Post-LIA glacier changes along a latitudinal transect in the Central Italian Alps

Abstract

Abstract. The variability of glacier response to atmospheric temperature rise in different topo-climatic settings is still a matter of debate. To address this question in the Central Italian Alps, we compile a post-LIA (Little Ice Age) multitemporal glacier inventory (1860–1954–1990–2003–2007) along a latitudinal transect that originates north of the continental divide in the Livigno Mountains and extends south through the Disgrazia and Orobie ranges, encompassing continental-to-maritime climatic settings. In these sub-regions, we examine the area change of 111 glaciers. Overall, the total glacierized area has declined from 34.1 to 10.1 km2, with a substantial increase in the number of small glaciers due to fragmentation. The average annual decrease (AAD) in glacier area has risen by about 1 order of magnitude from 1860–1990 (Livigno: 0.45; Orobie: 0.42; and Disgrazia: 0.39 % a−1) to 1990–2007 (Livigno: 3.08; Orobie: 2.44; and Disgrazia: 2.27 % a−1). This ranking changes when considering glaciers smaller than 0.5 km2 only (i.e., we remove the confounding caused by large glaciers in Disgrazia), so that post-1990 AAD follows the latitudinal gradient and Orobie glaciers stand out (Livigno: 4.07; Disgrazia: 3.57; and Orobie: 2.47 % a−1). More recent (2007–2013) field-based mass balances in three selected small glaciers confirm post-1990 trends showing the consistently highest retreat in continental Livigno and minimal area loss in maritime Orobie, with Disgrazia displaying transitional behavior. We argue that the recent resilience of glaciers in Orobie is a consequence of their decoupling from synoptic atmospheric temperature trends, a decoupling that arises from the combination of local topographic configuration (i.e., deep, north-facing cirques) and high winter precipitation, which ensures high snow-avalanche supply, as well as high summer shading and sheltering. Our hypothesis is further supported by the lack of correlations between glacier change and glacier attributes in Orobie, as well as by the higher variability in ELA,sub>0 positioning, post-LIA glacier change, and interannual mass balances, as we move southward along the transect.

Analysis of the mass balance time series of glaciers in the Italian Alps

“…2) are also anti-correlated with the winter NAO (Spearman correlation significant at the 0.01 level). In line with the findings of Reichert et al (2001), Six et al (2001) and Thibert et al (2013), a negative correlation was calculated between B s /B a and the NAO in the accumulation season. For the Italian glaciers the albedo feedback from wet/dry winters (with low/high NAO, respectively) can at least partly explain this behavior.…”

“…There are notably high correlations in the Ortles Cevedale between Careser and La Mare and between Fontana Bianca and La Mare glaciers. A similarly high correlation is observed between Pendente and Malavalle glaciers in Val Ridanna, whereas there is a much lower correlation between the two glaciers of the Gran Paradiso Group, which suggests that differences in local topo-climatic factors can be decisive on such small ice bodies (e.g., Kuhn, 1995;DeBeer and Sharp, 2009;Carturan et al, 2013c;Scotti et al, 2014;Colucci and Guglielmin, 2015). For most glaciers, B a is more correlated to B s than to B w (Table 4) ablation.…”

Destabilisation of Creeping Permafrost: The Plator Rock Glacier Case Study (Central Italian Alps)

“…Zone 1 is the root (upper) zone of the rock glacier, where the talus supplying it flattens to a partly depressed zone closed downslope by a small lobe and the edge of scarp 1 ( Figure 2). A semi-permanent avalanche-derived snowfield occupies the depression and suggests the former presence of a small cirque glacier during the Little Ice Age (LIA) (Bonardi et al, 2012;Scotti et al, 2014). Zone 2 occupies the mid-portion between scarps 1 and 2, where a tension crack is present.…”

Plant and arthropod colonisation of a glacier foreland in a peripheral mountain range

“…However, almost all the previous works were performed on glacier forelands located in the inner massifs of the Alpine chain, while knowledge about peripheral mountain ranges is still poor due to the scarcity of glaciers. 50 Nevertheless, in the context of climate change, peripheral mountain ranges of any mountain system deserve particular attention for at least three reasons: (1) they display plausible future scenarios for the whole chain and allow to directly test the fate of high mountain 55 ecosystems, as the relatively low elevation makes them particularly susceptible to climate change (Bona et al 2013;Pauli, Gottfried, and Grabherr 2003); (2) they are presently characterised by high values of species richness and endemism, since they were largely ice-free during 60 glacial periods and acted as refugia for many plant (Martini et al 2012;Schönswetter et al 2005) and arthropod species (Latella, Verdari, and Gobbi 2012;Lohse, Nicholls, and Stone 2011); (3) their spatial arrangement causes remarkable climatic differences with 65 respect to the inner massifs, affecting the altitudinal distribution of glaciers and their response to climate change (Scotti, Brardinoni, and Crosta 2014), as well as the elevation of vegetation belts (Caccianiga et al 2008;Pirola and Credaro 1977 (Ceriani and Carelli 2000). The high winter precipitation causes Orobian glaciers to be supply-limited rather than con-15 trolled by ablation, so they are able to persist at lower elevation and retreat comparatively less than the Rhaetian ones (Scotti, Brardinoni, and Crosta 2014).…”