Widespread collapse of the Ross Ice Shelf during the late Holocene

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Yokoyama, Y, Anderson, JB, Yamane, M, Simkins, LM, Miyairi, Y, Yamazaki, T, Koizumi, M, Suga, H, Kusahara, K, Prothro, L, Hasumi, H, Southon, JR, Ohkouchi, N
• Format: Article in Journal/Newspaper
• Language: English
• Published: Natl Acad Sciences 2016
• Subjects: Earth Sciences; Atmospheric Sciences; Climate Change Processes; Antarctic; Ross Ice Shelf; Ross Sea; Antarc*; ice core; Ice Shelf; Ice Shelves; Iceberg*
• Online Access: https://doi.org/10.1073/pnas.1516908113; http://ecite.utas.edu.au/109886

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.