Widespread collapse of the Ross Ice Shelf during the late Holocene

Abstract

The stability of modern ice shelves is threatened by atmospheric and oceanic warming. The geologic record of formerly glaciated continental shelves provides a window into the past of how ice shelves responded to a warming climate. Fields of deep (−560 m), linear iceberg furrows on the outer, western Ross Sea continental shelf record an early post-Last Glacial Maximum episode of ice-shelf collapse that was followed by continuous retreat of the grounding line for ∼200 km. Runaway grounding line conditions culminated once the ice became pinned on shallow banks in the western Ross Sea. This early episode of ice-shelf collapse is not observed in the eastern Ross Sea, where more episodic grounding line retreat took place. More widespread (∼280,000 km2) retreat of the ancestral Ross Ice Shelf occurred during the late Holocene. This event is recorded in sediment cores by a shift from terrigenous glacimarine mud to diatomaceous open-marine sediment as well as an increase in radiogenic beryllium (10Be) concentrations. The timing of ice-shelf breakup is constrained by compound specific radiocarbon ages, the first application of this technique systematically applied to Antarctic marine sediments. Breakup initiated around 5 ka, with the ice shelf reaching its current configuration ∼1.5 ka. In the eastern Ross Sea, the ice shelf retreated up to 100 km in about a thousand years. Three-dimensional thermodynamic ice-shelf/ocean modeling results and comparison with ice-core records indicate that ice-shelf breakup resulted from combined atmospheric warming and warm ocean currents impinging onto the continental shelf.

Radiocarbon variability recorded in coral skeletons from the northwest of Luzon Island, Philippines

“…We measured 55 samples with ages ranging from 1968 to 1994. Graphite target samples were then analyzed with single-stage accelerator mass spectrometry (Yamane et al 2014;Yokoyama et al 2016) at the Atmosphere and Ocean Research Institute, The University of Tokyo.…”

Past ice-sheet behaviour: retreat scenarios and changing controls in the Ross Sea, Antarctica

“…These banks served as pinning points for retreating ice streams and likely evolved into semi-independent ice rises during deglaciation. WRS banks supported an extensive ice shelf that buttressed WRS grounding lines and contributed to the long-lived presence of the EAIS in the WRS Yokoyama et al, 2016). While slight bottlenecking of ERS inter-ice-stream ridges may have played a role in determining positions of grounding-line stability and the formation of large-scale GZWs (Mosola and Anderson, 2006), the ERS sea floor is much more topographically subdued than in the WRS.…”

“…These findings are supported by modelling results that indicate the presence of independent, detached ice rises on WRS banks late in deglaciation . Additionally, Yokoyama et al (2016) argue that a grounded ice shelf remained pinned on WRS banks until the late Holocene.…”

Holocene Refreshening and Reoxygenation of a Bothnian Sea Estuary Led to Enhanced Phosphorus Burial

“…2a) following the protocol summarized in Yamane et al (2014) for ultra-small sample sizes (Yokoyama et al 2010(Yokoyama et al , 2016. Six samples are within the composite splice (Andrén et al 2015), and one sample was obtained from a core catcher that is removed from the splice by 44 cm.…”