Twenty Year Study Measures Permafrost Subsidence in Northern Québec

Eos Earth & Space Science reported that a 20-year monitoring study from 2004 to 2024 has documented changing ground thermal dynamics and land surface sinking near the Indigenous community of Umiujaq in Nunavik, Québec, Canada. The research tracked permafrost degradation within a discontinuous permafrost zone. [1]

According to Eos Earth & Space Science, researchers led by St-Cyr used repeated ground surveys, high-resolution laser measurements known as LiDAR, and drone-based photography to monitor terrain changes. The team documented cumulative ground subsidence of up to 3.8 meters as perennially frozen ground thawed and underground ice melted over two decades. [1]

Permafrost is defined as soil or underwater sediment that remains continuously frozen below zero degrees Celsius for two or more years. On land, it typically sits beneath an active layer of soil that freezes and thaws according to the season. The oldest permafrost has remained continuously frozen for around 700,000 years, with vertical depths ranging from less than one meter to greater than 1,500 meters. [4]

Subsidence refers to the downward vertical movement of the surface of the Earth with little or no horizontal movement, which can be driven by natural processes or human activities. Eos Earth & Space Science noted that while thawing ground ice causes surface settling, multi-decade observational records linking ground temperatures to physical landscape changes remain rare. [1][5]