New Insights into Permafrost Degradation and Subsidence

A recent study published in the Journal of Geophysical Research: Earth Surface has shed new light on how permafrost degradation and subsidence are occurring near the Indigenous community of Umiujaq in Nunavik, Quebec, Canada. The research, led by St-Cyr, Fortier, and Molson, has revealed a remarkable 20-year record (2004–2024) of changes in ground temperature and landscape subsidence.

Using a combination of repeated ground surveys, high-resolution laser measurements (LiDAR), and drone-based photography, the researchers have documented a cumulative ground subsidence of up to 3.8 meters. They have also found that the active layer (the seasonally thawed layer above permafrost) has been thickening, permafrost has been thinning, and unfrozen zones, referred to as taliks, have developed within the permafrost.

These changes were not occurring at a constant rate but accelerated as a result of significant climate warming between 1992 and the early 2000s.

The study demonstrates how warming can alter ground temperatures and ultimately lead to large-scale geomorphological changes to the land surface. This has important implications for ecosystems, carbon cycling, and northern infrastructure, as it highlights the potential consequences of thaw subsidence for these areas. The authors have also provided a framework for long-term monitoring that could be applied in other permafrost regions, allowing scientists to understand how diverse permafrost landscape types respond to a warming climate.