200 years of equilibrium-line altitude variability across the European Alps (1901−2100)

Abstract

Mountain glaciers are key indicators of climate change. Their response is revealed by the environmental equilibrium-line altitude (ELA), i.e. the regional altitude of zero mass balance averaged over a long period of time. We introduce a simple approach for distributed modelling of the environmental ELA over the entire European Alps based on the parameterization of ELA in terms of summer temperature and annual precipitation at a glacier. We use 200 years of climate records and forecasts to model environmental ELA from 1901 to 2100 at 5 arcmin grid cell resolution. Historical environmental ELAs are reconstructed based on precipitation from the Long-term Alpine Precipitation reconstruction (LAPrec) dataset and temperature from the Historical Instrumental climatological Surface Time series of the greater Alpine region (HISTALP). The simulations of future environmental ELAs are forced with high-resolution EURO-CORDEX regional climate model projections for the European domain using three different greenhouse gas emissions scenarios (Representative Concentration Pathways, RCP). Our reconstructions yielded an environmental ELA across the European Alps of 2980 m above sea level for the period 1901−1930, with a rise of 114 m in the period 1971−2000. The environmental ELA is projected to exceed the maximum elevation of 69%, 81% and 92% of the glaciers in the European Alps by 2071−2100 under mitigation (RCP2.6), stabilization (RCP4.5) and high greenhouse gas emission (RCP8.5) scenarios, respectively.

Classifying disequilibrium of small mountain glaciers from patterns of surface elevation change distributions

“…The initial glacier state is perturbed by moving the ELA to 3300 m a.s.l., in order to simulate the glacier stabilizing at significantly reduced size. The new ELA value is within the range of expected environmental ELA for the year 2040 in our study region (Žebre and others, 2021). The modelled glacier reaches a new equilibrium after 195 years, having lost about 65% of its initial volume.…”

“…The vertical extent was chosen to broadly approximate the LIA extent of glaciers in the Ötztal range (Charalampidis and others, 2018) and the ELA is based on values of transient ELA reported for Hintereisferner by Kerschner (1997) and environmental ELA around 1900 in our study region (Žebre and others, 2021). The term environmental ELA refers to the ‘regional altitude of zero glacier mass balance without the effects of shading, avalanching, snow drifting, glacier geometry or debris-cover’ (Anderson and others, 2018; Žebre and others, 2021). The simulation is not intended to exactly model the evolution of any particular glacier.…”

Contemporary mass balance on a cold Eastern Alpine ice cap as a potential link to the Holocene climate

“…Because the ice caps to be studied are located on summits and represent free atmosphere temperatures, Alpine ice core research can contribute significantly to the investigation of elevation-dependent warming and related processes 52 . The analysis of 200 years of equilibrium line variability in the European Alps 53 confirms the potential of the combination of glacier mass balance and HISTALP data for process studies like ours to bridge the gap to Holocene climate and glacier processes.…”

Significant mass loss in the accumulation area of the Adamello glacier indicated by the chronology of a 46 m ice core

“…Ice core studies from mid-latitude mountain glaciers are essential to infer recent climate variability and anthropogenic impact on a regional scale, but they are challenging because these ice masses are, with the exception of very few sites, mostly represented by temperate, or polythermal glaciers, in the better-case scenario. Notoriously, the ongoing climate warming is globally causing a progressive reduction in ice bodies (Zemp et al, 2015) and already seriously compromises the climatic and environmental signal embedded in the ice of the most thermally unstable glaciers (Zhang et al, 2015). Particularly because of the most recent strong warming, such ice masses may further experience years with negative mass balance even in what had formerly been the accumulation zone.…”