Limited Impact of Thwaites Ice Shelf on Future Ice Loss From Antarctica

Gudmundsson, G. Hilmar; Barnes, Jowan; Goldberg, Daniel; Morlighem, Mathieu

doi:10.1029/2023gl102880

Cited by 10 publications

(2 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From 2000 to 2022, the vast majority of pinning points in the 3,000-km stretch of coastline in West Antarctica from George VI Ice Shelf to Hull Glacier, along with an 800-km stretch of coastline in Wilkes Land, reduced in area or completely disappeared. Over the past 50 years, thinning at some of the most rapidly changing ice shelves means that they are close to being, or have already become, completely unanchored—for example, Thwaites Eastern Ice Shelf 47 and Pine Island Glacier 10 —which means that there is limited potential for further reductions in buttressing. Instead, the greatest concern may lie with those major ice shelves that are still substantially pinned but have shown clear signs of accelerated pinning-point loss.…”

Section: Bleak Future For Some Ice Shelvesmentioning

confidence: 99%

Progressive unanchoring of Antarctic ice shelves since 1973

Miles,

Bingham

2024

Nature

View full text Add to dashboard Cite

Mass loss of the Antarctic Ice Sheet has been driven primarily by the thinning of the floating ice shelves that fringe the ice sheet1, reducing their buttressing potential and causing land ice to accelerate into the ocean2. Observations of ice-shelf thickness change by satellite altimetry stretch back only to 1992 (refs. 1,3–5) and previous information about thinning remains unquantified. However, extending the record of ice-shelf thickness change is possible by proxy, by measuring the change in area of the surface expression of pinning points—local bathymetric highs on which ice shelves are anchored6. Here we measure pinning-point change over three epochs spanning the periods 1973–1989, 1989–2000 and 2000−2022, and thus by proxy infer changes to ice-shelf thickness back to 1973–1989. We show that only small localized pockets of ice shelves were thinning between 1973 and 1989, located primarily in the Amundsen Sea Embayment and the Wilkes Land coastline. Ice-shelf thinning spreads rapidly into the 1990s and 2000s and is best characterized by the proportion of pinning points reducing in extent. Only 15% of pinning points reduced from 1973 to 1989, before increasing to 25% from 1989 to 2000 and 37% from 2000 to 2022. A continuation of this trend would further reduce the buttressing potential of ice shelves, enhancing ice discharge and accelerating the contribution of Antarctica to sea-level rise.

show abstract

Section: Bleak Future For Some Ice Shelvesmentioning

confidence: 99%

Progressive unanchoring of Antarctic ice shelves since 1973

Miles,

Bingham

2024

Nature

View full text Add to dashboard Cite

show abstract

“…Thwaites Ice Tongue however offers little to no resistance to flow ( 20 ). Simulations of the unpinning of the Eastern ice shelf indicate little impact on the system ( 7 , 21 , 22 ). The dominant physical process that drives the glacier retreat is therefore missing from these models.…”

mentioning

confidence: 99%

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

Rignot,

Ciracì,

Scheuchl

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

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.

show abstract

Rift propagation signals the last act of the Thwaites Eastern Ice Shelf despite low basal melt rates

Wild,

Kachuck,

Luckman

et al. 2024

J. Glaciol.

View full text Add to dashboard Cite

Rift propagation, rather than basal melt, drives the destabilization and disintegration of the Thwaites Eastern Ice Shelf. Since 2016, rifts have episodically advanced throughout the central ice-shelf area, with rapid propagation events occurring during austral spring. The ice shelf's speed has increased by ~70% during this period, transitioning from a rate of 1.65 m d−1 in 2019 to 2.85 m d−1 by early 2023 in the central area. The increase in longitudinal strain rates near the grounding zone has led to full-thickness rifts and melange-filled gaps since 2020. A recent sea-ice break out has accelerated retreat at the western calving front, effectively separating the ice shelf from what remained of its northwestern pinning point. Meanwhile, a distributed set of phase-sensitive radar measurements indicates that the basal melting rate is generally small, likely due to a widespread robust ocean stratification beneath the ice–ocean interface that suppresses basal melt despite the presence of substantial oceanic heat at depth. These observations in combination with damage modeling show that, while ocean forcing is responsible for triggering the current West Antarctic ice retreat, the Thwaites Eastern Ice Shelf is experiencing dynamic feedbacks over decadal timescales that are driving ice-shelf disintegration, now independent of basal melt.

show abstract

Limited Impact of Thwaites Ice Shelf on Future Ice Loss From Antarctica

Cited by 10 publications

References 33 publications

Progressive unanchoring of Antarctic ice shelves since 1973

Progressive unanchoring of Antarctic ice shelves since 1973

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

Rift propagation signals the last act of the Thwaites Eastern Ice Shelf despite low basal melt rates

Contact Info

Product

Resources

About