Search

There have been rapid recent reductions in sea ice age and extent in the Canadian Arctic, but little previous analysis of how this has impacted the navigability of Arctic shipping. In this study we analyze how navigability changed over the period 1972–2016 by converting Canadian Ice Service ice charts to shipping navigability charts for different hull strength classifications based on the Arctic Ice Regime Shipping System. Analysis focuses on the southern route of the Northwest Passage, and the Arctic Bridge route across Hudson Bay, for changes in early-season (∼25 June), mid-season (∼3 September), and late-season (∼15 October) conditions. Results reveal that there has been a marked easing in shipping navigability for all vessels over the past decade, driven by reductions in the area and age of sea ice, particularly across the southern route of the Northwest Passage. Both medium (Type B) and little (Type E) ice strengthened vessels were able to transit the full length of this route in the middle part of the shipping season in 2012–2016, but not in 1972–1976 or 1992–1996.

AbstractRADARSAT-2 imagery collected each winter from 2015/2016 to 2019/2020 is used to quantify and characterize the variability in the motion of, and the discharge from, the major marine-terminating ice masses of the Queen Elizabeth Islands (QEI: Devon, Ellesmere and Axel Heiberg Islands) in the Canadian High Arctic. The majority of the glaciers did not experience significant variations in flow speeds over the observation period, and for most that did the variations are attributed to pulse and surge processes. However, there are exceptions where the velocity record indicates continued acceleration of the glaciers by processes that appear distinct from surging or pulsing, such as dynamic thinning. These include Trinity and Wykeham glaciers (Prince of Wales Icefield) and Belcher Glacier (Devon Ice Cap). The combination of surface velocities with ice thicknesses indicates that average ice discharge to the ocean for the QEI over the observation period was 2.78 ± 0.52 Gt a−1(ranging between ∼2.37 ± 0.48 Gt a−1and ∼3.20 ± 0.55 Gt a−1), ∼50% of which was channeled through the Trinity-Wykeham glacier basin alone. The results presented here, combined with those of previous studies, provide a comprehensive record of ice motion and discharge from the QEI between 2008 and 2020.

ABSTRACTLinks between climate and glacier surges are poorly understood but are required to enable prediction of surges and mitigation of associated hazards. Here, we investigate the role of snow accumulation, rain, and temperature on surge periodicity, area changes, and timing of surge initiation since the 1930s at Donjek Glacier, Yukon, Canada. Snow accumulation measured in three ice cores collected at Eclipse Icefield indicates that a cumulative accumulation of 15.5 ± 1.46 or 16.6 ± 2.0 m w.e. occurred in the ten to twelve years between each of its last eight surges, depending on ice motion spatiotemporal offset corrections. Although we find consistent snow accumulation between surges, the transient snow line has risen 10.3 m decade−1vertically since the 1950s, and Burwash Landing weather station records indicate a 0.5°C decade−1increase in mean annual air temperature since the 1960s. Changes in surface mass balance are accompanied by a consistent surge interval but decreasing surge extent. The three recent surge events initiated in years with the rainiest summers on record. These findings highlight a complex interplay between external (i.e., climate) and internal glacier processes that control surging at Donjek Glacier, with climate having a more direct influence on surge extent than on recurrence interval.

ABSTRACTSince the 1960s, warming air and sea surface temperatures have led to decreasing sea ice extent and longer periods of open water in the Canadian Arctic Archipelago (CAA), together with changes in glacier discharge patterns. An important question, therefore, is whether there is a relationship between changing sea ice conditions, glacier dynamics, and iceberg production in this region. Using synthetic aperture radar (SAR) (Radarsat-1, Radarsat-2, and ALOS PALSAR) and optical (Landsat 7 and 8) satellite imagery, iceberg plume events and sea ice break-up/freeze-up dates between 1997 and 2015 are investigated for 40 tidewater glaciers around the Prince of Wales (POW) Icefield, Ellesmere Island. Results show a clear relationship between the presence of sea ice and the production of icebergs, with ~49% of total iceberg plume events occurring during the 3–4 month long summer open water season and ~51% of events when sea ice was present the remaining 8–9 months of the year. There is no clear evidence of recent increases in iceberg production on a regional basis, but on a local, individual glacier scale there has been a connection between periods of increased iceberg plume events and: (a) acceleration in the surface velocity of Trinity and Wykeham glaciers; (b) increase in terminus retreat rates for glaciers which have not accelerated in flow speed over the past ~5–10 years. Comparisons with ocean temperature, surface air temperature from NCEP-NCAR reanalysis, and tidal data showed no clear relationship with iceberg plume events.

In Greenland, 87% of the glacierized area terminates in the ocean, but mass lost at the ice‐ocean interface, or frontal ablation, has not yet been fully quantified. Using measurements and models we calculate frontal ablation of Greenland's 213 outlet and 537 peripheral glaciers and find a total frontal ablation of 481.8 ± 24.0 for 2000–2010 and 510.2 ± 18.6 Gt a−1for 2010–2020. Ice discharge accounted for ∼90% of frontal ablation during both periods, while mass loss due to terminus retreat comprised the remainder. Only 16 glaciers were responsible for the majority (>50%) of frontal ablation from 2010 to 2020. These estimates, along with the climatic‐basal balance, allow for a more complete accounting of Greenland Ice Sheet and peripheral glacier mass balance. In total, Greenland accounted for ∼90% of Northern Hemisphere frontal ablation for 2000–2010 and 2010–2020. We estimate the mass of ice lost from all Greenland glaciers that entered the ocean during each of the last two decades. This ice loss at the front of these marine‐terminating glaciers is called frontal ablation and is approximately equal to the mass of icebergs entering the ocean. Frontal ablation is important because 87% of glacier area in Greenland ends in the ocean, through 750 outlets, and previous work has only approximated frontal ablation. This study quantifies it for the first time, helping to close the mass budget for the Greenland Ice Sheet and better partition its mass balance into components. We find that Greenland accounts for ∼90% of all Northern Hemisphere frontal ablation and, of that contribution, just 17 glaciers for 2000–2010 and 16 glaciers for 2010–2020 account for more than half of total Greenland frontal ablation. Frontal ablation of the Greenland Ice Sheet averaged 510.2 ± 18.6 Gt a−1for 2010–2020, ∼90% of which came from ice dischargeThe frontal ablation we measured is larger than the total mass loss from the ice sheet, indicating a positive climatic‐basal balanceOnly 16 glaciers account for 50% of the total frontal ablation from the Greenland Ice Sheet Frontal ablation of the Greenland Ice Sheet averaged 510.2 ± 18.6 Gt a−1for 2010–2020, ∼90% of which came from ice discharge The frontal ablation we measured is larger than the total mass loss from the ice sheet, indicating a positive climatic‐basal balance Only 16 glaciers account for 50% of the total frontal ablation from the Greenland Ice Sheet

ABSTRACTSpeckle-tracking of historically acquired ALOS PALSAR and RADARSAT-2 datasets are used to determine the dynamics of major glaciers and ice masses in western Canada over the past decade. For the icefields of the St. Elias Mountains and those that fringe the northern British Columbia/Alaska border, our results are largely consistent with earlier studies that used the same data, but different speckle-tracking techniques, to derive ice motion. However, our results are generally more spatially comprehensive than those previously published, in particular in fast-flowing regions such as Hubbard, Seward, Tweedsmuir and Lowell glaciers. We also produce new velocity maps for the icefields located in the Coast Mountains of southwestern British Columbia and for the Chaba, Clemenceau and Columbia icefields of the Rocky Mountains. Generally, faster flow is present on large ocean- and land-terminating outlet glaciers, particularly those in high accumulation maritime regions. These results, taken together with velocity maps of the Canadian Arctic and Yukon produced in previous studies, mean that baseline maps of glacier velocities determined from speckle tracking of SAR datasets are now available for nearly all the major ice masses of Canada.

River piracy—the diversion of the headwaters of one stream into another one—can dramatically change the routing of water and sediment, with a profound effect on landscape evolution. Stream piracy has been investigated in glacial environments, but so far it has mainly been studied over Quaternary or longer timescales. Here we document how retreat of Kaskawulsh Glacier—one of Canada’s largest glaciers—abruptly and radically altered the regional drainage pattern in spring 2016. We use a combination of hydrological measurements and drone-generated digital elevation models to show that in late May 2016, meltwater from the glacier was re-routed from discharge in a northward direction into the Bering Sea, to southward into the Pacific Ocean. Based on satellite image analysis and a signal-to-noise ratio as a metric of glacier retreat, we conclude that this instance of river piracy was due to post-industrial climate change. Rapid regional drainage reorganizations of this type can have profound downstream impacts on ecosystems, sediment and carbon budgets, and downstream communities that rely on a stable and sustained discharge. We suggest that the planforms of Slims and Kaskawulsh rivers will adjust in response to altered flows, and the future Kaskawulsh watershed will extend into the now-abandoned headwaters of Slims River and eventually capture the Kluane Lake drainage.

AbstractHere we use high resolution (5 m) Radarsat Constellation Mission (RCM) imagery acquired in winters 2022 and 2023 to determine motion across glaciers of the St. Elias Icefield in Yukon/Alaska. Our regional velocity mapping largely conforms with previous studies, with faster motion (>600 m/yr) for the glaciers originating in the Yukon that drain southward and westward to the coast of Alaska and relatively slower motion (100–400 m/yr) for the land terminating glaciers that drain eastward and northeastward and stay within the Yukon. We also identify two new glacier surges within the icefields: the surge of Nàłùdäy (Lowell) Glacier in Winter 2022, and Chitina Glacier in Winter 2023, and track the progression of each surge from January to March utilizing ∼4-day repeat RCM imagery. To evaluate the quality of RCM-derived velocities, we compare our results with 50 simultaneous measurements at three on-ice dGPS stations located on two Yukon glaciers and find the average absolute difference between measurements to be 6.6 m/yr. Our results demonstrate the utility of RCM data to determine glacier motion across large regions with complex topography, to support process-based studies of fast flowing and surge-type glaciers and continue the legacy of velocity products derived from the Radarsat-2 mission.

ABSTRACTThis study presents detailed observations of calving behavior variability from daily oblique photographs acquired over a five-year period (2007–2011) covering the terminus of Rink Isbræ, a major West Greenland outlet glacier. The evidence suggests that calving at Rink is characterized by two styles with distinct temporal and spatial footprints. The first style is characterized by frequent small magnitude events, which show clear seasonal variability with a marked increase in frequency immediately following ice mélange breakup and a peak in July. The second style is characterized by the sporadic detachment of kilometer-sized tabular icebergs with no clear seasonal signal. We suggest that two sets of mechanisms control calving variability at this location, namely (1) melt-driven processes enhancing submarine undercutting and (2) mechanically driven buoyant flexure. The presence of sea ice and/or ice mélange in the fjord presents an additional factor limiting calving in the winter.

Over the last two decades, Trinity, Wykeham, Ekblaw, and Cadogan glaciers have retreated and been identified as the primary sources of iceberg flux from Prince of Wales (POW) Icefield, Ellesmere Island, accounting for ∼83% of total solid ice discharge. In this study, we used a total of 167 Radarsat‐2 Synthetic Aperture Radar scene pairs collected between 2009 and 2019 to derive winter surface velocities of these four major basins of the POW Icefield. Over this period both Cadogan and Ekblaw glaciers underwent multiyear acceleration and deceleration limited to their lower parts, consistent with characteristics of “pulse‐type” glaciers. Trinity and Wykeham glaciers are currently the fastest flowing glaciers in the CAA and are grounded below sea level for ∼40 km up‐glacier from their termini. Both glaciers underwent multiyear repeating periods of velocity acceleration between 2009 and 2019 which coincided with significant thinning at their termini. As of 2017, Trinity and Wykeham were each within ∼10 m of flotation over their lowermost 4 km. We also identified a shift in flow since 2014 on Trinity and Wykeham, after which winter flow rates began to propagate up‐glacier and were nearly identical to flow rates observed throughout the rest of the year, indicating that seasonal variability in flow has become less apparent in recent years. Our findings suggest that Trinity and Wykeham glaciers have transitioned to a flow type dominated by dynamic thinning, which is strongly influenced by subglacial topography and may be susceptible to instability of the glacier front and large‐scale collapse. Trinity, Wykeham, Ekblaw, and Cadogan are the four primary glacier basins on the Prince of Wales (POW) Icefield, and are responsible for the majority of solid ice discharged from it. Previous work on tidewater glacier dynamics in the Canadian Arctic has mainly focused on quantifying surface velocities and ice fluxes to the ocean, but less research has been undertaken on the physical processes controlling variability in glacier flow. Here, we use remote sensing methods to measure changes in ice flow, surface elevation, and terminus buoyancy to identify the processes controlling glacier motion in this region. We find that ice flow of the four major glaciers on the POW Icefield are strongly controlled by their underlying bed topography. Trinity and Wykeham glaciers are two of the fastest flowing glaciers in the Canadian Arctic and appear to have recently entered a period of instability at their termini, which, if they continue at the current rates of thinning, could lead to their large‐scale acceleration, retreat, and collapse. We report updated winter velocity and surface elevation change estimates for four major basins on the Prince of Wales IcefieldFlow for Trinity, Wykeham, Cadogan, and Ekblaw glaciers is strongly influenced by bed topographyVelocity changes, surface thinning, and terminus buoyancy resulted in instability and near flotation of the termini of Trinity and Wykeham glaciers We report updated winter velocity and surface elevation change estimates for four major basins on the Prince of Wales Icefield Flow for Trinity, Wykeham, Cadogan, and Ekblaw glaciers is strongly influenced by bed topography Velocity changes, surface thinning, and terminus buoyancy resulted in instability and near flotation of the termini of Trinity and Wykeham glaciers

We mapped the terminus position for every marine‐terminating glacier in the Northern Hemisphere for 2000, 2010, and 2020, including the Greenland Ice Sheet, to provide the first complete measure of their variability. In total, these 1,704 glaciers lost an average of 389.7 ± 1.6 km2a−1(total 7,527 ± 31 km2) from 2000 to 2020 with 123 glaciers becoming no longer marine‐terminating over this period. Overall, 85.3% of glaciers retreated, 2.5% advanced, and the remaining 12.3% did not change outside of uncertainty limits. Outlet glaciers of the Greenland Ice Sheet are responsible for 61.9% of total area loss, although their rate of retreat was 34% less in 2010–2020 than 2000–2010. Glaciers with the largest area loss terminate in ice shelves or ice tongues, are surge‐type, have an unstable basal geometry, or have an unusually wide calving margin. North of the equator, 1,704 glaciers touched the ocean in 2000. Here, we present the first analysis to document the frontal position of every one of these glaciers in 2000, 2010, and 2020. We found that 85.3% retreated and are now reduced in area. Only 2.5% of glaciers advanced or increased in area. The remaining 12.3% did not change within uncertainty limits. Total area losses were 389.7 ± 1.6 km2per year (total 7,527 ± 31 km2) over the 20‐year period. Glaciers flowing from the Greenland Ice Sheet accounted for over 60% of total area losses. We found wide variations in the response of glaciers to similar changes in air and ocean temperature and sea ice concentrations, showing that environmental conditions alone cannot explain why some glaciers retreated more than others. Instead, unique glacier characteristics are the most important factor in controlling the variability of terminus retreat. Glaciers with floating ice at their front (ice shelves or ice tongues), those that undergo periodic changes in their flow velocity (surges), those which have a weak connection to their beds, and glaciers that are unusually wide, experienced the largest area loss from 2000 to 2020. There were 1704 marine‐terminating glaciers in 2000 in the Northern Hemisphere, of which 85.3% retreated and 2.5% advanced from 2000 to 2020Tidewater glaciers lost a total area of 7,527 ± 31 km2from 2000 to 2020, with the Greenland Ice Sheet responsible for 61.9% of total lossesVariations in retreat are best explained by glacier characteristics: ice shelves/tongues, surging, basal geometry, and calving width There were 1704 marine‐terminating glaciers in 2000 in the Northern Hemisphere, of which 85.3% retreated and 2.5% advanced from 2000 to 2020 Tidewater glaciers lost a total area of 7,527 ± 31 km2from 2000 to 2020, with the Greenland Ice Sheet responsible for 61.9% of total losses Variations in retreat are best explained by glacier characteristics: ice shelves/tongues, surging, basal geometry, and calving width

AbstractFor much of the 20th century, multiyear landfast sea ice (MLSI) formed a permanent ice cover in Yelverton Bay, Ellesmere Island. This MLSI formed following the removal of ice shelf ice from Yelverton Bay in the early 1900s, including the well-documented Ice Island T-3. The MLSI cover survived intact for 55–60 years until 2005, when >690 km2(90%) of MLSI was lost from Yelverton Bay. Further losses occurred in 2008, and the last of the Yelverton Bay MLSI was lost in August 2010. Ground penetrating radar (GPR) transects and ice cores taken in June 2009 provide the first detailed assessment of MLSI in Yelverton Inlet, and indeed the last assessment now that it has all been replaced with first-year ice. A detailed history of ice shelf, glacier, and MLSI changes in Yelverton Bay since the early 1900s is presented using remotely sensed imagery (air photos, space-borne optical, and radar scenes) and ancillary evidence from in situsurveys. Recent changes in the floating ice cover here align with the broad-scale trend of long-term reductions in age and thickness of sea ice in the Arctic Ocean and Canadian Arctic Archipelago.

AbstractA review of published literature and satellite imagery from the late 1960s onwards has revealed 90 surge-type glaciers in the Karakoram mountains, of which 50 have not previously been described in detail. These glaciers were identified by a number of surface features indicative of surge-type behavior such as looped moraines, rapid terminus advance, strandlines and rapid changes in surface crevassing. These observations indicate that surge-type behavior is more common and widespread than previously believed on Karakoram glaciers. There is strong spatial clustering of the surge-type glaciers, and a doubling in the number of new surges in the 14 years after 1990 (26 surges) than in the 14 years before 1990 (13 surges). This is coincident with a period of increased precipitation and positive glacier mass balance in this region, and supports previous studies which have found that mass balance has an important control on the frequency of glacier surging.

Concerns over greenhouse-gas forcing and global temperatures have initiated research into understanding climate forcing and associated Earth-system responses. A significant component is the Earth's cryosphere, as glacier-related, feedback mechanisms govern atmospheric, hydrospheric and lithospheric response. Predicting the human and natural dimensions of climate-induced environmental change requires global, regional and local information about ice-mass distribution, volumes, and fluctuations. The Global Land-Ice Measurements from Space (GLIMS) project is specifically designed to produce and augment baseline information to facilitate glacier-change studies. This requires addressing numerous issues, including the generation of topographic information, anisotropic-reflectance correction of satellite imagery, data fusion and spatial analysis, and GIS-based modeling. Field and satellite investigations indicate that many small glaciers and glaciers in temperate regions are downwasting and retreating, although detailed mapping and assessment are still required to ascertain regional and global patterns of ice-mass variations. Such remote sensing/GIS studies, coupled with field investigations, are vital for producing baseline information on glacier changes, and improving our understanding of the complex linkages between atmospheric, lithospheric, and glaciological processes.

AbstractAnalysis of relationships between uplift and denudation in complex mountain environments requires integrated approaches using remote sensing and geographic information systems (GIS) analyses in combination with field investigations. We present multidisciplinary research focusing on the Nanga Parbat Himalaya of northern Pakistan. Remote sensing of the subsurface includes radio‐echo sounding to investigate glaciers, magnetotelluric sounding, and seismic tomography to investigate shallow to deep aspects of the lithosphere. Remote sensing of the landscape includes satellite image acquisition, multispectral analysis, geomorphometric analysis of a satellite‐derived digital elevation model (DEM), and the application of GIS and pattern recognition procedures to analyze topographic complexity and the geomorphology of the mountain massif. Detailed mapping requires topographic normalization of satellite imagery using the non‐Lambertian model. Radar measurement of thicknesses of glacier ice, coupled with assessment of satellite imagery and field data, have enabled calculation of ice and sediment discharge. Collectively, scientific observations reinforce prior understandings of rapid rates of uplift and high rates of surficial denudation. The integration of data has thus enabled a systematic approach to study localized coupling between tectonic and surface processes. In future studies of this kind, it will become ever more important for geoscientists to integrate quantitative remote sensing and GIS into a standard analytical framework in order to solve complex problems.

The article reports on the Canadian university Students on Ice (SOI) expedition to Antarctica in February 2009. Three field courses on board the ship MV Ushuaia were offered by the universities of Alberta, Ottawa, and Northern British Columbia and were credited in the undergraduate degrees of the students. The ship worked as a floating classroom, giving the students first-hand experience of the Antarctic landscapes and habitats. Among the students' experiences was the 1,000 kilometer turbulent crossing of Drake Passage.

Significant attention has focused on the potential for increased shipping activity driven by recently observed declines in Arctic sea ice cover. In this study, we describe the first coupled spatial analysis between shipping activity and sea ice using observations in the Canadian Arctic over the 1990–2015 period. Shipping activity is measured by using known ship locations enhanced with a least cost path algorithm to generate ship tracks and quantified by computing total distance traveled in kilometers. Statistically significant increases in shipping activity are observed in the Hudson Strait (150–500 km traveled yr−1), the Beaufort Sea (40–450 km traveled yr−1), Baffin Bay (50–350 km traveled yr−1), and regions in the southern route of the Northwest Passage (50–250 km traveled yr−1). Increases in shipping activity are significantly correlated with reductions in sea ice concentration (Kendall's tau up to −0.6) in regions of the Beaufort Sea, Western Parry Channel, Western Baffin Bay, and Foxe Basin. Changes in multiyear ice‐dominant regions in the Canadian Arctic were found to be more influential on changes to shipping activity compared to seasonal sea ice regions. First observational coupled spatial analysis of the influence of declining sea ice on increasing ship activity in the Canadian ArcticShipping activity increases are significantly correlated to declining sea ice in several regionsThe presence of multiyear ice seems to influence shipping activity more than seasonal first‐year ice

The article offers information on the International Polar Year (IPY) Antarctic University Expedition to be held in February 2009.

At latitude 67°N, Penny Ice Cap on Baffin Island is the southernmost large ice cap in the Canadian Arctic, yet its past and recent evolution is poorly documented. Here we present a synthesis of climatological observations, mass balance measurements and proxy climate data from cores drilled on the ice cap over the past six decades (1953 to 2011). We find that starting in the 1980s, Penny Ice Cap entered a phase of enhanced melt rates related to rising summer and winter air temperatures across the eastern Arctic. Presently, 70 to 100% (volume) of the annual accumulation at the ice cap summit is in the form of refrozen meltwater. Recent surface melt rates are found to be comparable to those last experienced more than 3000 years ago. Enhanced surface melt, water percolation and refreezing have led to a downward transfer of latent heat that raised the subsurface firn temperature by 10°C (at 10 m depth) since the mid‐1990s. This process may accelerate further mass loss of the ice cap by pre‐conditioning the firn for the ensuing melt season. Recent warming in the Baffin region has been larger in winter but more regular in summer, and observations on Penny Ice Cap suggest that it was relatively uniform over the 2000‐m altitude range of the ice cap. Our findings are consistent with trends in glacier mass loss in the Canadian High Arctic and regional sea‐ice cover reduction, reinforcing the view that the Arctic appears to be reverting back to a thermal state not seen in millennia. Summer melt rates on Penny Ice Cap have increased greatly in the past decadesThe firn temperature of the ice cap is risingThe present thermal state of the ice cap resembles that last seen 3000 years ago