Isotropic thaw subsidence in undisturbed permafrost landscapes

Abstract

[1] Observations in undisturbed terrain within some regions of the Arctic reveal limited correlation between increasing air temperature and the thickness of the seasonally thawed layer above ice-rich permafrost. Here we describe landscape-scale, thaw-induced subsidence lacking the topographic contrasts associated with thermokarst terrain. A high-resolution, 11 year record of temperature and vertical movement at the ground surface from contrasting physiographic regions of northern Alaska, obtained with differential global positioning systems technology, indicates that thaw of an ice-rich layer at the top of permafrost has produced decimeter-scale subsidence extending over the entire landscapes. Without specialized observation techniques the subsidence is not apparent to observers at the surface. This "isotropic thaw subsidence" explains the apparent stability of active layer thickness records from some landscapes of northern Alaska, despite warming near-surface air temperatures. Integrated over extensive regions, it may be responsible for thawing large volumes of carbon-rich substrate and could have negative impacts on infrastructure.

Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction

“…Our comprehensive observations of intensified thaw subsidence in places of shallow ALT (Fig. 10) indicate the opposite to modelling estimations of ALT as a function of surface subsidence by Liu et al (2012), but are in accordance with the results of ground-based ALT measurements corrected for thaw subsidence by Shiklomanov et al (2013), and suggest near-surface occurrence of ground ice in areas of strong subsidence. Where deeper thaw encounters ice-rich basal soil horizons or ice-wedge tops, this results not only in active layer deepening, but also in subsidence.…”

“…Similarly, Short et al (2011) showed −10 to −15 cm of terrain displacement during summer 2010 near Collinson Head on Herschel Island, a location of constant rapid coastal erosion rates (Lantuit and Pollard, 2008). Remote sensing data showed that seasonal thaw settlement in Alaska is in the range of 1-4 cm (Little et al, 2003) and can be up to 12 cm in places (Liu et al, 2014), while in situ long-term observations of permafrost thaw subsidence are 0.8-1.7 cm a −1 (Shiklomanov et al, 2013). Generally, longterm subsidence occurs by thaw at the top of ice-rich permafrost and drainage of meltwater.…”

Terrestrial laser scanning for quantifying small-scale vertical movements of the ground surface in Artic permafrost regions

“…Besides these spatially confined processes, relatively uniform and gradual isotropic thaw subsidence, which is 30 not exhibited by any surface disturbance, was recently observed in Arctic permafrost regions (e.g. Shiklomanov et al, 2013).…”

“…Little et al, 2003;Shiklomanov et al, 2013;Beck et al, 2015;Streletskiy et al, 2016) or thaw-tubes (e.g. Nixon et al, 2003;Short et al, 2014).…”

Vertical movements of frost mounds in subarctic permafrost regions analyzed using geodetic survey and satellite interferometry

“…A number of research teams have also successfully used d-GPS technology to monitor frost heave and thaw subsidence. For example, Little (2006), Little et al (2003) and Nelson et al (2001) collected d-GPS measurements in flat areas of northern Alaska, where they recorded heave and subsidence movements of up to 0.06 m. Shiklomanov et al (2013) used d-GPS technology to quantify isotropic thaw subsidence in permafrost areas of northern Alaska, and Wirz et al (2015) derived the temporal variability of mountain permafrost slopes using d-GPS measurements.…”