Evolution of two cirque glaciers in Lombardy and their relation to climatic factors (1962–2016)

ABSTRACT

In order to assess the climate–glacier relationship in the Southern European Alps, two small glaciers in Lombardy, Suretta Sud and Lupo, have been chosen for investigation. GPS profiling in 2016 allowed the determination of elevation changes since 2007 and thus the determination of the glacier mass balance using the geodetic method. Older maps have been digitized to reconstruct mass changes back to 1962. The two glaciers react synchronously and show overall mass losses, but the narrower observation pattern at Suretta Sud reveals positive mass changes from 1970 to 1982. Long-term meteorological series of precipitation and air temperature of representative stations have been analysed, they show highly significant warming trends of 0.32–0.40°C per decade during summer, but no significant trend in winter precipitation. Since 2009/2010, annual mass balance measurements applying the glaciological method were undertaken by the Servizio Glaciologico Lombardo. These annual observations reveal that, despite the decadal mass loss observed by geodetic observations, years with positive mass changes still occur. These years showed below average winter precipitation and below average summer temperatures, indicating that glacier behaviour is influenced by both parameters. Ice thicknesses observed by echo radio sounding allow to calculate glacier volume and the bedrock topography. Maximum ice thicknesses are around 40 m and the cirques are not overdeepened by glacial erosion. Using very simple extrapolations of observed rates of downwasting results in theoretical life expectancies of these glacierets of 50–70 yr.

KEYWORDS:

• Glacier mass balance
• GPS profiling: echo radiosounding

Acknowledgements

The work of many volunteers of the Servizio Glaciologico Lombardo is greatly acknowledged. Meteorological data from the Curò station were kindly provided by CML (Centro Meteo Lombardo), meteoswiss made the two long-term records of Sils Maria and San Bernardino available. Martin Rickenbacher from Swisstopo was extremely helpful with the provision and assessment of historic maps of the Montespluga region.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Wilfried Hagg is a Physical Geographer with a research focus on runoff modelling in glacierized catchments. His PhD thesis compared the hydrological response of glacier retreat between Central Asia and the European Alps. After a postdoc position on Bavarian glaciers, he lectured at the Geography Department of the Ludwig-Maximilians University in Munich. At the moment, he is a Heisenberg fellow and investigates glaciers in the Italian Alps and in Central Asia.

Riccardo Scotti is a Postdoctoral Fellow in Geomorphology, Glaciology and Quaternary Geology at Università di Bologna, Dept. of Biological, Geological and Environmental Sciences (BiGeA). His professional preparation is listed as follows: Università di Milano-Bicocca, Milano, Dept. of Earth and Environmental Sciences, Postdoctoral fellow- 2013–2015; Università di Milano-Bicocca, Milano, Dept. of Earth and Environmental Sciences, Ph.D., Feb. 2013; Università di Milano, Milano, Dept. of Earth Sciences, M.Sc., Feb. 2009; Università di Milano, Milano, Dept. of Earth Sciences, B.Sc, Oct. 2005.

Fabio Villa is a freelance consultant in geomatics from 2009. His professional preparation is listed as follows: Università di Milano-Bicocca, Milano, Dept. of Earth and Environmental Sciences, Postdoctoral fellow- 2008–2009; Università di Milano-Bicocca, Milano, Dept. of Geology, Ph.D., Feb. 2008; Università di Milano-Bicocca, Milano, Dept. of Environmental Sciences, M.Sc, Jul. 2003.

Elisabeth Mayer is a physical geographer who graduated from the Ludwig-Maximilians-University in Munich and specialized in hydrological modelling during her PhD. She developed a runoff model capable of simulating glacier melt below debris covers and worked in the Tian Shan as well as in the European Alps.

Achim Heilig received the Diploma degree in physical geography from the Ludwig Maximilian University of Munich, Germany, in 2005 and the Ph.D. degree in natural sciences from the University of Heidelberg, Germany, in 2009. Following his doctorate studies, he held several postdoctoral positions in Munich, Germany; Heidelberg, Germany; Boise, USA; and Davos, Switzerland. He is currently a Postdoctoral Researcher with the Department of Earth and Environmental Sciences, Ludwig Maximilian University of Munich. His main research interests are in the field of geophysical instrumentation to monitor changes in seasonal snow, perennial firn and ice. Those changes involve seasonal variations in accumulation, liquid water percolation, and densification of snow and firn, as well as long-term changes in ice and firn. Dr. Heilig was a recipient of German Research Foundation (DFG) Grant HE 7501/1-1 through project URSAM in 2015.

Christoph Mayer is a geophysicist who entered into glaciology during his PhD on numerical modelling of ice sheet/ice shelf coupling at the Alfred Wegener Institute, Helmholtz Zentrum für Polar- und Meeresforschung. After several postdoc contracts in Bremerhaven, Innsbruck, and Copenhagen, where he dealt with field investigations of the Greenland Ice Sheet and refining remote-sensing techniques, he started his work at the Bavarian Academy of Sciences and Humanities, working on glacier reactions in high mountain ranges.

Wennemar Tamm contributed in the frame of his final thesis at the Department of Geography of the Ludwig-Maximilians-University in Munich.

Tassilo Hock contributed in the frame of his final thesis at the Department of Geography of the Ludwig-Maximilians-University in Munich.

Additional information

Funding

Wilfried Hagg is supported by the DFG Heisenberg programme (project HA 5061/3-1).