Monitoring permafrost and periglacial processes in Sierra Nevada (Spain) from 2001 to 2016

Abstract

Outside the Alps, the Sierra Nevada is probably the best studied European massif with respect to its past and current environmental dynamics. A multi‐approach research program started in the early 2000s focused on the monitoring of frozen ground conditions in this National Park. Here, we present data on the thermal state and distribution of permafrost and seasonal frozen ground in different sites across the highest areas of the massif. New results confirm the absence of widespread permafrost conditions, with seasonal frost prevailing above 2500 m. Small permafrost patches have been only detected in glaciated areas of the Veleta and Mulhacén cirques during the Little Ice Age at elevations of 3000–3100 m. The remnants of those glaciers are still preserved under the thick debris layer covering the cirque floors. Geomatic and geophysical surveying of a rock glacier existing in the Veleta cirque, together with the monitoring of soil temperature at different depths, have revealed permanently frozen conditions undergoing a process of degradation. In the rest of the massif, a seasonal frost regime prevails, even at the highest plateaus at 3300–3400 m, where annual soil temperatures average 2.5°C. The monitoring of soil temperatures in other different periglacial features has also revealed positive average values ranging between 2°C (inactive sorted‐circles) and 3–4°C (inactive and weakly active solifluction lobes). Consequently, we conclude that the present‐day climatic regime does not allow the existence of permafrost in the Sierra Nevada, and environmental dynamics is controlled by the intensity and duration of seasonal frost in the ground.

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

“…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). If the decrease of winter precipitation and increase of annual temperatures continue (Pérez-Luque et al 2016), it is expected that the fossil relict ice and permafrost will disappear in the next decades.…”

“…Currently, there are no glaciers in Sierra Nevada and periglacial dynamics prevail between 2600 m and the summits above 3400 m; small permanent snow fields only exist in northern glacial cirques at the foot of the highest peaks (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.…”

Climate sensitivity and geomorphological response of cirque glaciers from the late glacial to the Holocene, Sierra Nevada, Spain

“…Located in the southern fringe of Iberia at latitude of 37ºN, the Sierra Nevada is the highest massif of the Betic Range (Fig.1) (Atlantic/Mediterranean) and subtropical high pressure belt/mid-latitude westerlies (Oliva et al, 2011). Currently, the mean annual air temperature at 2500 m is 4.4 ºC , whereas at the highest summits of the massif at 3400 it is 0 ºC (2001-2016) (Gómez-Ortiz et al, 2019). Annual precipitation reaches 710 mm, mostly as snow between October and April (Oliva, 2009;Oliva et al, 2008).…”

“…2019) and a protalus lobe in the Mulhacén cirque (Serrano et al, 2018), where small isolated permafrost patches exist under the debris cover Serrano et al, 2018). These landforms are geoindicators of the end of cold periods and are out of balance with current climate conditions, and therefore, tend to become inactive Gómez-Ortiz et al, 2019).…”

“…These processes, highly sensitive to small climatic variations, led to intense geomorphic readjustments typical of the paraglacial phase (Oliva et al, 2016;Palacios et al, 2019;Serrano et al, 2018;Gómez-Ortiz et al, 2019 and references therein). As a result, landforms from this cirque are considered key geoindicators for monitoring the impact of climate change on mountain geomorphological processes in southern Europe (Gómez-Ortiz et al, 2019). The other cirque that hosted a glacier during the LIA in the Sierra Nevada is located under the northern rock wall of Mulhacén peak.…”