Abstract
The history of glaciations on Southern Hemisphere sub-polar islands is unclear. Debate surrounds the extent and timing of the last glacial advance and termination on sub-Antarctic South Georgia in particular. Here, using sea-floor geophysical data and marine sediment cores, we resolve the record of glaciation offshore of South Georgia through the transition from the Last Glacial Maximum to Holocene. We show a sea-bed landform imprint of a shelf-wide last glacial advance and progressive deglaciation. Renewed glacier resurgence in the fjords between c. 15,170 and 13,340 yr ago coincided with a period of cooler, wetter climate known as the Antarctic Cold Reversal, revealing a cryospheric response to an Antarctic climate pattern extending into the Atlantic sector of the Southern Ocean. We conclude that the last glaciation of South Georgia was extensive, and the sensitivity of its glaciers to climate variability during the last termination more significant than implied by previous studies.
Highlights
The history of glaciations on Southern Hemisphere sub-polar islands is unclear
A notable period absent in most geological records from South Georgia is the phase of warming that brought about the deglaciation of Antarctica, from B18 ka to the start of the Holocene
We combined and analysed newly-acquired and existing sea-floor bathymetric datasets to reveal the imprint of former glaciations for an entire sub-polar ice cap on South Georgia (Supplementary Fig. 1)
Summary
The history of glaciations on Southern Hemisphere sub-polar islands is unclear. Debate surrounds the extent and timing of the last glacial advance and termination on sub-Antarctic South Georgia in particular. It is reasonable to assume, that glacier behaviour on the island was strongly coupled to Southern Hemisphere (Antarctic) climate variability in the past, as it is today It follows that an improved understanding of South Georgia’s glaciations can shed light on ice mass response to climate variability in an under-sampled but regionally-important Southern Ocean sector, and can provide as yet unknown long-timescale context for changes in the sub-Antarctic cryosphere over recent decades. A notable period absent in most geological records from South Georgia is the phase of warming that brought about the deglaciation of Antarctica, from B18 ka to the start of the Holocene During this deglaciation conditions were interrupted by a period of renewed cooling from about 14,540 to 12,760 kyr ago[28]. This chronozone, known as the Antarctic Cold Reversal (ACR), is documented in Antarctic ice 39°30′W
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