Water in the glacial cellar – A journey into the depths brings new insights to the surface | Polarjournal
Snowstorm and darkness at noon on the glacier. Photo: Andreas Alexander

The wind howls and swells. The icy cold snow blows up in our faces. The dry snowflakes hurt the skin and without snow goggles it would be completely impossible to keep the eyes open in this snowstorm. For hours we have been struggling to pull ourselves and about 100 kg of equipment on two sledges up the icy mountain flanks. By now it has become noon and we have managed to transport the generator, the drill, all the ropes and carabiners halfway up the distance. It’s dark and the raging snowstorm makes it hard to see your own hand in front of your eyes. We tremble not only because of the felt -20°C, but also exhausted by the hardships we have put on ourselves. What crazy idea did came over me again?

For years, I have been fascinated by the icy worlds. Especially the glaciers, which crawl down the mountain flanks in their majestic violence, have gotten a hold on me. The eternal ice reflects the former primal power of nature and shows again and again how tiny and insignificant humans really are. Ice, in its raw power, has the power to show us our limits. But what was once considered eternal is no longer stable.

On the surface of glaciers,deep gutters, formed by meltwater and precipitation, snake-like wind their way until they end up in deep glacial mills. Andreas Alexander has always been fascinated by such things. Photo: Frans Lansing

The virgin white dress, which envelops glaciers in winter, gives way to a dirty blue-black costume in summer. Torrential floods rush across the surfaces of glaciers in summer, transporting the former splendour and decimating the glaciers in size completely. The enormous power of the water leaves traces: Deep meltwater channels are milled by the water into the surface of the ice. But the bubbling masses don’t stop at the surface. Deep black shafts open up on the surface of glaciers: the glacier mills or moulins. Gurgling and loudly roaring, the water here disappears into the yawning depth; Thunders down into the bottomless abyss, deep into the innermost part of the glacier, before it wildly emerges below the glacier. I have watched this humility-infusing spectacle over and over again. There always was a question whirling in my head: What actually is happening down there? What happens after the water has disappeared from the surface?

Especially in the polar regions, where it is freezing cold all year round, it can happen that glaciers are thoroughly frozen, at ice temperatures well below 0°C. With the effect that the glaciers are frozen where they sit on the mountain. The substrate under the glaciers is frozen permanently, also called permafrost. The latter strongly is declining in many regions of the world, due to the current global changes. These frighteningly rapid changes have raised the question of whether the permafrost is changing also deep beneath the glaciers. However, in search of answers, I found that there had been no measurements. The glacier bottom was considered inaccessible and measuring instruments would not survive in this insidious and diabolical environment anyway. When I came up with my idea to study the temperatures in the ground beneath a glacier, some glacier researchers also told me that this would not be worth it. It takes hundreds, even thousands of years, for anything to change down there. Physics is clear.

Four sleds (pulkas) that have fallen victim to science. In the course of the 5 years, several such sledges “entered” the eternal hunting grounds. Photo: Andreas Alexander

But these arguments did not convince me really. What followed were five years of hard work, with countless days far beyond any sweat and pain thresholds. Always exposed to the wild elements of nature. Sledge by sledge, together with countless fantastic assistants, I pulled up tons of equipment on steep, icy mountain flanks. Once a line of a sled tore under the load and the sled snapped into the depths. Another time we hung on the rope for three days and dug our way through 40 meters of snow into the depths of the glacier. In some daring action, we climbed down more than 100 meters deep under glaciers, waded through an underground lake with a 100,000€ measuring device, forced ourselves through narrow passages with a drill, robbed hundreds of meters on the back under the ice, laid extension cables in glacier mills and drilled lots of holes into the rock under the ice. Always looking for answers.

One of many days when the path into the glacier had to be cleared. Photo: Andreas Alexander

Svalbard, located far north of Norway, just 1300 km from the North Pole, is regularly referred to as the “Ground Zero of Climate Change”. Here, it all reveals long beforehand what global warming will hold in other parts of the world in the future. The archipelago still is characterized by ice, permafrost and icy wind. But this picture is changing rapidly, new temperature records are regularly broken, and by the year 2100 even a 10°C temperature rise is expected. The snow keeps coming later and the former cold desert is getting wetter by the day. Rain was once considered a special feature here, but now it regularly pours down in both summer and winter. The permafrost is thawing at a rapid pace and the glaciers are disappearing like a child’s ice cream on a hot July day. One record chases the other.

Svalbard is the place where I decided to get to the bottom of the changes that are taking place. Glacier by glacier, we have mapped drainage systems under the ice, measured temperatures and experienced many surprises.

The drill is frozen in the ice under the glacier and must be saved with the pliers of a pocket knife. Photo: Andreas Alexander

Driven by curiosity, we have placed temperature sensors down to 1.1 meters deep in the rock under various glaciers. This may not sound like much at first, but it is, considering that the necessary equipment must first be towed up to the mountain by hand, then roped down to 100 meters deep under the glacier and also overcoming several creeping passages and many underground waters. As expected, the measured rock temperatures were cold. In winter, we measured up to -6°C in the rock deep under various glaciers. Now theoretically, this would be the end of the story. Nothing is happening here for hundreds, even thousands of years. But theory is not enough for me. I wanted to know more, so we kept some of the measuring instruments under the glacier over summertime. With the risk that, in summer, the raging water masses would simply wash them away. But no guts, no glory!

If the instruments have survived a turbulent summer under the glacier in the end, the only challenge that remains is in order to get to the data, you would have to get the instruments back somehow. The best way to do this is in autumn, after the water has stopped flowing and the snow, as well as the slow creep of the ice, have just not closed the entrances. Most recently, we embarked on such a data rescue operation in October 2019. Among other things, it was necessary to transport several hundred kilograms of equipment by foot for about 20 kilometers to the glacier, to pitch a tent there, then to recover the instruments and carry out new measurements.

Whoever thinks of climbing into a glacier in Polar bear area in the middle of polar night in order to drill under the glacier, will have to be prepared to tow a bit of equipment. This kind of thing is tiring for people and dogs. Photo: Andreas Alexander

This time, we had brought dogs, after years of struggling with far too heavy sledges on steep mountain flanks. Not only to help us pull, but also to provide company to the nightly polar bear guard in front of the tent. Because that was another problem: after a busy day, you can’t just hide in your sleeping bag and recover from the hardships of the day. No, at any time someone has to be awake and keep watch in front of the tent, should a polar bear happen to come along in search of food. We didn’t meet a polar bear until the end of this tour, but even so this mission has provided more than enough adventures. Hardly any snow in late autumn in the high Arctic has made it unnecessarily difficult to transport the equipment across boulders and only tentatively frozen rivers. Nightly polar bear watch in the rain and rapidly melting snow forced us to make an early return journey in the end, with an overzealous dog pushing me face first into an icy river. In the end, not only four scientists had laid down on the ground completely destroyed, also exhausted dogs and four completely shredded sledges, but also an incredible treasure trove of data were the result.

Not all cave systems in the glacier survive. Here, a complete cave system collapsed in late summer 2019. Photo: Andreas Alexander

Arriving at the glacier, we were surprised by huge changes. Parts of the cave systems in which we had climbed six months earlier had collapsed. The temperature sensors we had drilled deep into the rock dangled in the air, large chunks of ice lay scattered inside the cave under the glacier, and new passages had opened up where previously only walls had been. And the data collected also spoke out.

A meltwater channel located under the glacier, some of which is filled with water. Photo: Andreas Alexander

So much for “no changes”: The temperatures under the glacier were anything but constant. During the winter it slowly became colder and colder, but as soon as summer came, the temperatures began to climb. Well, not really surprising when water suddenly flows through the drainage system. The really surprising thing were sudden temperature rises. If the rock temperature rises from -1.7°C to +0.2°C at a depth of more than one metre within four days, then this is not necessarily normal and means the end of the permafrost there. A look at the respective weather conditions on the glacier surface was very revealing. As it turned out, it had been the days of record melting and rainstorms on the glacier surface that had caused the greatest temperature fluctuations under the glacier. But that’s not all. The rain of a single day had washed away 90 cm of frozen rock from under the glacier. Just like that. Thus, within a few months, a tiny shaft through which you had to force yourselv through, turned into a huge cave in which an entire orchestra could have marched through. I really do not want to imagine how a future temperature rise on Svalbard, with the associated sequence of record melting and an increase in rain events, will affect the glaciers and the permafrost below. But my data shows a bleak foreboding of what will come when it begins to rain in the desert.

One of many creep-through passages under the glacier where the water flows in summer. These amounts of water will rise just like the amount of precipitation in the future. Photo: Andreas Alexander

t is becoming increasingly apparent that change is not stopping on the surface, but is penetrating much deeper. In a recent study, researchers surveyed moulins inside the Greenland ice sheet. The surprising finding: With an area of up to 500 m2, the measured moulins were simply much bigger than anything one could have imagined or guessed from the opening on the surface. What appears to be intact on the surface is in fact deeply devoured and hollowed out, like a pumpkin for Halloween. With far-reaching consequences for future ice melt and rising global sea levels. Beneath the surface of our planet’s icy giants, there is more hidden han we previously anticipated. We are only at the very beginning of really understanding what is going on here. And yet it is becoming increasingly apparent that monsters may be lurking in the depths, which could cause many nightmares in the future. But that is not enough. Where there is light, there is also shadow. Transferred to Svalbard, this means that changes do not only happen in summer, when it is bright. No, even before the dark season, when the sun never crosses the horizon, the profound changes do not stop. But that’s another story to tell.

Andreas Alexander is a PhD student in glacier research at the University of Oslo. The mechanical engineer and geologist had studied in Germany, Alaska, Japan, Greenland and on Svalbard, where he also spent several years. In his doctoral thesis, he deals with glacier cavity research, as well as with the development of new technologies for measurement in inaccessible, flooded and highly turbulent glacier caves. This serves to broaden knowledge in the field of glacial hydrology and ultimately to better predict future sea level changes. In addition to his work in science and teaching, he also works as a guide in the Arctic and Antarctic.

Links to the works:

Alexander, A., Obu, J., Schuler, T.V., Kääb, A., Christiansen, H.H. (2020) The Cryosphere 14 (4217 – 4231): Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard; https://doi.org/10.5194/tc-14-4217-2020

Covington et al (2020) Geophys Res Lett 47 (20): Moulin Volumes Regulate Subglacial Water Pressure on the Greenland Ice Sheet; https://doi.org/10.1029/2020GL088901

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