Geometric and thermal constraints on the timing of Alaskan tidewater glacier retreat

• Main Author: Waghorn, Lucy
• Other Authors: Sutherland, Dave, Hager, Alex
• Format: Thesis
• Language: English
• Published: University of Oregon 2022
• Subjects: tidewater glacier; glacier retreat; sills; sea surface temperature; air temperature; glacier; glaciers; Tidewater; Alaska
• Online Access: https://scholarsbank.uoregon.edu/xmlui/handle/1794/27432

Glaciers around the world are retreating at increasing rates, prompting concerns over sea level rise and the future of the cryosphere. In southern Alaska, some have retreated while their neighbors have advanced, indicating that local atmospheric conditions are not the only influence on glacier retreat. One possible factor is the interaction of ocean water with the glacier at the terminus. However, fjord geometry can alter the ocean water that interacts with the terminus, and the interaction of fjord geometry and ocean temperature anomalies has not been investigated in Alaska thus far. To investigate the interaction of fjord geometry and glacier retreat, we used bathymetry, air temperature (AT), sea surface temperature (SST), and terminus position data. Here we show that high SST anomalies may enhance glacial retreat in fjords with shallow sills. During a high SST anomaly, some glaciers in shallow-silled fjords retreated rapidly from a point of relative stability. It is possible that shallow sills influence fjord water circulation where only the warmest part of the water column can enter the near terminus region, potentially leading to enhanced glacier retreat after high SST anomalies. Many glaciers also showed enhanced retreat in the two years after a high AT anomaly. Though other factors can also contribute, understanding the processes and interactions that lead to glacier retreat is becoming increasingly important as climate change alters the atmosphere and environment.