No abstract

Abstract. This paper analyzes the evolution of the Monte Perdido Glacier, the third largest glacier in the Pyrenees, from 1981 to the present. We assessed the evolution of the glacier's surface area by analysis of aerial photographs from 1981, 1999, and 2006, and changes in ice volume by geodetic methods with digital elevation models (DEMs) generated from topographic maps (1981 and 1999), airborne lidar (2010) and terrestrial laser scanning (TLS, 2011, 2012, 2013, and 2014) data. We interpreted the changes in the glacier based on climate data from nearby meteorological stations. The results indicate that the degradation of this glacier accelerated after 1999. The rate of ice surface loss was almost three times greater during 1999–2006 than during earlier periods. Moreover, the rate of glacier thinning was 1.85 times faster during 1999–2010 (rate of surface elevation change  = −8.98 ± 1.80 m, glacier-wide mass balance  = −0.73 ± 0.14 m w.e. yr−1) than during 1981–1999 (rate of surface elevation change  = −8.35 ± 2.12 m, glacier-wide mass balance  = −0.42 ± 0.10 m w.e. yr−1). From 2011 to 2014, ice thinning continued at a slower rate (rate of surface elevation change  = −1.93 ± 0.4 m yr−1, glacier-wide mass balance  = −0.58 ± 0.36 m w.e. yr−1). This deceleration in ice thinning compared to the previous 17 years can be attributed, at least in part, to two consecutive anomalously wet winters and cool summers (2012–2013 and 2013–2014), counteracted to some degree by the intense thinning that occurred during the dry and warm 2011–2012 period. However, local climatic changes observed during the study period do not seem sufficient to explain the acceleration of ice thinning of this glacier, because precipitation and air temperature did not exhibit statistically significant trends during the study period. Rather, the accelerated degradation of this glacier in recent years can be explained by a strong disequilibrium between the glacier and the current climate, and likely by other factors affecting the energy balance (e.g., increased albedo in spring) and feedback mechanisms (e.g., heat emitted from recently exposed bedrock and debris covered areas).

Raúl maRtín 4 resumen -En este trabajo se presenta un mapa de síntesis que ofrece una visión global de la distribución del permafrost en los pirineos a escala regional. la elaboración del mapa está basada en la utilización de indicadores de permafrost (glaciares rocosos, gelifluxión, cavidades heladas, suelos ordenados, sondeos eléctri-cos verticales y registros térmicos de suelos) y un modelo digital del terreno (mdT) con información sobre la inclinación de las laderas y su orientación, la altitud y la radiación solar directa potencial. El mapa resultante contiene información sobre la distribución espacial del "permafrost probable" y del "permafrost posible", una aproximación que muestra el estado actual del conocimiento sobre permafrost en los pirineos.Palabras clave: Permafrost de montaña, cartografía, glaciares rocosos, SIG, pirineos.Abstract -mountain peRmafRost map of the spanish pyRenees. Since the 1980's with the development of research on rock glaciers and periglacial landforms as permafrost indicators that the mountain permafrost is known to occur in the pyrenees. In this paper we present a map of the distribution of mountain permafrost in the pyrenees. The mapping is based on indicators of permafrost (rock glaciers, gelifluction processes, ice caves, patterned ground, vertical electric sounding and ground thermal regimes) and geographical information extracted from a digital Elevation model, such as slope angle and aspect, altitude and potential direct solar radiation. The map represents the spatial distribution of "probable" and "possible permafrost" and represents the present-day state of the art on pyrenean permafrost.

RESUMEN. Los glaciares rocosos son considerados geoindicadores fiables

A review of selected, well-dated, multiproxy paleoclimatic records (lacustrine, dendrochronological, geomorphological) characterizes the main environmental changes occurred in the Southern Pyrenees during the last millennium. Warmer and relatively arid conditions prevailed during the Medieval Climate Anomaly (MCA, <1300 AD), with a significant development of xerophytes and Mediterranean vegetation and limited deciduous tree formations (mesophytes). The Little Ice Age (LIA, 1300–1800 AD) was generally colder and moister, with an expansion of deciduous taxa and cold-adapted mountainous conifers. Two major phases occurred within this period: (i) a transition MCA-LIA, characterized by fluctuating, moist conditions and relatively cold temperatures (ca. 1300 and 1600 AD); – (ii) a second period, characterized by coldest conditions and higher humidity, coinciding with maximum (recent) glacier advances (ca. 1600–1850 AD). After the LIA a warming and more arid phase started coinciding with glacier retreat, and interrupted by a short-living cooling episode during the late 19th to early 20th centuries. Some records suggest a response to solar activity with colder and slightly moister conditions during solar minima. Centennial-scale hydrological fluctuations are in phase with reconstructions of NAO variability, which appears to be the main forcing for humidity in the region during the last millennium