An Antarctic mountainscape and a massive slide. Photo: Sam Hennessey
A seasoned mountain guide reflects on the vagaries of the Antarctic snowpack.
The Ilyushin II-76’s engines roar, blast through my cheap and useless earplugs, and echo through my head. The flight heads south from Punta Arenas, Chile, towards Antarctica. An exotic destination to be sure, but instead of excitement, I can only muster up a kind of resigned complacency. Off to ice jail—again.
Since 2012, I have spent a part of most winters “down south,” working primarily as a mountain guide on Mt. Vinson, the highest peak on the continent. Much to the disappointment of family, girlfriends, and quite often, myself, this means two months away from home and missing Christmas, not to mention leaving town just as the skiing starts to get good. With the noise of the engines rattling between my ears, one question lingers: Why?
The easy answer is the people: an international group of misfits working together in tough conditions to make a seriously complex operation function…just barely. Tied up in all of this, though, is the Antarctic environment: midnight sun, icecaps stretching out to forever, and a sense of isolation you can’t find anywhere else on earth. Early travelers were driven by a desire to find adventure through enduring the most rugged climate on the planet, but these days we cater to an increasingly soft and wealthy clientele. The company tries hard to sanitize the experience with heated tents, luxury food, and canned “excursions,” but the landscape refuses to be tamed, a constant reminder that at the end of the day, we’re all tourists down here. Windstorms destroy camps, bad visibility creates delays that occasionally stretch for weeks, and frostbite is quite common amongst the unprepared climbers who flock to Mt. Vinson.
Living here, it’s hard to escape the snow. You sleep in it, drink it, and spend much of your time shoveling just to keep everything on top. Not a bad situation for someone who likes to think about snow. Full immersion.
“Skiers on the way to the South Pole often feel these massive collapses—occasionally experiencing them traveling towards them, triggered by some unknown source, and then rumbling away into the distance.”
The snowpack here is like nowhere else. Average snowfall, measured in centimeters, is single digits on average (although there is no detailed record keeping), and high air temperatures for the season rarely exceed -15° C, even at basecamp. Good skiing, when it exists, is most often due to the wind—a slope can be blown-in with creamy, fast powder one day, only to be a scoured mess of ice and sastrugi the next. For the nerds, the upper snowpack (when it’s not a dense wind slab or scoured down to ice) typically consists of radiation crusts and advanced facets formed by the intense temperature gradient at the surface during the sunny summer months. Surface hoar growth is common, although the air is so dry it only occurs when a cloud layer moves in, often forming a defined bathtub ring that can be seen for miles. It’s the behavior of this “super continental” snowpack that defies all logic, occasionally making moments that burn in my mind—reality mixing with dreams.
One day, I was digging a quick hand pit, marveling at the size of the near-surface facets (5 mm!) capped by a crust in the upper snowpack, when Pachi Ibarra stepped off the skintrack with a mischievous smile and gave a quick jump. With a sound like a shotgun blast, the entire slope collapsed. She laughed as I just about fell over backwards trying to get my skis pointed downhill. Nothing moved. Instead, we listened as the collapse extended away, seemingly traveling several kilometers up the glacier.
On uniform slopes, glaciers, and icecaps, conditions can form this crust/facet combination with remarkable continuity. Skiers on the way to the South Pole often feel these massive collapses—occasionally experiencing them traveling towards them, triggered by some unknown source, and then rumbling away into the distance. In our case, Pachi, one of the most experienced Antarctic climbers, knew exactly what was going to happen, and was able to nearly give me a heart attack in the process.
2021 was a snowy year on Mount Vinson—close to 30 cm fell throughout our two-month season. Impressive totals, to be sure, and when the wind began to rip, we had a full-blown avalanche cycle on our hands. Several days of north winds had the steep southerly aspects around basecamp producing solid size 2 natural wind slabs, just like you might have thought. More difficult to predict, however, was what happened when things calmed down.
On the ascent in Antarctica. “Living here, it’s hard to escape the snow. You sleep in it, drink it, and spend much of your time shoveling just to keep everything on top. Not a bad situation for someone who likes to think about snow. Full immersion.” Photo: Sam Hennessey
After a few days of sunny weather, a truly large avalanche, 120 cm deep and over 100 m wide, released on a stubborn angle…facing windward (north). A little investigation revealed that the slide likely involved several seasons’ worth of snowpack. Why this meter-thick, knife-hard slab decided to release at that moment, with barely any new load and no discernable weak layer, completely baffled me. An earthquake? Motion of the glacier? Phases of the moon? Your guess is as good as mine.
“Don’t worry about it. Avalanches never happen below zero Fahrenheit, I know about this kind of stuff,” my friend Scott Patch once joked as we nervously bounced across a hollow wind slab high on Denali. His years with the Big Sky Ski Patrol makes him one of the world’s premier avalanche mitigators. I couldn’t help but remember his words and laugh when, years later, I walked onto the summit plateau of the Vinson Massif to be greeted with the unmistakable jagged profile of a crown, maybe 30 m wide, at 4800m elevation, in a place so cold the high temperature rarely gets above -30° C, and so dry that crampon marks from previous years were still clearly visible. It seems improbable, but I learned long before not to be surprised.
Sky and snow and gravity in play. Antarctica. Photo: Sam Hennessey
Low on Mt. Tyree, Antarctica’s second highest peak, Nate Opp, Seth Timpano, and I paused before starting up the side of a wide snow gully. With a quiet whoomph, the slope settled, and a thin crack shot out in front of our boots as it moved a centimeter downhill and then stops. Reaching down, I grabbed at the slab only to find that it was just 5 cm thick. Holding a chunk of it in my hand, it crumbled easier than a bad basal layer back home in Montana. The large facets that gave it structure were clearly striated, with proper 3-d shape. A thick layer of surface hoar capped it all off. Slabs made of weak layers – I wouldn’t believe it either.
I’m writing this at the tail end of another season on the ice. Here in the high cold desert, the erosion of the wild character of the place continues to accelerate. The airplanes keep coming, packed with clients, guides, and curious sightseers. People like me. The Ilyushin has been replaced by a 757, complete with Icelandic stewardesses and inflight entertainment. It’s been so dry that my ski tracks from last season are still visible in places, and the big news is that some influencers went live on Instagram from the summit of Mt. Vinson.
It’s been a slow season as far as avalanches are concerned, but I’m sure that some day in the future, maybe next year, maybe the year after that, the snow will start falling or the wind will blow from just the right direction, and strange things will start to happen, keeping the magic alive.
