Marty, C. and Blanchet, J. 2012. Long-term changes in annual maximum snow depth and snowfall in Switzerland based on extreme value statistics. Climatic Change 111: 705-721.
The authors write that "heavy snowfall and extreme snow depth cause serious loss of human life and property in many middle and high latitude countries almost every winter," and they say that "it can be argued that the most damaging and memorable winters are those with extremely large amounts of snow," since "heavy snowfalls are often accompanied by extreme snow storms and avalanches which cause hazardous conditions on roads, railways and airports - sometimes even leading to the interruption of major transport routes." And with these facts in mind, they note that "climate models predict a likely increase in the frequency of extreme precipitation events in a future warmer world," citing the IPCC (2007), while adding that such is also predicted by regional climate models, citing Frei et al. (2006) and Beniston et al. (2007).
What was done
To see to what extent these predictions may or may not have been in process of fulfillment in Switzerland over the past eight decades, Marty and Blanchet computed annual maximum snow depth (HSmax) and annual maximum new snow amount over three successive days (HN3max) for each of 25 measurement stations located at altitudes ranging from 200 to 2500 meters asl, based on data collected during the last 80 winters (1930/1931 to 2009/2010), after which, as they describe it, "the generalized extreme value (GEV) distribution with time as a covariate [was] used to asses such trends."
What was learned
The two Swiss researchers from the Institute for Snow and Avalanche Research at Davos say their "analysis of extreme snow depth and extreme snowfall" revealed that "none of the stations, not even the highest one at 2,500 m asl, has experienced significant (p<0.05) increasing extreme amounts during the last 80 years." Quite to the contrary, in fact, they report that "almost half (44%) of the stations reveal a significantly decreasing trend of extreme snow depth," while "the other half showed no significant trends." In addition, their GEV analysis indicated that "all stations show decreasing tendencies for HSmax." And last of all, in harmony with these findings, they indicate that several other studies have shown that "mean snow depth and snow days have been decreasing in the Alps in the last 20 years (Marty, 2008; Durand et al., 2009; Valt and Cianfarra, 2010), especially at altitudes below 1,300 m (Laternser and Schneebeli, 2003; Scherrer et al., 2004)."
What it means
Clearly, the predictions of the IPCC regarding a propensity for more extreme precipitation events to occur in a warming world has not been seen in Switzerland. In fact, just the opposite appears to be the case there.
Beniston, M., Stephenson, D., Christensen, O., Ferro, C., Frei, C., Goyette, S., Halsnaes, K., Holt, T., Jylha, K., Koffi, B., Palutikof, J., Scholl, R., Semmler, T. and Woth, K. 2007. Future extreme events in European climate: an exploration of regional climate model projections. Climatic Change 81: 71-95.
Durand, Y., Giraud, G., Laternser, M., Etchevers, P., Merindol, L. and Lesaffre, B. 2009. Reanalysis of 47 years of climate in the French Alps (1958-2005): climatology and trends for snow cover. Journal of Applied Meteorology and Climatology 48: 2487-2512.
Frei, C., Scholl, R., Fukutome, S., Schmidli, J. and Vidale, P.L. 2006. Future changes of precipitation extremes in Europe. Journal of Geophysical Research 111: 10.1029/2005JD005965.
IPCC. 2007. Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland.
Laternser, M. and Schneebeli, M. 2003. Long-term snow climate trends of the Swiss Alps (1931-99). International Journal of Climatology 23: 733-750.
Marty, C. 2008. Regime shift of snow days in Switzerland. Geophysical Research Letters 35: 10.1029/2008GL033998.
Scherrer, S.C., Appenzeller, C. and Laternser, M. 2004. Trends in Swiss Alpine snow days: the role of local- and large-scale climate variability. Geophysical Research Letters 31: 10.1029/2004GL020255.
Valt, M. and Cianfarra, P. 2010. Recent snow cover variability in the Italian Alps. Cold Regions Science and Technology 64: 146-157.Reviewed 25 July 2012