Tracking the southern hemisphere westerlies during and since the last glacial maximum with multiproxy lake records from the Falkland Islands (52 °S)

Spoth, Meghan; Hall, Brenda L.; Lowell, Thomas V.; Diefendorf, Aaron F.; Corcoran, M. C.; Brickle, Paul

doi:10.1016/j.quascirev.2023.108135

Cited by 2 publications

(1 citation statement)

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“…Covariance of Patagonian and South Georgian glacier fluctuations may indicate a shared regional climate forcing (Strelin et al, 2014). One such forcing is changes in the southern westerly winds (SWWs), which have a major impact on precipitation rates and temperature (Mayr et al, 2007;Lamy et al, 2010;Perren et al, 2020;Fletcher et al, 2021;Zwier et al, 2021;Spoth et al, 2023). However, there is significant uncertainty about the precise timing of South Georgia Holocene glacial readvances, making it difficult to test this common forcing idea or assess the impact South Georgia's glacial history had on the marine realm.…”

Section: Introductionmentioning

confidence: 99%

South Georgia marine productivity over the past 15 ka and implications for glacial evolution

Wilkin,

Kender,

Dejardin

et al. 2024

J. Micropalaeontol.

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Abstract. The subantarctic islands of South Georgia are located in the Southern Ocean, and they may be sensitive to future climate warming. However, due to a lack of well-dated subantarctic palaeoclimate archives, there is still uncertainty about South Georgia's response to past climate change. Here, we reconstruct primary productivity changes and infer Holocene glacial evolution by analysing two marine gravity cores: one near Cumberland Bay on the inner South Georgia shelf (GC673: ca. 9.5 to 0.3 cal. kyr BP) and one offshore of Royal Bay on the mid-shelf (GC666: ca. 15.2 cal. kyr BP to present). We identify three distinct benthic foraminiferal assemblages characterised by the dominance of Miliammina earlandi, Fursenkoina fusiformis, and Cassidulinoides parkerianus that are considered alongside foraminiferal stable isotopes and the organic carbon and biogenic silica accumulation rates of the host sediment. The M. earlandi assemblage is prevalent during intervals of dissolution in GC666 and reduced productivity in GC673. The F. fusiformis assemblage coincides with enhanced productivity in both cores. Our multiproxy analysis provides evidence that the latest Pleistocene to earliest Holocene (ca. 15.2 to 10.5 cal. kyr BP) was a period of high productivity associated with increased glacial meltwater discharge. The mid–late Holocene (ca. 8 to 1 cal. kyr BP), coinciding with a fall in sedimentation rates and lower productivity, was likely a period of reduced glacial extent but with several short-lived episodes of increased productivity from minor glacial readvances. The latest Holocene (from ca. 1 cal. kyr BP) saw an increase in productivity and glacial advance associated with cooling temperatures and increased precipitation which may have been influenced by changes in the southwesterly winds over South Georgia. We interpret the elevated relative abundance of F. fusiformis as a proxy for increased primary productivity which, at proximal site GC673, was forced by terrestrial runoff associated with the spring–summer melting of glaciers in Cumberland Bay. Our study refines the glacial history of South Georgia and provides a more complete record of mid–late Holocene glacial readvances with robust chronology. Our results suggest that South Georgia glaciers were sensitive to modest climate changes within the Holocene.

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