Unprecedented Retreat of Columbia Glacier Relative to the Last Millennium Public Deposited

http://ir.library.oregonstate.edu/concern/undergraduate_thesis_or_projects/wh246v040

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Columbia Glacier, Alaska’s most rapidly retreating body of ice, provides a compelling insight into the fragile state of tidewater glaciers worldwide. Catastrophic retreat of the glacier’s terminal ice margin began in 1978 when contact was lost with its stabilizing terminal moraine shoal. Since this time, Columbia Glacier has lost ~20 km in length and ~100 km2 of previously ice covered area. Here we used magnetic and geochemical variability in a proximal marine sediment record to analyze the magnitude of recent retreat in relation to a millennial timescale, and suggest potential driving mechanisms of glacier destabilization. At ~0.9 kya, a distinct shift in magnetic minerology coincides with a change in sediment geochemistry. This sediment provenance change records the glacier’s most recent substantial advance, in which it crossed the Contact Fault and began eroding mafic lithologies distinctive of the region’s basalt and granitic intrusions. The marine record depicts Columbia Glacier remaining stable in this extended position south of the Contact Fault until the most recent rapid mass loss ensued, making recent retreat of Columbia Glacier unprecedented since ~0.9kya. Analyzing the driving mechanisms behind this anomalous retreat proved difficult due to tidewater glaciers’ complex relationship with non-climatic forcings. However, we found that a 1.2°C temperature anomaly occurred during times of Columbia Glacier destabilization in both modern day retreat, and the prehistorical retreat that occurred ~0.9kya. Using a glacial destabilization model simulation, we further concluded that a 1.1±.2°C temperature increase induced Columbia Glacier retreat. Thus, we conclude that the initial detachment of Columbia Glacier from its marine shoal, an event that triggered catastrophic retreat by a positive feedback system of calving and resupplying ice flow, was likely the result of a 1.2°C surface air temperature increase over a 70-year period.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Advisor
Non-Academic Affiliation
Keyword
Rights Statement
Language
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Steven Van Tuyl(steve.vantuyl@oregonstate.edu) on 2017-05-01T21:20:58Z (GMT) No. of bitstreams: 1 Thesis turn in.pdf: 2093861 bytes, checksum: f260d305237119964dc8769eb0edbe1a (MD5)
  • description.provenance : Submitted by Zoe Kilmer (kilmerz@onid.orst.edu) on 2017-04-07T21:21:42Z No. of bitstreams: 1 Thesis turn in.pdf: 2093861 bytes, checksum: f260d305237119964dc8769eb0edbe1a (MD5)
  • description.provenance : Made available in DSpace on 2017-05-01T21:20:58Z (GMT). No. of bitstreams: 1 Thesis turn in.pdf: 2093861 bytes, checksum: f260d305237119964dc8769eb0edbe1a (MD5)

Relationships

In Administrative Set:
Last modified: 07/27/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items