Late-Holocene climatic changes as detected by the growth and decay of ice wedges on the southern shore of Hudson Strait, northern Québec, Canada

Abstract

The dating of cryoturbated palaeosols associated with past ice-wedge activity on late-Holocene sandy fluvial terraces in a region of continuous permafrost leads to an interpretation of periods of ice-wedge growth and active cracking that alternated with periods of decay, dormancy and active layer deepening. The reconstruc tion corresponds with palaeoclimatic information obtained from existing Arctic-wide and regional proxy rec ords. The ‘Little Ice Age’ stands out as a period of intense ice-wedge activity in the study area. It was followed by a warm thawing interval during the first half of the twentieth century. From ad 1946 to 1991, a well-documented cooling of the climate took place, which reactivated 94% of the studied ice wedges. The pyramidal shape of ice-wedge tops and the depths of the upgrowth features could be correlated between sites several kilometres apart, clearly indicating a regional climatic response. The mean annual air temperature dropped from about–7.8°C in 1946 to–8.9°C in 1991. The threshold temperature for active ice wedges probably lies within this range.