Guest post by Mike Jonas
Snow levels are important to the people of Australia’s Snowy Mountains because the ski industry provides a large proportion of the region’s income. There has been a series of scare stories from the Sydney Morning Herald (SMH) newspaper, and Australia’s National broadcaster, the ABC, about disappearing snow. For example, SMH reported back in 2011 that “AUSTRALIA’S ski slopes could be completely bare of natural winter snow by 2050 unless concerted action is taken against global warming“, and the ABC and SMH have wasted no opportunity over the years to reinforce that message.
There are, unsurprisingly, many people in the Snowies who think their snow will disappear within about 30 years. After all, if prospects were that bad in 2011, and with the gloom and doom messages getting more strident every year, prospects must be truly dismal by now. Mustn’t they?
Snowy Hydro, the Snowy Mountains hydropower company that supplies about a third of Australia’s renewable electricity, measures snow depths because it needs to know how much water it is going to get from the snow melt each year.
They provide a chart of the snow depth here. The data is collated from seven stations at Spencers Creek, between Perisher and Charlotte Pass.
I put the annual max depth into a spreadsheet and plotted it.
The linear trend was a loss of less than half a cm (0.2 in) per annum. Not exactly scary. And the data isn’t that accurate anyway – in recent years, they have only reported the depth to the nearest cm.
To my eye, the level has been picking up since about 2006.
I added in a 3rd-order polynomial fit (the curved line), which shouldn’t be taken too seriously because the data is only over a short period and the early data is highly variable. It’s an interesting way of looking at the data, nothing more. And it should be noted that the peak and trough in the curve are close enough to the end points to possibly be end-effects.
I looked for other historical records of snow depth that went up to 2018, and found only one – for the ski resort of South Perisher. South Perisher is very close to Spencer’s Creek, and its data is very similar to Snowy Hydro’s, but the data starts in 1954 so I did the same graph for South Perisher :
The peak on the curved line has moved to the left, and both peak and trough could still just be end-effects. But – and I think this matters – the linear trend for the 1954-2018 series was stronger at -0.76cm p.a. than the 1978-2018 series at -0.48cm p.a. This is just the sort of effect that could be expected from data with a multi-decadal cycle in it. [NB. That doesn’t prove there’s a cycle – the time period of the data is too short.]. There was some South Perisher data for 2019, but it had not reached maximum in the given data so I left it out of the graphs.
One last point to note: the last two years’ (2017, 2018) snow levels have been above-average on both time-scales.
Even the 2019 depth for South Perisher, which had not yet reached maximum in the given data, is higher at 203cm.
The data shows that the rate of snow loss is slowing, not accelerating, and that snow levels might even be increasing again. And that’s good news for Australia’s ski industry.
I hesitate to make any kind of forecast or prediction, but it does look very likely that all messages of impending doom are badly wide of the mark.