The Sulden/Solda Glacier (Eastern Italian Alps): fluctuations, dynamics, and topographic control over the last 200 years

Abstract

The Sulden/Solda glacier, located in the Ortler/Ortles massif (South Tyrol, Eastern Italian Alps), currently (2017 data) covers an area of ca. 5.2 km². The glacier ranges in elevation from about 3500 m to 2440 m a.s.l., and it is largely debris-covered below 2900 m. By combining bibliographic resources, topographic maps and aerial images, we reconstructed the evolution of the Sulden Glacier since the beginning of the 19^th century. The result is a detailed history of the glacier variations over the last 200 years, which reveals the complex interactions existing between glacier dynamics and valley morphology. The Sulden Glacier is formed by three ice bodies originating in the uppermost part of the Sulden catchment. In the past, the three glaciers merged to a single valley glacier that flowed northward down to the village of Sulden/Solda, at an elevation of ca. 1900 m a.s.l.. The evolution of these three ice bodies has not been uniform through time, and this heterogeneity drove some of the most impressive dynamics which have characterized the glacier history. In particular, the most prominent advances of the 19th century, including the 1818 surge, were driven by the lateral ice bodies of the Sulden Glacier that advanced and pushed the glacier tongue forward. When retreating, the morphology of the valley floor – characterized by several valley steps, played an important role in fragmenting the glacier, creating very large bodies of dead ice. The last prominent advance of the Sulden Glacier occurred in the 1920s (and lasted until 1927) and, excluding the small advance in the 1980s, the glacier has been retreating since the 1930s. From topographic reconstructions we can estimate the volume of ice lost from 1936 to 2019 in ca. 169 million m3 (18.7 m w.e.). Out of these, ca. 144 million m³ (the 85%) have been lost after 1985, highlighting the inexorable impact of recent global warming.