Modeling the retreat of the Aneto Glacier (Spanish Pyrenees) since the Little Ice Age, and its accelerated shrinkage over recent decades

Abstract

The Aneto, located on the Maladeta Massif (Central Pyrenees), is the largest glacier of the Pyrenees. The glacier is 675 m long, occupies an area of 48.64 ha and has a maximum altitude of 3269 m. In this study, we present a detailed area, volume, ice thickness, and Equilibrium Line Altitude reconstruction of the glacier for different periods (LIA, 1957, 1983, 2000, 2006, 2015, and 2017) and analyze its retreat. To estimate the glacier extent during the LIA, the moraines were mapped by using photo interpretation techniques whereas for the recent stages digital satellite images and aerial photographs were used. Moreover, we estimated the topography of the glacier using a simple steady-state model that assumes a perfectly plastic ice rheology, which allowed reconstructing the theoretical ice profiles of the glacier. To reconstruct the ice surface, a digital elevation model was created and combined with the bedrock topography in order to obtain the ice thickness of each stage. The results of the study reveal a considerable retreat of the Aneto Glacier since the LIA. The length of the glacier has reduced from 1970 to 675 m from LIA to2017, and its tongue has retreated from 2385 to 3029 m a.s.l. Furthermore, the glaciated area has been reduced from 245 to 48.64 ha from LIA to 2017 and the ELA has risen from 2919 to 3139 m a.s.l. The data obtained indicates that in the LIA–2017 period the glacier volume has been reduced from 82.57 m × 106 m3 to 3.48 m × 106 m3 and the maximum ice thickness from 95 to 27m. We also reconstructed the climatic conditions, showing an increase in temperature of ~1.14°C from LIA to 2017. These data reveal a vast retreat of the glacier since the LIA, which has accelerated since the 1980’s and even more since the year 2000.

Response of Very Small Glaciers to Climate Variations and Change: Examples from the Pirin Mountains, Bulgaria

“…For example, between the LIA and 2012, the total area of the small glaciers in the Julian Alps decreased from 2.367 to 0.383 km 2 , and the largest of them, Canin glacier, shrank by 88% [54]. Triglav glacier in the Julian Alps of Slovenia diminished even more: from 22 ha in 1897 to between 0.7 and2 ha in 2000-2014 [41,55], the Calderone glacier in the Apennines-from 9.88 ha in 1884 to 3.5 ha in 2006 [45,56], Debeli Namet glacier in the Durmitor-from 11 ha in 1878 to an average of 2.1 ha for 2011-2021 [14,15,46], Aneto glacier in the Pyrenees-from 245 ha in 1850 to 48 ha in 2017 [57,58]; and Monte Perdido glacier in the Pyrenees (from 556 ha in 1850 to 38 ha in 2016) [50,53]).…”

Maximum glacier extent of the Penultimate Glacial Cycle in the Upper Garonne Basin (Pyrenees): new chronological evidence

“…According to our results, during this phase, the main Upper Garonne Glacier was ~ 78 km long and covered ~ 900 km 2 . Considering the position of the frontal moraine ridge EM-2 at 480 m, and the derived palaeoglacier reconstruction, the ELA was located at 1711 ± −65/55 m (AAR), 1719 ± −95/60 m (global AABR) and 1704 ± −105/70 m (mid-latitude AABR), with an average of 1711 m. This altitude suggests a reduction of 9.3 °C with respect of current ELA at 3139 m and assuming no change in the summer precipitation (Campos et al 2021). As expected, these results show that glaciers had similar extents in the terminal basin during the MIS 6 and lLGM glacial advances and thus climate conditions were probably similar (Fernandes et al 2017).…”

Climate reconstruction of the Little Ice Age maximum extent of the tropical Zongo Glacier using a distributed energy balance model

“…[Paul and Bolch, 2019] reviewed a number of studies of the evolution of Alpine glaciers since the LIA and concluded that it could be summarized by a km scale retreat, a rise in the equilibriumline altitude (ELA) of 100-200 m, and an up-valley retreat of several hundred meters in glacier terminus positions. In Pyrenean glaciers, Campos et al [2021] reported ELA rises of 220 m.…”