Holocene glacial history of southern Spitsbergen

Climate change affects the extent of glaciers in Svalbard, and warmer periods of the Holocene may serve as analogues for predicting their future decay. While the Holocene glacial history of central, western and northern Svalbard is relatively well-studied, knowledge of glacier fluctuations in southern Spitsbergen remains limited. We reconstruct the Holocene glacier dynamics in Hornsund and adjacent areas, using geomorphological, geochronological, and historical data. New and published radiocarbon (¹⁴C) and cosmogenic nuclide (¹⁰Be) dates were combined with historical maps dating back to the 1600s and photographs from 1872 to 1936. The ages of mollusc shells from till deposits and Little Ice Age (LIA) moraines suggest glacier retreat in the Early Holocene, enabling colonisation of glacier-free branches of Hornsund. During the first half of the Late Holocene, the extent of tidewater glaciers remained reduced compared to their LIA maxima. Their limited advance was likely constrained by increasing sea-surface temperatures and atmospheric warming between c. 2.2–1.8 and 1.5–0.7 cal ka BP. The maximum Late Holocene glacier extents were associated with surges, probably preceded by ice mass accumulation due to climatic cooling and increased precipitation. However, many surges may also have occurred under warmer conditions. Most glaciers in southern Spitsbergen are highly sensitive to climatic changes, both through mass balance and surging, due to their specific topographic settings (low-elevation, gently sloping, long, multi-branched glaciers with overdeepenings in the bedrock). The interaction between climate variability and glacier surging played a crucial role in glacier evolution throughout the Holocene.