Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves.
Iceberg calving from all Antarctic ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance. Rapid changes to iceberg calving naturally arise from the sporadic detachment of large tabular bergs but can also be triggered by climate forcing. Here we provide a direct empirical estimate of mass loss due to iceberg calving and melting from Antarctic ice shelves. We find that between 2005 and 2011, the total mass loss due to iceberg calving of 755 ± 24 gigatonnes per year (Gt/y) is only half the total loss due to basal melt of 1516 ± 106 Gt/y. However, we observe widespread retreat of ice shelves that are currently thinning. Net mass loss due to iceberg calving for these ice shelves (302 ± 27 Gt/y) is comparable in magnitude to net mass loss due to basal melt (312 ± 14 Gt/y). Moreover, we find that iceberg calving from these decaying ice shelves is dominated by frequent calving events, which are distinct from the less frequent detachment of isolated tabular icebergs associated with ice shelves in neutral or positive mass balance regimes. Our results suggest that thinning associated with ocean-driven increased basal melt can trigger increased iceberg calving, implying that iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to ocean forcing than expected from steady state calving estimates.
State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China; Joint Center for Global Change Studies, Beijing 100875, China;
Yan
Y
Liu
State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China; Joint Center for Global Change Studies, Beijing 100875, China; Arctic Centre, University of Lapland, 96100 Rovaniemi, Finland; Department of Earth Sciences, Uppsala University, Uppsala 75236, Sweden; xcheng@bnu.edu.cn john.moore.bnu@gmail.com.
John C
JC
Moore
State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China; Joint Center for Global Change Studies, Beijing 100875, China; xcheng@bnu.edu.cn john.moore.bnu@gmail.com.
Xiao
X
Cheng
Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania, Australia; Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie, Eidgenössische Technische Hochschule Zürich, 8093 Zurich, Switzerland;
Rupert M
RM
Gladstone
Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI 48109-2143;
Jeremy N
JN
Bassis
Department of Geography, McMicken College of Arts & Sciences, University of Cincinnati, OH 45221-0131; and.
Hongxing
H
Liu
Department of Geography, Shanghai Normal University, Shanghai 200234, China.
Jiahong
J
Wen
State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing 100875, China; Joint Center for Global Change Studies, Beijing 100875, China;
Fengming
F
Hui
Antarctica; basal melt; ice shelf; iceberg calving; mass balance