21st June 2017
This piece follows on from a previous article I wrote in 2012 for Protect Our Winters (POW) (Bain 2012). It takes a quick look at what the observed trends have been in Australian snowfalls over the past few decades. Regardless of people’s stance on climate change, these observations are a hard look at the likely future of Australia’s alpine environment is and our winter enjoyment.
As we all know, snow cover is strongly driven by precipitation and temperature. Observed long term changes in these factors are leading to significant changes to the Australian snow pack. Snow accumulation in mainland Australia is known to show considerable inter-annual and decadal variability (Grose et al 2015) and this needs to be kept in mind. However, multiple studies have shown that snow depths at many sites have undergone long-term declines in recent decades (Davis 2013; Bhend et al 2012; Nicholls 2005; Hennessy et al 2003).
In the high Australian Alps from 1950 to 2007 there has been an increase in winter temperatures approaching 1C. From 1954 to 2013, Australia has seen an overall decrease in snow depth of about 10% (Pepler et al 2015). However, these decreases have not been consistent across the snow season. The mid-winter snow depths have only decreased a small amount, whereas spring snow depth has dropped by almost 40% (Nicholls 2005) due to late season warming. Pepler et al (2015) has reported this decline in spring snow depth as an 18% decline in late September and a 30% decline in early October. These declines have occurred despite no significant changes in the average precipitation (Davis 2013) or the frequency of extreme precipitation events (Fiddes et al 2014), with snow melt being the driving force rather than a lack of snowfall during this period.
Only three out of the last 15 years have had enough snow to reach the long term (1954 to present) average peak depth at Spencers Creek, and the lowest peak also occurred during this period (Domensino 2016). These figures show what many snow enthusiasts in Australia have suspected, that the snow seasons are changing.
In regards to the actual storms and snowfalls across the season, light snowfalls of up to 10cm have shown a decline in frequency of about 5 days per decade since 1988. However, thankfully, the rarer heavy snowfall events have shown no change in frequency (Fiddes et al 2014).
Temperatures in the Australian Alps are increasing at a greater rate in the higher altitudes than in the lower altitudes (Hennessy et al 2008). The result of these changes in snowfalls and temperatures is that the gradual build-up of snow will become less likely, making it harder to retain the snow already on the ground (Fiddes et al 2014). Some evidence of this is that there has been a 5% decline in the length of the snow season in the 2000-2013 period as compared to the 1954-1999 period (Pepler et al 2015).
The outcomes of these observations for the future have been examined under predicted climate scenarios (Hennessy et al 2008; Bhend et al 2012). Declines in snow depth, an earlier end to the snow season and deceased extent of snow covered areas are projected with high confidence for the future for mainland alpine areas. In addition, there seems as though there will be even more uncertainty in predictions and seasonal outlooks.
Changes in snow fall will have wide economic implications. Our snow industry is worth an estimated $1.8b employing approximately 18,000 people (Muller 2013), and is already based around a short and at times fickle snow season. In addition, the spring snow melt is very important for the hydro-electric and irrigation industries. In the very near future, if not already, snow making will have to become the dominant means of achieving an effective ski season (Hennessy et al 2008).
Our unique Snowy Mountains contain highly specialised, sensitive alpine environments. This is due in part to their old age; having only minor glacial activity; and being found as a series of small alpine ‘islands’ atop of mountains within a sub-alpine ‘sea’.
Our endemic alpine species have largely evolved in isolation from other continents and often on isolated mountain tops only tens of kilometres apart. Species such as the Mountain Pygmy-possum (Burramys parvus) and Broad-toothed Rat (Mastacomys fuscus) and vegetation communities such as the short alpine herbfields, alpine bogs and peatlands have very narrow environmental tolerances. These vegetation communities are reliant on long-lasting snow for a cool moist environment and are at risk from the observed changes in snowfall. Other changes may include introduced predators (foxes & cats) moving higher in the mountains because the thinner snow allows them to find alpine prey more easily (Green and Osborne 1981). One environmental change already observed is the earlier spring migration of birds to the Alps as a result of the reduction in snow (Green 2002).
All of these observations do not bode well for our alpine environment, our economic industries that rely on the snowfall or all of us who enjoy and appreciate the Australian snow season. One thing is for sure though, with a shorter season and thinner snow pack, we are all going to have to make the most of those storm events when they come, as thankfully, for now we are likely to continue to see the big events occur, at least very occasionally.
Bain, D (2012).
Bhend, J., Bathols, J., and Hennessy, K (2012). Climate change impacts on snow in Victoria. Aspendale, Australia: CSIRO report for the Victorian Department of Sustainability and Environment 42.
Davis, CJ (2013). Towards the development of long-term winter records for the Snowy Mountains. Australian Meteorological and Oceanographic Journal. 63: 303-313.
Domensino,B(2016) Snow season high becoming a low point. http://www.weatherzone.com.au/news/snow-season-high-becoming-a-low-point/524859
Fiddes, SL., Pezza, AB., and Barras, V (2015). A new perspective on Australian snow. Atmospheric Science Letters. 16: 246-252.
Green, K (2002). Impacts of global warming on the Snowy Mountains, in: Climate change impacts on biodiversity in Australia. CSIRO Sustainable Ecosystems, Canberra.
Green, K. and Osborne, WS (1981). The diet of foxes, Vulpes vulpes in relation to abundance of prey above the winter snowline in New South Wales. Australian Wildlife Research. 8: 349-360.
Grose, M. et al. (2015). Southern Slopes Cluster Report, Climate Change in Australia Projections for Australia’s Natural Resource Management Regions: Cluster Reports, eds. Ekström, M. et al., CSIRO and Bureau of Meteorology, Australia.
Hennessy, KJ., Whetton, PH., Smith. IN., Bathols, JM., Hutchinson, M., and Sharples, J (2003). The impact of climate change on snow conditions in mainland Australia. Report the Victorian Department of Sustainability and Environment, Victorian Greenhouse Office, Parks Victoria, New South Wales National Parks and Wildlife Service, New South Wales Department of Infrastructure, Planning and Natural Resources, Australian Greenhouse Office and Australian Ski Areas Association. CSIRO. https://www.researchgate.net/publication/228606768_The_Impact_of_Climate_Change_on_Snow_Conditions_in_Mainland_Australia
Hennessy, KJ., Whetton, PH., Walsh, K., Smith, IN., Bathols, JM., Hutchinson, M., Sharples, J (2008). Climate change effects on snow conditions in mainland Australia and adaptation at ski resorts through snowmaking. Climate Research 35: 255-270. https://www.researchgate.net/publication/51986536_Climate_change_effects_on_snow_conditions_in_mainland_Australia_and_adaptation_at_ski_resorts_through_snowmaking
Muller, G (2013). Climate change threat to $1.8b snow industry http://www.abc.net.au/radionational/programs/bushtelegraph/alpine-tourism/5023908
Nicholls, N (2005). Climate variability, climate change and the Australian snow season. Australian Meteorological Magazine, 54, 177-185.
Pepler, AS., Trewin, B., and Ganter, C (2015). The influences of climate drivers on the Australian snow season. Australian Meteorological and Oceanographic Journal. 65(2): 195-205.