Invited Perspective: What Lies Beneath a Changing Arctic?

Abstract

Abstract. As permafrost thaws in the Arctic, new subsurface pathways open for the movement of groundwater, energy, and solutes. We identify different ways that these subsurface changes are driving observed surface phenomena, including the potential for increased contaminant transport, modification to water resources, and enhanced rates of infrastructure (e.g. buildings and roads) damage. Further, as permafrost thaws it allows groundwater to transport carbon, nutrients, and other dissolved constituents from terrestrial to aquatic environments via progressively deeper subsurface flow paths. Cryohydrogeology, the study of groundwater in cold regions, must be included in Northern research initiatives to account for this hidden catalyst of environmental and societal change.

A review of groundwater in high mountain environments

“…Permafrost acts as a barrier to groundwater flow (Mckenzie et al, 2020). In high mountain areas where topographic gradients are high, permafrost limits deeper groundwater flow paths that would otherwise occur (Ge et al, 2011;Rogger et al, 2017).…”

Guidelines for cold‐regions groundwater numerical modeling

“…Despite the present limitations, we are confident that these cold‐regions groundwater models can enable communities, stakeholders, and scientists from different fields to address fundamental water resources challenges in cold regions. Considering the necessity of including hydrogeology in northern research initiatives (McKenzie et al, 2020), such modeling tools can assist in managing groundwater resources, testing usage scenarios, and developing hydrogeological understanding of cold‐regions aquifers.…”

“…These dynamic groundwater flow systems can sustain perennial flow networks between aquifers and surface water bodies through unfrozen pathways (Devoie, Craig, Connon, & Quinton, 2019; Jepsen, Voss, Walvoord, Minsley, & Rover, 2013; Walvoord & Kurylyk, 2016) (Figure 1c,d). However, the overall effect of permafrost thaw on groundwater flow systems, and more particularly on groundwater–surface water interactions, remains unknown, with studies suggesting that these interactions can be highly variable and dependent on the physical setting (Lemieux et al, 2020; McKenzie et al, 2020; Walvoord & Kurylyk, 2016). For example, the impact of permafrost thaw on northern groundwater resources is mixed—some communities will suffer from a loss of surface water availability due to permafrost thaw (e.g., Smith, Sheng, MacDonald, & Hinzman, 2005; White, Gerlach, Loring, Tidwell, & Chambers, 2007), while others may benefit as newly formed aquifers created by permafrost thaw can provide critical drinking water resources (Lemieux et al, 2016).…”

“…For example, the impact of permafrost thaw on northern groundwater resources is mixed-some communities will suffer from a loss of surface water availability due to permafrost thaw (e.g., Smith, Sheng, MacDonald, & Hinzman, 2005;White, Gerlach, Loring, Tidwell, & Chambers, 2007), while others may benefit as newly formed aquifers created by permafrost thaw can provide critical drinking water resources (Lemieux et al, 2016). Groundwater processes in permafrost environments are also of great importance for northern infrastructure (McKenzie et al, 2020), as heat advection may accelerate thawing and environmental changes. As examples, F I G U R E 1 Conceptual hydrogeologic permafrost systems under the present climate conditions for (a) summer and (b) winter, and its potential changes in a warmer climate for (c) summer and (d) winter cryohydrogeology is important for thawing under road embankments (Chen, Fortier, McKenzie, & Sliger, 2020) and the formation of aufeis (or icing) (Chesnokova, Baraër & Bouchard, 2020;Ensom et al, 2020).…”

Opposing Effects of Climate and Permafrost Thaw on CH4 and CO2 Emissions From Northern Lakes

“…Arctic amplification has caused temperatures in northern peatland regions to increase much faster than the global average, and these regions are furthermore experiencing rapid permafrost thaw (Olefeldt et al., 2016; Treat & Jones, 2018). To understand the climate sensitivity of peatland lake CO 2 and CH 4 emissions it is thus necessary to account for both the direct effects of warming and the indirect effects arising from increased hydrological connectivity following permafrost thaw (McKenzie et al., 2021).…”