Weather

Australian snow in a changing climate

Ben Domensino, 31 July 2019

 

The Australian alps rise to just under 2,300 metres above sea level at the top of Mt Kosciuszko. Most of our ski resorts lie between 1,400 and 2,000 metres in the NSW and Victorian alps. By comparison, some resorts in Switzerland, the United States and France reach above 3,800 metres.

As a general rule, the atmosphere gets colder with height and the higher you go, the better the snow. The elevation of our ski resorts make them vulnerable to even small changes in temperature, and just a couple of degrees can be the difference between rain and snow.

How much snow do the Australian alps see each season and has this changed in recent decades?

Snowy Hydro has been measuring the natural snow depth at Spencers Creek in NSW since the 1950s. This site is located near Charlotte Pass at an elevation of 1,830 metres, and is considered the best available historical record of natural snow depth in the Australian alps.

Snow depths at Spencers Creek vary a lot from year to year, which comes down to two things: temperature and the availability of moisture. These fluctuate each season with individual weather events and under the influence of broad-scale climate drivers, including El Nino, La Nina, the Indian Ocean Dipole and the Southern Annular Mode.

But beneath this clear year-to-year variability, the average peak snow depth at Spencers Creek has also decreased by nearly 40cm during the last 60 years.

This trend is in line with an increase in temperatures and reduction in rainfall that have been observed in southeastern Australia during winter, over the last century.

In addition to the declining natural snow depth, recent studies have also found that Australia's snow season is now shorter than it was several decades ago. 

What's likely to happen to Australia's snow in the future?

Australia's alpine snow cover is expected to continue to change in the future in line with our climate.

The mean temperature in southeastern Australia has warmed by just under 1°C during the last century and further warming is expected this century.

According to the CSIRO, there is very high confidence that future warming would likely cause a further reduction in natural snow cover in the Australian alps. However, the amount of this future change is uncertain.

There is also likely to be a reduction in the total area of snow cover, and the length of the snow season, if the atmosphere continues to warm in the coming decades.

In reality, the future decline of Australia's snow should continue to be a gradual process and one that is masked by individual snow events. However, what we see as a normal snow season today could become less frequent later this century if the atmosphere keeps getting warmer.

Thankfully, Australian ski resorts are already developing ways to cope with the changing climate. 

Artificial snowmaking and grooming are used extensively throughout the Australian alps to help keep snow on the slopes during the cooler months of the year.

Snow guns are able to create snow on clear nights and sunny days, and can even produce snow when the temperature is above zero degrees, under the right conditions.

Perisher alone has more than 230 snow-guns and has spent more than $22 million on its snowmaking system since 2007, with plans to extend this operation in the future.

Fortunately, there is still plenty of snow on the slopes today and it's not going to disappear any time soon. However, it's important to be aware of how vulnerable this unique part of our country is to climate change and how it could be affected in the future.