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Snowpack and Streamflow Trends in the Central Andes
Reference
Masiokas, M.H., Villalba, R., Luckman, B.H., Le Quesne, C. and Aravena, J.C. 2006. Snowpack variations in the central Andes of Argentina and Chile, 1951-2005: Large-scale atmospheric influences and implications for water resources in the region. Journal of Climate 19: 6334-6352.

Background
The authors write that "either directly or indirectly, over 10 million people in central Chile and central-western Argentina depend on the freshwater originating from the winter snowpack in the central Andes to meet water demands for drinking, domestic consumption, irrigation, industry and hydroelectric generation." In addition, they note that "coupled atmosphere-ocean general circulation models especially targeted to investigate high-elevation sites [have shown] that for the next 80 years the central Andes will probably experience significant temperature increases," citing Bradley et al. (2004); and they report that "independent general circulation model simulations also predict a significant decrease in precipitation over the region for the next five decades (Cubasch et al., 2001), with likely impacts on the hydrological cycle and long-term water resource availability." Hence, we assume they decided it was about time to see what has been happening in this regard in response to what climate alarmists describe as the "unprecedented" CO2-induced global warming of the past few decades.

What was done
Masiokas et al. developed, in their words, "the first regional snowpack series" - expressed as annual maximum snow-water equivalent (MSWE) - "using snow course data from both sides of the central Andes in Chile and Argentina," which series "covers the 1951-2005 period and is derived from the six longest and most complete snow course records in the region," which stretches from 30 to 37S latitude. And to enable them to examine the influence of the regional MSWE records on runoff, they compared them against mean monthly streamflow data for the main rivers in central-western Argentina and central Chile.

What was learned
The Canadian and Chilean researchers report that "the regional MSWE record is approximately normally distributed and shows a non-significant positive linear trend (+3.95% per decade) over the 1951-2005 interval." In addition, they found that "river discharges on both sides of the central Andes are strongly correlated with the snowpack record and show remarkably similar interannual variability and trends, highlighting the existence of a marked regional hydrologic signal between 31 and 37S." In fact, they found that "over the past 55 years >85% of the streamflow variance could be explained by the snowpack record alone."

What it means
In spite of climate-model-based warnings of reduced precipitation, decreased river discharge and restricted water availability in the central Andes of Argentina and Chile in response to supposedly unprecedented CO2-induced global warming over the past several decades, snow-water equivalents and river discharges there have not exhibited any evidence whatsoever of these worrisome negative consequences.

References
Bradley, R.S., Keimig, F.T. and Diaz, H.F. 2004. Projected temperature changes along the American cordillera and the planned GCOS network. Geophysical Research Letters 31: 10.1029/2004GL020229.

Cubasch, U. et al. 2001. Projections of future climate change. In: Houghton, J.T. et al., Eds. Climate Change 2001: The Scientific Basis, Cambridge University Press, Cambridge, pp. 525-582.

Reviewed 18 April 2007