CONICET | Buscador de Institutos y Recursos Humanos

Recent studies have revealedthat in high-altitude mountain environments the global warming trend over thelast few decades tends to be strongly amplified. However, few attempts havebeen made to monitor the possible effects of such climate changes on high-altituderock glaciers. In this paper, we provide a geomorphic analysis of the Varasrock glacier, and present the first observations of rock glacier temperature (airand ground) and surface velocities in the Andes of northwestern Argentina. Anetwork of 30 boulders was monitored every year between 2012 and 2016 using adifferential Global Positioning System. Over the observational period, theVaras active rock glacier registered velocities between 125 and 5 cm/yr, exceptfor four boulders which did not shift. Over the five years of monitoring, themean annual air and ground (at 5 and 50 cm depth) temperature remained above 0ºC. A long-term instrumental weather dataset (106 years), located ~130 km fromthe Varas rock glacier, at La Quiaca station, reveals a warming trend of 0.8 ºCduring the last century, with a steep increase during the last two and half decades.The warming trend recorded in the region may have produced or facilitated theinactivity of the more-exposed sectors of the Varas active rock glacier. However,there also may be a delay in the, relatively slow, and full response of rockglaciers to the last few decades of warming. Finally, the observations allow usto propose a formation sequence in the Varas rock glacier valley, sincepostglacial time.