Can shrubs help to reconstruct historical glacier retreats?

Abstract

In the 21st century, most of the world's glaciers are expected to retreat due to further global warming. The range of this predicted retreat varies widely as a result of uncertainties in climate and glacier models. To calibrate and validate glacier models, past records of glacier mass balance are necessary, which often only span several decades. Long-term reconstructions of glacier mass balance could increase the precision of glacier models by providing the required calibration data. Here we show the possibility of applying shrub growth increments as an on-site proxy for glacier summer mass balance, exemplified by Salix shrubs in Finse, Norway. We further discuss the challenges which this method needs to meet and address the high potential of shrub growth increments for reconstructing glacier summer mass balance in remote areas.

Shrubs shed light on 20th century Greenland Ice Sheet melting

“…Regarding a regional transfer function (Table 1), CWT performed better in comparison to ST, which frequently has been usedpartly in combination with other proxiesto reconstruct variables related to GrIS-melt Fettweis et al 2011;Frauenfeld et al 2011;Hanna et al 2011;Box 2013). These findings are supported by other studies showing the ability of tree rings (Watson & Luckman 2004;Larocque & Smith 2005;Wood et al 2011) and shrub rings (Buras et al 2012) to reconstruct variables related to glacier melt. To our knowledge, the reconstruction shown in the present study is the first GrIS-melt reconstruction derived from shrub wood-anatomy data.…”

“…The mechanisms behind the observed correlations are most likely dependencies of both variables upon a similar set of climate parameters (Buras et al 2012). The mechanisms behind the observed correlations are most likely dependencies of both variables upon a similar set of climate parameters (Buras et al 2012).…”

“…One may be surprised to find shrub cell-walls with an average thickness of 2.78 lm correlating with GrISmelt data representative of 184 000 km², as it is obvious that there is no direct mechanistic link between these two parameters. The mechanisms behind the observed correlations are most likely dependencies of both variables upon a similar set of climate parameters (Buras et al 2012). GrIS-melt is affected by various factors, of which air temperature appears to be the most influential ).…”

“…Ring-widths have earlier been used to successfully explore for correlations with glacier-melt related variables (Watson & Luckman 2004;Larocque & Smith 2005;Wood et al 2011;Buras et al 2012), but to our knowledge no study has investigated the relationships with wood-anatomy parameters. Ring-widths have earlier been used to successfully explore for correlations with glacier-melt related variables (Watson & Luckman 2004;Larocque & Smith 2005;Wood et al 2011;Buras et al 2012), but to our knowledge no study has investigated the relationships with wood-anatomy parameters.…”

“…Several studies from the Arctic and Alpine regions have reported significant correlations between growth of various shrub species and summer temperature (Weijers et al 2010(Weijers et al , 2012Blok et al 2011;Buras et al 2012;Buras & Wilmking 2014;Myers-Smith et al 2015;Lehej cek et al 2016) and Buras et al (2012) reported the possibility of using Salix spp. Therefore, to support the available reconstructions it is desirable to obtain additional, independent estimates of past GrISmelt, in particular in regions where climate station data are lacking.…”