Invited Perspective: What Lies Beneath a Changing Arctic?

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.