Abstract. Antarctica's ice shelves resist the flow of grounded ice towardsthe ocean through “buttressing” arising from their contact with ice rises,rumples, and lateral margins. Ice shelf thinning and retreat reducebuttressing, leading to increased delivery of mass to the ocean that adds toglobal sea level. Ice shelf response to large annual cycles in atmosphericand oceanic processes provides opportunities to study the dynamics of bothice shelves and the buttressed grounded ice. Here, we explore whetherseasonal variability of sea surface height (SSH) can explain observedseasonal variability of ice velocity. We investigate this hypothesis usingseveral time series of ice velocity from the Ross Ice Shelf (RIS),satellite-based estimates of SSH seaward of the RIS front, ocean models ofSSH under and near RIS, and a viscous ice sheet model. The observed annualchanges in RIS velocity are of the order of 1–10 m a−1 (roughly 1 % ofmean flow). The ice sheet model, forced by the observed and modelled rangeof SSH of about 10 cm, reproduces the observed velocity changes whensufficiently large basal drag changes near the grounding line areparameterised. The model response is dominated by grounding line migrationbut with a significant contribution from SSH-induced tilt of the ice shelf.We expect that climate-driven changes in the seasonal cycles of winds andupper-ocean summer warming will modify the seasonal response of ice shelvesto SSH and that nonlinear responses of the ice sheet will affect the longertrend in ice sheet response and its potential sea-level rise contribution.
The East Antarctic Ice Sheet (EAIS) has the potential to raise global sea levels by ∼52 m. Here, we model the evolution of select EAIS catchments to 2100 using three basal melt rate parameterizations and force our model with surface mass balance and ocean thermal anomalies from 10 global climate models. While the domain loses mass under low‐emission scenarios, it gains ∼10‐mm sea‐level rise equivalent ice volume (SLRe) under high‐emission scenarios. The primary region of thinning is within 50 km upstream of Totten Glacier's grounding line. Totten's glacial discharge is modulated by the migration of its grounding line, which is sensitive to brief intrusions of ocean water at temperatures higher than present. Once the grounding line is dislodged, Totten's ice velocity increases by up to 70% of present‐day values, resulting in ∼6‐mm SLRe loss from this sector.
more » « less- PAR ID:
- 10455837
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 47
- Issue:
- 9
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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