consult with the Bureau of Standards in Washington and find out: (1) whether the wick lantern gave off less fumes
than the pressure lantern; and (2) whether moisture in the kerosene or Stoddard solvent (in consequence of thawing rime in
the stovepipe) would be apt to cause carbon monoxide.” A few days later, he had his answer. Yes, carbon monoxide might be
a problem. Poulter, however, did not suggest any cures that Byrd had not already tried. On August 11, 1934, near the end of
the southern winter, help arrived. Byrd was, by this point, too weak to continue on his own. Without outside help, his heater
would have killed him. He would have succumbed to the fumes.
The human furnace, for a typical adult male, burns through something like seventeen hundred calories a day just to get by.
When the body is cold, the burn rate can go up another four hundred calories or so just to stay warm. Shivering can increase
heat production four times, but only until the body’s supply of glycogen — a form of sugar stored in the liver and easily
converted to the glucose needed by active muscles — is gone. Then shivering stops, and the body temperature plummets.
At rest, the organs generate most of the body’s heat. The brain by itself accounts for something like one-sixth of the total.
In motion, the muscles take over. Moving uphill on skis can burn through more than a thousand calories an hour. Two hours
on skis can burn more calories than a full day at rest. Physically fit men, such as polar explorers, can maintain activity
levels that burn more than six hundred calories an hour all day long. It is difficult, at this level of activity, to feel
satiated. “A pemmican soup,” wrote Frederick Cook of a meal he enjoyed close to the North Pole in 1908, “flavored with musk
ox tenderloins, steaming with heat — a luxury seldom enjoyed in our camps — next went down with warming, satisfying gulps.
This was followed by a few strips of frozen fresh meat, then by a block of pemmican. Later, a few squares of musk ox suet
gave the taste of sweets to round up our meal. Last of all, three cups of tea spread the chronic stomach-folds, after which
we reveled in the sense of fullness of the best meal of many weeks.”
Through most of the nineteenth century, the explorers ate pemmican. Pemmican — the real thing, as opposed to the beef jerky
marketed as pemmican today — was dried and pulverized meat and bones and berries. Think of something approximating perhaps
dried Spam with berries. The meat and bones often came from moose or bison or elk. It tasted as good as it sounds. George
Tyson, afloat on ice in 1873 with Eskimo hunters and their wives, described a meal: “We pound the bread fine, then take brackish
ice, or saltwater ice, and melt it in a tin pemmican can over the lamp; then put in the pounded bread and pemmican, and, when
all is warm, call it ‘tea,’ and drink it. It reminds me very much of greasy dish-water.”
When possible, explorers supplemented their diets with fresh game, in part for the sheer pleasure of fresh food and in part
because of the knowledge that it kept scurvy at bay. There might be seal meat or caribou or fox. Polar bear was not an unusual
meal. Many men ate their meat frozen, a habit they learned from the Eskimos. It was noted more than once that food could be
cooked with fire or with ice. Father Henry, living in his ice cellar in Canada’s Northwest Territories, subsisted on frozen
fish. “For six years,” wrote a journalist who knew Father Henry,
he had been living on nothing but frozen fish, and he was none the worse off for it. When he awoke he groped on the ground,
picked up a great chunk of fish frozen so hard that he had to thaw it out a little with his lips and breath before he could
bite into it, and with this he regaled himself…. Boiled rice warmed you while you ate it, but its warmth died out of you almost
as soon as it was eaten. Frozen fish worked the other way: you did not feel its radiation immediately; but twenty minutes
later it began to warm you and it kept you warm for hours.
All of the warm-blooded animals need food to stay warm. Some animals conserve calories by hibernating at cooler than normal
body temperatures, but others do not. Polar bears, other than pregnant females, hunt seals through the year. Arctic foxes
roam the sea ice in winter. Beneath the snow, subnivean life churns on. Lemmings, the size of gerbils, dash through tunnels
of hoarfrost at the bottom of the snowpack. Smaller animals lose heat more quickly than larger animals. For their size, smaller
animals have more exposed skin — more surface area to cool off for every ounce of fat, muscle, and brain tissue. For their
size, they need to burn more calories than larger animals, yet they are not big enough to store much fat. In colder climates,
a small animal that cannot store fat cannot hibernate. The smallest hibernator in the far north is the ground squirrel, several
times larger than the lemming. And so lemmings eat through the winter. They gnaw on twigs and branches under the snow. Occasionally,
when times are hard, they eat each other.
