Tree rings record the responses of a landslide to changing climate in the zone of discontinuous permafrost

Rapid warming at high latitudes is outstripping the geomorphic legacies of colder climate regimes. Landslides are among the geomorphic processes now re-equilibrating to the new climates, and some of them pose hazards to human infrastructure. The Slate Creek landslide on the northern flank of the Alaska Range is encroaching on a major highway. Although its morphology resembles that of composite landslides located in non-permafrost terrain, portions of this landslide contain permafrost (perennially frozen ground). How has this subarctic landslide responded to changing climate over the last 70 years, and how might it respond in the future? We use tree-growth disturbances and remote sensing to reconstruct changes in ground motion between 1949 and the early 2020s and then relate these changes to climate. Results show that unlike unfrozen landslides, changes in air temperature were the main controller of this landslide's activity, with moisture playing a negligible role. Consistent with temperature's importance, the record of ground motion shows intermittent correlation with the Pacific Decadal Oscillation, a decadal-scale variation in ocean temperature and pressure over the North Pacific. As temperatures continue to rise and permafrost disappears, extreme rainfall events may soon replace temperature as the primary driver of this landslide's activity.