Holocene glacier history of northeastern Cordillera Darwin, southernmost South America (55°S)

Abstract

In the Cordillera Darwin, southernmost South America, we used 10Be and 14C dating, dendrochronology, and historical observations to reconstruct the glacial history of the Dalla Vedova valley from deglacial time to the present. After deglacial recession into northeastern Darwin and Dalla Vedova, by ~16 ka, evidence indicates a glacial advance at ~13 ka coeval with the Antarctic Cold Reversal. The next robustly dated glacial expansion occurred at 870 ± 60 calendar yr ago (approximately AD 1150), followed by less-extensive dendrochronologically constrained advances from shortly before AD 1836 to the mid-twentieth century. Our record is consistent with most studies within the Cordillera Darwin that show that the Holocene glacial maximum occurred during the last millennium. This pattern contrasts with the extensive early- and mid-Holocene glacier expansions farther north in Patagonia; furthermore, an advance at 870 ± 60 yr ago may suggest out-of-phase glacial advances occurred within the Cordillera Darwin relative to Patagonia. We speculate that a southward shift of westerlies and associated climate regimes toward the southernmost tip of the continent, about 900–800 yr ago, provides a mechanism by which some glaciers advanced in the Cordillera Darwin during what is generally considered a warm and dry period to the north in Patagonia.

New cosmogenic nuclide constraints on Late Glacial and Holocene glacier fluctuations in the sub-Antarctic Indian Ocean (Kerguelen Islands, 49°S)

“…However, two additional contrasting patterns of glacier fluctuations have been observed recently. In the Darwin Cordillera (southernmost Patagonia), Reynhout et al (2021) provided the first 10 Be moraine chronology that shows a maximum Holocene extent during the last millennium corroborating the radiocarbon-dating-based results from previous studies by Hall et al (2019), while on the Antarctic Peninsula, a maximal glacier advance was recorded during the Mid-Holocene (8 -4 ka; Kaplan et al, 2020).…”

Abrupt Changes in Atmospheric Circulation During the Medieval Climate Anomaly and Little Ice Age Recorded by Sr‐Nd Isotopes in the Siple Dome Ice Core, Antarctica

“…An oxygen isotopic record of Sphagnum moss from Ariel Peatland (54°S, Figure 1a) indicates a period of stronger Andean rain shadow from 1020 to 1390 CE (930–560 yr BP), interpreted as stronger SWW at this latitude (Xia et al., 2018). Glaciers in Cordillera Darwin (∼55°S), to the west, also may have responded to a southward shift in SWW at this time, which would have caused increased precipitation and reduced ablation; advances are dated to 1080 ± 60 CE (870 yr BP) and 1200 ± 110 CE (750 yr BP; Hall et al., 2019; Reynhout et al., 2022). Thus, while glaciers and hydroclimate reconstructions from farther north in Patagonia indicate warmer, drier conditions consistent with weakened SWW, records from 54° to 55°S perhaps are consistent with intensified SWW.…”

“…Changes in their position are thought to directly drive changes in global climate through their influence on low‐to‐high‐latitude ocean heat transport (Denton et al., 2021). Holocene proxy records from around the Southern Hemisphere including speleothems, glacier chronologies, and lake, marine, and bog cores, show a largely coherent pattern of SWW variability that correlates with CO 2 changes recorded by ice cores (Browne et al., 2017; García et al., 2020; Hall et al., 2019; Lamy et al., 2001; Moreno et al., 2018, 2014; Reynhout et al., 2022; Saunders et al., 2018; Schimpf et al., 2011; Xia et al., 2018). While Holocene SWW and CO 2 variations have been relatively small compared to changes on glacial‐interglacial timescales (Marcott et al., 2014; Moreno et al., 2018), studies of these recent fluctuations, and their drivers, are relevant for understanding and modeling carbon cycle dynamics during warm climate boundary conditions.…”

Holocene History of Río Tranquilo Glacier, Monte San Lorenzo (47°S), Central Patagonia

“…In addition, the maximum Holocene glacier extent in southern South America likely occurred sometime during the early part of the epoch. Such patterns appear robust generally south of (at least) 47 °S, the location of San Lorenzo, although recently published glacier chronologies from Cordillera Darwin (55 °S) suggests that the scenario may be different in the southernmost tip of the continent (e.g., Menouno et al, 2013;Hall et al, 2019;Reynhout et al, 2021).…”