Climate change and snow-cover duration in the Australian Alps

Abstract

This study uses a model of snow-cover duration, an observed climate data set for the Australian alpine area, and a set of regional climate-change scenarios to assess quantitatively how changes in climate may affect snow cover in the Australian Alps. To begin, a regional interannual climate data set of high spatial resolution is prepared for input to the snow model and the resulting simulated interannual and spatial variations in snow-cover duration are assessed and compared with observations. The model provides a reasonable simulation of the sensitivities of snow-cover duration to changes in temperature and precipitation in the Australian Alps, although its performance is poorer at sites highly marginal for snow cover. (In a separate comparison, the model also performs well for sites in the European Alps.) The input climate data are then modified in line with scenarios of regional climate change based on the results of five global climate models run in enhanced greenhouse experiments. The scenarios are for the years 2030 and 2070 and allow for uncertainty associated with projecting future emissions of greenhouse gases and with estimating the sensitivity of the global climate system to enhanced greenhouse forcing. Attention focuses on the climate changes most favourable ('best-case scenario') and least favourable ('worst-case scenario') for snow cover amongst the range of climate changes in the scenarios. Under the best case scenario for 2030, simulated average snow-cover duration and the frequency of years of more than 60 days cover decline at all sites considered. However, at the higher sites (e.g., more than 1700 m) the effect is not very marked. For the worst case scenario, a much more dramatic decline in snow conditions is simulated. At higher sites, simulated average snow cover duration roughly halves by 2030 and approaches zero by 2070. At lower sites (around 1400 m), near zero average values are simulated by 2030 (compared to durations of around 60 days for current climate).These simulated changes, ranging between the best and worst case, are likely to be indicative of how climate change will affect natural snow-cover duration in the Australian Alps. However, note that the model does not allow directly for changes in the frequency and intensity of snow-bearing circulation systems, nor do the climate-change scenarios allow possible changes in interannual variability (particularly that due to the E1Nifio-Southem Oscillation) and local topographical effects not resolved by global climate models. The simulated changes in snow cover are worthy of further consideration in terms of their implications for the ski industry and tourism, water resources and hydroelectric power, and land-use management and planning.

Sensitivity Analysis of Snow Cover to Climate Change Scenarios and Their Impact on Plant Habitats in Alpine Terrain

“…Studies of Martin et al (1994), Bultot et al (1994), Whetton et al (1996) and Beniston (1997) showed a marked sensitivity of simulated snow cover duration to increasing temperature, with the strongest sensitivity at low elevation sites. The study of Martin et al (1994) also examined the impact of variations in precipitation of 10% and, in agreement with the current study, found snow cover duration to be rather insensitive to such variations.…”

Snowmaking and Climate Change

“…In the study by Whetton (1998), the CSIRO snow model was driven with monthly temperature and precipitation data from 1966 to 1985 on a 1/40 th degree grid (about 2.5 km). To enhance performance of the model, the ANU Centre for Resource and Environmental Studies (ANU CRES) developed improved databases for elevation, temperature and precipitation on the same grid, and extended the monthly climate datasets from 1951 to 2000.…”

“…The most recent projections of natural snow cover taking into account greenhouse warming were published by Whetton (1998), based upon CSIRO's (1996) climate change scenarios and CSIRO's snow model (Whetton et al 1996). Since 1998, CSIRO has released new Australian climate change projections (May 2001) and the snow model has been modified to give a broader range of outputs and more reliable projections of natural snow (See Appendix 1).…”

“…A moderate decline in August and September snow depths is evident at three sites, possibly indicative of the tendency for mid to late season snow depth to be determined by temperature-dependent ablation (melt and evaporation), whereas the depth of early season snow is determined by precipitation. Projected changes in natural snow conditions Whetton (1998) Table 4. For snow, the low impact scenario is the combination of the lowest warming and the greatest precipitation increase, while the high impact scenario is the highest warming combined with the greatest precipitation decrease.…”

Habitat‐specific responses in the flowering phenology and seed set of alpine plants to climate variation: implications for global‐change impacts

“…CSIRO 1994;Whetton et al 1996;IPCC 2001). However, the average date of snowmelt in the Colorado Rocky Mountains has not Kudo & Hirao 13 changed during past 25 years despite a trend for warmer spring temperature, probably due to the increase in winter snowfall .…”