Abstract
Abstract. Recent observations and ice-dynamic modeling suggest that a marine ice-sheet instability (MISI) might have been triggered in West Antarctica. The corresponding outlet glaciers, Pine Island Glacier (PIG) and Thwaites Glacier (TG), showed significant retreat during at least the last 2 decades. While other regions in Antarctica have the topographic predisposition for the same kind of instability, it is so far unclear how fast these instabilities would unfold if they were initiated. Here we employ the concept of similitude to estimate the characteristic timescales of several potentially MISI-prone outlet glaciers around the Antarctic coast. Our results suggest that TG and PIG have the fastest response time of all investigated outlets, with TG responding about 1.25 to 2 times as fast as PIG, while other outlets around Antarctica would be up to 10 times slower if destabilized. These results have to be viewed in light of the strong assumptions made in their derivation. These include the absence of ice-shelf buttressing, the one-dimensionality of the approach and the uncertainty of the available data. We argue however that the current topographic situation and the physical conditions of the MISI-prone outlet glaciers carry the information of their respective timescale and that this information can be partially extracted through a similitude analysis.
Highlights
Sea-level rise poses a future challenge for coastal regions worldwide (IPCC, WG II, 2014)
The resulting bed profiles collapse towards the reference showing similar downsloping while still exhibiting their characteristic pattern (Figs. 3b and A2b)
By far the slowest response is shown by Support Force Glacier (SFG), which is 10 times slower than Pine Island Glacier (PIG)
Summary
Sea-level rise poses a future challenge for coastal regions worldwide (IPCC, WG II, 2014). This topographic situation makes these parts of the ice sheet prone to a so-called marine ice-sheet instability (MISI; Weertman, 1974; Mercer, 1978; Schoof, 2007; Pattyn, 2018) This kind of instability constitutes a large uncertainty in projections of future sea-level rise (IPCC, WG I, 2013; Joughin and Alley, 2011; Huybrechts et al, 2011; Golledge et al, 2015; Winkelmann et al, 2015; DeConto and Pollard, 2016; Pattyn et al, 2018): if the grounding line (that separates grounded from floating ice) enters a region of retrograde bed slope, a positive ice-loss feedback can be initiated. Resulting self-sustained retreat, acceleration and discharge of the ice sheet can be hindered by the buttressing effect of ice shelves and topographic features (Dupont and Alley, 2005; Goldberg et al, 2009; Gudmundsson et al, 2012; Favier et al, 2012; Asay-Davis et al, 2016) or strong basal friction (Joughin et al, 2009; Ritz et al, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
