Capturing high-resolution ice sheets and glacier surface mass balance in a changing climate

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.