Fluctuations of Glaciar Esperanza Norte in the north Patagonian Andes of Argentina during the past 400 yr

Abstract

Abstract.The number of studies of Little Ice Age (LIA) glacier fluctuations in southern South America has increased in recent years but is largely biased towards sites in the south Patagonian Andes. In this paper we present a detailed record of length and areal fluctuations of Glaciar Esperanza Norte (GEN) in the north Patagonian Andes of Argentina during the past four centuries. The GEN record was reconstructed through the dendro-geomorphological dating of moraines and the analysis of satellite imagery, aerial photographs and documentary material complemented with extensive field surveys. The maximum LIA extent at GEN was associated with an outer moraine dated to the mid 17th century. At least 19 subsequent readvances or standstills evidenced by morainic ridges were identified inside the most extensive LIA moraine. The dating and spacing of these moraines and the additional information available indicate that the ice front retreated much more rapidly during the 20th century than during earlier centuries. Comparison with the record of LIA fluctuations of Glaciar Frías, an ice mass of similar characteristics located 110 km to the north of GEN, shows a similar pattern of recession over the past 400 yr. Both glacier records have the peak LIA event occurring roughly during the same interval (early-mid 17th century) and show a minor readvance during the 1970s, but there are still a few discrepancies in the dating of some inner moraines. These differences may be due to local, specific factors or associated with the inherent uncertainties in the dating of the moraines. The chronologies of GEN and Frías are among the most detailed currently available in Patagonia, but a larger number of study sites is needed to develop robust, regionally representative glacier chronologies. Detailed glaciological, geomorphological and meteorological data are also needed to understand the glacier-climate relationships in this region and develop reliable paleoclimatic reconstructions.

Modelling and climatic interpretation of the length fluctuations of Glaciar Frías (north Patagonian Andes, Argentina) 1639–2009 AD

“…According to the modelled glacier length, the best estimate of the temperature anomaly should be 0.7 • C lower in the period 1800-1840. The overestimate of early 19th century temperature in the climate reconstructions is supported by the 1795, 1807, and 1830 moraines of Glaciar Esperanza Norte (Ruiz et al, 2012). The disagreement between the two reconstructions in the first half of the 20th century is remarkable, as for both reconstructions this period is part of the calibration period.…”

“…Likewise, the regenerated portions of Glaciar Castaño Overo and the Glaciar Río Manso have retreated noticeably over the last decades (WGMS, 2008, updated;and earlier volumes;Masiokas et al, 2010). Recently, Ruiz et al (2012) reconstructed the length fluctuations of Glaciar Esperanza Norte, 110 km south of Glaciar Frías.…”

Recent geodetic mass balance of Monte Tronador glaciers, northern Patagonian Andes

“…Esperanza Norte is also a clean ice glacier located ca. 100 km south of Tronador (Ruiz et al, 2012). Note the overall retreating pattern is only interrupted by re-advances in the late 1970s.…”

“…6a), and the marked shift towards warmer temperatures afterwards. The lower temperatures and slightly larger precipitations in the late 1970s were likely responsible for the generalized re-advances of Monte Tronador and others northern Patagonian glaciers in that decade (Leclercq et al, 2012;Masiokas et al, 2009;Ruiz et al, 2012; see also Fig. 6c).…”

“…1). Unfortunately, the lack of mass balance data hampers the possibility of exploiting the relatively more complete and longer glacier fluctuation series available for this region (Davies and Glasser, 2012;Leclercq et al, 2012;Masiokas et al, 2009;Paul and Mölg, 2014;Ruiz et al, 2012).…”