Characteristics of dynamic thickness change across diverse outlet glacier geometries and basal conditions
Accepted to Journal of Glaciology: link
In Greenland, outlet glaciers are retreating and thinning due to various external influences, but the exact reasons for the varying rates of these changes among different glaciers remain unclear. Our research explores the effects of changes in ice pressure and basal lubrication on thinning rates and patterns by conducting numerical simulations across simplified Greenland-like glacier models. We discovered that a 10 km retreat at the glacier front over ten years can lead to sustained thinning rates up to 16 meters per year due to changes in ice pressure, particularly in glaciers with high basal drag (over 60 kPa) and lateral stress (over 70 kPa). We also found that localized changes in basal lubrication can cause thinning upstream and thickening downstream by as much as 12 meters per year.
The duration of the lubrication effect tends to have a greater impact on thickness changes than the intensity. Moreover, intermittent retreats of the grounding line over uneven terrain produce a step-like thinning pattern consistent with observed changes in several Greenland glaciers. These results emphasize the importance of the entire grounding zone, rather than just the ice front position, in influencing glacier thinning through changes in resistive stress.
Combined Altimetry and Ice Dynamic Modeling Reveals Grounding State Transition of Helheim Glacier (1998-2022)
Paper in preparation. Collaboration with UB Earth Sciences.
This study investigates the previously identified insights at a real-world glacier. We focus on the dramatic changes of Helheim Glacier, one of Greenland’s largest outlet glaciers, over the past quarter-century (1998-2022). By combining novel surface elevation observations from laser altimetry with ice flow modeling, we reveal that the glacier’s grounding state—whether its terminus is floating or grounded—plays a crucial role in controlling its long-term evolution. Our observations and modeling demonstrate that Helheim has undergone a fundamental transition: the recent rapid retreat since 2016 has completely removed its floating ice section, leaving the glacier fully grounded today. This work represents a critical step forward in understanding the mechanisms controlling Greenland outlet glacier behavior, combining high-precision observations with numerical modeling to explain the complex interplay between glacier dynamics and terminus conditions.