Contemporary and past aeolian deposition rates in periglacial conditions (Ebba Valley, central Spitsbergen)

Quantitative measurements of aeolian activity at high latitudes are not currently carried out on a large scale, even though these processes are important elements of the geomorphic system of polar regions, which are particularly affected by climate change. This study presents the results of aeolian deposition rates measured and calculated for one of the central Spitsbergen postglacial valleys (Ebba Valley). The results are based on seven summer season field campaigns (2012-2018), as well as on AMS C-14 and OSL dating of niveo-aeolian and aeolian sediments. Contemporary mean aeolian deposition rates ranged from 0.1 to 22.9 g.m -(2) day (-1) over selected parts of the valley and averaged from 2.1 to 12.3 g-m(2) day (-1) over the studied summer seasons. Interestingly strong relationships (r(2) = 0.71, p = 0.017) between mean air temperature and mean aeolian deposition were observed, possibly indicating the importance of the source material delivered to the valley by fluvioglacial processes. Moreover, aeolian deposition dependence on the source material reflected in the local nature of the process was observed. Niveo-aeolian deposition rates were estimated for the period since the 11th century, through the Little Ice Age, till the second half of the 20th century and revealed a rather constant value of 0.05 cm per year. Since then, the niveo-aeolian deposition rate has significantly increased and equalled 0.3 cm per year, which may be related to rising air temperatures and associated pan-Arctic environmental changes

Divergence of Arctic shrub growth associated with sea ice decline

Abstract Arctic sea ice extent (SIE) is declining at an accelerating rate with a wide range of ecological consequences. However, determining sea ice effects on tundra vegetation remains a challenge. In this study, we examined the universality or lack thereof in tundra shrub growth responses to changes in SIE and summer climate across the Pan-Arctic, taking advantage of 23 tundra shrub-ring chronologies from 19 widely distributed sites (56°N to 83°N). We show a clear divergence in shrub growth responses to SIE that began in the mid-1990s, with 39% of the chronologies showing declines and 57% showing increases in radial growth (decreasers and increasers, respectively). Structural equation models revealed that declining SIE was associated with rising air temperature and precipitation for increasers and with increasingly dry conditions for decreasers. Decreasers tended to be from areas of the Arctic with lower summer precipitation and their growth decline was related to decreases in the standardized precipitation evapotranspiration index. Our findings suggest that moisture limitation, associated with declining SIE, might inhibit the positive effects of warming on shrub growth over a considerable part of the terrestrial Arctic, thereby complicating predictions of vegetation change and future tundra productivity