Glaciers Are Melting. One Ski Resort is Fighting Back

The Italian region of Trentino is using new technology to combat glacial melt on one of Europe’s oldest, coldest battlefields.
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Michael Blann

NOTHING IN CHRISTIAN Casarotto’s scientific training prepared him for the dead bodies. “The first time, I found a leg,” the glaciologist says. “There wasn’t any flesh left and the articulation had decomposed, but there was a bone with the shreds of trousers and a boot.”

On another occasion, while surveying a glacier near the Austrian-Italian border, he and his colleagues from MUSE, the state science museum in the Italian city of Trento, came across a complete torso with the head still attached. There were scraps of grey-green clothing clinging to the body, and a rusted helmet half-covered the young man’s skull.

A century ago, the region now known as Trentino-Alto Adige was part of the Austro-Hungarian Empire. During the First World War, an estimated 150,000 men lost their lives in these mountains, as the Italians battled imperial forces for control of the high ground. Freezing temperatures, formidable terrain and the risk of further exposure to enemy fire meant that many soldiers were simply left where they fell, or given ersatz burials in crevasses.

As the climate crisis worsens, however, the glaciers which once formed the front line are melting. The natural tombs which encased these soldiers for over a hundred years are being desecrated, as global heating disinters their occupants – their remains often eerily preserved by the ice.

Casarotto has spent two decades monitoring the health of Trentino’s glaciers. As the concentration of carbon dioxide in the Earth’s atmosphere has grown and average temperatures have continued to rise, he’s watched as these ancient rivers of ice shrink and disappear at previously unprecedented rates. Normally, he and his colleagues talk in terms of “deep time”. Ice ages. Epochs. Geological eras. But man-made climate change is disrupting systems that have endured for millennia, causing natural timeframes to concertina and collapse. These days, Casarotto frequently finds himself confronted by grisly relics of a more recent past. “I find at least one dead body a year,” he says, “or a bit of a body – a hand or a leg or something.”

Blankets protect the Marmolada's ice

Michael Blann

IT'S NOT YET 6AM when I meet Casarotto in his official MUSE car, just north of Trento, but the June Sun has already warmed the air to nearly 20°C. With his bird’s nest of black hair and a wicked laugh, the 46-year-old talks animatedly as he drives, peppering his speech with the word “fantastico”, and occasionally taking both hands from the wheel to emphasise a point.

The key metric for measuring the health of a glacier, he explains, is its “mass balance”. This is the difference between the “accumulation” of newly-formed ice and the “ablation”, or melting, of existing ice. New ice accumulates because of snowfall, which compresses slowly, reaching a halfway point known as “firn” before transforming into its glacial state. If more ice melts than accumulates, the mass balance of the glacier is negative, and it will start to shrink. To remain healthy or grow, a glacier must maintain a mass balance of zero or above. “There are two ways it can happen,” Casarotto says. “Lots of snow over the winter, or less melting over the summer. It’s like your bank balance – either you save more, or you spend less.”

Today, we’re climbing up to the accumulation zone of the Marmolada glacier, in the shadow of the peak of the same name, where Casarotto can take his end-of-winter mass balance measurements. The important factor in creating glacial ice isn’t the depth of the snow, he explains, because snow contains variable amounts of air. Instead, he’s looking to measure the quantity of water within the past winter’s accumulated snowfall. To calculate this, we grab shovels and start digging.

When the pit is above head height, Casarotto takes out a series of what look like cocktail sticks, and marks out the individual layers of snowfall in the wall of the newly-dug hole. Each stratum of snow, layered like the folds in filo pastry, represents a different precipitation event, he explains. He scrapes a few flakes onto a plastic slate and hunches over it with a loupe – like a lapidarist looking for flaws in a diamond. “Here,” he says excitedly, passing it over. “See this orange layer? That’s where the snowfall picked up dust from the Sahara back in February.”

Next, he carves out half-litre samples of each layer of snow using a metal cylinder – like a giant wine measure, with the bottom cut out – and dumps them into a bag attached to a tiny scale. Weighing each half-litre allows him to calculate the snow’s density, and therefore its water content. Subtracting a set of ice measurements, which he’ll make at the end of the summer, will give him the annual mass balance figure for this glacier. It’s been a good winter, he notes with satisfaction. There’s around four metres of medium-density snow – 160ml of water per half-litre – lying on top of the glacial ice beneath. “Last year, it was just half that,” he says.

Just as each precipitation event is different, every glacier has idiosyncrasies that affect its health. Rates of accumulation and ablation can be impacted by a whole range of factors, including the surface area of the glacier, the angle and aspect of the slope, and the composition of the rock underneath. These also affect a glacier’s internal dynamics, and how quickly it moves. While they’re often thought of as inert and lifeless, glaciers in some parts of the world move up to 30m a day. Studies have also shown that many glaciers, including in the Alps, are teeming with microbial life.

Casarotto talks about the seven major glaciers he works on with an almost paternal affection, delighting in describing their quirks. Yet as distinctive as each is, they have one thing in common: in the 20 years he’s been studying them, the annual mass balance of Trentino’s glaciers has nearly always been in the red. “In 2013 to 2014, the balance was near zero, and in one case it was positive, but very, very little,” he says. It’s a trend that’s getting worse. “In the last 15 years I’ve seen an acceleration of the reduction. In the last ten years, it's been terrible.”

The longest historical sequence of annual mass balance measurements available to Casarotto and his colleagues – for the Careser glacier, in the Cevedale group, where Casarotto found the disembodied torso – shows a particularly dramatic decline. The series of measurements stretches back to 1967, but the last year with a significant positive balance was 1977, and the annual mass balance has been negative, without fail, since 1986.

“What was, in the 1960s, one large glacier is now separated into seven small glaciers,” Casarotto says. Each of these is now shrinking at an even faster rate. When they’re smaller than one hectare, the internal glacier dynamics will stop. “The glacier stops moving. And without movement, it’s no longer a glacier.”

Of the seven ice patches which make up what remains of the Careser glacier, he says, “five, we would already consider to be extinct.”

Christian Casarotto, a glaciologist monitoring Trentino's glaciers

Michael Blann

WHEN A GLACIER dies, the impact is felt far beyond its immediate surroundings. Because of their capacity to freeze and store precipitation, mountain glaciers act like natural water towers, accumulating ice in winter and then releasing meltwater in spring at a steady, predictable rate. This helps regulate the flow to streams, rivers and lakes in the valleys and plains below.

In the short term, as a glacier like the Careser sickens, there’s usually an increase in the average rate of flow. Longer term, once the glacier has melted beyond the point where it can effectively create new ice at altitude, the steady, predictable stream of water disappears. “Without these reservoirs, the water just comes straight down,” says Casarotto. The consequences of unregulated precipitation can be catastrophic. Flash floods, landslides and avalanches become more common. Entire ecosystems can be upended. “In some valleys in Trentino where there was a small glacier, we’ve seen the flow of water change completely,” he says, with disastrous effects for local flora and fauna.

The melting of mountain glaciers is a problem on a global scale. Almost three quarters of a billion people live in high mountain environments worldwide. A landmark 2019 report found that as many as 1.65 billion people (including those downstream) will be affected as the glaciers decline in the Himalayan region. Elsewhere around the world, significant populations stand to be affected in the next few decades, according to Jemma Wadham, professor of glaciology at the University of Bristol. It is, she says, nothing less than “a threat to life and livelihoods and people's existence”.

“Take a river like the Indus, for example,” Wadham says, referring to the river basin that supplies water to some 270 million in China, India and Pakistan. “At the headwaters, most of the river water is glacial meltwater. As that starts to decrease, from about 2050 onwards, people suddenly won't have sufficient water – and they’re very vulnerable.” In her recent book, Ice Rivers, Wadham describes glacial melt as “one of the big humanitarian time bombs of climate change”. In an interview with journalist Ronan Farrow for his 2018 book War on Peace, the late US diplomat Richard Holbrooke said that if the shrinking glaciers feeding the Indus were ignored, the issue “could very well precipitate World War III”.

Even in Trentino, a prosperous part of the world with a long and proud history of high-altitude research, the issue receives far less attention than it merits, according to Cristian Ferrari, head of the glaciological commission of the Società Alpinisti Tridentini (SAT), the region’s 150-year-old alpine club.

At SAT’s headquarters, a handsome palazzo in the centre of Trento built from the distinctively pink-coloured local stone, Ferrari pulls out century-old watercolours and photographs of the region’s glaciers from across the decades, placing them next to shots from the present day. “You can see that in 20 years time, I’ll have a lot less work to do, and a lot fewer glaciers to measure,” he says.

The changes are obvious when laid out like this in black-and-white and Kodachrome. But Ferrari says he frequently struggles to communicate just how serious the situation is, both to politicians and the general public: “We try to raise awareness, but the media only want to talk about ice in August, when there is no other interesting news.” Yet the water supply issues that he, Casarotto and others are seeing at altitude will have significant consequences for this town, the region around it, and the country as a whole.

Italy relies heavily on hydroelectricity, with some 15 per cent of its power needs generated by dams, many of which are glacier-fed. The industry is particularly important in Trentino-Alto Adige, which boasts the country’s second-largest hydroelectric capacity and exports energy to the surrounding regions. The viridescent vines which cover Trentino’s valleys, producing D.O.C. wines from world-famous local varieties such as Gewurztraminer or Teroldego, also depend on steady, regulated sources of water. Trentino’s apple industry, which accounts for around 35 per cent of agricultural output and produces some 500,000 metric tonnes of fruit per year, is equally thirsty.

But in a region that relies heavily on its natural assets to attract visitors, it’s the winter tourism sector, which attracts some 13 million overnight stays per year – and 48 per cent of the total tourism spend – that stands to be hardest hit. Which is why, on the same high-alpine passes where pitched battles once raged, the industry is fighting back.

The Presena glacier, wrapped in geotextile blankets

Michael Blann

AS I STEP out of a ski lift and follow Felice Longhi and Alessandro Daldoss onto the snow of the Presena glacier, a steel cable, punched into the mountainside 20 metres above our heads, begins to quiver. The sonorous chug of a massive, 12.8-litre Mercedes Benz engine grows louder, as a PistenBully 600 snowcat, attached to the cable by its crane-mounted winch, grunts into view. Five burly-looking men jump out and run around the front, where the machine’s normal bulldozer blade has been replaced by a surprisingly delicate-looking roll of white fabric – a strip of protective geotextile tarpaulin, which the men begin to lay out over the snow.

The Presena glacier, now part of the ski resort of Passo Tonale, used to be the front line, explains Longhi, the director of the nearby Forte Strino First World War Museum. “If you look under the cable car, you can still find barbed wire poking out of the snow.” Today, however, these men and the local community are more concerned with a new fight. They’re mounting a desperate rearguard action to stave off, or at least slow down, the death of their glacier.

Daldoss, vice president of the Carosello-Tonale company, which manages the slopes and lifts at Passo Tonale, is commanding the operation. Tanned and trim, with reflective gold sunglasses and ageing rockstar hair swept back from his forehead, he talks with the brusque self-assurance of a Branson-style businessman-adventurer. “When we first did this, everyone was laughing at us,” he says. “Now, they all want to come and see how to do this on their glaciers.”

He watches as his men drive steel pegs into the snow to secure the top edge of the six-by-15-metre strip of geotextile and weigh down the sides with sausage-shaped sandbags. This sheet is one of more than 10,000 that the team will use to cover a million square metres of the Presena’s ice this summer, he explains. To ensure there are no gaps, the men stitch the sheets together with a handheld sewing machine, unrolling each strip as carefully as a bolt of silk, as the heavy snowcat backs, beeping, down the glacier. “It’s like when we’re doing cannelloni,” says Daldoss. “Exactly the same.”

Made of a non-woven polypropylene felt called Toptex GLS, a material developed specially for this purpose by the Austrian company TenCate Geosynthetics, these sheets have proved impressively effective when it comes to reducing the rate of ablation, and slowing the Presena’s summer melt. The science behind them is relatively simple, according to Antonella Senese, a glaciologist from the University of Milan who has studied the use of geotextile sheets on several glaciers, including the Presena.

Her findings, published in a 2020 paper for the scientific journal Cold Regions Science and Technology, show that white geotextiles can increase a glacier’s ability to reflect sunlight – its “albedo” – by as much as 50 per cent. The geotextiles’ insulating properties have a part to play too, Senese says. “In fact, we found that the most effective geotextile sheet we tried was the one with double thickness.” Wrapping a glacier in what she describes as “a blanket” to keep it cooler might sound counterintuitive, but between thermal insulation and the boosting of a glacier’s albedo, geotextiles can reduce melting by up to 69 per cent, Senese says.

There’s certainly no denying the impact of the geotextiles being used on the Presena. Flipping through the photos on his phone, Daldoss shows me the difference between the covered and uncovered areas of snow at the end of last summer. There is a steep step where the two meet. “That’s about five metres,” he says. “We needed a ladder to climb up.”

Daldoss and his team aren’t necessarily motivated by environmental concerns. “Everybody’s talking about global warming, but this is mostly for business,” he says. “We're not working for Greenpeace, I'm sorry.” But saving this much snow each summer has undoubtedly given the Presena glacier a new lease of life. According to Christian Casarotto’s data, of all the glaciers in Trentino, the Presena is the only one where the mass balance is consistently in the black – and it has been since 2008, when Passo Tonale began using the sheets. “Where there are the sheets, the [mass] balance has been positive every single year,” Casarotto says.

Gains this impressive do not come easily. Rolling out a million square metres of lightweight tarpaulin on a windswept glacier, 3,000m above sea level, requires a military-style logistical operation each summer. “It should take a team of 11 people, with two snowcats, working for a month and a half,” Daldoss explains. “But of course it depends on the weather. Last year we were lucky. Two years ago, we spent about three months, because every three days, rain came. When there's a storm, you can't work.”

On a sunny, still day in early June the process of laying out the sheets appears relatively straightforward. But Daldoss tells me that this top section is the easy part. “Where it's steeper, the men who are working on it are using crampons,” he says. He only employs locals who can handle ropes, harnesses, and high-mountain environments “[because] you need people with the attributes,” he says, cupping his hands between his legs: “You need people with balls.”

Benjamin Pötz, product manager for TechnoAlpin

Michael Blann

GEOTEXTILES MIGHT BE one the most effective ways of slowing a glacier’s demise, but they’re not the only weapon in Daldoss’ arsenal. He and his team – to use Christian Casarotto’s financial analogy – aren’t just capping their spending, they’re also regularly topping up the glacier’s mass balance, with snowy deposits from a network of seven massive snow cannons.

The creation of artificial snow – conjuring up perfectly-formed crystals out of water and thin air – is now seen as standard in most ski towns. Resorts have become increasingly reliant on the technology to ensure their slopes are covered during the profitable Christmas period. The headquarters of snow cannon manufacturer TechnoAlpin, a vast building in the German-speaking part of Trentino-Alto Adige clad in translucent white glass that recalls freshly fallen flakes, is testament to the lucrative nature of this still-young industry.

Over coffee on their sales floor balcony, product manager Benjamin Pötz tells me proudly that the company, just 30 years old, now turns over €250 million annually and supplies 60 per cent of the global snowmaking market. TechnoAlpin recently signed a multi-million euro deal to design and build all the snowmaking infrastructure – cannons, pipes, pumps and even artificial lakes – for the 2022 Beijing Winter Olympics.

As we stroll around gantries overlooking their factory floor, technicians tinker with rows of jet engine-like devices, and Pötz explains how the process of making the weather works. “We create ice with these nozzles called nucleators. They spray out a tiny bit of water in compressed air, and when air gets decompressed, it gets cold and freezes – like if you have a spray can.”

Arranged around the nucleators are nozzles spraying larger drops of water. “Those bigger droplets jump onto the ice, and make the big flakes,” Pötz says. Adjusting the number and size of these larger droplets allows them to generate snow of any weight and consistency. “It’s the same process as in nature.”

Yet there are crucial differences. Generating artificial snow requires vast quantities of water and energy. When set to produce snow of a standard weight and wetness, the TR10 fan gun, TechnoAlpin’s latest, most efficient model, can make around 90 cubic metres an hour, Pötz says. But to do so, it requires 10 litres of water a second, and 23KW/h of electricity – roughly 10 times as much as an electric oven, one of the most power-hungry domestic appliances. The technology isn’t cheap, either. A single, mobile-mounted TR10 will set a ski resort back around €50,000. On glaciers like the Presena, there’s the added complication of having to mount the cannons onto moving ice, which can bend and snap the pipes, entailing further maintenance costs.

“We spend about €200,000 just making snow each year,” Daldoss, of the Carosello-Tonale company, explains. The geotextile sheets they use are costly too, and usually need to be replaced after a couple of seasons, as the weather tears them or heat-absorbing dirt becomes ingrained in the felt, reducing its albedo effect. “We spend €200,000 each year putting them down and taking them off,” says Daldoss, “but if you include maintenance, the whole project is maybe €500,000 or €600,000.”

For a ski resort operator like the Carosello-Tonale company, half a million euros might be an acceptable annual expense. But it severely limits the likelihood that similar techniques could ever be used on any of the “wild” glaciers in Trentino – or anywhere else in the world. “You think that here you spend €200,000 [on installation],” says Daldoss. “But we're using our machines, and our men. If you wanted to cover a glacier like the Adamello [Trentino’s largest], for example, you'd need to go with a helicopter, move machines over there, move them back. You’d spend at least €2 million. It’s impossible, it’s too big.”

Then, of course, there are the environmental costs. The irony of a project such as that at Presena is that the energy-intensive technologies being used to save the glacier are contributing to the root cause of its demise. Making replacement geotextile sheets every two to three years requires more polypropylene, a fossil fuel derivative. Add in the phenomenal amount of electricity needed to power the snow cannons, the diesel burned by the snowcats and the resources required to keep people working safely in challenging, high-altitude environments, and the limitations of the approach become clear.

Improvements are being worked on. Pötz says that TechnoAlpin recently installed a snowmaking system powered entirely by hydroelectricity in Switzerland. It’s also looked into using wind turbines as a source of power. Senese is currently exploring geotextiles made from more environmentally-friendly materials – research that’s funded by, among others, the makers of San Pellegrino mineral water. “We’re testing a biochemical derived from corn,” she says. “I hope that we will have some protocols, some standards, for a sustainable use of geotextiles soon”.

Yet, as Senese points out, neither of these changes would remove the need for a massive amount of infrastructure on any “wild” glacier where these technological “fixes” might be trialled. There would be digging and disruption needed to install the equipment, pollution from the snowcats, and a constant human presence required to keep it all going.

“In theory,” Senese says, “it could work.” It might, at least, help to stop glaciers bleeding out at their current rate. “Maybe using geotextiles over a famous glacier could help raise awareness,” she suggests. But at what cost? The sections of glacier that survived would need to be enclosed, managed and tended constantly. The next generation might flock to see the remains of these once-mighty ice rivers, but they’d be no more wild than the last Tasmanian Tiger, confined to a zoo.

The Fedaia dam

Michael Blann

HALFWAY UP THE Marmolada glacier, Christian Casarotto stops for a drink. It’s baking hot, despite our early start, and the exertion of the climb – 800 vertical metres of ascent on touring skis, with climbing skins strapped to their bases – effectively kills conversation. The only sounds are the crunch of Gore-Tex and the synthetic “zweep” of the skins on snow.

The further we climb, the more our perspective shifts. Behind us, we can see the deep blue oblong of the Fedaia dam, the glacier-fed hydroelectric facility at the base of the mountain. To our right, the Fassa Valley, a UNESCO world heritage site, opens up, crowned by the iconic peaks of the Gruppo del Sassolungo. Somewhere off to our left, a dog barks, chasing the silhouette of a sky runner up the hill. Otherwise, we’re alone.

As we pause to catch our breath, Casarotto points his ski pole at a cluster of stones nestled beneath a crag. “That was a cable car they put up in the First World War. This was Austrian territory, and they built a whole ice city in the glacier.” There were 12 kilometres of tunnels carved into the ice, complete with a hospital, a chapel and sleeping quarters for 300 men. “Back then, of course, the level of the glacier was a lot higher,” he says.

To the untrained eye, the Marmolada, a Caspar David Friedrich fantasy of red rock, white snow and deep shadow known as the Queen of the Dolomites, looks in rude health. There’s seemingly plentiful ice and snow covering its 3,343m-high flanks. The data, however, is unequivocal. The glacier here has lost almost 80 per cent of its volume in the last 70 years. It has, according to Casarotto, “perhaps 15, or maybe 20 years left”.

In glaciological terms, 15 or 20 years is barely the blink of an eye. From a human perspective, however, it’s hard not to feel that a death this long, slow and drawn-out ought to be somehow preventable. Yet the fossil fuel consumption that will lead to the destruction of the Marmolada – first breaking it into pieces, like the Careser glacier, then melting through each of those at an even faster rate – has already happened. Change is already locked into the system, and studies show that even if the targets laid out in the Paris Climate agreement are met – limiting global average temperature rises to 2°C – then ten per cent of the world’s glaciers will be gone by the middle of this century. This majestic mass of ice and snow will be among those that die.

Casarotto’s measurements show that last winter was a good one for the Marmolada, but one season of good snowfall won’t save this glacier. In fact, MUSE’s models suggest that of all the glaciers Casarotto currently cares for, only one, the Adamello, will survive beyond 2080. Watching him work, there’s a sense that he’s going through the motions – performing surgically precise mass balance measurements with the air of a doctor offering palliative care. No matter what he does, the outcome won’t change.

“With this much snow, perhaps this year will be positive,” he says, hopefully, as we remove the skins from our skis and prepare to ride down to the car. “But of course, I don’t know how the temperatures will be this summer.”