Lichenometric ages of the little ice age moraines on king george island and of the last volcanic activity on penguin island (west antarctica)

Abstract

The recently observed recession of glaciers on King George Island is associated with decades of climate warming in the Antarctic Peninsula region. However, with only 60 years of glaciological observations in the study area ages of the oldest moraines are still uncertain. The goal of the study was to estimate ages of lichen colonization on the oldest moraines of the Ecology and White Eagle Glaciers on King George Island and on the Principal Cone of Penguin Island volcano. The first lichenometric studies on these islands from the late 1970s used rates that had about four to five times slower Rhizocarpon growth rates. We re‐examined the sites and measured 996 thalli diameters to establish the surface ages. To estimate the age we used (1) long‐term Rhizocarpon lichen group growth rates established by authors using data from a previous lichenometric study on King George Island, and (2) previous data of lichen growth rates from other sub‐Antarctic islands. Our results suggest growth rates between 0.5 and 0.8 mm yr–1. According to these rates the ages of the oldest moraine ridges are of the Little Ice Age and were colonized at the beginning of the twentieth century. The mid‐twentieth century age of lichen colonization on the historically active Penguin Island volcano might support the date of the last eruption reported by whalers in the end of the nineteenth and the beginning of the twentieth century.

Rock surface micro−roughness, Schmidt hammer rebound and weathering rind thickness within LIA Skálafellsjökull foreland, SE Iceland

“…Obtained lichenometric ages (Table 1) are older then those of Evans et at. (1999) who used linear growth rate of 0.8 mm year −1 and exceptionally short colonisation lag time which is contradictory to numerous liche− nometrical studies (Gordon and Sharp 1983;Bradwell 2001;Angiel and Dąbski 2012). Evant et al 1999 concluded that such an approach produces underestimated dates for certain moraines of neighbouring Heinabergsjökull, which apparently also applies to younger moraines of Skálafellsjökull.…”

Fluctuation of Glacial Retreat Rates in the Eastern Part of Warszawa Icefield, King George Island, Antarctica, 1979–2018

“…Larger land-terminating glaciers in ASPA-128 (for example, Sphinx and Tower glaciers) with feeding areas below 300 m a.s.l., also experienced significant area loss ( Figure 6). Correspondingly large decreases in the ice cover were observed 30 km to the east in ASPA-151 (for example, Reference [6] for glaciers fed from the Krakow Icefield (300 m a.s.l.)). As simulated by Rückamp et al [8], the small independent ice cap on Bellingshausen Dome (summit at 270 m a.s.l., eastern King George Island) will disappear within the next 300 years under the current climate conditions.…”

“…The first field studies of glaciers in Admiralty Bay were conducted in the 1950s and reported a general reduction in ice extent [7]. Since the 1950s, an increased glacier retreat has been reported on King George Island by numerous studies [6,[8][9][10][11][12]]. An increase in surface temperature was also observed over the past several years.…”

“…The late-Holocene maximum extent of glaciers on King George Island is marked by large ice-cored moraines, which were formed at the termination of the Little Ice Age (LIA) at the beginning of the 20th century [6]. Lichenometric studies of moraine ages in ASPA-128 and ASPA-151 (Antarctic Specially Protected Areas) indicate that the post-LIA glacier retreat was relatively slow until the 1940s [6]. The first field studies of glaciers in Admiralty Bay were conducted in the 1950s and reported a general reduction in ice extent [7].…”

Mapping Glacier Forelands Based on UAV BVLOS Operation in Antarctica

“…The mean annual air temperature (MAAT) calculated for joined periods [2006][2007] and 2012 is −1.5 • C [28]. An increase in MAAT by 1.2 • C occurred for the period of 1948-2011 on KGI [29], which resulted in retreat of local glaciers [16,30,31]. However, a set of end moraines developed at the contemporary margin of Baranowski Glacier and recent deceleration of glacial surface lowering [18] can be attributed to a slightly negative temperature trend observed since the beginning of the twenty-first century [32].…”