Glaciers all over the world are shrinking under the onslaught of global warming. But in some cases, resistance is possible, says a veteran glaciologist. His calculations show that several thousand snow machines in the right place at the right time could make one of the major glaciers of Switzerland grow again—eventually. This summer he is reality testing the idea on a small man-made glacier.
Officials in the Swiss town of Pontresina asked Hans Oerlemans, a retired professor from Utrecht University in the Netherlands, to look at options to save the nearby Morteratsch glacier, which has long been an economic mainstay of the town. Oerlemans has been studying the glacier for more than 20 years, and he is well known in Pontresina.
The glacier has brought tourists and revenue to the town, Oerlemans told Eos, because its snout has been so accessible. “You’d arrive at the train station, walk for 25 minutes, with a stroller even, and you could touch it. But it’s retreated in recent years. You don’t see the snout anymore from the road; it’s just rock. You can’t change that back in a few years, but the community thought we should think about it.”
It wouldn’t be the first time a Swiss community took steps to protect a glacier from climate change. In nearby Diavolezza, a small glacier is covered with white fleece cloth each summer to protect it from the Sun and keep it in business as a ski run.
“For the Morteratsch, that was not an option,” Oerlemans said. “That glacier is a hundred times as large.” Together with Swiss glaciologist Felix Keller of the Academia Engiadina in Samedan, Switzerland, Oerlemans decided that the best way to help the glacier would be if summer snow were to cover the ablation zone, the part of the glacier where more ice melts off during the warm months than falls as snow in winter.
The balance between the melting in a glacier’s ablation zone and the accumulation of snow higher up determines the length of the ice mass. Less melting in the ablation zone would mean that more ice survives the summer and thus thickens the glacier there, leaving more ice available to stream down and extend the glacier’s reach. Protecting the ablation zone would thus eventually let the snout move closer to the town again.
Oerlemans had heard that this protective approach seems to work with the fleece-covered glacier in Diavolezza. “They claim it’s thickened 5 to 10 meters in 10 years,” he said.
The fleece, and presumably the snow as well in Oerlemans’s scheme, helps the glacier by reflecting sunlight from the ablation zone. Some energy that would otherwise have melted the ice is also diverted to melting the newly fallen snow, but that’s a lesser effect, Oerlemans’s calculations show.
Field Testing the Idea
At a site near the Diavolezza glacier, Oerlemans and Keller are now testing whether a small real-world glacier agrees with his model. “Just by freezing water, we have made a little glacier, we have a snow machine and a weather station, and the goal is simple: We have to carry this glacier through the summer.”
According to the computer model Oerlemans used, half a square kilometer would have to be covered by snow to have the desired effect on the Morteratsch glacier. After 10 to 15 years, this could lead to a lengthening of the glacier by 800 meters, a momentous turnaround for a feature that has been shrinking 30–40 meters a year recently and that has lost 2.5 kilometers of its length since 1860.
Summer snows can’t be conjured up at will, so the snow that is to protect the Morteratsch will have to be generated artificially. Snow machines—also called snow cannons or snow lances—force a high-pressure mixture of air and water through a nozzle. The rapid expansion of the air as it exits the nozzle causes it to cool rapidly and turns the water into ice crystals.
It would take 4,000 to 5,000 snow lances to produce enough artificial snow. However, the lances could run without fuel or electricity because in summer, meltwater from the higher reaches of the glacier fills a few small lakes. If water were piped down from there, the drop in height could provide the snow lances with enough pressure to function, as is being done already in some places in Switzerland, according to Oerlemans.
Covering the ablation zone with artificial snow can take place only during certain times of the year. In winter, no liquid water is available. In high summer, the air temperature in the ablation zone will often be too high for snow production to work. But with enough snow lances, on the days snow production is possible, a thick enough layer, about 10 centimeters, could be deposited to last and protect the underlying ice. “And for this to work you don’t need high-quality snow,” Oerlemans said. “The important thing is that it is white. That means the meteorological conditions are a bit more lenient.”
Climate Wild Card
Whether the summer snow layers could have the desired effect for the Morteratsch itself “depends on how fast the climate is warming,” Oerlemans warns. “The problem with this whole story is that the warming in the Alps, especially the summer temperatures, is 2 to 2.5 times the global average. The question is, Will it remain like that?”
He thinks not, but the jury is out. In a 2014 paper, a team reviewing climate predictions for the Alps and using model calculations tentatively projected that the rate of increase of the mountain region’s warming later this century would diminish to match or slightly exceed the global average of 0.25°C per decade and then accelerate again to 0.36°C per decade. Those rates don’t come close to the 0.5°C per decade the Alps have experienced since 1980, according to the paper.
On the other hand, the next year, in 2015, a collaboration called the Mountain Research Initiative EDW Working Group (EDW stands for elevation-dependent warming) identified several mechanisms expected to contribute to faster warming in regions like the Alps, such as reduced albedo because of vanishing snow cover and rising concentrations of water vapor in the air. If those effects keep temperatures in the Alps rising as fast as they are now, Oerlemans says, “then the glaciers are gone; there’s no way you can do anything. If warming became more modest, you would at least have a chance.”
Is It Worth the Cost and Effort?
Oerlemans’s glacier-building scheme meets with a mixture of respect and raised eyebrows from one of his Swiss colleagues, glaciologist Daniel Farinotti of the Swiss Federal Institute of Technology in Zurich. “The research is very sound; Hans uses a state-of-the-art model and comes to that result. If it’s really so important to you to make this glacier grow, for whatever reason, Hans tells you there is an option of doing so. But what would it cost? And what will you gain with that?”
Even in wealthy Switzerland, the millions of dollars the project would require are out of reach of a town like Pontresina. Oerlemans will present the project at the World Water Week in Stockholm later this month and has started a foundation to raise funds for it.
Looking at the big picture, “obviously, this won’t save any other glacier,” noted Farinotti. “This won’t save us from climate change, or glacier retreat somewhere else, and it is not something you can upscale to save, say, all the glaciers in the Alps. But if it is important to a community economically, if that is the target they are pursuing, why not?”
On the other hand, he has some doubts about conclusions other people might draw from this. “If the message is, you don’t need to care about climate change, I would not be in favor,” Farinotti said. Asked if the message could also be that you should care about climate change, just look at the enormous effort and expense of counteracting only one of the many consequences of it, Farinotti agreed: “That’s another way to look at it; that could be a strong message.”
Oerlemans has his own reservations about how far the project should be taken, if it turns out to work at all. But that doesn’t deter him from continuing to study the concept. “I still have questions, but if you don’t do this kind of [study], you’ll never know,” he said.
—Bas den Hond (email: firstname.lastname@example.org), Freelance Science Journalist
den Hond, B. (2017), Artificial snow could make Alpine glacier grow again, Eos, 98, https://doi.org/10.1029/2017EO079213. Published on 04 August 2017.
Text © 2017. The authors. CC BY-NC-ND 3.0
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