The triggers of the disaggregation of Voyeykov Ice Shelf (2007), Wilkes Land, East Antarctica, and its subsequent evolution

Abstract

The weakening and/or removal of floating ice shelves in Antarctica can induce inland ice flow acceleration. Numerical modelling suggests these processes will play an important role in Antarctica's future sea-level contribution, but our understanding of the mechanisms that lead to ice tongue/shelf collapse is incomplete and largely based on observations from the Antarctic Peninsula and West Antarctica. Here, we use remote sensing of structural glaciology and ice velocity from 2001 to 2020 and analyse potential ocean-climate forcings to identify mechanisms that triggered the rapid disintegration of ~2445 km2 of ice mélange and part of the Voyeykov Ice Shelf in Wilkes Land, East Antarctica between 27 March and 28 May 2007. Results show disaggregation was pre-conditioned by weakening of the ice tongue's structural integrity and was triggered by mélange removal driven by a regional atmospheric circulation anomaly and a less extensive latent-heat polynya. Disaggregation did not induce inland ice flow acceleration, but our observations highlight an important mechanism through which floating termini can be removed, whereby the break-out of mélange and multiyear landfast sea ice triggers disaggregation of a structurally-weak ice shelf. These observations highlight the need for numerical ice-sheet models to account for interactions between sea-ice, mélange and ice shelves.

The impact of landfast sea ice buttressing on ice dynamic speedup in the Larsen-B Embayment, Antarctica

“…2014 saw the beginning of a fall in SIE, culminating in a record Antarctic sea ice low in 2022 (Turner et al, 2022), which already looks set to be exceeded by even lower sea ice extent in 2023. Several studies have indicated the importance of sea ice in maintaining glacier stability in Antarctica and Greenland (Arthur et al, 2021;Christoffersen et al, 2012), and the results of this study do little to suggest otherwise. However, to more accurately judge the extent to which sea ice stabilises ice shelves, a greater understanding of the mechanisms by which this happens is required.…”

Closing the loops on Southern Ocean dynamics: From the circumpolar current to ice shelves and from bottom mixing to surface waves

“…There is evidence that this only occurs once the ice shelf has thinned sufficiently or for a rift system that is close to detachment (Bassis et al, 2008). Moreover, if present, fast ice or mélange (a consolidated agglomeration of icebergs and fast ice) exerts a backstress on ice shelves (Massom et al, 2010;Greene et al, 2018), which can delay or prevent iceberg calving (Stevens et al, 2013;Massom et al, 2015Massom et al, , 2018Arthur et al, 2021;Gomez-Fell et al, 2022).…”

How Does the Southern Annular Mode Control Surface Melt in East Antarctica?

“…Surface melt can instigate the loss of ice shelves because it reduces pore space in the overlying firn layer (Ligtenberg et al., 2014; Munneke et al., 2014), potentially leading to meltwater ponds (Arthur et al., 2020; Leeson et al., 2020; van Wessem et al., 2023), hydrofracture (van der Veen, 1998; Weertman, 1973), and, in extreme cases, ice shelf collapse (Banwell et al., 2013; MacAyeal et al., 2003; Robel & Banwell, 2019). Meltwater‐driven disintegration is particularly associated with the unique melt environment of the Antarctic Peninsula (Laffin et al., 2022; Morris & Vaughan, 2003; Scambos et al., 2000, 2009), but the loss of the Voyeykov (Arthur et al., 2021) and Conger (Lhermitte et al., 2023; Wille et al., 2024) Ice Shelves shows that East Antarctic ice shelves are also vulnerable to collapse. Although the latter two collapses were not directly driven by surface meltwater, the projected increase in surface melt rates under a warmer climate (Gilbert & Kittel, 2021; Trusel et al., 2015) suggests that the risk of meltwater‐driven collapse will increase, necessitating further research into the processes controlling surface melt, and especially in East Antarctica, which holds approximately 90% of Antarctica’s sea level rise equivalent (Morlighem et al., 2020).…”