Significance: Climate warming is impacting the cryosphere in high mountain ranges, thereby enhancing the probability for more and larger mass-wasting processes to occur. This tree-ring–based snow avalanche reconstruction in the Indian Himalayas shows an increase in avalanche occurrence and runout distances in recent decades. Statistical modeling suggests that this increase in avalanche activity is linked to contemporaneous climate warming. These findings contradict the intuitive assumption that warming results in less snow, and thus fewer snow avalanches in the region, with major implications for disaster risk management and risk mitigation in a region with steadily increasing human occupation.

Rockfall in high-mountain regions is thought to be changing due to accelerating climate warming and permafrost degradation, possibly resulting in enhanced activity and larger volumes involved in individual falls. Yet the systematic lack of long-term observations of rockfall largely hampers an in-depth assessment of how activity may have been altered by a warming climate. Here we compile a continuous time series from 1920 to 2020 of periglacial rockfall activity using growth-ring records from 375 trees damaged by past rockfall at Täschgufer (Swiss Alps). We show that the ongoing warming favours the release of rockfall and that changes in activity correlate significantly with summer air temperatures at interannual and decadal timescales. An initial increase in rockfall occurred in the late 1940s to early 1950s following early twentieth century warming. From the mid-1980s, activity reached new and hitherto unprecedented levels. This long-term record of rockfall activity can help to inform the design of vital mitigation and risk reduction measures in inhabited mountain environments.

Badlands and gullied areas are among those geomorphic environments with the highest erosion rates worldwide. Nevertheless, records of their evolution and their relations with anthropogenic land transformation are scarcer. Here we combine historical data with aerial photographs and tree-ring records to reconstruct the evolution of a badland in a Mediterranean environment of Central Spain. Historical sources suggest an anthropogenic origin of this badland landscape, caused by intense quarrying activities during the 18^thcentury. Aerial photographs allowed detection of dramatic geomorphic changes and the evolution of an emerging vegetation cover since the 1960s, due to widespread reforestation. Finally, tree-ring analyses of exposed roots allowed quantification of recent channel incision of the main gully, and sheet erosion processes. Our results suggest that reforestation practices have influenced the initiation of an episode of incision in the main channel in the 1980s, through the hypothesized creation of disequilibrium in water-sediment balance following decoupling of hillslopes from channel processes. These findings imply an asymmetry in the geomorphic response of badlands to erosion such that in the early evolution stages, vegetation removal results in gullying, but that reforestation alone does not necessarily stabilize the landforms and may even promote renewed incision.