Advances in understanding subglacial meltwater drainage from past ice sheets

Meltwater drainage beneath ice sheets is a fundamental consideration for understanding ice–bed conditions and bed-modulated ice flow, with potential impacts on terminus behavior and ice-shelf mass balance. While contemporary observations reveal the presence of basal water movement in the subglacial environment and inferred styles of drainage, the geological record of former ice sheets, including sediments and landforms on land and the seafloor, aids in understanding the spatiotemporal evolution of efficient and inefficient drainage systems and their impact on ice-sheet behavior. We highlight the past decade of advances in geological studies that focus on providing process-based information on subglacial hydrology of ice sheets, how these studies inform theory, numerical models and contemporary observations, and address the needs for future research

Deglaciation of the central Barents Sea

The marine-based Barents Sea Ice Sheet covered the polar continental shelf north of Norway and western Russia during the Last Glacial Maximum. Initial ice sheet retreat along the western margin is well established, while the retreat pattern in the interior parts of the ice sheet remains poorly known. Here we present new geological data from the central Barents Sea. The results are based on analysis of several marine geophysical datasets, including geomorphological mapping of multibeam swath bathymetry data and analysis of seismic and acoustic stratigraphy. The new results provide insights into the configuration and dynamics of the ice sheet during its retreat across the central Barents Sea. In particular they show clear changes in the location of the main ice divides and domes, with ice flow becoming gradually more topographically controlled as deglaciation progressed. Major troughs were characterised by episodic retreat and reoccurring cycles of fast and slow ice flow, sometimes leading to stagnation and ice shelf formation. Meanwhile, adjacent bank areas were covered by comparatively slowly retreating ice, although evidence of streaming ice is also seen locally

The First International Conference on ‘Processes and Palaeo-Environmental Changes in the Arctic:From Past to Present’ (PalaeoArc)

The new international network PalaeoArc (Processes and Palaeo Environmental Changes in the Arctic: From Past to Present) held its first meeting in Poznan, 20-24 May 2019. The meeting was hosted by the Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, Poznan, and organized by a local committee chaired by Witold Szczuciński

Geophysical constraints on the dynamics and retreat of the Barents Sea ice sheet as a paleobenchmark for models of marine ice sheet deglaciation

Our understanding of processes relating to the retreat of marine-based ice sheets, such as the West Antarctic Ice Sheet and tidewater-terminating glaciers in Greenland today, is still limited. In particular, the role of ice-stream instabilities and oceanographic dynamics in driving their collapse are poorly constrained beyond observational timescales. Over numerous glaciations during the Quaternary, a marine-based ice sheet has waxed and waned over the Barents Sea continental shelf, characterized by a number of ice streams that extended to the shelf edge and subsequently collapsed during periods of climate and ocean warming. Increasing availability of offshore and onshore geophysical data over the last decade has significantly enhanced our knowledge of the pattern and timing of retreat of this Barents Sea Ice Sheet (BSIS), particularly so from its Late Weichselian maximum extent. We present a review of existing geophysical constraints that detail the dynamic evolution of the BSIS through the last glacial cycle, providing numerical modelers and geophysical workers with a benchmark dataset with which to tune ice-sheet reconstructions, and explore ice-sheet sensitivities and drivers of dynamic behavior. Although constraining data are generally spatially sporadic across the Barents and Kara seas, behaviors such as ice-sheet thinning, major ice-divide migration, asynchronous and rapid flow switching, and ice stream collapses are all evident. Further investigation into the drivers and mechanisms of such dynamics within this unique paleo analogue is seen as a key priority for advancing our understanding of marine-based ice-sheet deglaciations, both in the deep past and short-term future