Cold (6 page)

The Russian tells me of plant material found in the tunnel that was still green after thousands of years. Grass had been covered
with snow in a summer blizzard, and then the snow was buried under blowing soil. Likewise, the bison bones had been buried
by the blowing loess, preserved for thousands of years. Occasionally, whole animals, flesh intact, are preserved in the permafrost.
In 1979, a Fairbanks gold miner found a frozen steppe bison. That is to say, he found not only bones and teeth but a frozen
carcass complete with skin and muscles and hair. Claw and tooth marks show that it was killed by an extinct lion. It had frozen
so quickly after its death that scavengers could not pick it to pieces. In the holes left behind by the lion’s teeth, coagulated
blood remained frozen in tiny pools. Shortly after the kill, or during the kill itself, snow may have been falling. The lion
may have fed on the carcass for several days or even weeks but abandoned it before spring, leaving meat and flesh and bones
behind. One can imagine the lion wandering away, overtaken and bewildered by blowing snow. At first the snow drifts against
the carcass. Later, loess carried by wind or a landslide settles on top of the snow. The dead steppe bison is buried. A new
layer of permafrost forms. Years pass. Miners dig into the icy ground. A university professor becomes involved. Carbon dating
of a piece of skin shows that the bison died thirty-six thousand years ago. The carcass stands today in a glass case at the
Museum of the North in Fairbanks, resurrected, looking more like a Texas longhorn than the modern bison of the Great Plains.

We walk past and through different features of frozen ground. I stand beneath an ice wedge — the same sort of ice wedge that
forms polygons in the ground farther north. Near Prudhoe Bay, the ground is laced with these things, but they are visible
only in their effect on the ground’s surface. If the first few feet of soil around Prudhoe Bay were magically removed, the
ground would become a honeycomb of ice. The soil, intact, obscures this reality. Here, underground, I can see the wedges themselves.
The ancient ground expanded in summer and contracted in autumn, opening cracks. The cracks filled with water, and the water
froze. The cycle was repeated again and again. And then the ice wedges were buried under the blowing loess that would become
the walls of this tunnel. Looking at an ice wedge in the wall of the tunnel, I see a record of the process. Sediment tracks
run up and down its body, marking each year’s sequence of cracking and freezing, reminiscent of tree rings. The wedge is more
than four feet wide at its top. Conservatively, it took hundreds of years to form.

Water is strange stuff. Most substances, when cooled, contract. This is why thermometers work: mercury shrinks as it cools
and expands as it warms. Warmth makes the molecules in a substance move faster. They dance around, bumping into one another.
As the temperature increases, they dance faster, and when they bump into one another, they push harder. They need more space.
A cooler temperature means slower movement, softer collisions, and less space. This holds true for water, but only to thirty-nine
degrees. After that, the water molecules start to line up. The water thickens. Hydrogen atoms in one molecule attract oxygen
atoms in others. The process of crystallization begins. At thirty-two degrees, the water starts to freeze. The molecules line
up like tiny soldiers in formation, with orderly space between them. Newly frozen water is nine percent bigger than liquid
water. Once frozen, if it continues to cool, expansion stops, and like most substances it shrinks.

Small caves and hollows line the tunnel’s walls. The ice holding the walls together has not melted, but some of it has sublimated
— disappeared into the air as vapor without ever going through a liquid phase. The walls are frozen and steaming at the same
time. This is true, too, of snow and ice at the surface — in glaciers, in freezers. The vaporization of ice — evaporation
from the solid phase — is the basis of the freezer burn that ruins frozen meat and fish.

Among the ice wedges, veins of ice run horizontally along the tunnel walls like veins of coal in a Virginia mountainside.
The Russian calls this “segregation ice.” It forms in keeping with another strange property of water: liquid water in finely
grained soil is sucked toward colder zones in the soil. We stare at a vein of segregation ice, a one-inch-thick stratum of
what looks like almost pure ice.

“People call it cryogenic suction,” the Russian says, “as though that explains everything. But cryogenic suction is a very
complicated mechanism.” In freezing soils, liquid water adheres to soil particles, forming thin layers of water around each
grain of soil. Molecules are bound more tightly to thin layers of water than to thick layers of water, and thin layers of
water tend to attract molecules of water from nearby thicker layers. When soil starts to freeze, the layers of liquid water
turn to ice and become thinner. Liquid water moves from warmer parts of the soil to parts of the soil where ice is forming.
Water is sucked toward what is sometimes called the “freezing front.” Segregation ice forms.

“I have seen segregated ice one meter thick,” the Russian tells me. “I saw it personally.” He has heard of segregation ice
twenty meters thick — sixty-six feet — but he has not seen it himself. He presents this information as though he does not
believe it.

We come to what looks like a small frozen pond or a puddle in the wall of the tunnel. It is shaped like a pond, seen edge
on, ten feet across. At the bottom, the ice is dirty, as if it had been filled with silt, and at the top the ice is clear.
The Russian calls it an “ice lens.” He says that it could have been a frozen pond that was covered by blowing soil and permanently
insulated from the summer, but he thinks that it more likely formed underground, a small pocket of flowing groundwater that
at some time in the distant past froze into place. We are at this point something like one hundred feet underground, surrounded
by soil and ice laid down when steppe bison and mammoths and saber-toothed tigers roamed the surface. Above us, moving toward
the surface, the ground is progressively younger. At the surface, the soil is almost brand-new, with four inches or so of
fine soil blowing in and settling on top of the hill every hundred years. Below us, deeper underground, in the lower tunnel,
it is older.

We wander off the steel grating and into the lower tunnel, heading deeper and farther back into the Pleistocene. Our steps
kick up clouds of fine soil. It is strikingly dry, bone-dry. Looking behind us, I see that the air is hazy with the clouds
of fine soil. I feel grit in my teeth. I feel it in my hair. It is in my eyes. We look for a moment at what seems to be an
old streambed, a layer of sand and stones worked round by flowing water in the distant past. Forty thousand years ago, where
we stand now would have been a pretty little stream. Steppe bison would have grazed along its banks. Extinct lions would have
stalked the bison and lapped water from the stream. We are forty thousand years underground.

But we are not alone. The Russian once sent a sample from the tunnel’s wall to a friend at another laboratory. The sample
contained living bacteria. His friend feeds the bacteria and grows it in a laboratory at temperatures hovering around five
below zero. This stuff lives and breeds at temperatures where it should be frozen solid.

Warmth is not always a good thing. It melts the permafrost. With soil that is as much as three-quarters ice, melting means
subsidence. Water flows out of the soil. The ground, melted and drained, sinks. Pools form. The sun warms the pools, setting
up convection currents in the water column that pump more heat into the ground. The pools grow wider and deeper. Trees that
had once grown on top of the permafrost die in waterlogged conditions. Animal burrows flood. The landscape changes. Build
a house on permafrost, and what felt like frozen bedrock beneath the foundation might flow away. The ground might slump. Your
house might sag into a water-filled depression. Your neighbors — sourdoughs who know to insulate the ground before they build
— might snicker behind your back. Or, this being Alaska, they might laugh in your face. They might invite you to laugh along
with them. They might loan you a set of house jacks and offer a deal on a truckload of gravel and cement.

The warmth can come from climate change — a warm winter, a hot summer, a year when the insulating blanket of snow fails to
fall from the sky or disappears in early spring. Or the warmth can come from the hyperactive ambitions of human beings. In
the 1800s, Alaskan gold miners who had found gold in streams reasoned that there would be more gold belowground, covered by
frozen soil. They built fires in mine tunnels to melt the permafrost, loosening gravel from ancient streams buried well below
the surface. Later, boilers were used to generate steam at the mine face. Some miners moved away from tunneling and instead
stripped away the entire surface, melting the gold-bearing gravel with strings of pipes pumping water into what were called
“thawing points.” By 1929, a single company had more than ten thousand thawing points operating simultaneously near Fairbanks.
Two hundred specialized miners, called “point doctors,” pounded the points into the ground and made sure the water flowed.
The result: pockmarked ground, thawed and ready for a dredge.

Occasionally, people have built unheated additions onto their homes for storage or as garages, only to see the heated part
of the house descend. The walk to the garage is uphill. Certain cabins in the Alaskan bush seem to have been built at odd
angles or with deep sags. In Dawson City, northwest of Fairbanks, two frame buildings built during the Klondike gold rush
lean together, the ground beneath warmed by the buildings above. To see them is to wonder just how much these people were
drinking when they laid the foundations, but they are due not so much to alcohol as to warming and drunkenly subsiding ground.

For victims of hypothermia, rewarming can be fatal. The core temperature of victims continues to drop even after they are
brought into a warm environment. Some believe this afterdrop to be nothing more than heat loss from the victim’s core to the
colder outer layers of the body. Even watermelons, taken from a freezer to a warm kitchen, suffer afterdrop: the warm inner
core of the melon loses heat to the colder parts near the rind even as the outer parts begin to warm. Others believe afterdrop
occurs when constricted blood vessels near the skin, reacting to the warmer air, reopen, allowing cold blood from the surface
to flood the body’s core. To make things worse, the cold blood from the surface may be rich in lactic acids, overstressing
an already stressed situation. Worst-case scenario: The cold blood hits the heart, causing ventricular fibrillation. The lower
heart chamber quivers. The blood stops moving. The victim drops to the ground. The victim dies. This is more common than one
might think. It happened after the School Children’s Blizzard. It happened to the German soldiers pulled from Norwegian coastal
waters in 1940. It happened to sixteen Danish fishermen in 1979. The fishermen, in the water for more than an hour, climbed
aboard a rescue boat, wrapped themselves in blankets, headed to the cabin for coffee, and one by one dropped dead.

And then there is frostbite. Apsley Cherry-Garrard, of Scott’s South Pole expedition, wrote of treating frostbite: “Then you
nursed back your feet and tried to believe you were glad — a frost-bite does not hurt until it begins to thaw. Later came
the blisters, and then the chunks of dead skin.” In Napoleon’s campaigns, the men treated frostbite by warming their frozen
extremities next to a fire. As one cannot actually feel a frozen extremity until the extremity warms up, it was not uncommon
for Napoleon’s men to burn themselves during rewarming. The men learned to rub frozen extremities with snow. This was painful,
too, but it did not cause burns.

During the School Children’s Blizzard, rubbing with snow was the treatment of choice. Addie Knieriem, a young girl who survived
the blizzard, was left with badly frozen feet. As always, the freezing had started in her skin, between the cells. The ice
crystals drew water from within the cells, dehydrating the cells themselves. Eventually, the fluid remaining within the cells
froze. Ice crystals tore cell membranes. The ice penetrated deeper into her tissues. Blood vessels froze. Tendons froze. Muscles
froze. Her rescuers rubbed her feet with snow. As her feet warmed, the feeling returned with a vengeance. She felt as though
someone was burning her feet. There would also have been a terrible, insatiable itchiness. Soon after, blood cells clotted
in her feet. The skin blistered. Her toes turned black. Her feet began to rot. Her room would have been filled with the foul
stench of gangrene. Her toes were amputated, and then one of her feet. At this point, with limited painkillers, Addie may
have wondered if warming up had been the wisest choice.

Today frostbitten extremities are rewarmed in warm baths. Painkillers are administered. Antibiotics are used. Rubbing with
snow is discouraged. Amputations remain common. C. Crawford Mechem, in a 2006 article, says that there are four degrees of
frostbite. First-degree frostbite symptoms include swelling, a waxy look to the skin, hard white spots, and numbness. By the
time third-degree frostbite occurs, symptoms include “blood-filled blisters, which progress to a black eschar over a matter
of weeks.” In fourth-degree frostbite, there is what Mechem calls “full-thickness damage affecting muscles, tendons, and bone,
with resultant tissue loss and sensory deficit.” In other words, tissue with fourth-degree frostbite is dead or as good as
dead. Addie Knieriem, on the prairie, suffered from fourth-degree frostbite in her feet. On rewarming, Mechem says, one should
expect “pain, throbbing, burning, or electric current-like sensations.” The last gasp of rewarmed nerve cells comes with intense
cries of pain.