The Himalayas have the largest number of glaciers on Earth outside the poles and have lost billions of tonnes of ice due to accelerated melting caused by global warming. It is also possible that thinning of or retreating glaciers can destabilize the ground below and around them, which they would have otherwise buttressed. This can make the area prone to landslides, rockfall, or slumps and even potentially lead to the collapse of entire mountain slopes. Although it is challenging to monitor catastrophic landslides in real time, non-catastrophic slow-moving landslides, which move downslope for months to decades (or even centuries) at rates ranging from millimeters to several meters per year, provide an excellent opportunity to study landslide processes.

Slow-moving landslides cause significant erosion, regulate hill slope angles and topographic relief, and are a principal geologic hazard that damages infrastructure. A potential consequence of climate warming drives these slope failures, wherein the warmer summer-air temperatures and more significant rainfall events over seasonal time scale through increased pore-water pressure drive heat into the active layer, melting ice and decreasing soil shear strength. Warming also triggers permafrost thawing, which causes active layer detachment failure, further leading to retrogressive thaw slumping and localized surficial landslide. Rapid permafrost thaw alters the geotechnical properties of the hillslope, including reduced cohesion and increased hydraulic connectivity, making hillslopes more susceptible to landslides. In addition, the topography can potentially exacerbate land-sliding by controlling ground ice distribution and water movement in the subsurface. Using field and aerial remote-sensing measurements of the morphological and morphometric characteristics of the landslides, we can assess the influence of thawing ground ice on their propagation style and dynamics.

Furthermore, the satellite-based interferometric synthetic aperture radar (InSAR) data can be analyzed alongside precipitation and groundwater data to explore hydrologic controls on landslide motion. This study will discuss the current state of research on slow-moving landslides and how they are affected by rising temperatures and increasing permafrost melting in the Himalayas. This research may highlight the need for observations and models to help identify and predict precipitation, temperature, and topography-controlled changes to landslide activity.