Degradation of buried ice and permafrost in the Veleta cirque (Sierra Nevada, Spain) from 2006 to 2013 as a response to recent climate trends

Abstract

Abstract. The Veleta cirque is located at the foot of the Veleta peak, one of the highest summits of the Sierra Nevada National Park (southern Spain). This cirque was the source of a glacier valley during the Quaternary cold periods. During the Little Ice Age it sheltered a small glacier, the most southerly in Europe, about which we have possessed written records since the 17th century. This glacier still had ice residues until the mid-20th century. This ice is no longer visible, but a residue persists along with discontinuous permafrost trapped under strata of rock blocks that make up an incipient rock glacier.From 2006 to 2013, this rock glacier was monitored by measurement of the temperature of the active layer, the degree of snow cover on the ground, movements of the body of the rock glacier and geophysical prospection inside it. The results show that the relict ice and trapped permafrost have been steadily declining. The processes that explain this degradation occur in chain, starting from the external radiation that affects the ground in summer, which is when the temperatures are higher. In effect, when this radiation steadily melts the snow on the ground, the thermal expansive wave advances into the heart of the active layer, reaching the ceiling of the frozen mass, which it then degrades and melts. In this entire linked process, the circulation of meltwaters fulfils a highly significant function, as they act as heat transmitters. The complementary nature of these processes explains the subsidence and continuous changes in the entire clastic pack and the melting of the frozen ceiling on which it rests. This happens in summer in just a few weeks.All these events, in particular the geomorphological ones, take place on the Sierra Nevada peaks within certain climate conditions that are at present unfavourable to the maintenance of snow on the ground in summer. These conditions could be related to recent variations in the climate, starting in the mid-19th century and most markedly since the second half of the 20th century.The work and results highlight the climate sensitivity of the peaks of the Sierra Nevada to the effect of climate change and its impact on the dynamics of ecosystems, which is a benchmark for evaluating the current evolution of landscapes of Mediterranean high mountains.

Multiproxy reconstruction of Holocene glaciers in Sierra Nevada (south Spain)

“…The LIA-glaciated environments in Iberian mountains are undergoing a rapid process of paraglacial readjustment following their deglaciation (Serrano et al 2018). In Sierra Nevada, the remnants of LIA glaciers are preserved in the form of ice bodies and permafrost patches buried under a thick debris cover (Gómez-Ortiz et al 2014). Some permafrost-related landforms, such as protalus lobes and rock glaciers, developed above those subsurface frozen masses, though their degradation in response to warming is accelerating their stabilization and generating subsidence and collapses on the surface debris cover (Gómez-Ortiz et al 2019).…”

“…Mean annual air temperatures at 2500 m average 4.4 °C with an annual precipitation of 710 mm, in the form of snow between October and May (1965-1992, Oliva et al 2014b. At the summit plateaus at 3300-3400 m, the mean annual ground temperature is ~ 0 °C (Oliva et al 2016a), with negative values in LIA-glaciated environments such as in the Veleta cirque (Gómez-Ortiz et al 2014). Cold-climate conditions determine ecological dynamics in the highest lands, with poorly developed soils and scarce vegetation cover.…”

Spatial and climatic characterization of three glacial stages in the Upper Krnica Valley, SE European Alps

“…The evolution of this buried ice body has been seen as largely dependent on water infiltration through the clastic material when no snow is present over the debris. This leads to penetration of the thermal wave deep in the ground that is able to trigger the degradation of the frozen sediments (Gómez-Ortiz et al, 2014). This mechanism is of course more effective if the infiltrating water is warmer and abundant.…”

Cryomorphological Topographies in the Study of Ice Caves

“…TLS is now used for the study of caves and galleries in order to obtain a metric cartography and to produce detailed tourist information of the site. In several studies [1][2][3] the methodology used to obtain the 3D geometry of cavities has been described in detail. The results obtained are used to map, perform 3D reconstructions and create videos and 3D models for use in tourism.…”