Modeled (1990–2100) variations in active‐layer thickness and ice‐wedge activity near Salluit, Nunavik (Canada)

Simulations with a one‐dimensional heat transfer model (TONE) were performed to reproduce the near surface ground temperature regime in the four main types of soil profiles found in Narsajuaq River Valley (Nunavik, Canada) for the period 1990–2100. The permafrost thermal regime was simulated using climate data from a reanalysis (1948–2002), climate stations (1989–1991, 2002–2019) and simulations based on climate warming scenarios RCP4.5 and RCP8.5 (2019–2100). The model was calibrated based on extensive field measurements made between 1989 and 2019. The results were used to estimate when soil thermal contraction cracking will eventually stop and to forecast the melting of ice wedges due to active‐layer thickening. For the period 1990–2019, all soil profiles experienced cracking every year until 2006, when cracking became intermittent during a warm period before completely stopping in 2009–2010, after which cracking resumed during colder years. Ice‐wedge tops melted from 1992 to 2010 as the active layer thickened, indicating that top‐down ice‐wedge degradation can occur simultaneously with cracking and growth in width. Our predictions show that ice wedges in the valley will completely stop cracking between 2024 and 2096, first in sandy soils and later in soils with thicker organic horizons. The timing will also depend on greenhouse gas concentration trajectories. All ice wedges in the study area will probably experience some degradation of their main body before the end of the century, causing their roots to become relict ice by the end of the 21st century.