Impacts of ecological succession and climate warming on permafrost aggradation in drained lake basins of the Tuktoyaktuk Coastlands, Northwest Territories, Canada

Abstract

Rapidly increasing air temperatures will alter permafrost conditions across the Arctic, but variation in soils, vegetation, snow conditions, and their effects on ground thermal regime complicate prediction across spatial and temporal scales. Processes that result in the emergence of new surfaces (lake drainage, channel migration, isostatic uplift, etc.) provide an opportunity to assess the factors influencing permafrost aggradation and terrain evolution under a warming climate. In this study we describe ground temperatures, vegetation, and snow and soil conditions at six drained lake basins (DLBs) that have exposed new terrain in the Tuktoyaktuk Coastlands in the last 20-100 years. We also use one-dimensional thermal modeling to assess the impact of ecological succession and future climate scenarios on permafrost conditions in historical and future DLBs. Our field observations show that deep snow pack and shallow organic layers at shrub-dominated DLBs promote increased thaw depth and ground temperatures compared to a sedge-dominated DLB and two ancient DLB reference sites. Modeling of past and future drainages shows that climate warming projected under RCP 8.5 will reduce rates of permafrost aggradation and thickness, and drive top-down thaw that could degrade permafrost in shrub-dominated DLBs by the end of the century. Permafrost at sedge-dominated sites was more resilient to warming under RCP 8.5, with the onset of top-down thaw delayed until about 2080.Together, this indicates that the effects of ecological succession on organic soil development and snow drifting will strongly influence the aggradation and resilience of permafrost in DLBs. Our analysis suggests that DLBs and other emergent landscapes will be the first permafrost-free environments to develop under a warming climate in the continuous permafrost zone. K E Y W O R D S climate change, drained lake, permafrost, tundra 1 | INTRODUCTION Air temperatures in northern Canada have increased at more than double the average global rate. 1,2 Accelerated warming has increased permafrost temperatures and active-layer thickness at sites across theThe data used in this study will be made available through a Northwest Territories Geological Survey Open Data Report.

Rapid Saline Permafrost Thaw Below a Shallow Thermokarst Lake in Arctic Alaska

“…The formation and drainage of lakes have shaped lake and drained lake basin (L‐DLB) landscapes in lowland permafrost regions (Grosse et al., 2013; Jones et al., 2022). The long‐term evolution of L‐DLB landscapes is well documented (Jorgenson & Shur, 2007; Wolfe et al., 2020); however, few studies have directly observed L‐DLB surface dynamics in the field using observational data sets (e.g., Arp et al., 2023; Jones & Arp, 2015; Jones et al., 2023b; Lantz et al., 2022). Even fewer studies have observed sub‐surface dynamics associated with sub‐lake permafrost thaw and talik formation (e.g., Creighton et al., 2018; Roy‐Leveillee & Burn, 2017).…”

Landcover succession for recently drained lakes in permafrost on the Yamal peninsula, Western Siberia

“…DLBs have previously found to be sites of wetland formation (Lantz et al, 2022), however they have been mostly described as wetlands in older basins on centennial or millennial timescales. Following drainage, landcover of the area has a tendency to become more heterogeneous over time (Figure 5).…”