Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier, West Antarctica

Warm water from the Southern Ocean has a dominant impact on the evolution of Antarctic glaciers and in turn on their contribution to sea level rise. Using a continuous time series of daily-repeat satellite synthetic-aperture radar interferometry data from the ICEYE constellation collected in March-J...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS Vol. 121; no. 22; p. e2404766121
Main Authors: Rignot, Eric, Ciracì, Enrico, Scheuchl, Bernd, Tolpekin, Valentyn, Wollersheim, Michael, Dow, Christine
Format: Journal Article
Language:English
Published: United States 28.05.2024
Subjects:
Antarctica
hydrology
interferometry
sea level rise
Southern Ocean
ISSN:1091-6490, 1091-6490
Online Access:Get more information
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Summary:Warm water from the Southern Ocean has a dominant impact on the evolution of Antarctic glaciers and in turn on their contribution to sea level rise. Using a continuous time series of daily-repeat satellite synthetic-aperture radar interferometry data from the ICEYE constellation collected in March-June 2023, we document an ice grounding zone, or region of tidally controlled migration of the transition boundary between grounded ice and ice afloat in the ocean, at the main trunk of Thwaites Glacier, West Antarctica, a strong contributor to sea level rise with an ice volume equivalent to a 0.6-m global sea level rise. The ice grounding zone is 6 km wide in the central part of Thwaites with shallow bed slopes, and 2 km wide along its flanks with steep basal slopes. We additionally detect irregular seawater intrusions, 5 to 10 cm in thickness, extending another 6 km upstream, at high tide, in a bed depression located beyond a bedrock ridge that impedes the glacier retreat. Seawater intrusions align well with regions predicted by the GlaDS subglacial water model to host a high-pressure distributed subglacial hydrology system in between lower-pressure subglacial channels. Pressurized seawater intrusions will induce vigorous melt of grounded ice over kilometers, making the glacier more vulnerable to ocean warming, and increasing the projections of ice mass loss. Kilometer-wide, widespread seawater intrusion beneath grounded ice may be the missing link between the rapid, past, and present changes in ice sheet mass and the slower changes replicated by ice sheet models.
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ISSN:1091-6490
1091-6490
DOI:10.1073/pnas.2404766121