Vanishing southern ice signals end to easy alpine access

2026-03-29 - 16:04

The snowy tops of the Southern Alps are a scenic backdrop southerners have had the luxury of taking for granted for generations. Those who know this alpine landscape best, however, describe what is happening up here now as confronting and dangerous. Until recent times, the alp’s snowcap has receded and advanced a little each season in fairly predictable patterns, albeit with an overall gradual decline in permanent ice. Today, tourists still view the scene in awe as they fly past every day but on the ground there is a changed landscape. Foot access to valley floors and alpine huts is a whole lot trickier and the thump of helicopter blades more frequent. University of Canterbury glaciologist Dr Heather Purdie says retreating glaciers are more fissured making them convoluted to traverse and many are coated in dust and rocks. In their wake, newly exposed moraine forms great mounds of jumbled rocks – a landscape so eroded in some places it is preventing the Department of Conservation from keeping public tracks open. Dr Heather Purdie and a colleague carry monitoring equipment up Rolleston Glacier in Aoraki Mt Cook National Park. Photo: Heather Purdie Freezing levels and snow lines have now crept so high up the mountainsides that large chunks of many glaciers, and even entire ancient bodies of ice, will soon sit permanently below them, no longer sustained by accumulating snow. As a result, the sport of alpine mountaineering – part of New Zealand’s culture and identity – is becoming more dangerous, and accessible to fewer people. Lower down too, the days of tourists or the average New Zealander being able to get up-close and personal with a glacier and experience its dramatic icy-blue beauty and chill, are gone. In Aoraki/Mt Cook National Park, traditional foot access to lower and medium-level locations along all glaciers has become more difficult with ice recession, says DoC’s Aoraki principal ranger, Dave Dittmer. The resulting “rough landscape” makes for slower going on foot, as hikers try to pick their own way through. “It is so changeable and large, it is not possible to maintain any trail or route along moraines on the glaciers.” He says DoC’s own alpine huts are not currently impacted with glacial recession in the park but in some valleys, the lower foot-access terrain leading to them is “significantly more difficult and challenging”. “Access along both the lower Hooker and Tasman Glaciers is difficult, for example access to the Copland Pass up the Hooker Valley and access past Ball Hut towards Beetham Hut via the Reay Stream on the Malte Brun Range.” Ball Hut, back in the day, could be reached in the comfort of an old landrover with tramper’s packs bouncing in the back, then it became foot-access only and now, with further erosion, even that is a challenge. Higher up, snowy-white glaciers traditionally provided a safe and magnificent pathway to peaks, huts and bivvies, as well as stabilising steep valley sides. Dr Heather Purdie at work on Tasman Glacier in Aoraki Mt Cook National Park. Photo: Heather Purdie “Last week the NZ Alpine Club removed Murchison Hut in the upper Murchison Valley.” Dittmer says, “This hut was located on a rock ridge that was slowly sliding downwards due to the Murchison Glacier recession.” The hut, owned by the club, had been officially deemed unfit to stay in since 2017. Dittmer says hikers need to do their research before visiting the area and even contact the rangers for the latest advice. True story For scientists, glaciers are the canary in a coal mine for climate change. They react quickly to any fluctuations and as glaciologists the world over say ... they don’t tell lies. Purdie, who has been monitoring New Zealand’s glaciers for the past two decades, has just returned from yet another end-of-summer data-collection trip to measure ice at Rolleston Glacier. This is the 17th year this glacier, regarded as a benchmark for the World Glacier Monitoring Service, has been measured. It sits high in a cirque – a bowl-shaped valley – and has lost around 11m in height since the study began. For many years, Purdie and her colleagues would step straight onto the glacier from its rocky margin; now they scramble down the rocks to reach the ice surface. The temperature can be as much as 1degC warmer per 200m drop in altitude. As the tops of glaciers like Rolleston melt lower, they sit in a warmer place and the newly exposed rock around them crumbles. The resulting dust coats their tops leading to more heat absorption, and at the same time crevasses form and are exposed, creating internal pouches of warmer air. “Some of the most dramatic change I have observed is at the Fox Glacier. Fox Glacier has undergone very rapid thinning and shortening. It is becoming increasingly debris (rock) covered and broken on its lower tongue.” For Purdie, who has had a life-long connection with these beautiful, brutal places, seeing the melt accelerate so quickly is unsettling. “Even as a scientist who has been monitoring glaciers in New Zealand for over 20 years, the rate of change is still really confronting. It’s sad these changes mean less people are going to be able to experience the glaciers. I used to work as a glacier guide at Fox Glacier; we could still take walking trips up the valley, so trips that families could go on, now all the glacier-hiking trips require helicopter access, which means that many people will not get the opportunity to walk on the ice.” She would like to see solutions that enabled foot access to continue. Rolleston Glacier is lowering as the snowline creeps up in the Southern Alps. Photo: Heather Purdie “One thing that concerns me from a recreational perspective is the loss of walking access as agencies tasked with managing backcountry infrastructure are tending to see helicopters as the answer to deteriorating access – this is a real shame. Last year I was in Nepal and despite their glaciers looking much like ours – they still support ground trails, bridges, tracks in the mountains – people still walk everywhere. It would be nice if we were to focus on supporting low-carbon access into the New Zealand mountains instead of removing or not maintaining tracks, bridges, huts.” Rob Brown manages the Back Country Trust, working with DoC, the Federated Mountain Clubs, NZ Deer Stalkers Association and Trail Fund NZ to coordinate volunteer hut and track maintenance across the country. He’s observed the physical changes, and worries that planning for how the altering landscape is managed has fallen off the radar. “Planning is not keeping pace with the changes. Things like access issues and different opportunities at Aoraki Mt Cook – it’s all becoming very limited there now, that’s why you’re ending up with this cul-de-sac at either Mueller Hut or the Hooker Valley.” He says the same situation existed on the Westland side where park plans compiled long ago for experiencing features like large glaciers were no longer relevant due to dramatic change. “Back then there was a bit of talk about the glaciers moving forward and back, a bit of thought that they might go backwards but nothing like what has happened.” He says four huts in the Aoraki area have been either moved or removed due to damage in the past five years or so, mainly from rock falls and subsidence caused by glacial recession in the valleys below them. “The changes have been significant. When I first went to Aoraki Mt Cook in 1988 the lake at the end of the Tasman Glacier was small. A puddle compared to what is there now. The same was the case with the Hooker Valley. Access to places like the Malte Brun Range from the Tasman Glacier was reasonably straightforward for both trampers and climbers. Hardly anyone goes there now, it’s out of the reach of a lot of people. The climbing season was much longer. Guides operated all summer long whereas these days as soon as things stop freezing higher up it is usually judged to be too dangerous for the higher peaks.” Mountaineering as a sport was adapting, however, with higher, more difficult rock climbs in Fiordland more popular and people taking advantage of warmer, longer hiking seasons. All that remains of Bryant Glacier high above the Dart Valley near Glenorchy. The glacier now has a permanent lake following ongoing melt. Photo: Jill Herron Meanwhile over in Mt Aspiring National Park, Brewster Glacier appears to have lost another 6-7m in volume this summer, Victoria University glaciologist Dr Brian Anderson says. He was part of a group who camped there this week to gather the latest depressing data, which will be collated with snowfall measurements taken each spring by the University of Otago. “We seem to have moved into this high-melt regime where we get six or seven metres of melt each year.” It’s been 30 years since Anderson began observing glaciers and over that period Franz Joesph’s once-magnificent great ice mass had advanced about 500m but retreated by 2.5km. At Brewster, landscape changes had also been dramatic with the solid head of the glacier now broken up into four or five pieces that no longer directly fed the main ice mass. “I remember years ago trying to balance on a ledge between the glacier and the lake to get samples. Now the glacier is nowhere near that lake, it’s hundreds of metres back.” He says people had a general awareness of what was happening but perhaps did not fully comprehend what was being lost. “Until you visit them and see what an incredibly dramatic and dynamic part of the landscape they are, it’s hard to fully grasp the enormity of what changes are happening, how fast they’re happening and ultimately what we’re losing. It’s easy to take the measurements ... but the mathematics doesn’t tell of all the impacts like valley walls collapsing and difficulties of access. It all just becomes more real.” Meanwhile Purdie predicts a grey view out the plane window for future tourists, unless humanity collectively pulls its socks up on emission reductions, and fast. “If global warning trends continue as they are then there will be very little ice left in the mountains. If people can actually reduce carbon emissions and slow warming then the models indicate that we could still keep glaciers high in the mountains; they will be smaller than they are today, but they could survive. But, given the very poor track record of society it seems we are destined to exceed 2-3 degrees warming. Models estimate that if we exceed 3 degrees not much ice will be left in New Zealand.”