Landslide response to climate change in permafrost regions

Rapid permafrost thaw in the high-latitude and high-elevation areas increases hillslope susceptibility to landsliding by altering geotechnical properties of hillslope materials, including reduced cohesion and increased hydraulic connectivity. This review synthesizes the fundamental processes that will increase landslide frequency and magnitude in permafrost regions in the coming decades with observational and analytical studies that document landslide regimes at high latitudes and elevations. We synthesize the available literature to address five questions of practical importance, which can be used to evaluate fundamental knowledge of landslide process and inform land management decisions to mitigate geohazards and environmental impacts. After permafrost thaws, we predict that landslides will be driven primarily by atmospheric input of moisture and freeze-thaw fracturing rather than responding to disconnected and perched groundwater, melting permafrost ice, and a plane of weakness between ground ice and the active layer. Transition between equilibrium states is likely to increase landslide frequency and magnitude, alter dominant failure styles, and mobilize carbon over timescales ranging from seasons to centuries. We also evaluate potential implications of increased landslide activity on local nutrient and sediment connectivity, atmospheric carbon feedbacks, and hazards to people and infrastructure. Last, we suggest three key areas for future research to produce primary data and analysis that will fill gaps in the existing understanding of landslide regimes in permafrost regions. These suggestions include 1) expand the geographic extent of English-language research on landslides in permafrost; 2) maintain or initiate long-term monitoring projects and aerial data collection; and 3) quantify the net effect on the terrestrial carbon budget. (C) 2019 Elsevier B.V. All rights reserved.