Permafrost and climate change at Herschel Island (Qikiqtaruq), Yukon Territory, Canada

Abstract

[1] Herschel Island, in the southern Beaufort Sea, is dominantly a glacier ice thrust feature composed of ice-rich, perennially frozen sediments. Climate data are available for Herschel Island from 1899 to 1905 and 1995-2006. Air temperatures at Herschel Island are similar to sites on the adjacent mainland. Late winter snow depth is only about 20 cm, or half the depth on the mainland, and local topography defines the sites of annually recurring snowdrifts. Near-surface ground temperatures, thaw depths, and ground ice contents have been investigated over a 750-m transect leading up Collinson Head, the easternmost part of the island. The ground temperature profile to 42-m depth indicates recent warming of permafrost because the temperature decreases with depth. The temperature at 15-m depth is À8.0°C, the same as the annual mean temperature at 1-m depth at windswept sites along the transect. A simulation of the ground thermal regime, calibrated with local ground properties, equilibrated with the climate of 1899-1905, and driven by the climate of the region during the 20th century reproduces the present ground temperature profile and the annual temperature cycle for 1-m depth at windswept sites. The model indicates that the mean annual temperatures at the top of permafrost and at 20-m depth have increased by 2.6 and 1.9°C, respectively, since 1899-1905, and the perturbation in ground temperature has reached about 120-m depth. Active layer thickness measured in the terrain types studied on Herschel Island is about 55 cm, 15 to 25 cm greater than field data from these units collected in 1985.

Modeling the temperature evolution of Svalbard permafrost during the 20th and 21st century

“…The heat flow model used in this study does not account for annual or inter-annual variations of water content in the active layer layers, like other model approaches do (e.g. Zhang et al, 2003;Burn and Zhang, 2009). However, the model performed well during calibration, even in the ice-rich site of Endalen.…”

Variability and change in the Canadian cryosphere

“…3b). Greater changes in permafrost temperature are observed in the colder tundra environments of the western Arctic, with increases of up to 0.8°C per decade since the early 1970s (Burn and Kokelj 2009;Burn and Zhang 2009). In the eastern Canadian Arctic and in northern Quebec warming has been more recent, beginning in the mid 1990s, and varies from no change in the discontinuous permafrost zone to up to +1.2°C per decade in colder permafrost or at bedrock sites.…”

Transformation of terrestrial organic matter along thermokarst-affected permafrost coasts in the Arctic

“…Permafrost on Qikiqtaruk is extremely ice-rich with mean ice volumes ranging between 30 and 60 vol%, and up to values N 90 vol%, when underlain by massive ground ice beds (Couture and Pollard, 2015;Fritz et al, 2015;Lantuit et al, 2012a). The active layer depth generally ranges between 40 and 60 cm in summer (Burn and Zhang, 2009;Kokelj et al, 2002). The vegetation on Qikiqtaruk is lowland tundra dominated by graminoids and dwarf shrubs, with a relatively species-rich forb flora and a well-developed moss layer (Kennedy et al, 2001;Myers-Smith et al, 2011;Smith et al, 1989).…”