Articles | Volume 8, issue 6
https://doi.org/10.5194/tc-8-2235-2014
https://doi.org/10.5194/tc-8-2235-2014
Research article
 | 
02 Dec 2014
Research article |  | 02 Dec 2014

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

R. Scotti, F. Brardinoni, and G. B. Crosta

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.

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Short summary
A post-LIA multitemporal glacier inventory along a latitudinal transect in the Central Italian Alps shows that average annual decrease (AAD) in glacier area has risen by about ten times from 1860--1990 to 1990--2007. When considering glaciers smaller than 0.5 km2, post-1990 AAD follows the latitudinal gradient with maritime-like Orobie glaciers shrinking much less than Disgrazia and Livigno glaciers. We argue that the recent resilience of glaciers in Orobie is due to local climatic decoupling.