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By Alison Criscitiello

Photos by Leo Hoorn/National Geographic

The horizontal bandsaw in my sub-zero ice-core-processing lab slices through ancient ice from Mount Logan’s summit plateau like a hot knife. Bits of potentially pre-Holocene snow crystals fly off the blade and get sucked away by a vacuum. Once each metre of this ice core is sliced lengthwise, one slab heads to another saw for more cuts, and the other is measured for electrical conductivity, then put into an imaging system. Every millimetre of this 327-m-long ice core will be dissected according to a pre-determined plan. But before this sample could arrive at the University of Alberta’s Canadian Ice Core Lab, we had to get it from one of earth’s harshest climates and transport it to the lab in pristine condition.
As an ice-core scientist and high-altitude mountaineer, I study past climate in polar and sub-polar regions using ice-core chemistry, which involves spending time in frigid climates. Drilling an ice core on Canada’s highest mountain required climbing it twice over two years—once to complete the site selection on the summit plateau, and once to complete the drilling itself. For both field seasons, it was important to climb to the 5,959-m summit and acclimatize in order to live and work for multiple days on the plateau, more than 5,300 m above sea level.

“Typical climbing parties take about three weeks to attempt to summit, and less than half of these attempts are successful. The odds were against us.”

National Geographic Explorer and scientist Alison Criscitiello operates the ice-core drill. 

I had climbed Mount Logan for “fun” before this project and had no intention of climbing it again, let alone multiple times more. Nevertheless, in May 2021, I led a small team onto the mountain to complete a radar survey across its vast summit plateau. Mount Logan, though not considered a highly technical climb in the world of mountaineering, is nonetheless a serious challenge because of its remoteness and extreme polar conditions. It also has the intimidating feature of requiring climbers to go up to get down—that is, to get off the summit plateau you need to ascend a high pass (Prospector’s Col) before descending the rest of the route. Typical climbing parties take about three weeks to attempt to summit, and less than half of these attempts are successful. The odds were against us.
On the first scientific expedition, we conducted a radar survey, allowing us to look at ice depths on the plateau and at the internal layers of ice from just below our skis down to bedrock, which enabled us to pinpoint an ideal drill site with the highest probability of recovering an old and well-preserved climate record. In addition to completing the radar survey, we installed the highest weather station in North America, which we bolted to bedrock on Prospector’s Col at 5,639 m—a spot that tends toward hurricane-force winds.
Standing on the summit on that trip felt different from my first, five years prior. In the interim I had gone from having no status in Canada to becoming a permanent resident. I had moved to Canada during my post doctorate and stayed to build and direct its first national ice-core lab, in Edmonton. This second time, I looked down at a country that I was learning to call home, with my dearest adventure pal, Rebecca, by my side and a scientific purpose fueling our sufferfest.

“Climbing Logan is no small effort, but in this case arriving on the barely oxygenated plateau was the true beginning of our scientific mission.”

A year later, I returned with a larger team for the drilling. When we set off on this year’s National Geographic and Rolex Perpetual Planet Mount Logan Expedition, I had no idea if we could pull it off. The logistics took years of planning. We flew into Logan’s base camp, on the Quintino Sella Glacier, May 2, and climbed the King Trench Route (the standard route up the mountain) like in previous years to access the summit plateau in ten days. Due to its high northern latitude, Logan’s altitude is heavily felt by the body, which made double-carrying up the mountain (climbing every section twice in order to acclimatize) particularly crucial. We encountered the same dicey spot as we did the previous year: King Col Icefall. The icefall, which has historically been a straight-forward ski, has in recent years become an exposed and mobile maze of sharp ice ridges called seracs. We carefully picked our way through this jumbled ice labyrinth, only to say good riddance until the ski down weeks later.
On May 15, we set off for the summit plateau but were pinned in place below Prospector’s Col by 90 km/hr winds; we dug ourselves into the side of the mountain to escape the gale and waited until morning when the storm broke. As soon as the winds eased, we skied up and over the saddle to our high camp on the summit plateau.
Climbing Logan is no small effort, but in this case arriving on the barely oxygenated plateau was the true beginning of our scientific mission. We had started as a team of seven, but altitude-related health issues resulted in three team members descending before the drilling would be complete. Upon arriving on the plateau, we conducted a final radar survey to narrow down on the drilling location. The drill and all other ice-coring equipment were heli-slung up to the plateau in 130-kg loads by a skilled oxygen-masked pilot. In one day, we set up the drill and camp, and the race was on to finish our work before the weather took a turn for the worse. On the first day we drilled 60 m of ice, but as work progressed, that rate decreased significantly due to the increased travel time of the drill up and down the borehole. By day 11, we were drilling 20–25 m per day.
The cores came up one after the other, day after day. Over the drilling campaign we saw three distinct volcanic layers in the ice; with so much monotony, that cloudy ice made us unreasonably excited. We settled on a shift schedule that allowed us to keep drilling 14 hours a day, while also allowing us to rest as our bodies slowly deteriorated from living and working that high. On May 30, we drilled our last section of core to 327 m, and immediately started packing up the equipment and camp. The race was now on to get down as quickly as possible, our bodies craving oxygen and warmth—the previous monotony revving to a sprint.

A section of ice core drilled at the summit plateau.

We had taken advantage of good weather while drilling, flying ice off the plateau in staged loads. As a result, the day after we drilled our final metre of ice core, we were able to fly the last of it off the plateau and ski all the way to base camp in under seven hours, getting lucky with the weather and flying out that evening.
After being heli-slung off the summit plateau, the ice was flown directly to a storage-container-sized -20°C freezer at Silver City, a small landing strip near Łù’àn Män (Kluane Lake). The freezer unit sat there for the duration of our time on the plateau, receiving ice loads, with spare parts for every component of the precious freezer and a technician on-site. When the last load arrived, it was trucked to the ice-core lab in Edmonton, nearly beating me home. With the ice safely in the ice-core archive, and a whole lot of analyses ahead, there are many more questions than answers for now about what discoveries are contained within the ice. It is possible that the oldest non-polar Arctic ice in the world just buzzed through our bandsaw, snowing 30,000-year-old dust on the freezer-lab floor.
This ice core from Mount Logan is an opportunity for investigating climate change and variability in atmospheric composition in the North Pacific and Gulf of Alaska. The list of studies planned for the ice core is long. We will use oxygen isotopes to reconstruct past temperature, marine aerosols will provide clues into past sea-surface conditions, volcanic ash will tell us about changes in forest-fire frequency over time (and changes over time in the vegetation that was burning), and many other tools will help investigate critical climate transitions in our earth’s history. This project was near impossible and driven by a deep desire for revelation—scientific and maybe otherwise.

Alison Criscitiello is a National Geographic Explorer and director of the Canadian Ice Core Lab at the University of Alberta.

The National Geographic and Rolex Perpetual Planet Mount Logan Expedition was composed of Alison Criscitiello, Rebecca Haspel, Etienne Gros, Dominic Winski, Bradley Markle, Seth Campbell, and Kirk Mauthner.