Australia's ski resorts face the prospect of a long downhill run as a warming climate reduces snow depth, cover and duration. The industry's ability to create artificial snow will also be challenged, scientists say.
Resorts are also going to become more reliant on big snow dumps such as this weekend's blizzard – after a poor start to the season – as the frequency of smaller, top-up snowfalls diminish.
A snow retreat has been observed for half a century, with rising temperatures rather than reduced precipitation to blame, according to a major CSIRO-Bureau of Meteorology report. Under high greenhouse gas emissions pathway, snow at lower-elevation sites such as Mt Buffalo could all but disappear by 2050.
Warming springs have led to stark impacts at the end of the ski season. Early October snow depths fell 30 per cent during the 2000-13 period compared with 1954-99, a separate study in 2015 found.
Snow is a "threshold variable". A slight temperature rise can turn snowflakes into rain that washes away, rather than adds to, snow cover.
That's why all climate projections point in one direction, says Tom Remenyi, a researcher at the Antarctic Climate & Ecosystems Cooperative Research Centre. It's both "encouraging and terrifying" that observations have matched models, giving researchers confidence about their bleak predictions, he said.
"What we're fearing is that at some point, it's not going to really snow that much any more. There's going to be a step change," Dr Remenyi said.
"The models say the paradigm shift will happen in the next 10-20 years."
Those blasted in this weekend's snow storms might wonder if snow will be in short supply, with as much as a metre expected for some resorts.
Sonya Fiddes, a researcher at Melbourne University's Australian-German Climate and Energy College who led a study on Australian snow trends, says that big dumps will still happen but warmer air and follow-up rains means the snow "probably won't stick around".
"The projected trends are for declining rainfall for south-eastern Australia, and an increase in extreme events," Ms Fiddes said.
Dr Remenyi concurs, noting models point to a 20 per cent drop in precipitation by the end of the century. Alpine summers may collect more rainfall – in fewer, larger events – but other seasons will see a decline.
The Victorian government is preparing a report in the future of alpine communities and the ski industry later this year.
NSW is working with the University of NSW to assess changing climate and snowmaking conditions, with research due out late this year or early 2018.
Colin Hackworth, chief executive of the Australian Ski Areas Association, said the $1.5 billion industry has long recognised "if you have no snow, you have no business". Investments in snowmaking dates from the 1980s.
Popular resorts such as Mt Buller in Victoria have managed to extend operational days from about 100 in the 1970s to 106 in a typical year now, even with less natural snow. Diversification has also brought in "snow tourists", with many visitors just heading to the mountains to seek the white stuff rather than to ski or snowboard, he says.
"The industry is remarkably resilient," Mr Hackworth said. "It's a mature industry but it's growing every year."
Nor are resorts denying global warming is serious. Thredbo in NSW recently hosted a Protect Our Winters event "to raise awareness of the impact of climate change on our mountain environment".
And Vail Resorts, which operates Perisher, calls climate change "one of the most significant challenges facing every country, every business and every person on our planet". It aims for a zero environmental footprint by 2030.
Challenges, though, are only likely to intensify. Snow guns are becoming less efficient as humidity rises, reduce output of artificial snow by as much as 70 per cent as they ice up, Dr Remenyi said.
New "snow factories" have been introduced to Mt Buller and Mt Selwyn in Victoria, and more are likely. They create ice shavings with longer durability than gun-fired snow.
But warming temperatures will raise costs to maintain artificial snow cover, Dr Remenyi said. A study he helped write on the potential impact of climate change on Victoria's resorts found that "by 2020- 2030 conditions suitable for snowmaking are projected to decline substantially".
And as the NSW Nature Conservation Council notes in a new study on the effects of a warming planet, impacts in alpine regions aren't restricted to humans' winter pastimes.
The endangered pygmy possum, for instance, has had its range shrunk to a little as 10 square kilometres.
"The wildlife that lives in the Australia snowfields are at the front line of global warming because they are so sensitive to rising temperatures and changed snowfall patterns," Kate Smolski, council chief executive, said.
"If deep, long-lasting snow cover disappears, the fragile ecology of snowfields will unravel because the plants and animals that live there have nowhere else to go."