Goodby alpine glaciers

The attractivity of the Swiss landscape is doubtless based on the mountains covered with snow and surrounded by glaciers (photo of Val Roseg, Engadine Valley, south-eastern Switzerland. Source: glacier monitoring program of VAW-ETH-Z)

The ongoing climate change risks to change this picture during the next decades. Last summer in a butcher store in the village of Turtmann in the Wallis/Valais they sold melons from the area and certainly without particular intension they placed them under the picture of the Rhone glacier at the beginning of the 19th century, which at that time had its end close to the still existing Hotel "Gletsch" in the Goms valley, situated along the road leading ot the Furka Pass.

This picture and a recent very nice book on the glaciers of the Wallis/Valais area, written by F.Funk-Salami and C.Wuilloud (a friend of mine) published in French and German last november is the motivation to write this article.

This very nicely written book is based on the personal experience of the two authors, as glaciologist (F.F.-S.) and forest engineer, mountain guide and head the division of natural dangers in the Valais-government (C.W.) respectively. It has been written (and the title translates this very well) to wake up the public and the politicians with the message: "Hey, do know that our very nice glaciers, which play an important role for our identity as mountainers, for the tourism and the energy production of our country, will most of them slowly disappear during the next 80 years ?"The following three graphs (source: VAW-ETH-Z cited above and the book) show the monitoring network of Swiss glaciers and the fact their length shortened between 10 and several hundred meters every year, especially during the last 20 years, in connection with the rising annual temperatures.

This book, in between the scientific informations indicated on the table of contents shown above, presents folk tales related to the glaciers, revealing e.g. that it was believed that the lost souls of ancestors would live in them and that between 1600 and 1850 the catholic priests in the concerned villages, tried with processions and exorcism acts to make the glaciers (which advanced a lot during this so called "little ice age") retreat and that way avoid that pastures and forests would be destroyed, but with mixed success. During this period already (as in recent years), glacier lakes, that regularly owerflew, threatened the local population (example below dating from 2001 in Täsch, Matter Valley near Zermatt).

This book reminded me of several important facts on glaciology and climate change predictions: (1) Whether a glacier grows in terms of length or volume (which is more important than the former) depends at what altitude the socalled equilibrium line lays, i.e. the limit between the ice/snow accumulation zone (all year below 0°C) and the ablation zone where the ice melts, which depends on the mean annual temperature of each year. But the annual position of this line not only depends on the temperature, but also the amount of precipitations plays an important role. The important retreat of the glaciers after their maximum around 1856 seems mainly be more due to decreasing winter precipitations than to increasing temperatures. However, for the years 1960 to 1980, when we had a lot of snow during winter time also below 700m in Switzerland, according to the temperature diagram above, the lower temperature could have been an important factor for the increase of glacier length during that period. The following two images of the Rhone glacier today and its evolution in length between 1900 and 2011 show: a) the limit between melting and accumulation in the back, where there is snow on the ice all year, whereas in the frontal part the grey ice melts during summer time and b) the length increase in the 1960ies (taken from the above mentionned VAW-ETH-Z-monitoring site).

(2) This book also mentions import findings of researchers of (Jöri et al. 2006) on several even warmer periods during the Holocene with glaciers more retreated than today (based on radiocarbon and dendrochronological dating of wood and peat liberated by many glaciers today, Nicolussi 2012). These findings do not at all disprove a human contribution to the actual global warming, as certain people interpret these results. As it has been shown by H.Wanner of University of Bern, these Holocene temperature fluctuations are due to very complex processes (among other the socalled Atlantic Oscillation). The following figure shows the findings of Jöri et al. (2006, source).

(3) Aside from the changing landscape and the related loss of esthetic mountain views, this book shows that the main impact are of economic and ecological nature: With decreasing glacial volume it will be more and more difficult to fill the hydroelectrical power lakes and the lowland rivers, once the the snow melt will be over in June, will have a very reduced flow regime, threatening also Swiss agriculture (Fuhrer et al. 2013). (4) This book also mentiones that the actual predictions for the climate of the Swiss Alps depend on the gulf stream which influences the Atlantic oscillation and brings warm air to Europe. Should it stop, e.g. because of a much lower ocean salinity due to all the melted ice in the Polar region, than the climate in the Alps might become colder again, independant of the unavoidable arrival of the next glacial period during the next 5000 to 10000 years.