Rates and processes of aeolian soil erosion in West Greenland

Abstract

In arid landscapes across the globe, aeolian processes are key drivers of landscape change, but arid Arctic regions are often overlooked. In the Kangerlussuaq region of West Greenland, strong katabatic winds have removed discrete patches of soil and vegetation, exposing unproductive glacial till and bedrock. Although lake-sediment records suggest that landscape destabilization began approximately 1000 years ago, the upland soil erosion has never been directly dated. We use a novel application of lichenometry to estimate the rates and timing of soil erosion. We show that the formation of deflation patches occurred approximately 800-230 years ago, in general agreement with lake-sediment records. In West Greenland, the 'Little Ice Age' (AD 1350-1880) was characterized by a cold and arid climate, conditions that increased susceptibility to erosion. On average, deflation patches are expanding at a rate of 2.5 cm yr −1 , and variation in the rate of patch expansion cannot be explained by proximity to the Greenland Ice Sheet (GrIS), slope, aspect, elevation, or patch size. An erosional threshold exists in this aeolian system, with climate conditions necessary for patch formation likely harsher than those necessary for continued patch expansion, a result that has implications for land management in arid regions. Currently, deflation patches are expanding throughout the study region and are forming in areas close to the GrIS, but future deflation rates are dependent on projected climate and potential land-use changes. Our results stress the importance of aeolian processes in arid polar landscapes such as Kangerlussuaq, and demonstrate the use of aeolian landforms in paleoclimate reconstructions and predicting future landscape change.

Fine-grained quartz from cryoconite holes of the Russell Glacier, southwest Greenland – a scanning electron microscopy study

“…However a fairly rapid and an efficient rounding of fine-grained particles under suspension conditions is considered by some studies (Foreman et al 2007;Mazzullo et al 1992;Mazzullo 1986;Werner, Merino 1997). Strong winds (see Study area) with a potential of mechanical rounding are a common feature in the Kangerlussuaq area, where wind erosion is an important geomorphic agent (Gillies et al 2009) that removes discrete patches of fine-grained soil and further exposing the bedrock (Heindel et al 2017). Along with our previous research, number of aeolian-origin grains of sand fraction occur in the sediments close to the ice margin .…”

Quantifying rates of soil deflation with Structure-from-Motion photogrammetry in west Greenland

“…These three scarps had annual retreat rates of −0.5 (± 1.1), −0.75 (± 1.0), and −0.6 (± 1.5) cm, respectively. While still less than 2.5 cm yr −1 , the retreat rates for these deflation patches are well within the range of rates estimated using lichenometry (Heindel, Culler, and Virginia 2017). Erosion along the scarp was especially noticeable at LLGRID6, where the scarp was more undercut than at any other deflation patch.…”

“…To capture these gradients in climate and land cover, we established four study sites within the Kangerlussuaq region, listed in increasing proximity to the GrIS: Town, Sugarloaf, Long Lake, and Inland ( Figure 1). These sites are part of a larger effort to understand the extent, age, and impact of deflation patches, using techniques such as lichenometry and satellite remote sensing (Heindel et al, 2015;Heindel, Culler, and Virginia 2017). For the purposes of this study, we chose ten deflation patches for photogrammetric analysis: two at Town, four at Sugarloaf, two at Long Lake, and two at Inland (Table 1).…”

“…Although modern rates of soil erosion are unknown, deflation-patch expansion during the past 425 years has been estimated to be 2.5 cm yr −1 using lichenometry (Heindel, Culler, and Virginia 2017). In that prior study, rates of patch expansion were found to be similar among patches and did not correlate with proximity to the GrIS, aspect, or slope.…”

“…Although deflation patches are generally low in biomass, they provide habitat for biological soil crusts (biocrusts), assemblages of lichens, mosses, algae, fungi, and other microorganisms (e.g., Weber, Büdel, and Belnap 2016). Deflation patches are bounded on the downwind side by a sharp erosional front, or scarp, that moves across the landscape (Heindel, Culler, and Virginia 2017). These scarps are often undercut, and deflation patches expand when blocks of soil and CONTACT Ruth C. Heindel ruth.heindel@colorado.edu vegetation collapse.…”