Author response to referee comments on “A 14.5 million-year record of East Antarctic Ice Sheet fluctuations from the central Transantarctic Mountains, constrained with cosmogenic 3He, 10Be, 21Ne, and 26Al”

Balter-Kennedy, Alexandra

doi:10.5194/tc-2020-57-ac1

Cited by 5 publications

(10 citation statements)

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“…While the most conservative approach is simply to conclude that moraine deposition occurred between 13.6 and 11.6 ka, the tight grouping afforded by the four up‐valley ages (12.8 ± 0.3 ka) provides a valuable measure of stratigraphic control with which we can reduce this uncertainty and arrive at a more realistic age estimate. Assuming that the moraine's true depositional age lies within the range of the 11 measured samples, any exposure age on this moraine that is younger than all ages on a stratigraphically younger surface must be erroneous (see Balter‐Kennedy et al., 2020). Following this treatment, we identify six exposure ages on the LLR moraine that are younger than all four ages of recessional erratics up‐valley and are thus chrono‐stratigraphically discordant.…”

Section: Resultsmentioning

confidence: 99%

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

et al. 2023

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The Younger Dryas (YD: 12.9-11.7 ka) is a canonical example of abrupt climate change and has evolved in interpretation from a cold snap of possibly global extent to a primarily Northern Hemisphere event centered on the North Atlantic and linked to meltwater-forced disturbance of Atlantic meridional overturning circulation (AMOC) (Broecker et al., 2010;McManus et al., 2004). Northern Hemisphere palaeoclimate data confirm the YD was accompanied by atmospheric circulation shifts (Mayewski et al., 1994), permafrost expansion (Isarin, 1997), and disruption of the Asian monsoon (Cheng et al., 2020;Liu et al., 2008), while ice cores document the rapidity of these shifts (<10 years; Alley, 2000;Steffensen et al., 2008). Nonetheless, a satisfactory trigger for the YD is elusive, partly because our understanding of the event's manifestation continues to evolve (Cheng et al., 2020). For instance, emerging data suggest an out-of-phase relationship between glacier records and traditional interpretations of Lateglacial climate proxies in Europe and the circum North Atlantic (Foreman et al., 2022;Wittmeier et al., 2020). Noting the apparent disparity between the 16°C cooling inferred from Greenland δ 18 O and the muted advances of local glaciers, Denton et al. (2005) hypothesized that YD cooling was greater in winter than summer, reflecting the impact of expanded winter sea ice on ocean-atmosphere heat transfer. Recent glacial studies have explored this model further, suggesting that North Atlantic YD summers did not cool or may even have been anomalously warm (

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Section: Resultsmentioning

confidence: 99%

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

et al. 2023

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“…2019; Balter‐Kennedy et al. 2020). Therefore, only small changes to ice velocities and dynamics are expected in most of the stranding sites mentioned in this study.…”

Section: Discussionmentioning

confidence: 99%

Identification and pairing reassessment of unequilibrated ordinary chondrites from four Antarctic dense collection areas

Righter¹,

Schutt

Lunning³

et al. 2021

Meteorit & Planetary Scien

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New analyses of Cr2O3 contents of olivines from type II chondrules in unequilibrated chondrites (UOC) from four dense collections are reported here. This survey of petrologic type 3 UOCs was undertaken to identify primitive chondrites that may have been overlooked, and to address possible pairing errors. We have identified 23 primitive UOCs (≤3.10) (only five identified previously, for a total of 28 overall), and also recommend other revisions to prior classifications and pairings.

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“…As such, the valleys and other ice‐free areas within the region have likely been modified and reworked numerous times. Exposure ages have recently been determined and range from the early Holocene to the Miocene, with the oldest ages closest to the Polar Plateau and at high elevations furthest from the glacier (Balter‐Kennedy et al, 2020; Diaz, Corbett, et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

“…The Shackleton Glacier has several exposed peaks of the TAM along the length of the glacier, spanning a range in elevations. Some ice‐free terrestrial areas at the LGM were also ice‐free through previous glacial maxima, becoming increasingly salty and challenging environment for soil organisms since at least the late quaternary (140,000 years ago), with some areas as old as 14 million years or more (Balter‐Kennedy et al, 2020; Denton et al, 1989; Diaz, Corbett, et al, 2020; Pollard & DeConto, 2009). Of all the ice‐free regions in the TAM, those of the Shackleton Glacier provide a repeated series of exposure ages, where ecosystem responses associated with the last interglacial have been replicated across elevational and latitudinal transects.…”

Section: Introductionmentioning

confidence: 99%

Response of Antarctic soil fauna to climate‐driven changes since the Last Glacial Maximum

Franco

Adams

Diaz

et al. 2021

Global Change Biology

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Understanding how terrestrial biotic communities have responded to glacial recession since the Last Glacial Maximum (LGM) can inform present and future responses of biota to climate change. In Antarctica, the Transantarctic Mountains (TAM) have experienced massive environmental changes associated with glacial retreat since the LGM, yet we have few clues as to how its soil invertebrate‐dominated animal communities have responded. Here, we surveyed soil invertebrate fauna from above and below proposed LGM elevations along transects located at 12 features across the Shackleton Glacier region. Our transects captured gradients of surface ages possibly up to 4.5 million years and the soils have been free from human disturbance for their entire history. Our data support the hypothesis that soils exposed during the LGM are now less suitable habitats for invertebrates than those that have been exposed by deglaciation following the LGM. Our results show that faunal abundance, community composition, and diversity were all strongly affected by climate‐driven changes since the LGM. Soils more recently exposed by the glacial recession (as indicated by distances from present ice surfaces) had higher faunal abundances and species richness than older exposed soils. Higher abundances of the dominant nematode Scottnema were found in older exposed soils, while Eudorylaimus, Plectus, tardigrades, and rotifers preferentially occurred in more recently exposed soils. Approximately 30% of the soils from which invertebrates could be extracted had only Scottnema, and these single‐taxon communities occurred more frequently in soils exposed for longer periods of time. Our structural equation modeling of abiotic drivers highlighted soil salinity as a key mediator of Scottnema responses to soil exposure age. These changes in soil habitat suitability and biotic communities since the LGM indicate that Antarctic terrestrial biodiversity throughout the TAM will be highly altered by climate warming.

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Author response to referee comments on “A 14.5 million-year record of East Antarctic Ice Sheet fluctuations from the central Transantarctic Mountains, constrained with cosmogenic 3He, 10Be, 21Ne, and 26Al”

Cited by 5 publications

References 0 publications

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

Lateglacial Shifts in Seasonality Reconcile Conflicting North Atlantic Temperature Signals

Identification and pairing reassessment of unequilibrated ordinary chondrites from four Antarctic dense collection areas

Response of Antarctic soil fauna to climate‐driven changes since the Last Glacial Maximum

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