Atmospheric warming threatens the untapped glacial archive of Ortles mountain, South Tyrol

Abstract

Ortles mountain (3905 m a.s.l.), South Tyrol, Italy, is the highest mountain of the Eastern European Alps, and its upper glacier, Alto dell’Ortles, presents a unique opportunity to obtain the first paleoenvironmental record from an ice core in this area. To study the suitability of this glacier as a drilling site, in 2009 we performed the first preliminary study of its glaciological characteristics at ˜3830 m a.s.l. The maximum thickness is ˜75 m, and lamination of the exposed ice layers is excellent down to bedrock. Firn and ice lenses were observed in a 10 m shallow core, and the firn/ice transition was below ˜24m. The seasonal chemical signal is clearly preserved only within the uppermost 2008 and 2009 snow/firn. A simple mass-balance model, the incipient ‘smoothing’ of the chemical record, and the observed ice lenses provide evidence that melting, infiltration and refreezing cycles occurred within the firn layers formed before 2008. Nevertheless, the mass balance of the upper part of Alto dell’Ortles was positive (˜800mma_1) during the last few years. We suggest that an environmental history is likely to be well preserved only within the ice layers formed before ˜1980, when summer air temperature was ˜2°C colder than today in this area. Clearly the continued warming trend predicted to occur over the next few decades, and the consequent increase in frequency and/or intensity of infiltration processes, will endanger the preservation of the glacial archive conserved in the deep ice layers of Ortles mountain.

Linking pollen deposition and snow accumulation on the Alto dell'Ortles glacier (South Tyrol, Italy) for sub-seasonal dating of a firn temperate core

“…For example, on the Alto dell'Ortles, fresh winter snow usually accumulates in windy conditions and has a density of 300 kg m −3 (Gabrielli et al, 2010). Similar values are reported by Nakazawa et al (2012Nakazawa et al ( , 2015.…”

“…This study focuses on the uppermost 10 m of firn accumulated on the glacier from spring 2005 to June 2009 that have been retrieved using a lightweight hand auger at 3830 m a.s.l. Our previous research (Festi et al, 2015;Gabrielli et al, 2010) proved that the seasonal/annual signature of pollen and stable isotopes is well preserved in these shallow firn layers. Figure 2a shows the formerly published timescale (Festi et al, 2015), which is based on the palynological analyses of 103 continuous ∼ 10 cm samples along the core.…”

“…1) and we improved the existing timescale based on the isotopic composition of the core (Gabrielli et al, 2010). In Festi et al (2015) we conducted accurate taxonomical identification and implemented a statistical approach consisting in performing a principal component analysis (PCA) on pollen concentration values and extracting the three principal components (PCs) indicative of the three flowering seasons.…”

Decay of a long-term monitored glacier: Careser Glacier (Ortles-Cevedale, European Alps)

“…As one of the few Tier 3 monitoring sites in the world with a 46 yr continuous time series of mass balance measurements (only 22 glaciers worldwide have longer series; Zemp et al, 2009), the Careser Glacier is frequently referred to as an emblematic example of accelerated deglaciation and of vanishing glaciers with long-term mass balance observation series (e.g. Paul et al, 2007;Pecci et al, 2008;Paul, 2010;Gabrielli et al, 2010;. The aims of this work are as follows: (i) to document the variations in length, area and volume of the glacier since 1897; (ii) to update and validate the series of direct mass balance measurements; (iii) to compare the current mass loss rates with secular trends; and (iv) to outline the possible future evolution of the glacier.…”

Mapping the suitability for ice-core drilling of glaciers in the European Alps and the Asian High Mountains

“…Some authors have investigated the relation between the quality of the stratigraphy and the glacier's features (Wagenbach and Geis, 1989;Welch and others, 1998;Campbell and others, 2012). This specific issue is typically examined for a glacier site based on ground explorations (Copland and Sharp, 2001;Schwikowski and others, 2006;Gabrielli and others, 2010). Traditional methods are impossible to perform at large scale for mapping potential drilling sites in remote areas such as the Asian High Mountains.…”