Polar ice sheets and glaciers worldwide are rapidly losing mass, acting as major contributors to global sea-level rise. This mass loss trend is expected to continue and further accelerate in a warming climate. Besides solid ice discharge of calving icebergs, mass loss is driven by a declining glacier surface mass balance (SMB), i.e., the difference between mass gained from snowfall accumulation and lost from meltwater runoff to the ocean. Reconstructions of past and projections of future glacier SMB often rely on global or regional climate models typically running on 5 to 100 km grids. Such spatial resolution remains, however, insufficient to accurately capture local SMB processes over small glaciers and ice caps.

To bridge this resolution gap, statistical downscaling has proven an efficient tool to spatially refine SMB outputs from coarse global and regional climate models to high-resolution (sub-)kilometer grids. In this presentation, we will assess the added value of statistical downscaling to accurately resolve local SMB processes, notably the high accumulation and melt rates generated over rugged mountain ranges and narrow outlet glaciers, respectively. We will discuss how high-resolution products proved essential to reconcile recent in situ and remote sensing mass change records, and to yield reliable future SMB projections. This talk will highlight the role of statistical downscaling in identifying mechanisms that currently drive, and may further accelerate, mass loss of polar ice sheets and glaciers across the globe.

How to cite: Noël, B.: Capturing high-resolution ice sheets and glacier surface mass balance in a changing climate, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5980, https://doi.org/10.5194/egusphere-egu25-5980, 2025.

The glacier surface forms a vital boundary where snow and ice mass exchange occurs through climatic processes. In addition to the visible upper surface, glaciers are bounded by other interfaces, including the underlying base of bedrock/sediment, the front of a calving glacier facing an ocean or lake, and the ice-shelf base in contact with sub-shelf seawater. These unseen boundaries are venues of glacial sliding, hydrology, calving and underwater melting, which play critical roles in glacier dynamics and mass change. These processes are also essential for understanding how glaciers affect surrounding environments through erosion, sedimentation, ice and meltwater discharge. Despite their importance, these boundaries are largely unexplored, in contrast to the increasing amount of data available on the glacier surface. As they are covered by ice and water, special techniques and tools are required for direct observation. For example, hot-water drilling and borehole measurements provide crucial information regarding subglacial processes, and in-situ observations of the ice-water interface can be carried out with uncrewed vehicles or underwater survey devices near the calving front. Based on our experiences in the Alps, Patagonia, Greenland and Antarctica, this presentation highlights the importance of the processes taking place at the hidden glacier boundaries.

How to cite: Sugiyama, S.: On the dark side: Exploring hidden boundaries of glaciers and ice sheets, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5296, https://doi.org/10.5194/egusphere-egu25-5296, 2025.