Permafrost aggradation along the emerging eastern coast of Hudson Bay, Nunavik (northern Québec, Canada)

Emerging polar coasts have different geothermal regimes than those in submergence. While the scientific community is mainly concerned with rapidly eroding permafrost coastlines in sedimentary formations where relative sea level is rising, much less research has been dedicated to permafrost dynamics in emergent coastal regions where post‐glacial uplift is ongoing. The eastern Hudson Bay coast of Nunavik (northern Québec, Canada) is undergoing glacio‐isostatic uplift at a current emergence rate of about 13 mm/yr, outpacing the current global sea‐level rise (~3 mm/yr) and progressively exposing new land to climate conditions favorable for permafrost formation. To observe incipient permafrost in the shore zone over time, in 2005 we strategically installed a thermistor cable down to a depth of 23 m at a high‐tide level site. We detected the formation and the continuing deepening of permafrost near the surface. Freezing of the ground was also favored by a succession of several cold years in Nunavik since 2010. The near 0°C temperature profile at greater depths also reveals the cooling influence of deep Hudson Bay waters on the shore zone ground temperature regime and the probable presence of subsea permafrost offshore of the measurement site.