Climate variability, climate change and the Australian snow season

‘Alpine systems are generally considered to be among the most vulnerable to future climate change’ (Hughes 2003), and changes in snow depth and cover in the Australian mountains would likely affect many animals. For instance, the Pygmy Possum depends on snow cover for stable, low temperatures during hibernation (Walter and Broome 1998). In years of shallow snow cover populations of Dusky Antechinus and Broad-toothed Rats decline, presumably because of increased predation by foxes when snow is reduced (Green and Osborne 1981). Hughes (2003) and Green (2002) summarise evidence of shifts in vertebrate ranges to higher elevations and toward earlier arrival of migratory bird species in the Australian alpine zone in the last few decades. As well, the Australian ski industry could be affected by changes in snow cover, and changes in snow cover may also affect the seasonality of runoff (Beniston 2003). It seems important, therefore, to determine whether the snow cover has been changing and, if so, to determine the causes of this change. Diaz et al. (2003) reported a decline in snow cover in many areas where temperature has been increasing over the past 50 years, but did not examine the relatively small alpine areas of Australia. Many researchers have investigated snow cover records in the Australian Snowy Mountains. Budin (1985) examined snow-depth data at several locations in southeast Australia, and demonstrated that high snow depth occurred in years with stronger than normal westerly winds over the southeast. Slatyer et al. (1985) developed an empirical model of the length of the snow season incorporating Aust. Met. Mag. 54 (2005) 177-185