Widespread rock wall permafrost degradation in Greenland by the end of the 21st century under CMIP6 projections

Abstract

Permafrost in rock walls is a critical component of cold mountain environments, as it plays a crucial role in slope stability. Under warming climate, the interstitial ice in fractures and porosities thaws, compromising slope stability and inducing failures. Although in Greenland this phenomenon is known to have recently generated catastrophic landslides that have severely impacted the local community, there is currently no knowledge of its broad distribution nor of its response to climate projections. Here we model current and future rock wall permafrost extents in Greenland, using field data and CMIP6 projections under different scenarios. In the current climatic conditions, rock wall permafrost is widespread in the region, and 76% of the rockwalls are likely hosting permafrost. By the end of the 21st century, two dominant climatic trends—arctic amplification and Atlantic Meridional Overturning Circulation (AMOC) weakening—emerge, shaping the future of rock wall permafrost in this region. While arctic amplification drives virtually certain degradation in northern sectors for all scenarios investigated, AMOC weakening poses varied impacts in southern sectors, including stationary conditions (possible) or cooling (very unlikely). Central West Greenland, a region known for landslide propensity, is very likely to experience substantial permafrost degradation. Overall, our findings suggest very likely degradation of rock wall permafrost across Greenland. We emphasize the need for comprehensive monitoring and proactive protection of people and infrastructure from rising rockfall and landslide hazard, both in Greenland and across Arctic.