A Stunning Look at the Hidden Mysteries of Glacier Caves


I used to be dangling from a skinny nylon rope, some 250 ft from the backside of an icy shaft. Looking up, I famous the spindrift — blinding snow whipped right into a frenzy by howling winds — that was sandblasting the entrance, some 20 ft above me. I used to be glad to be out of the climate, hanging in close to silence.

As my eyes adjusted to the decrease gentle, I discovered myself staring down right into a chasm that was far larger than something I believed we’d discover beneath the floor of the Greenland ice sheet.

All I might suppose was: “This shouldn’t be here.”

Will roped me in because I wrote my Ph.D. dissertation about glacier caves and had been studying them for more than 15 years. I was supposed to be the science expert, but I sure didn’t feel like one staring into that inexplicably large hole.

Between climbs, and later over beers, Doug and I became convinced that we could understand how glacier caves in the Everest region were forming — if only we could explore and map them. While I’d never seen a glacier, and Doug had only briefly visited a few caves, we figured that combining Doug’s glaciology and mountaineering experience with my background in cave exploration and mapping might help us figure out how to explore some of the world’s highest caves, and probably even survive the expedition.

On our first expedition in November 2005, we spent around seven weeks exploring and mapping glacier caves at elevations above 16,400 feet in the Everest region, including caves that were a short hike from Mount Everest base camp. Gasping for breath in the thin air, we survived rock slides, ice falls and collapsing cave floors. And we slowly learned the glacier caves’ secrets.

Glacier caves in the Everest region, we discovered, were forming along bands of porous debris in the ice. Water from lakes on the glacier surface would flow through debris bands and melt the ice around them to form a cave. The caves could then rapidly enlarge as the rate of melting increased, allowing entire lakes to drain through them.

Having unraveled my first scientific mystery, I was hooked. I completed my undergraduate degree in 2006 and began working with Doug and a growing list of adventurous collaborators to explore and map dozens of other glacier caves in Alaska, Nepal and Svalbard, Norway, first as a graduate student, later as a post doctoral fellow and finally as a professor. Along the way, I learned how to photograph the frozen darkness so that I could share our findings with scientists who lacked the technical skill sets to venture into glacier caves.

The discoveries we made scampering beneath the world’s glaciers over the next decade helped us document the role that glacier caves play in mediating how glaciers respond to climate change. In Nepal, where thick blankets of debris on glacier surfaces should insulate glaciers from melting, we found glacier caves were melting ice below the debris. Caves were turning Everest’s glaciers into Swiss cheese and rotting them from the inside out.

In other parts of the world, including in Alaska and Svalbard, glacier caves followed fractures in the ice and funneled rivers of meltwater to glacier beds. The surge of summer meltwater lubricates the contact between the ice and underlying rocks and causes glaciers to slide faster than they would if meltwater wasn’t present.

While I’d explored glacier caves around the world before working with Will, there was one place I hadn’t gotten to explore: the inside of the Greenland ice sheet.

The Greenland ice sheet extends more than 650,000 square miles — roughly the size of Alaska. If it melted completely, it could raise the sea level by 23 feet.

Each summer, rising temperatures transform the frozen surface of the edge of the Greenland ice sheet into a network of rivers and lakes. All of the rivers, and many lakes, disappear into moulins and continue flowing toward the ocean along the interface of the ice sheet and the rocky bed beneath it. As the flow of meltwater into that interface increases, friction between the ice and bed is reduced, and the ice sheet speeds up, sending ice into the ocean faster than in winter.

Some glaciologists are worried that as climate warming triggers more melting, and new caves form in areas of the ice sheet that didn’t previously melt, increased lubrication might cause the ice sheet to dump ice into the ocean and raise sea levels faster than expected.



Source link Nytimes.com

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