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The acceleration of glacier mass loss in the Canadian Arctic due to rising global temperatures over recent decades has significant implications for sea-level rise. Marine-terminating glaciers are particularly crucial to study because of their susceptibility to both internal and external controls, which complicates identification of the specific drivers of their retreat. Sydkap Glacier, located on Southern Ellesmere Island in the Canadian Arctic, is one of the larger glaciers in the region and has been undergoing terminus-driven dynamic change. This thesis aims to establish a historical record based on remote sensing observations to identify the primary driving forces behind the observed changes. The data include terminus change derived from optical satellite imagery, and vertical change obtained through a combination of recent digital elevation models and historical aerial imagery from 1959 and 1975 that were used to reconstruct past glacier extent using structure-from-motion photogrammetry methods. Additionally, velocity data were acquired from NASA’s ITS_LIVE composites of annual ice velocity, and an investigation of topographical controls was conducted. Collectively, this research provides a detailed record of Sydkap Glacier from 1959 to 2023. Sydkap Glacier experienced a topographically moderated retreat phase of a tidewater glacier cycle between 1972 and the early 2000s. Subsequently, regional trends of increasing temperatures and atmospheric forcing caused a regime shift from the tidewater glacier cycle to one dominated by surface mass balance processes and terminus retreat.

Thwaites Eastern Ice Shelf is the remaining floating extension of Thwaites Glacier, anchored by an offshore pinning point at its northern terminus. Over the past two decades, TEIS has experienced progressive fracturing around a prominent shear zone upstream of its pinning point. Our study analyzes the shear zone fracture evolution from 2002 - 2022 and its control on the flow dynamics of the ice shelf, using remote sensing and in-situ GPS observations. We outlined three areas of interest within TEIS: the pinning-point shear zone, the mid-shelf region, and the region upstream of the pinning point. Then we compiled multi-year shear-zone fracture length and orientation statistics from Landsat and Sentinel-1 imagery and assessed their changes against evolving flow dynamics and shear strain rates. We found that the emergence of the shear zone fractures is dynamically linked with the shelf’s interaction with its neighbouring Thwaites Western Ice Tongue (TWIT) in different phases. These phases include the TWIT-driven acceleration phase (2002-2006), TEIS/TWIT shear-margin disintegration phase (2007-2012), TWIT disintegration phase (2012-2017) and TEIS mid-shelf acceleration phase (2017-2022). Post-2010, we observed the emergence of new rifts from the western part of the shear zone, which localized strain and expanded eastwards in the subsequent years. By 2016-17, the shearing-induced fractures rapidly grew, penetrating the entire shelf width. Subsequently, the mid-shelf ice accelerated eastward, while the ice upstream of the pinning point exhibited deceleration. In the austral winter of 2020, an upstream shift of the line of shearing caused an increase in the mid-shelf ice acceleration, as revealed by in-situ GPS observation. Our findings underscore two insights. First, the ongoing disintegration driven by shearing against the pinning point occurred in a two-stage process: growth of large shearing fractures, externally controlled by the flow of the neighboring TWIT earlier i

Knowledge gaps about how the ocean melts Antarctica's ice shelves, borne from a lack of observations, lead to large uncertainties in sea level predictions. Using high-resolution maps of the underside of Dotson Ice Shelf, West Antarctica, we reveal the imprint that ice shelf basal melting leaves on the ice. Convection and intermittent warm water intrusions form widespread terraced features through slow melting in quiescent areas, while shear-driven turbulence rapidly melts smooth, eroded topographies in outflow areas, as well as enigmatic teardrop-shaped indentations that result from boundary-layer flow rotation. Full-thickness ice fractures, with bases modified by basal melting and convective processes, are observed throughout the area. This new wealth of processes, all active under a single ice shelf, must be considered to accurately predict future Antarctic ice shelf melt., QC 20240828

Climate change is drastically affecting agricultural practices and the Arctic environment as warmer conditions and extreme weather events are becoming increasingly common. Agricultural practices are having to adapt to longer periods of drier conditions and heavy rain events. At the same time, warmer global temperatures and decreasing sea ice concentrations are allowing for increased marine traffic throughout the year, posing the threat of an oil spill. The application of microwave radar systems for environmental monitoring is not a new practice but the conditions that are being monitored are continuing to evolve with the changing climate. This thesis aims to determine the usability of C-band (5.5GHz) and L-band (1.26 GHz) ground-based polarimetric microwave radar systems for agricultural monitoring (C-band and L-band) as well as detecting diesel fuel in the Arctic Ocean (C-band). Findings of the agricultural monitoring study suggest that both C-band and L-band scatterometers can detect changes in vegetation height, while C-band was only correlated with soil moisture at 5cm whereas L-band had correlations at all soil moisture depths that were monitored. Results of the diesel fuel study determined that there were significant changes to received C-band backscatter during the transition from open water to sea ice, as well as when diesel fuel emerged to the surface of the sea ice. These studies will contribute to a baseline of data that can be used to better understand satellite data for agricultural remote sensing purposes. The results of the agricultural remote sensing studies l further the understanding of the sensitivity of L-band microwave radar to vegetation cover as well as the optimal radar system parameters to determine soil moisture from radar backscatter values. The outcome of the diesel-contaminated sea ice experiments will improve and aid northern Canadian communities’ preparedness and response protocols to an oil spill in the Arctic marine environment in pa

Rift propagation, rather than basal melt, drives the destabilization and disintegration of the Thwaites Eastern Ice Shelf. Since 2016, rifts have episodically advanced throughout the central ice-shelf area, with rapid propagation events occurring during austral spring. The ice shelf's speed has increased by ~70% during this period, transitioning from a rate of 1.65 m d−1 in 2019 to 2.85 m d−1 by early 2023 in the central area. The increase in longitudinal strain rates near the grounding zone has led to full-thickness rifts and melange-filled gaps since 2020. A recent sea-ice break out has accelerated retreat at the western calving front, effectively separating the ice shelf from what remained of its northwestern pinning point. Meanwhile, a distributed set of phase-sensitive radar measurements indicates that the basal melting rate is generally small, likely due to a widespread robust ocean stratification beneath the ice–ocean interface that suppresses basal melt despite the presence of substantial oceanic heat at depth. These observations in combination with damage modeling show that, while ocean forcing is responsible for triggering the current West Antarctic ice retreat, the Thwaites Eastern Ice Shelf is experiencing dynamic feedbacks over decadal timescales that are driving ice-shelf disintegration, now independent of basal melt.

Knowledge gaps about how the ocean melts Antarctica’s ice shelves, borne from a lack of observations, lead to large uncertainties in sea level predictions. Using high-resolution maps of the underside of Dotson Ice Shelf, West Antarctica, we reveal the imprint that ice shelf basal melting leaves on the ice. Convection and intermittent warm water intrusions form widespread terraced features through slow melting in quiescent areas, while shear-driven turbulence rapidly melts smooth, eroded topographies in outflow areas, as well as enigmatic teardrop-shaped indentations that result from boundary-layer flow rotation. Full-thickness ice fractures, with bases modified by basal melting and convective processes, are observed throughout the area. This new wealth of processes, all active under a single ice shelf, must be considered to accurately predict future Antarctic ice shelf melt.

The Upernavik Isstrøm, located in northwest Greenland, consists of five marine-terminating glaciers (referred to as U0 to U4, north to south) that have all been responding asynchronously to climate change. All five outlets share similar oceanic, atmospheric, and dynamic influences as they are geographically close, yet contrasting ice-flow behaviour was observed between outlets. This thesis presents a detailed analysis of the varying ice dynamics by updating the observational record of Upernavik’s outlets with recently derived satellite data, examining the role of floating ice tongues by evaluating a variety of proxies for floating ice, and modelling the drivers of ice-flow speed at the two fastest outlets, U1 and U2, with a recent flowline model, Icepack. We found recent patterns in floatation for U1 and U2 that indicated both outlets have new floating ice tongues that persisted through 2021. We evaluated four proxies of floating termini, including tabular iceberg calving, plume polynyas, hydrostatic elevation, and slope, and found only hydrostatic elevation and slope to be reliable proxies. While we initially hypothesized that floating ice tongues drove the acceleration of U1 and U2, our measured velocity data and modelled ice-flow sensitivity to changes in basal slipperiness, shear margin strength, thinning, and terminus retreat, showed ice-flow was realistically explained by changes in basal slipperiness. Icepack was capable of handling this complex case study and the simplified model provided great context regarding the forcings acting on Upernavik’s outlets. This strongly supports that U1 and U2 are seasonally and inter-annually controlled by subglacial hydrology. While the timing and magnitude of observed changes in thinning and retreat varies between outlets, all outlets displayed behaviour characteristic of glaciers controlled by meltwater availability at the bed. These results emphasize the importance of including subglacial hydrology in future studies of U

The Upernavik Isstrøm, located in northwest Greenland, consists of five marine-terminating glaciers (referred to as U0 to U4, north to south) that have all been responding asynchronously to climate change. All five outlets share similar oceanic, atmospheric, and dynamic influences as they are geographically close, yet contrasting ice-flow behaviour was observed between outlets. This thesis presents a detailed analysis of the varying ice dynamics by updating the observational record of Upernavik’s outlets with recently derived satellite data, examining the role of floating ice tongues by evaluating a variety of proxies for floating ice, and modelling the drivers of ice-flow speed at the two fastest outlets, U1 and U2, with a recent flowline model, Icepack. We found recent patterns in floatation for U1 and U2 that indicated both outlets have new floating ice tongues that persisted through 2021. We evaluated four proxies of floating termini, including tabular iceberg calving, plume polynyas, hydrostatic elevation, and slope, and found only hydrostatic elevation and slope to be reliable proxies. While we initially hypothesized that floating ice tongues drove the acceleration of U1 and U2, our measured velocity data and modelled ice-flow sensitivity to changes in basal slipperiness, shear margin strength, thinning, and terminus retreat, showed ice-flow was realistically explained by changes in basal slipperiness. Icepack was capable of handling this complex case study and the simplified model provided great context regarding the forcings acting on Upernavik’s outlets. This strongly supports that U1 and U2 are seasonally and inter-annually controlled by subglacial hydrology. While the timing and magnitude of observed changes in thinning and retreat varies between outlets, all outlets displayed behaviour characteristic of glaciers controlled by meltwater availability at the bed. These results emphasize the importance of including subglacial hydrology in future studies of U