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Eight and a Half Centuries of Snowpack Variations in the Andes of Chile and Argentina
Masiokas, M.H., Villalba, R., Christie, D.A., Betman, E., Luckman, B.H., Le Quesne, C., Prieto, M.R. and Mauget, S. 2012. Snowpack variations since AD 1150 in the Andes of Chile and Argentina (30°-37°S) inferred from rainfall, tree-ring and documentary records. Journal of Geophysical Research 117: 10.1029/2011JD016748.

The authors write that "the Andean snowpack is the main source of freshwater and arguably the single most important natural resource for the populated, semi-arid regions of central Chile and central-western Argentina," as it "provides most of the water needed for human consumption, agriculture, industries, hydroelectric generation and aquifer recharge." And, hence, the world's climate alarmists are wont to agonize over what global warming might do to this precious natural resource.

What was done
Masiokas et al. developed the first reconstruction and quantitative analysis of variations in snow accumulation of the past eight-and-a-half centuries in the Andes between 30° and 37°S, based on "instrumental rainfall and streamflow data from adjacent lowlands, a variety of documentary records, and century-long tree-ring series of precipitation-sensitive species from the western side of the Andes," a process they describe as "the first attempt to reconstruct annually-resolved, serially complete snowpack variations spanning most of the past millennium in the Southern Hemisphere," which record "allows testing the relative severity of recent 'extreme' conditions in a substantially longer context."

What was learned
The eight researchers thankfully report that "variations observed in the last 60 years are not particularly anomalous when assessed in a multi-century context," noting that both extreme high and low snowpack values "have not been unusual when assessed in the context of the past eight centuries." Indeed, they say that "the most extreme dry decades are concentrated between the late 16th century and the mid-18th century," and that there were "decade-long periods of high snowpack levels that equaled or probably surpassed those recorded during the past six decades."

What it means
Contrary to the worries of climate alarmists, it would appear that there is nothing unusual, unnatural or unprecedented about the highs and lows of the Andean snowpack over the last six decades of global warming.

Reviewed 18 July 2012