Abstract
Thermokarst is a leading destructive geomorphic process in permafrost regions, triggered by the melting of ground ice. Ice-wedge thermokarst features, such as thermokarst lakes and drained-lake basins, are the most abundant thermokarst landforms in the Arctic. In this study, we reassess interactions among factors that drive thermokarst development and evaluate the role of ice-wedge systems in thermokarst-lake formation and evolution. We summarize the factors affecting thermokarst and evaluate mechanisms that facilitate thermokarst-lake development in landscapes of the continuous permafrost zone with abundant ice wedges. Specifically, we (1) review the conditions governing thermokarst development, including climate, ground-ice content, and regional variability; (2) compare the roles of vegetation, soil, snow, water, and disturbance in initiating thermokarst; and (3) examine the patterns and processes governing thermokarst-lake development in the continuous permafrost zone, where ice wedges are abundant and strongly control landscape evolution. Once thermokarst is initiated, both ice wedges and segregated ice are important to the formation and evolution of thermokarst lakes, whereas ice wedges alone are rarely responsible for lake formation. We identify key processes in thermokarst-lake formation in ice-wedge environments and synthesize their roles into a new conceptual model that better accounts for patterns observed across lake-dominated Arctic landscapes.