title: 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 km(2)) 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 ((10)Be) 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.
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa 275-8564, Japan; Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan; yokoyama@aori.u-tokyo.ac.jp.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yokoyama
authors.affiliation: Department of Earth Science, Rice University, Houston, TX 77005;
authors.forename: John B
authors.initials: JB
authors.lastname: Anderson
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa 275-8564, Japan; Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan;
authors.forename: Masako
authors.initials: M
authors.lastname: Yamane
authors.affiliation: Department of Earth Science, Rice University, Houston, TX 77005;
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Simkins
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa 275-8564, Japan;
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miyairi
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa 275-8564, Japan; Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamazaki
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa 275-8564, Japan; Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan;
authors.forename: Mamito
authors.initials: M
authors.lastname: Koizumi
authors.affiliation: Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan;
authors.forename: Hisami
authors.initials: H
authors.lastname: Suga
authors.affiliation: Antarctic Climate & Ecosystems Cooperative Research Centre, Hobart, Tasmania 7001, Australia;
authors.forename: Kazuya
authors.initials: K
authors.lastname: Kusahara
authors.affiliation: Department of Earth Science, Rice University, Houston, TX 77005;
authors.forename: Lindsay
authors.initials: L
authors.lastname: Prothro
authors.affiliation: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwa-no-ha, Kashiwa 275-8564, Japan;
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Hasumi
authors.affiliation: Department of Earth System Science, University of California, Irvine, CA 92697.
authors.forename: John R
authors.initials: JR
authors.lastname: Southon
authors.affiliation: Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka 237-0061, Japan;
authors.forename: Naohiko
authors.initials: N
authors.lastname: Ohkouchi
keywords: Antarctica; Ross Sea; ice sheet; ice shelf; radiocarbon