Wratten, E.E., Cooley, S.W., Mann, P.J., Whalen, D., Fraser, P., and Lim, M. Remote Sensing of Sea Ice and Icebergs. (2022)

Landfast ice is a defining feature among Arctic coasts, providing a critical transport route for communities and exerting control over the exposure of Arctic coasts to marine erosion processes. Despite its significance, there remains a paucity of data on the spatial variability of landfast ice and limited understanding of the environmental processes’ controls since the beginning of the 21st century. We present a new high spatiotemporal record (2000–2019) across the Northwest Canadian Arctic, using MODIS Terra satellite imagery to determine maximum landfast ice extent (MLIE) at the start of each melt season. Average MLIE across the Northwest Canadian Arctic declined by 73% in a direct comparison between the first and last year of the study period, but this was highly variable across regional to community scales, ranging from 14% around North Banks Island to 81% in the Amundsen Gulf. The variability was largely a reflection of 5–8-year cycles between landfast ice rich and poor periods with no discernible trend in MLIE. Interannual variability over the 20-year record of MLIE extent was more constrained across open, relatively uniform, and shallower sloping coastlines such as West Banks Island, in contrast with a more varied pattern across the numerous bays, headlands, and straits enclosed within the deep Amundsen Gulf. Static physiographic controls (namely, topography and bathymetry) were found to influence MLIE change across regional sites, but no association was found with dynamic environmental controls (storm duration, mean air temperature, and freezing and thawing degree day occurrence). For example, despite an exponential increase in storm duration from 2014 to 2019 (from 30 h to 140 h or a 350% increase) across the Mackenzie Delta, MLIE extents remained relatively consistent. Mean air temperatures and freezing and thawing degree day occurrences (over 1, 3, and 12-month periods) also reflected progressive northwards warming influences over the last two decades, but none showed a statistically significant relationship with MLIE interannual variability. These results indicate inferences of landfast ice variations commonly taken from wider sea ice trends may misrepresent more complex and variable sensitivity to process controls. The influences of different physiographic coastal settings need to be considered at process level scales to adequately account for community impacts and decision making or coastal erosion exposure.

Forbes, D. & Craymer, M. & James, T. & Whalen, D. Canadian Journal of Earth Sciences. (2022)

The Mackenzie Delta is an extensive river-mouth depocentre, the second largest delta on the Arctic Ocean, and lies in the zone of continuous permafrost. We report the first measurements of natural consolidation subsidence in a high-latitude delta with ice-bonded sediments. Several years of episodic GPS records on a network of 15 stable monuments throughout the central and outer delta reveal downward motion between 1.5 ± 0.7 and 5.3 ± 1.1 mm/yr relative to a nearby monument on bedrock. Additional shallow subsidence results from loss of near-surface excess ice with deeper seasonal thaw in a warming climate. Isostatic adjustment is a third component of subsidence, captured in the NAD83v70VG crustal velocity model. Sedimentation rates over much of the outer delta are less than the rate of subsidence combined with rising sea level. Scenarios for future inundation are evaluated using interpolated IPCC AR5 projections, NAD83v70VG, and a LiDAR DEM with realistic consolidation, thaw subsidence, and sedimentation rates, on time scales of 40 and 90 years. These reveal increases in area flooded at mean water level from 33% in 2010 to 65% or as much as 85% in 2100, depending on the emissions scenario, driving delta-front retreat and removing a large proportion of avian nesting habitat. The three components of subsidence together increase the relative sea-level rise by a factor of two to eight, depending on the scenario. Consolidation subsidence may also contribute to rising low-flow water levels in the central delta, increasing river-lake connectivity, with negative impacts on aquatic biodiversity and productivity.

Lim, M., Whalen D., Mann P., Fraser P., Berry B., Irish C., Cockney K., Woodward J. Frontiers in Earth Science (2020)

Permafrost coasts are extensive in scale and complex in nature, resulting in particular challenges for understanding how they respond to both long-term shifts in climate and short-term extreme weather events. Taking examples from the Canadian Beaufort Sea coastline characterized by extensive areas of massive ground ice within slump and block failure complexes, we conduct a quantitative analysis of the practical performance of helicopter-based photogrammetry. The results demonstrate that large scale (>1 km2) surface models can be achieved at comparable accuracy to standard unmanned aerial vehicle surveys, but 36 times faster. Large scale models have greater potential for progressive alignment and contrast issues and so breaking down image sequences into coherent chunks has been found the most effective technique for accurate landscape reconstructions. The approach has subsequently been applied in a responsive acquisition immediately before and after a large storm event and during conditions (wind gusts >50 km h−1) that would have prohibited unmanned aerial vehicle data acquisition. Trading lower resolution surface models for large scale coverage and more effective responsive monitoring, the helicopter-based data have been applied to assess storm driven-change across the exposed outer islands of the Mackenzie Delta area for the first time. These data show that the main storm impacts were concentrated on exposed North orientated permafrost cliff sections (particularly low cliffs, >20 m in height) where cliff recession was 43% of annual rates and in places up to 29% of the annual site-wide erosion volume was recorded in this single event. In contrast, the thaw-slump complexes remained relatively unaffected, debris flow fans were generally more resistant to storm erosion than the ice-rich cliffs, perhaps due to the relatively low amounts of precipitation that occurred. Therefore, the variability of permafrost coast erosion rates is controlled by interactions between both the forcing conditions and local response mechanisms. Helicopter-based photogrammetric surveys have the potential to effectively analyze these controls with greater spatial and temporal consistency across more representative scales and resolutions than has previously been achieved, improving the capacity to adequately constrain and ultimately project future Arctic coast sensitivity.

Scharffenberg, K.C., Whalen, D., MacPhee, S.A., Marcoux, M., Iacozza, J., Davoren, G., and Loseto L.L. Oceanographic, ecological, and socio-economic impacts of an unusual summer storm in the Mackenzie Estuary. Arctic Science. September 25, 2019

With increased warming and open water due to climate change, the frequency and intensity of storm surges is expected to increase. Although studies have shown that strong storms can negatively impact Arctic ecosystems, the impact of storms on Arctic marine mammals is relatively unknown. In July 2016, an unusually large storm occurred in the Mackenzie Delta while instrumented seabed moorings equipped with hydrophones and oceanographic sensors were in place to study environmental drivers of beluga habitat use during their summer aggregation. The storm lasted up to 88 h, with maximum wind speeds reaching 60 km/h; historical wind data from Tuktoyaktuk revealed a storm of similar duration has not occurred in July in at least the past 28 years. This provided a unique opportunity to study the impacts of large storms on oceanographic conditions, beluga habitat use, and the traditional subsistence hunt that occurs annually in the delta. The storm resulted in increased water levels and localized flooding as well as a significant drop in water temperature (∼10 °C) and caused belugas to leave the area for 5 days. Although belugas returned after the storm ended, the subsistence hunt was halted resulting in the lowest beluga harvest between 1978 and 2017.

Kokelj, S.V., Palmer, M. J., Lantz, T. C., Burn, C. R. Permafrost and Periglacial Processes. March 23, 2017

Annual mean ground temperatures (Tg) decline northward from approximately −3.0°C in the boreal forest to −7.0°C in dwarf-shrub tundra in the Tuktoyuktuk Coastlands and Anderson Plain, NWT, Canada. The latitudinal decrease in Tg from forest to tundra is accompanied by an increase in the range of values measured in the central, tall-shrub tundra zone. Field measurements from 124 sites across this ecotone indicate that in undisturbed terrain Tg may approach 0°C in the forest and −4°C in dwarf-shrub tundra. The greatest range of local variation in Tg (~7°C) was observed in the tall-shrub transition zone. Undisturbed terrain units with relatively high Tg include riparian areas and slopes with drifting snow, saturated soils in polygonal peatlands and areas near lakes. Across the region, the warmest permafrost is associated with disturbances such as thaw slumps, drained lakes, areas burned by wildfires, drilling-mud sumps and roadsides. Soil saturation following terrain subsidence may increase the latent heat content of the active layer, while increases in snow depth decrease the rate of ground heat loss in autumn and winter. Such disturbances increase freezeback duration and reduce the period of conductive ground cooling, resulting in higher Tg and, in some cases, permafrost thaw. The field measurements reported here confirm that minimum Tg values in the uppermost 10 m of permafrost have increased by ~2°C since the 1970s. The widespread occurrence of Tg above −3°C indicates warm permafrost exists in disturbed and undisturbed settings across the transition from forest to tundra.

Andrachuk, M., Smit, B. Community-based vulnerability assessment of Tuktoyaktuk, NWT, Canada to environmental and socio-economic changes. Reg Environ Change 12, 867–885 (2012).

Environmental change in the Canadian Arctic has implications for livelihoods, food systems, infrastructure and Inuit culture. Although Inuit communities are located in industrialized countries, their integral connections with the natural environments contribute to significant exposures and sensitivities to changing conditions. This paper characterizes the vulnerability of Tuktoyaktuk in the western Canadian Arctic to climate change in the context of ongoing socio-economic and environmental changes. Existing stresses in the community influence infrastructure, livelihoods and wellbeing. Strategies for adapting to adverse conditions have largely been tactical and short term, rather than planned actions in anticipation of changes in climate. In light of projected intensification of climate change and a proposed natural gas pipeline in the Tuktoyaktuk area, the community is expected to experience new stresses in the future. Future adaptation planning and policy needs to enable community involvement in the protection of important community attributes.

Ford, J.D., and Pearce, T. Environment Research Letters, Volume 5, Number 1. February 2, 2010.

This letter systematically reviews and synthesizes scientific and gray literature publications (n = 420) to identify and characterize the nature of climate change vulnerability in the Inuvialuit Settlement Region of the western Canadian Arctic and identify gaps in understanding. The literature documents widespread evidence of climate change, with implications for human and biophysical systems. Adaptations are being employed to manage changing conditions and are indicative of a high adaptive capacity. However, barriers to adaptation are evident and are expected to constrain adaptive capacity to future climate change. Continued climate change is predicted for the region, with differential exposure sensitivity for communities, groups and sectors: a function of social–economic–biophysical characteristics and projected future climatic conditions. Existing climate risks are expected to increase in magnitude and frequency, although the interaction between projected changes and socio-economic–demographic trends has not been assessed. The capacity for adapting to future climate change has also not been studied. The review identifies the importance of targeted vulnerability research that works closely with community members and other stakeholders to address research needs. Importantly, the fully categorized list of reviewed references accompanying this letter will be a valuable resource for those working or planning to work in the region, capturing climate change research published since 1990. At a broader level, the systematic review methodology offers a promising tool for climate/environmental change studies in general where there is a large and emerging body of research but limited understanding of research gaps and needs.