This thesis presents a detailed study of recent changes in the mass balance and dynamics of Penny Ice Cap (PIC), and projects its evolution under a warming climate. Mass losses from 2005-2014 were quantified from airborne altimetry elevation change measurements, and adjusted for vertical ice motion caused by firn compaction and/or ice dynamics. Mass loss from PIC increased four-fold between the mid-1990s (-1.3 ± 0.7 Gt a-1) and 2005-2013 (-5.4 ± 1.9 Gt a-1). The adjustment calculations indicate that mass loss may be overestimated by 19% if vertical motion is not properly accounted for. The velocity response to increased surface melt was quantified using satellite imagery and historical ground measurements from Highway Glacier, on the southern part of PIC. Over the period 1985-2011, the six largest outlet glaciers on the ice cap decelerated at an average rate of 21 m a-1 over the 26 year period (0.81 m a-1), or 12% decade-1. Highway Glacier decelerated by 71% between 1953 and 2009/11. The recent slowdown of outlet glaciers has coincided with increases in mass loss and an inferred reduction in basal sliding. The ice-cap-wide mass balance was modeled from 1958 to 2099 with an enhanced temperature index model. Since the mid-1990s mass balance rates over PIC have become increasingly negative. Peak mass loss is projected to occur in the late 2070s and PIC is expected to lose 16-20% of its 2014 ice volume by 2099 assuming a moderate climate warming scenario (RCP4.5). If a +2°C offset is applied to this scenario, the ice cap is expected to lose 30-40% of its initial ice volume by 2099.
These results provide the first comprehensive evaluation of the impact of vertical ice motion on mass loss derived from geodetic measurements over a large Arctic ice cap. The ice velocity record provides insights into the relationship between surface melt rates and glacier motion over the past 30-60 years. This study projects the mass change of the largest ice cap in the southern Canadian Arctic to 2099, calibrated and validated with a wealth of spatially distributed data for the first time.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/36179 |
| Date | January 2017 |
| Creators | Schaffer, Nicole |
| Contributors | Copland, Luke |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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